From a00e0d714fbded07a7a2254391ce9ed5a5cb9d82 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 8 Feb 2011 17:14:39 -0800 Subject: rcu: Remove conditional compilation for RCU CPU stall warnings The RCU CPU stall warnings can now be controlled using the rcu_cpu_stall_suppress boot-time parameter or via the same parameter from sysfs. There is therefore no longer any reason to have kernel config parameters for this feature. This commit therefore removes the RCU_CPU_STALL_DETECTOR and RCU_CPU_STALL_DETECTOR_RUNNABLE kernel config parameters. The RCU_CPU_STALL_TIMEOUT parameter remains to allow the timeout to be tuned and the RCU_CPU_STALL_VERBOSE parameter remains to allow task-stall information to be suppressed if desired. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- Documentation/RCU/00-INDEX | 2 +- Documentation/RCU/stallwarn.txt | 23 +++++++++++++---------- kernel/rcutree.c | 26 +------------------------- kernel/rcutree.h | 12 ------------ kernel/rcutree_plugin.h | 12 ------------ lib/Kconfig.debug | 30 ++---------------------------- 6 files changed, 17 insertions(+), 88 deletions(-) diff --git a/Documentation/RCU/00-INDEX b/Documentation/RCU/00-INDEX index 71b6f500ddb9..1d7a885761f5 100644 --- a/Documentation/RCU/00-INDEX +++ b/Documentation/RCU/00-INDEX @@ -21,7 +21,7 @@ rcu.txt RTFP.txt - List of RCU papers (bibliography) going back to 1980. stallwarn.txt - - RCU CPU stall warnings (CONFIG_RCU_CPU_STALL_DETECTOR) + - RCU CPU stall warnings (module parameter rcu_cpu_stall_suppress) torture.txt - RCU Torture Test Operation (CONFIG_RCU_TORTURE_TEST) trace.txt diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt index 862c08ef1fde..4e959208f736 100644 --- a/Documentation/RCU/stallwarn.txt +++ b/Documentation/RCU/stallwarn.txt @@ -1,22 +1,25 @@ Using RCU's CPU Stall Detector -The CONFIG_RCU_CPU_STALL_DETECTOR kernel config parameter enables -RCU's CPU stall detector, which detects conditions that unduly delay -RCU grace periods. The stall detector's idea of what constitutes -"unduly delayed" is controlled by a set of C preprocessor macros: +The rcu_cpu_stall_suppress module parameter enables RCU's CPU stall +detector, which detects conditions that unduly delay RCU grace periods. +This module parameter enables CPU stall detection by default, but +may be overridden via boot-time parameter or at runtime via sysfs. +The stall detector's idea of what constitutes "unduly delayed" is +controlled by a set of kernel configuration variables and cpp macros: -RCU_SECONDS_TILL_STALL_CHECK +CONFIG_RCU_CPU_STALL_TIMEOUT - This macro defines the period of time that RCU will wait from - the beginning of a grace period until it issues an RCU CPU - stall warning. This time period is normally ten seconds. + This kernel configuration parameter defines the period of time + that RCU will wait from the beginning of a grace period until it + issues an RCU CPU stall warning. This time period is normally + ten seconds. RCU_SECONDS_TILL_STALL_RECHECK This macro defines the period of time that RCU will wait after issuing a stall warning until it issues another stall warning - for the same stall. This time period is normally set to thirty - seconds. + for the same stall. This time period is normally set to three + times the check interval plus thirty seconds. RCU_STALL_RAT_DELAY diff --git a/kernel/rcutree.c b/kernel/rcutree.c index dd4aea806f8e..18f7a593d4c7 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -140,10 +140,8 @@ module_param(blimit, int, 0); module_param(qhimark, int, 0); module_param(qlowmark, int, 0); -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR -int rcu_cpu_stall_suppress __read_mostly = RCU_CPU_STALL_SUPPRESS_INIT; +int rcu_cpu_stall_suppress __read_mostly; module_param(rcu_cpu_stall_suppress, int, 0644); -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ static void force_quiescent_state(struct rcu_state *rsp, int relaxed); static int rcu_pending(int cpu); @@ -450,8 +448,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) #endif /* #else #ifdef CONFIG_NO_HZ */ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR - int rcu_cpu_stall_suppress __read_mostly; static void record_gp_stall_check_time(struct rcu_state *rsp) @@ -587,26 +583,6 @@ static void __init check_cpu_stall_init(void) atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); } -#else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ - -static void record_gp_stall_check_time(struct rcu_state *rsp) -{ -} - -static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) -{ -} - -void rcu_cpu_stall_reset(void) -{ -} - -static void __init check_cpu_stall_init(void) -{ -} - -#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ - /* * Update CPU-local rcu_data state to record the newly noticed grace period. * This is used both when we started the grace period and when we notice diff --git a/kernel/rcutree.h b/kernel/rcutree.h index e8f057e44e3e..e1a6663c0155 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -254,7 +254,6 @@ struct rcu_data { #endif /* #else #ifdef CONFIG_NO_HZ */ #define RCU_JIFFIES_TILL_FORCE_QS 3 /* for rsp->jiffies_force_qs */ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR #ifdef CONFIG_PROVE_RCU #define RCU_STALL_DELAY_DELTA (5 * HZ) @@ -272,13 +271,6 @@ struct rcu_data { /* scheduling clock irq */ /* before ratting on them. */ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR_RUNNABLE -#define RCU_CPU_STALL_SUPPRESS_INIT 0 -#else -#define RCU_CPU_STALL_SUPPRESS_INIT 1 -#endif - -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ /* * RCU global state, including node hierarchy. This hierarchy is @@ -325,12 +317,10 @@ struct rcu_state { /* due to lock unavailable. */ unsigned long n_force_qs_ngp; /* Number of calls leaving */ /* due to no GP active. */ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR unsigned long gp_start; /* Time at which GP started, */ /* but in jiffies. */ unsigned long jiffies_stall; /* Time at which to check */ /* for CPU stalls. */ -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ char *name; /* Name of structure. */ }; @@ -366,11 +356,9 @@ static int rcu_preempted_readers(struct rcu_node *rnp); static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags); #endif /* #ifdef CONFIG_HOTPLUG_CPU */ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR static void rcu_print_detail_task_stall(struct rcu_state *rsp); static void rcu_print_task_stall(struct rcu_node *rnp); static void rcu_preempt_stall_reset(void); -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); #ifdef CONFIG_HOTPLUG_CPU static int rcu_preempt_offline_tasks(struct rcu_state *rsp, diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index a3638710dc67..38426ef1bcd6 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -54,10 +54,6 @@ static void __init rcu_bootup_announce_oddness(void) #ifdef CONFIG_RCU_TORTURE_TEST_RUNNABLE printk(KERN_INFO "\tRCU torture testing starts during boot.\n"); #endif -#ifndef CONFIG_RCU_CPU_STALL_DETECTOR - printk(KERN_INFO - "\tRCU-based detection of stalled CPUs is disabled.\n"); -#endif #if defined(CONFIG_TREE_PREEMPT_RCU) && !defined(CONFIG_RCU_CPU_STALL_VERBOSE) printk(KERN_INFO "\tVerbose stalled-CPUs detection is disabled.\n"); #endif @@ -356,8 +352,6 @@ void __rcu_read_unlock(void) } EXPORT_SYMBOL_GPL(__rcu_read_unlock); -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR - #ifdef CONFIG_RCU_CPU_STALL_VERBOSE /* @@ -430,8 +424,6 @@ static void rcu_preempt_stall_reset(void) rcu_preempt_state.jiffies_stall = jiffies + ULONG_MAX / 2; } -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ - /* * Check that the list of blocked tasks for the newly completed grace * period is in fact empty. It is a serious bug to complete a grace @@ -862,8 +854,6 @@ static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags) #endif /* #ifdef CONFIG_HOTPLUG_CPU */ -#ifdef CONFIG_RCU_CPU_STALL_DETECTOR - /* * Because preemptable RCU does not exist, we never have to check for * tasks blocked within RCU read-side critical sections. @@ -888,8 +878,6 @@ static void rcu_preempt_stall_reset(void) { } -#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ - /* * Because there is no preemptable RCU, there can be no readers blocked, * so there is no need to check for blocked tasks. So check only for diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c768bcdda1b7..93ce6de3300d 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -875,22 +875,9 @@ config RCU_TORTURE_TEST_RUNNABLE Say N here if you want the RCU torture tests to start only after being manually enabled via /proc. -config RCU_CPU_STALL_DETECTOR - bool "Check for stalled CPUs delaying RCU grace periods" - depends on TREE_RCU || TREE_PREEMPT_RCU - default y - help - This option causes RCU to printk information on which - CPUs are delaying the current grace period, but only when - the grace period extends for excessive time periods. - - Say N if you want to disable such checks. - - Say Y if you are unsure. - config RCU_CPU_STALL_TIMEOUT int "RCU CPU stall timeout in seconds" - depends on RCU_CPU_STALL_DETECTOR + depends on TREE_RCU || TREE_PREEMPT_RCU range 3 300 default 60 help @@ -899,22 +886,9 @@ config RCU_CPU_STALL_TIMEOUT RCU grace period persists, additional CPU stall warnings are printed at more widely spaced intervals. -config RCU_CPU_STALL_DETECTOR_RUNNABLE - bool "RCU CPU stall checking starts automatically at boot" - depends on RCU_CPU_STALL_DETECTOR - default y - help - If set, start checking for RCU CPU stalls immediately on - boot. Otherwise, RCU CPU stall checking must be manually - enabled. - - Say Y if you are unsure. - - Say N if you wish to suppress RCU CPU stall checking during boot. - config RCU_CPU_STALL_VERBOSE bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" - depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU + depends on TREE_PREEMPT_RCU default y help This option causes RCU to printk detailed per-task information -- cgit v1.2.2 From e59fb3120becfb36b22ddb8bd27d065d3cdca499 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 7 Sep 2010 10:38:22 -0700 Subject: rcu: Decrease memory-barrier usage based on semi-formal proof Commit d09b62d fixed grace-period synchronization, but left some smp_mb() invocations in rcu_process_callbacks() that are no longer needed, but sheer paranoia prevented them from being removed. This commit removes them and provides a proof of correctness in their absence. It also adds a memory barrier to rcu_report_qs_rsp() immediately before the update to rsp->completed in order to handle the theoretical possibility that the compiler or CPU might move massive quantities of code into a lock-based critical section. This also proves that the sheer paranoia was not entirely unjustified, at least from a theoretical point of view. In addition, the old dyntick-idle synchronization depended on the fact that grace periods were many milliseconds in duration, so that it could be assumed that no dyntick-idle CPU could reorder a memory reference across an entire grace period. Unfortunately for this design, the addition of expedited grace periods breaks this assumption, which has the unfortunate side-effect of requiring atomic operations in the functions that track dyntick-idle state for RCU. (There is some hope that the algorithms used in user-level RCU might be applied here, but some work is required to handle the NMIs that user-space applications can happily ignore. For the short term, better safe than sorry.) This proof assumes that neither compiler nor CPU will allow a lock acquisition and release to be reordered, as doing so can result in deadlock. The proof is as follows: 1. A given CPU declares a quiescent state under the protection of its leaf rcu_node's lock. 2. If there is more than one level of rcu_node hierarchy, the last CPU to declare a quiescent state will also acquire the ->lock of the next rcu_node up in the hierarchy, but only after releasing the lower level's lock. The acquisition of this lock clearly cannot occur prior to the acquisition of the leaf node's lock. 3. Step 2 repeats until we reach the root rcu_node structure. Please note again that only one lock is held at a time through this process. The acquisition of the root rcu_node's ->lock must occur after the release of that of the leaf rcu_node. 4. At this point, we set the ->completed field in the rcu_state structure in rcu_report_qs_rsp(). However, if the rcu_node hierarchy contains only one rcu_node, then in theory the code preceding the quiescent state could leak into the critical section. We therefore precede the update of ->completed with a memory barrier. All CPUs will therefore agree that any updates preceding any report of a quiescent state will have happened before the update of ->completed. 5. Regardless of whether a new grace period is needed, rcu_start_gp() will propagate the new value of ->completed to all of the leaf rcu_node structures, under the protection of each rcu_node's ->lock. If a new grace period is needed immediately, this propagation will occur in the same critical section that ->completed was set in, but courtesy of the memory barrier in #4 above, is still seen to follow any pre-quiescent-state activity. 6. When a given CPU invokes __rcu_process_gp_end(), it becomes aware of the end of the old grace period and therefore makes any RCU callbacks that were waiting on that grace period eligible for invocation. If this CPU is the same one that detected the end of the grace period, and if there is but a single rcu_node in the hierarchy, we will still be in the single critical section. In this case, the memory barrier in step #4 guarantees that all callbacks will be seen to execute after each CPU's quiescent state. On the other hand, if this is a different CPU, it will acquire the leaf rcu_node's ->lock, and will again be serialized after each CPU's quiescent state for the old grace period. On the strength of this proof, this commit therefore removes the memory barriers from rcu_process_callbacks() and adds one to rcu_report_qs_rsp(). The effect is to reduce the number of memory barriers by one and to reduce the frequency of execution from about once per scheduling tick per CPU to once per grace period. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- Documentation/RCU/trace.txt | 48 +++++++--------- kernel/rcutree.c | 130 +++++++++++++++++++------------------------- kernel/rcutree.h | 9 +-- kernel/rcutree_plugin.h | 7 +-- kernel/rcutree_trace.c | 12 ++-- 5 files changed, 88 insertions(+), 118 deletions(-) diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index 6a8c73f55b80..e731ad20d166 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -21,23 +21,23 @@ rcu_pending() function decided that there was core RCU work to do). The output of "cat rcu/rcudata" looks as follows: rcu_sched: - 0 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=10951/1 dn=0 df=1101 of=0 ri=36 ql=0 b=10 - 1 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=16117/1 dn=0 df=1015 of=0 ri=0 ql=0 b=10 - 2 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=1445/1 dn=0 df=1839 of=0 ri=0 ql=0 b=10 - 3 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=6681/1 dn=0 df=1545 of=0 ri=0 ql=0 b=10 - 4 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=1003/1 dn=0 df=1992 of=0 ri=0 ql=0 b=10 - 5 c=17829 g=17830 pq=1 pqc=17829 qp=1 dt=3887/1 dn=0 df=3331 of=0 ri=4 ql=2 b=10 - 6 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=859/1 dn=0 df=3224 of=0 ri=0 ql=0 b=10 - 7 c=17829 g=17830 pq=0 pqc=17829 qp=1 dt=3761/1 dn=0 df=1818 of=0 ri=0 ql=2 b=10 + 0 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=10951/1/0 df=1101 of=0 ri=36 ql=0 b=10 + 1 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=16117/1/0 df=1015 of=0 ri=0 ql=0 b=10 + 2 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=1445/1/0 df=1839 of=0 ri=0 ql=0 b=10 + 3 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=6681/1/0 df=1545 of=0 ri=0 ql=0 b=10 + 4 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=1003/1/0 df=1992 of=0 ri=0 ql=0 b=10 + 5 c=17829 g=17830 pq=1 pqc=17829 qp=1 dt=3887/1/0 df=3331 of=0 ri=4 ql=2 b=10 + 6 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=859/1/0 df=3224 of=0 ri=0 ql=0 b=10 + 7 c=17829 g=17830 pq=0 pqc=17829 qp=1 dt=3761/1/0 df=1818 of=0 ri=0 ql=2 b=10 rcu_bh: - 0 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=10951/1 dn=0 df=0 of=0 ri=0 ql=0 b=10 - 1 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=16117/1 dn=0 df=13 of=0 ri=0 ql=0 b=10 - 2 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=1445/1 dn=0 df=15 of=0 ri=0 ql=0 b=10 - 3 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=6681/1 dn=0 df=9 of=0 ri=0 ql=0 b=10 - 4 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=1003/1 dn=0 df=15 of=0 ri=0 ql=0 b=10 - 5 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=3887/1 dn=0 df=15 of=0 ri=0 ql=0 b=10 - 6 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=859/1 dn=0 df=15 of=0 ri=0 ql=0 b=10 - 7 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=3761/1 dn=0 df=15 of=0 ri=0 ql=0 b=10 + 0 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=10951/1/0 df=0 of=0 ri=0 ql=0 b=10 + 1 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=16117/1/0 df=13 of=0 ri=0 ql=0 b=10 + 2 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=1445/1/0 df=15 of=0 ri=0 ql=0 b=10 + 3 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=6681/1/0 df=9 of=0 ri=0 ql=0 b=10 + 4 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=1003/1/0 df=15 of=0 ri=0 ql=0 b=10 + 5 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=3887/1/0 df=15 of=0 ri=0 ql=0 b=10 + 6 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=859/1/0 df=15 of=0 ri=0 ql=0 b=10 + 7 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=3761/1/0 df=15 of=0 ri=0 ql=0 b=10 The first section lists the rcu_data structures for rcu_sched, the second for rcu_bh. Note that CONFIG_TREE_PREEMPT_RCU kernels will have an @@ -85,18 +85,10 @@ o "qp" indicates that RCU still expects a quiescent state from o "dt" is the current value of the dyntick counter that is incremented when entering or leaving dynticks idle state, either by the - scheduler or by irq. The number after the "/" is the interrupt - nesting depth when in dyntick-idle state, or one greater than - the interrupt-nesting depth otherwise. - - This field is displayed only for CONFIG_NO_HZ kernels. - -o "dn" is the current value of the dyntick counter that is incremented - when entering or leaving dynticks idle state via NMI. If both - the "dt" and "dn" values are even, then this CPU is in dynticks - idle mode and may be ignored by RCU. If either of these two - counters is odd, then RCU must be alert to the possibility of - an RCU read-side critical section running on this CPU. + scheduler or by irq. The number after the first "/" is the + interrupt nesting depth when in dyntick-idle state, or one + greater than the interrupt-nesting depth otherwise. The number + after the second "/" is the NMI nesting depth. This field is displayed only for CONFIG_NO_HZ kernels. diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 18f7a593d4c7..90104a19c564 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -128,7 +128,7 @@ void rcu_note_context_switch(int cpu) #ifdef CONFIG_NO_HZ DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { .dynticks_nesting = 1, - .dynticks = 1, + .dynticks = ATOMIC_INIT(1), }; #endif /* #ifdef CONFIG_NO_HZ */ @@ -262,13 +262,25 @@ void rcu_enter_nohz(void) unsigned long flags; struct rcu_dynticks *rdtp; - smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ local_irq_save(flags); rdtp = &__get_cpu_var(rcu_dynticks); - rdtp->dynticks++; - rdtp->dynticks_nesting--; - WARN_ON_ONCE(rdtp->dynticks & 0x1); + if (--rdtp->dynticks_nesting) { + local_irq_restore(flags); + return; + } + /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ + smp_mb__before_atomic_inc(); /* See above. */ + atomic_inc(&rdtp->dynticks); + smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */ + WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); local_irq_restore(flags); + + /* If the interrupt queued a callback, get out of dyntick mode. */ + if (in_irq() && + (__get_cpu_var(rcu_sched_data).nxtlist || + __get_cpu_var(rcu_bh_data).nxtlist || + rcu_preempt_needs_cpu(smp_processor_id()))) + set_need_resched(); } /* @@ -284,11 +296,16 @@ void rcu_exit_nohz(void) local_irq_save(flags); rdtp = &__get_cpu_var(rcu_dynticks); - rdtp->dynticks++; - rdtp->dynticks_nesting++; - WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); + if (rdtp->dynticks_nesting++) { + local_irq_restore(flags); + return; + } + smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */ + atomic_inc(&rdtp->dynticks); + /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ + smp_mb__after_atomic_inc(); /* See above. */ + WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); local_irq_restore(flags); - smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ } /** @@ -302,11 +319,15 @@ void rcu_nmi_enter(void) { struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); - if (rdtp->dynticks & 0x1) + if (rdtp->dynticks_nmi_nesting == 0 && + (atomic_read(&rdtp->dynticks) & 0x1)) return; - rdtp->dynticks_nmi++; - WARN_ON_ONCE(!(rdtp->dynticks_nmi & 0x1)); - smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ + rdtp->dynticks_nmi_nesting++; + smp_mb__before_atomic_inc(); /* Force delay from prior write. */ + atomic_inc(&rdtp->dynticks); + /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ + smp_mb__after_atomic_inc(); /* See above. */ + WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); } /** @@ -320,11 +341,14 @@ void rcu_nmi_exit(void) { struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); - if (rdtp->dynticks & 0x1) + if (rdtp->dynticks_nmi_nesting == 0 || + --rdtp->dynticks_nmi_nesting != 0) return; - smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ - rdtp->dynticks_nmi++; - WARN_ON_ONCE(rdtp->dynticks_nmi & 0x1); + /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ + smp_mb__before_atomic_inc(); /* See above. */ + atomic_inc(&rdtp->dynticks); + smp_mb__after_atomic_inc(); /* Force delay to next write. */ + WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); } /** @@ -335,13 +359,7 @@ void rcu_nmi_exit(void) */ void rcu_irq_enter(void) { - struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); - - if (rdtp->dynticks_nesting++) - return; - rdtp->dynticks++; - WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); - smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ + rcu_exit_nohz(); } /** @@ -353,18 +371,7 @@ void rcu_irq_enter(void) */ void rcu_irq_exit(void) { - struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); - - if (--rdtp->dynticks_nesting) - return; - smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ - rdtp->dynticks++; - WARN_ON_ONCE(rdtp->dynticks & 0x1); - - /* If the interrupt queued a callback, get out of dyntick mode. */ - if (__this_cpu_read(rcu_sched_data.nxtlist) || - __this_cpu_read(rcu_bh_data.nxtlist)) - set_need_resched(); + rcu_enter_nohz(); } #ifdef CONFIG_SMP @@ -376,19 +383,8 @@ void rcu_irq_exit(void) */ static int dyntick_save_progress_counter(struct rcu_data *rdp) { - int ret; - int snap; - int snap_nmi; - - snap = rdp->dynticks->dynticks; - snap_nmi = rdp->dynticks->dynticks_nmi; - smp_mb(); /* Order sampling of snap with end of grace period. */ - rdp->dynticks_snap = snap; - rdp->dynticks_nmi_snap = snap_nmi; - ret = ((snap & 0x1) == 0) && ((snap_nmi & 0x1) == 0); - if (ret) - rdp->dynticks_fqs++; - return ret; + rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks); + return 0; } /* @@ -399,16 +395,11 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp) */ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) { - long curr; - long curr_nmi; - long snap; - long snap_nmi; + unsigned long curr; + unsigned long snap; - curr = rdp->dynticks->dynticks; - snap = rdp->dynticks_snap; - curr_nmi = rdp->dynticks->dynticks_nmi; - snap_nmi = rdp->dynticks_nmi_snap; - smp_mb(); /* force ordering with cpu entering/leaving dynticks. */ + curr = (unsigned long)atomic_add_return(0, &rdp->dynticks->dynticks); + snap = (unsigned long)rdp->dynticks_snap; /* * If the CPU passed through or entered a dynticks idle phase with @@ -418,8 +409,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) * read-side critical section that started before the beginning * of the current RCU grace period. */ - if ((curr != snap || (curr & 0x1) == 0) && - (curr_nmi != snap_nmi || (curr_nmi & 0x1) == 0)) { + if ((curr & 0x1) == 0 || ULONG_CMP_GE(curr, snap + 2)) { rdp->dynticks_fqs++; return 1; } @@ -841,6 +831,12 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) __releases(rcu_get_root(rsp)->lock) { WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); + + /* + * Ensure that all grace-period and pre-grace-period activity + * is seen before the assignment to rsp->completed. + */ + smp_mb(); /* See above block comment. */ rsp->completed = rsp->gpnum; rsp->signaled = RCU_GP_IDLE; rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ @@ -1367,25 +1363,11 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) */ static void rcu_process_callbacks(struct softirq_action *unused) { - /* - * Memory references from any prior RCU read-side critical sections - * executed by the interrupted code must be seen before any RCU - * grace-period manipulations below. - */ - smp_mb(); /* See above block comment. */ - __rcu_process_callbacks(&rcu_sched_state, &__get_cpu_var(rcu_sched_data)); __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data)); rcu_preempt_process_callbacks(); - /* - * Memory references from any later RCU read-side critical sections - * executed by the interrupted code must be seen after any RCU - * grace-period manipulations above. - */ - smp_mb(); /* See above block comment. */ - /* If we are last CPU on way to dyntick-idle mode, accelerate it. */ rcu_needs_cpu_flush(); } diff --git a/kernel/rcutree.h b/kernel/rcutree.h index e1a6663c0155..bd891def3303 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -84,11 +84,9 @@ * Dynticks per-CPU state. */ struct rcu_dynticks { - int dynticks_nesting; /* Track nesting level, sort of. */ - int dynticks; /* Even value for dynticks-idle, else odd. */ - int dynticks_nmi; /* Even value for either dynticks-idle or */ - /* not in nmi handler, else odd. So this */ - /* remains even for nmi from irq handler. */ + int dynticks_nesting; /* Track irq/process nesting level. */ + int dynticks_nmi_nesting; /* Track NMI nesting level. */ + atomic_t dynticks; /* Even value for dynticks-idle, else odd. */ }; /* @@ -218,7 +216,6 @@ struct rcu_data { /* 3) dynticks interface. */ struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ int dynticks_snap; /* Per-GP tracking for dynticks. */ - int dynticks_nmi_snap; /* Per-GP tracking for dynticks_nmi. */ #endif /* #ifdef CONFIG_NO_HZ */ /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 38426ef1bcd6..764b5fcc7c56 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1182,7 +1182,6 @@ int rcu_needs_cpu(int cpu) { int c = 0; int snap; - int snap_nmi; int thatcpu; /* Check for being in the holdoff period. */ @@ -1193,10 +1192,10 @@ int rcu_needs_cpu(int cpu) for_each_online_cpu(thatcpu) { if (thatcpu == cpu) continue; - snap = per_cpu(rcu_dynticks, thatcpu).dynticks; - snap_nmi = per_cpu(rcu_dynticks, thatcpu).dynticks_nmi; + snap = atomic_add_return(0, &per_cpu(rcu_dynticks, + thatcpu).dynticks); smp_mb(); /* Order sampling of snap with end of grace period. */ - if (((snap & 0x1) != 0) || ((snap_nmi & 0x1) != 0)) { + if ((snap & 0x1) != 0) { per_cpu(rcu_dyntick_drain, cpu) = 0; per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1; return rcu_needs_cpu_quick_check(cpu); diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index c8e97853b970..4a21ca55ef7c 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -57,10 +57,10 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) rdp->passed_quiesc, rdp->passed_quiesc_completed, rdp->qs_pending); #ifdef CONFIG_NO_HZ - seq_printf(m, " dt=%d/%d dn=%d df=%lu", - rdp->dynticks->dynticks, + seq_printf(m, " dt=%d/%d/%d df=%lu", + atomic_read(&rdp->dynticks->dynticks), rdp->dynticks->dynticks_nesting, - rdp->dynticks->dynticks_nmi, + rdp->dynticks->dynticks_nmi_nesting, rdp->dynticks_fqs); #endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi); @@ -115,9 +115,9 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp) rdp->qs_pending); #ifdef CONFIG_NO_HZ seq_printf(m, ",%d,%d,%d,%lu", - rdp->dynticks->dynticks, + atomic_read(&rdp->dynticks->dynticks), rdp->dynticks->dynticks_nesting, - rdp->dynticks->dynticks_nmi, + rdp->dynticks->dynticks_nmi_nesting, rdp->dynticks_fqs); #endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, ",%lu,%lu", rdp->offline_fqs, rdp->resched_ipi); @@ -130,7 +130,7 @@ static int show_rcudata_csv(struct seq_file *m, void *unused) { seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pqc\",\"pq\","); #ifdef CONFIG_NO_HZ - seq_puts(m, "\"dt\",\"dt nesting\",\"dn\",\"df\","); + seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\","); #endif /* #ifdef CONFIG_NO_HZ */ seq_puts(m, "\"of\",\"ri\",\"ql\",\"b\",\"ci\",\"co\",\"ca\"\n"); #ifdef CONFIG_TREE_PREEMPT_RCU -- cgit v1.2.2 From 12f5f524cafef3ab689929b118f2dfb8bf2be321 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 29 Nov 2010 21:56:39 -0800 Subject: rcu: merge TREE_PREEPT_RCU blocked_tasks[] lists Combine the current TREE_PREEMPT_RCU ->blocked_tasks[] lists in the rcu_node structure into a single ->blkd_tasks list with ->gp_tasks and ->exp_tasks tail pointers. This is in preparation for RCU priority boosting, which will add a third dimension to the combinatorial explosion in the ->blocked_tasks[] case, but simply a third pointer in the new ->blkd_tasks case. Also update documentation to reflect blocked_tasks[] merge Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- Documentation/RCU/trace.txt | 29 +++++--- kernel/rcutree.c | 5 +- kernel/rcutree.h | 21 ++++-- kernel/rcutree_plugin.h | 163 ++++++++++++++++++++++++++------------------ kernel/rcutree_trace.c | 11 ++- 5 files changed, 135 insertions(+), 94 deletions(-) diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index e731ad20d166..5a704ffd0bbc 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -166,14 +166,14 @@ o "gpnum" is the number of grace periods that have started. It is The output of "cat rcu/rcuhier" looks as follows, with very long lines: c=6902 g=6903 s=2 jfq=3 j=72c7 nfqs=13142/nfqsng=0(13142) fqlh=6 -1/1 .>. 0:127 ^0 -3/3 .>. 0:35 ^0 0/0 .>. 36:71 ^1 0/0 .>. 72:107 ^2 0/0 .>. 108:127 ^3 -3/3f .>. 0:5 ^0 2/3 .>. 6:11 ^1 0/0 .>. 12:17 ^2 0/0 .>. 18:23 ^3 0/0 .>. 24:29 ^4 0/0 .>. 30:35 ^5 0/0 .>. 36:41 ^0 0/0 .>. 42:47 ^1 0/0 .>. 48:53 ^2 0/0 .>. 54:59 ^3 0/0 .>. 60:65 ^4 0/0 .>. 66:71 ^5 0/0 .>. 72:77 ^0 0/0 .>. 78:83 ^1 0/0 .>. 84:89 ^2 0/0 .>. 90:95 ^3 0/0 .>. 96:101 ^4 0/0 .>. 102:107 ^5 0/0 .>. 108:113 ^0 0/0 .>. 114:119 ^1 0/0 .>. 120:125 ^2 0/0 .>. 126:127 ^3 +1/1 ..>. 0:127 ^0 +3/3 ..>. 0:35 ^0 0/0 ..>. 36:71 ^1 0/0 ..>. 72:107 ^2 0/0 ..>. 108:127 ^3 +3/3f ..>. 0:5 ^0 2/3 ..>. 6:11 ^1 0/0 ..>. 12:17 ^2 0/0 ..>. 18:23 ^3 0/0 ..>. 24:29 ^4 0/0 ..>. 30:35 ^5 0/0 ..>. 36:41 ^0 0/0 ..>. 42:47 ^1 0/0 ..>. 48:53 ^2 0/0 ..>. 54:59 ^3 0/0 ..>. 60:65 ^4 0/0 ..>. 66:71 ^5 0/0 ..>. 72:77 ^0 0/0 ..>. 78:83 ^1 0/0 ..>. 84:89 ^2 0/0 ..>. 90:95 ^3 0/0 ..>. 96:101 ^4 0/0 ..>. 102:107 ^5 0/0 ..>. 108:113 ^0 0/0 ..>. 114:119 ^1 0/0 ..>. 120:125 ^2 0/0 ..>. 126:127 ^3 rcu_bh: c=-226 g=-226 s=1 jfq=-5701 j=72c7 nfqs=88/nfqsng=0(88) fqlh=0 -0/1 .>. 0:127 ^0 -0/3 .>. 0:35 ^0 0/0 .>. 36:71 ^1 0/0 .>. 72:107 ^2 0/0 .>. 108:127 ^3 -0/3f .>. 0:5 ^0 0/3 .>. 6:11 ^1 0/0 .>. 12:17 ^2 0/0 .>. 18:23 ^3 0/0 .>. 24:29 ^4 0/0 .>. 30:35 ^5 0/0 .>. 36:41 ^0 0/0 .>. 42:47 ^1 0/0 .>. 48:53 ^2 0/0 .>. 54:59 ^3 0/0 .>. 60:65 ^4 0/0 .>. 66:71 ^5 0/0 .>. 72:77 ^0 0/0 .>. 78:83 ^1 0/0 .>. 84:89 ^2 0/0 .>. 90:95 ^3 0/0 .>. 96:101 ^4 0/0 .>. 102:107 ^5 0/0 .>. 108:113 ^0 0/0 .>. 114:119 ^1 0/0 .>. 120:125 ^2 0/0 .>. 126:127 ^3 +0/1 ..>. 0:127 ^0 +0/3 ..>. 0:35 ^0 0/0 ..>. 36:71 ^1 0/0 ..>. 72:107 ^2 0/0 ..>. 108:127 ^3 +0/3f ..>. 0:5 ^0 0/3 ..>. 6:11 ^1 0/0 ..>. 12:17 ^2 0/0 ..>. 18:23 ^3 0/0 ..>. 24:29 ^4 0/0 ..>. 30:35 ^5 0/0 ..>. 36:41 ^0 0/0 ..>. 42:47 ^1 0/0 ..>. 48:53 ^2 0/0 ..>. 54:59 ^3 0/0 ..>. 60:65 ^4 0/0 ..>. 66:71 ^5 0/0 ..>. 72:77 ^0 0/0 ..>. 78:83 ^1 0/0 ..>. 84:89 ^2 0/0 ..>. 90:95 ^3 0/0 ..>. 96:101 ^4 0/0 ..>. 102:107 ^5 0/0 ..>. 108:113 ^0 0/0 ..>. 114:119 ^1 0/0 ..>. 120:125 ^2 0/0 ..>. 126:127 ^3 This is once again split into "rcu_sched" and "rcu_bh" portions, and CONFIG_TREE_PREEMPT_RCU kernels will again have an additional @@ -232,13 +232,20 @@ o Each element of the form "1/1 0:127 ^0" represents one struct current grace period. o The characters separated by the ">" indicate the state - of the blocked-tasks lists. A "T" preceding the ">" + of the blocked-tasks lists. A "G" preceding the ">" indicates that at least one task blocked in an RCU read-side critical section blocks the current grace - period, while a "." preceding the ">" indicates otherwise. - The character following the ">" indicates similarly for - the next grace period. A "T" should appear in this - field only for rcu-preempt. + period, while a "E" preceding the ">" indicates that + at least one task blocked in an RCU read-side critical + section blocks the current expedited grace period. + A "T" character following the ">" indicates that at + least one task is blocked within an RCU read-side + critical section, regardless of whether any current + grace period (expedited or normal) is inconvenienced. + A "." character appears if the corresponding condition + does not hold, so that "..>." indicates that no tasks + are blocked. In contrast, "GE>T" indicates maximal + inconvenience from blocked tasks. o The numbers separated by the ":" are the range of CPUs served by this struct rcu_node. This can be helpful diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 90104a19c564..0ac1cc03f935 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1901,10 +1901,7 @@ static void __init rcu_init_one(struct rcu_state *rsp, j / rsp->levelspread[i - 1]; } rnp->level = i; - INIT_LIST_HEAD(&rnp->blocked_tasks[0]); - INIT_LIST_HEAD(&rnp->blocked_tasks[1]); - INIT_LIST_HEAD(&rnp->blocked_tasks[2]); - INIT_LIST_HEAD(&rnp->blocked_tasks[3]); + INIT_LIST_HEAD(&rnp->blkd_tasks); } } diff --git a/kernel/rcutree.h b/kernel/rcutree.h index bd891def3303..5a439c180e69 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -107,7 +107,7 @@ struct rcu_node { /* an rcu_data structure, otherwise, each */ /* bit corresponds to a child rcu_node */ /* structure. */ - unsigned long expmask; /* Groups that have ->blocked_tasks[] */ + unsigned long expmask; /* Groups that have ->blkd_tasks */ /* elements that need to drain to allow the */ /* current expedited grace period to */ /* complete (only for TREE_PREEMPT_RCU). */ @@ -120,11 +120,20 @@ struct rcu_node { u8 grpnum; /* CPU/group number for next level up. */ u8 level; /* root is at level 0. */ struct rcu_node *parent; - struct list_head blocked_tasks[4]; - /* Tasks blocked in RCU read-side critsect. */ - /* Grace period number (->gpnum) x blocked */ - /* by tasks on the (x & 0x1) element of the */ - /* blocked_tasks[] array. */ + struct list_head blkd_tasks; + /* Tasks blocked in RCU read-side critical */ + /* section. Tasks are placed at the head */ + /* of this list and age towards the tail. */ + struct list_head *gp_tasks; + /* Pointer to the first task blocking the */ + /* current grace period, or NULL if there */ + /* is no such task. */ + struct list_head *exp_tasks; + /* Pointer to the first task blocking the */ + /* current expedited grace period, or NULL */ + /* if there is no such task. If there */ + /* is no current expedited grace period, */ + /* then there can cannot be any such task. */ } ____cacheline_internodealigned_in_smp; /* diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 764b5fcc7c56..774f010a4619 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -130,12 +130,12 @@ static void rcu_preempt_qs(int cpu) * We have entered the scheduler, and the current task might soon be * context-switched away from. If this task is in an RCU read-side * critical section, we will no longer be able to rely on the CPU to - * record that fact, so we enqueue the task on the appropriate entry - * of the blocked_tasks[] array. The task will dequeue itself when - * it exits the outermost enclosing RCU read-side critical section. - * Therefore, the current grace period cannot be permitted to complete - * until the blocked_tasks[] entry indexed by the low-order bit of - * rnp->gpnum empties. + * record that fact, so we enqueue the task on the blkd_tasks list. + * The task will dequeue itself when it exits the outermost enclosing + * RCU read-side critical section. Therefore, the current grace period + * cannot be permitted to complete until the blkd_tasks list entries + * predating the current grace period drain, in other words, until + * rnp->gp_tasks becomes NULL. * * Caller must disable preemption. */ @@ -143,7 +143,6 @@ static void rcu_preempt_note_context_switch(int cpu) { struct task_struct *t = current; unsigned long flags; - int phase; struct rcu_data *rdp; struct rcu_node *rnp; @@ -165,15 +164,26 @@ static void rcu_preempt_note_context_switch(int cpu) * (i.e., this CPU has not yet passed through a quiescent * state for the current grace period), then as long * as that task remains queued, the current grace period - * cannot end. + * cannot end. Note that there is some uncertainty as + * to exactly when the current grace period started. + * We take a conservative approach, which can result + * in unnecessarily waiting on tasks that started very + * slightly after the current grace period began. C'est + * la vie!!! * * But first, note that the current CPU must still be * on line! */ WARN_ON_ONCE((rdp->grpmask & rnp->qsmaskinit) == 0); WARN_ON_ONCE(!list_empty(&t->rcu_node_entry)); - phase = (rnp->gpnum + !(rnp->qsmask & rdp->grpmask)) & 0x1; - list_add(&t->rcu_node_entry, &rnp->blocked_tasks[phase]); + if ((rnp->qsmask & rdp->grpmask) && rnp->gp_tasks != NULL) { + list_add(&t->rcu_node_entry, rnp->gp_tasks->prev); + rnp->gp_tasks = &t->rcu_node_entry; + } else { + list_add(&t->rcu_node_entry, &rnp->blkd_tasks); + if (rnp->qsmask & rdp->grpmask) + rnp->gp_tasks = &t->rcu_node_entry; + } raw_spin_unlock_irqrestore(&rnp->lock, flags); } @@ -210,10 +220,7 @@ EXPORT_SYMBOL_GPL(__rcu_read_lock); */ static int rcu_preempted_readers(struct rcu_node *rnp) { - int phase = rnp->gpnum & 0x1; - - return !list_empty(&rnp->blocked_tasks[phase]) || - !list_empty(&rnp->blocked_tasks[phase + 2]); + return rnp->gp_tasks != NULL; } /* @@ -252,6 +259,21 @@ static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags) rcu_report_qs_rnp(mask, &rcu_preempt_state, rnp_p, flags); } +/* + * Advance a ->blkd_tasks-list pointer to the next entry, instead + * returning NULL if at the end of the list. + */ +static struct list_head *rcu_next_node_entry(struct task_struct *t, + struct rcu_node *rnp) +{ + struct list_head *np; + + np = t->rcu_node_entry.next; + if (np == &rnp->blkd_tasks) + np = NULL; + return np; +} + /* * Handle special cases during rcu_read_unlock(), such as needing to * notify RCU core processing or task having blocked during the RCU @@ -262,6 +284,7 @@ static void rcu_read_unlock_special(struct task_struct *t) int empty; int empty_exp; unsigned long flags; + struct list_head *np; struct rcu_node *rnp; int special; @@ -305,7 +328,12 @@ static void rcu_read_unlock_special(struct task_struct *t) empty = !rcu_preempted_readers(rnp); empty_exp = !rcu_preempted_readers_exp(rnp); smp_mb(); /* ensure expedited fastpath sees end of RCU c-s. */ + np = rcu_next_node_entry(t, rnp); list_del_init(&t->rcu_node_entry); + if (&t->rcu_node_entry == rnp->gp_tasks) + rnp->gp_tasks = np; + if (&t->rcu_node_entry == rnp->exp_tasks) + rnp->exp_tasks = np; t->rcu_blocked_node = NULL; /* @@ -361,18 +389,16 @@ EXPORT_SYMBOL_GPL(__rcu_read_unlock); static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp) { unsigned long flags; - struct list_head *lp; - int phase; struct task_struct *t; - if (rcu_preempted_readers(rnp)) { - raw_spin_lock_irqsave(&rnp->lock, flags); - phase = rnp->gpnum & 0x1; - lp = &rnp->blocked_tasks[phase]; - list_for_each_entry(t, lp, rcu_node_entry) - sched_show_task(t); - raw_spin_unlock_irqrestore(&rnp->lock, flags); - } + if (!rcu_preempted_readers(rnp)) + return; + raw_spin_lock_irqsave(&rnp->lock, flags); + t = list_entry(rnp->gp_tasks, + struct task_struct, rcu_node_entry); + list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) + sched_show_task(t); + raw_spin_unlock_irqrestore(&rnp->lock, flags); } /* @@ -402,16 +428,14 @@ static void rcu_print_detail_task_stall(struct rcu_state *rsp) */ static void rcu_print_task_stall(struct rcu_node *rnp) { - struct list_head *lp; - int phase; struct task_struct *t; - if (rcu_preempted_readers(rnp)) { - phase = rnp->gpnum & 0x1; - lp = &rnp->blocked_tasks[phase]; - list_for_each_entry(t, lp, rcu_node_entry) - printk(" P%d", t->pid); - } + if (!rcu_preempted_readers(rnp)) + return; + t = list_entry(rnp->gp_tasks, + struct task_struct, rcu_node_entry); + list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) + printk(" P%d", t->pid); } /* @@ -430,10 +454,15 @@ static void rcu_preempt_stall_reset(void) * period that still has RCU readers blocked! This function must be * invoked -before- updating this rnp's ->gpnum, and the rnp's ->lock * must be held by the caller. + * + * Also, if there are blocked tasks on the list, they automatically + * block the newly created grace period, so set up ->gp_tasks accordingly. */ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp) { WARN_ON_ONCE(rcu_preempted_readers(rnp)); + if (!list_empty(&rnp->blkd_tasks)) + rnp->gp_tasks = rnp->blkd_tasks.next; WARN_ON_ONCE(rnp->qsmask); } @@ -457,45 +486,49 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp) { - int i; struct list_head *lp; struct list_head *lp_root; int retval = 0; struct rcu_node *rnp_root = rcu_get_root(rsp); - struct task_struct *tp; + struct task_struct *t; if (rnp == rnp_root) { WARN_ONCE(1, "Last CPU thought to be offlined?"); return 0; /* Shouldn't happen: at least one CPU online. */ } - WARN_ON_ONCE(rnp != rdp->mynode && - (!list_empty(&rnp->blocked_tasks[0]) || - !list_empty(&rnp->blocked_tasks[1]) || - !list_empty(&rnp->blocked_tasks[2]) || - !list_empty(&rnp->blocked_tasks[3]))); + + /* If we are on an internal node, complain bitterly. */ + WARN_ON_ONCE(rnp != rdp->mynode); /* - * Move tasks up to root rcu_node. Rely on the fact that the - * root rcu_node can be at most one ahead of the rest of the - * rcu_nodes in terms of gp_num value. This fact allows us to - * move the blocked_tasks[] array directly, element by element. + * Move tasks up to root rcu_node. Don't try to get fancy for + * this corner-case operation -- just put this node's tasks + * at the head of the root node's list, and update the root node's + * ->gp_tasks and ->exp_tasks pointers to those of this node's, + * if non-NULL. This might result in waiting for more tasks than + * absolutely necessary, but this is a good performance/complexity + * tradeoff. */ if (rcu_preempted_readers(rnp)) retval |= RCU_OFL_TASKS_NORM_GP; if (rcu_preempted_readers_exp(rnp)) retval |= RCU_OFL_TASKS_EXP_GP; - for (i = 0; i < 4; i++) { - lp = &rnp->blocked_tasks[i]; - lp_root = &rnp_root->blocked_tasks[i]; - while (!list_empty(lp)) { - tp = list_entry(lp->next, typeof(*tp), rcu_node_entry); - raw_spin_lock(&rnp_root->lock); /* irqs already disabled */ - list_del(&tp->rcu_node_entry); - tp->rcu_blocked_node = rnp_root; - list_add(&tp->rcu_node_entry, lp_root); - raw_spin_unlock(&rnp_root->lock); /* irqs remain disabled */ - } + lp = &rnp->blkd_tasks; + lp_root = &rnp_root->blkd_tasks; + while (!list_empty(lp)) { + t = list_entry(lp->next, typeof(*t), rcu_node_entry); + raw_spin_lock(&rnp_root->lock); /* irqs already disabled */ + list_del(&t->rcu_node_entry); + t->rcu_blocked_node = rnp_root; + list_add(&t->rcu_node_entry, lp_root); + if (&t->rcu_node_entry == rnp->gp_tasks) + rnp_root->gp_tasks = rnp->gp_tasks; + if (&t->rcu_node_entry == rnp->exp_tasks) + rnp_root->exp_tasks = rnp->exp_tasks; + raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */ } + rnp->gp_tasks = NULL; + rnp->exp_tasks = NULL; return retval; } @@ -586,8 +619,7 @@ static DEFINE_MUTEX(sync_rcu_preempt_exp_mutex); */ static int rcu_preempted_readers_exp(struct rcu_node *rnp) { - return !list_empty(&rnp->blocked_tasks[2]) || - !list_empty(&rnp->blocked_tasks[3]); + return rnp->exp_tasks != NULL; } /* @@ -647,12 +679,13 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp) static void sync_rcu_preempt_exp_init(struct rcu_state *rsp, struct rcu_node *rnp) { - int must_wait; + int must_wait = 0; raw_spin_lock(&rnp->lock); /* irqs already disabled */ - list_splice_init(&rnp->blocked_tasks[0], &rnp->blocked_tasks[2]); - list_splice_init(&rnp->blocked_tasks[1], &rnp->blocked_tasks[3]); - must_wait = rcu_preempted_readers_exp(rnp); + if (!list_empty(&rnp->blkd_tasks)) { + rnp->exp_tasks = rnp->blkd_tasks.next; + must_wait = 1; + } raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ if (!must_wait) rcu_report_exp_rnp(rsp, rnp); @@ -661,9 +694,7 @@ sync_rcu_preempt_exp_init(struct rcu_state *rsp, struct rcu_node *rnp) /* * Wait for an rcu-preempt grace period, but expedite it. The basic idea * is to invoke synchronize_sched_expedited() to push all the tasks to - * the ->blocked_tasks[] lists, move all entries from the first set of - * ->blocked_tasks[] lists to the second set, and finally wait for this - * second set to drain. + * the ->blkd_tasks lists and wait for this list to drain. */ void synchronize_rcu_expedited(void) { @@ -695,7 +726,7 @@ void synchronize_rcu_expedited(void) if ((ACCESS_ONCE(sync_rcu_preempt_exp_count) - snap) > 0) goto unlock_mb_ret; /* Others did our work for us. */ - /* force all RCU readers onto blocked_tasks[]. */ + /* force all RCU readers onto ->blkd_tasks lists. */ synchronize_sched_expedited(); raw_spin_lock_irqsave(&rsp->onofflock, flags); @@ -707,7 +738,7 @@ void synchronize_rcu_expedited(void) raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ } - /* Snapshot current state of ->blocked_tasks[] lists. */ + /* Snapshot current state of ->blkd_tasks lists. */ rcu_for_each_leaf_node(rsp, rnp) sync_rcu_preempt_exp_init(rsp, rnp); if (NUM_RCU_NODES > 1) @@ -715,7 +746,7 @@ void synchronize_rcu_expedited(void) raw_spin_unlock_irqrestore(&rsp->onofflock, flags); - /* Wait for snapshotted ->blocked_tasks[] lists to drain. */ + /* Wait for snapshotted ->blkd_tasks lists to drain. */ rnp = rcu_get_root(rsp); wait_event(sync_rcu_preempt_exp_wq, sync_rcu_preempt_exp_done(rnp)); diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index 4a21ca55ef7c..1cedf94e2c4f 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -161,7 +161,6 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp) { unsigned long gpnum; int level = 0; - int phase; struct rcu_node *rnp; gpnum = rsp->gpnum; @@ -178,13 +177,11 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp) seq_puts(m, "\n"); level = rnp->level; } - phase = gpnum & 0x1; - seq_printf(m, "%lx/%lx %c%c>%c%c %d:%d ^%d ", + seq_printf(m, "%lx/%lx %c%c>%c %d:%d ^%d ", rnp->qsmask, rnp->qsmaskinit, - "T."[list_empty(&rnp->blocked_tasks[phase])], - "E."[list_empty(&rnp->blocked_tasks[phase + 2])], - "T."[list_empty(&rnp->blocked_tasks[!phase])], - "E."[list_empty(&rnp->blocked_tasks[!phase + 2])], + ".G"[rnp->gp_tasks != NULL], + ".E"[rnp->exp_tasks != NULL], + ".T"[!list_empty(&rnp->blkd_tasks)], rnp->grplo, rnp->grphi, rnp->grpnum); } seq_puts(m, "\n"); -- cgit v1.2.2 From a26ac2455ffcf3be5c6ef92bc6df7182700f2114 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 12 Jan 2011 14:10:23 -0800 Subject: rcu: move TREE_RCU from softirq to kthread If RCU priority boosting is to be meaningful, callback invocation must be boosted in addition to preempted RCU readers. Otherwise, in presence of CPU real-time threads, the grace period ends, but the callbacks don't get invoked. If the callbacks don't get invoked, the associated memory doesn't get freed, so the system is still subject to OOM. But it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit moves the callback invocations to a kthread, which can be boosted easily. Also add comments and properly synchronized all accesses to rcu_cpu_kthread_task, as suggested by Lai Jiangshan. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- Documentation/filesystems/proc.txt | 1 - include/linux/interrupt.h | 1 - include/trace/events/irq.h | 3 +- kernel/rcutree.c | 340 +++++++++++++++++++++++++++++++++++- kernel/rcutree.h | 8 + kernel/rcutree_plugin.h | 4 +- kernel/softirq.c | 2 +- tools/perf/util/trace-event-parse.c | 1 - 8 files changed, 348 insertions(+), 12 deletions(-) diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index b0b814d75ca1..60740e8ecb37 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -836,7 +836,6 @@ Provides counts of softirq handlers serviced since boot time, for each cpu. TASKLET: 0 0 0 290 SCHED: 27035 26983 26971 26746 HRTIMER: 0 0 0 0 - RCU: 1678 1769 2178 2250 1.3 IDE devices in /proc/ide diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index bea0ac750712..6c12989839d9 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -414,7 +414,6 @@ enum TASKLET_SOFTIRQ, SCHED_SOFTIRQ, HRTIMER_SOFTIRQ, - RCU_SOFTIRQ, /* Preferable RCU should always be the last softirq */ NR_SOFTIRQS }; diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h index 1c09820df585..ae045ca7d356 100644 --- a/include/trace/events/irq.h +++ b/include/trace/events/irq.h @@ -20,8 +20,7 @@ struct softirq_action; softirq_name(BLOCK_IOPOLL), \ softirq_name(TASKLET), \ softirq_name(SCHED), \ - softirq_name(HRTIMER), \ - softirq_name(RCU)) + softirq_name(HRTIMER)) /** * irq_handler_entry - called immediately before the irq action handler diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 0ac1cc03f935..18e33313873e 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -47,6 +47,8 @@ #include #include #include +#include +#include #include "rcutree.h" @@ -82,6 +84,20 @@ DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); int rcu_scheduler_active __read_mostly; EXPORT_SYMBOL_GPL(rcu_scheduler_active); +/* + * Control variables for per-CPU and per-rcu_node kthreads. These + * handle all flavors of RCU. + */ +static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task); +static DEFINE_PER_CPU(wait_queue_head_t, rcu_cpu_wq); +static DEFINE_PER_CPU(char, rcu_cpu_has_work); +static char rcu_kthreads_spawnable; + +static void rcu_node_kthread_setaffinity(struct rcu_node *rnp); +static void invoke_rcu_kthread(void); + +#define RCU_KTHREAD_PRIO 1 /* RT priority for per-CPU kthreads. */ + /* * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s * permit this function to be invoked without holding the root rcu_node @@ -1009,6 +1025,8 @@ static void rcu_send_cbs_to_online(struct rcu_state *rsp) /* * Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy * and move all callbacks from the outgoing CPU to the current one. + * There can only be one CPU hotplug operation at a time, so no other + * CPU can be attempting to update rcu_cpu_kthread_task. */ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) { @@ -1017,6 +1035,14 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) int need_report = 0; struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); struct rcu_node *rnp; + struct task_struct *t; + + /* Stop the CPU's kthread. */ + t = per_cpu(rcu_cpu_kthread_task, cpu); + if (t != NULL) { + per_cpu(rcu_cpu_kthread_task, cpu) = NULL; + kthread_stop(t); + } /* Exclude any attempts to start a new grace period. */ raw_spin_lock_irqsave(&rsp->onofflock, flags); @@ -1054,6 +1080,19 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) raw_spin_unlock_irqrestore(&rnp->lock, flags); if (need_report & RCU_OFL_TASKS_EXP_GP) rcu_report_exp_rnp(rsp, rnp); + + /* + * If there are no more online CPUs for this rcu_node structure, + * kill the rcu_node structure's kthread. Otherwise, adjust its + * affinity. + */ + t = rnp->node_kthread_task; + if (t != NULL && + rnp->qsmaskinit == 0) { + kthread_stop(t); + rnp->node_kthread_task = NULL; + } else + rcu_node_kthread_setaffinity(rnp); } /* @@ -1151,7 +1190,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) /* Re-raise the RCU softirq if there are callbacks remaining. */ if (cpu_has_callbacks_ready_to_invoke(rdp)) - raise_softirq(RCU_SOFTIRQ); + invoke_rcu_kthread(); } /* @@ -1197,7 +1236,7 @@ void rcu_check_callbacks(int cpu, int user) } rcu_preempt_check_callbacks(cpu); if (rcu_pending(cpu)) - raise_softirq(RCU_SOFTIRQ); + invoke_rcu_kthread(); } #ifdef CONFIG_SMP @@ -1361,7 +1400,7 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) /* * Do softirq processing for the current CPU. */ -static void rcu_process_callbacks(struct softirq_action *unused) +static void rcu_process_callbacks(void) { __rcu_process_callbacks(&rcu_sched_state, &__get_cpu_var(rcu_sched_data)); @@ -1372,6 +1411,281 @@ static void rcu_process_callbacks(struct softirq_action *unused) rcu_needs_cpu_flush(); } +/* + * Wake up the current CPU's kthread. This replaces raise_softirq() + * in earlier versions of RCU. Note that because we are running on + * the current CPU with interrupts disabled, the rcu_cpu_kthread_task + * cannot disappear out from under us. + */ +static void invoke_rcu_kthread(void) +{ + unsigned long flags; + wait_queue_head_t *q; + int cpu; + + local_irq_save(flags); + cpu = smp_processor_id(); + per_cpu(rcu_cpu_has_work, cpu) = 1; + if (per_cpu(rcu_cpu_kthread_task, cpu) == NULL) { + local_irq_restore(flags); + return; + } + q = &per_cpu(rcu_cpu_wq, cpu); + wake_up(q); + local_irq_restore(flags); +} + +/* + * Timer handler to initiate the waking up of per-CPU kthreads that + * have yielded the CPU due to excess numbers of RCU callbacks. + */ +static void rcu_cpu_kthread_timer(unsigned long arg) +{ + unsigned long flags; + struct rcu_data *rdp = (struct rcu_data *)arg; + struct rcu_node *rnp = rdp->mynode; + struct task_struct *t; + + raw_spin_lock_irqsave(&rnp->lock, flags); + rnp->wakemask |= rdp->grpmask; + t = rnp->node_kthread_task; + if (t == NULL) { + raw_spin_unlock_irqrestore(&rnp->lock, flags); + return; + } + wake_up_process(t); + raw_spin_unlock_irqrestore(&rnp->lock, flags); +} + +/* + * Drop to non-real-time priority and yield, but only after posting a + * timer that will cause us to regain our real-time priority if we + * remain preempted. Either way, we restore our real-time priority + * before returning. + */ +static void rcu_yield(int cpu) +{ + struct rcu_data *rdp = per_cpu_ptr(rcu_sched_state.rda, cpu); + struct sched_param sp; + struct timer_list yield_timer; + + setup_timer_on_stack(&yield_timer, rcu_cpu_kthread_timer, (unsigned long)rdp); + mod_timer(&yield_timer, jiffies + 2); + sp.sched_priority = 0; + sched_setscheduler_nocheck(current, SCHED_NORMAL, &sp); + schedule(); + sp.sched_priority = RCU_KTHREAD_PRIO; + sched_setscheduler_nocheck(current, SCHED_FIFO, &sp); + del_timer(&yield_timer); +} + +/* + * Handle cases where the rcu_cpu_kthread() ends up on the wrong CPU. + * This can happen while the corresponding CPU is either coming online + * or going offline. We cannot wait until the CPU is fully online + * before starting the kthread, because the various notifier functions + * can wait for RCU grace periods. So we park rcu_cpu_kthread() until + * the corresponding CPU is online. + * + * Return 1 if the kthread needs to stop, 0 otherwise. + * + * Caller must disable bh. This function can momentarily enable it. + */ +static int rcu_cpu_kthread_should_stop(int cpu) +{ + while (cpu_is_offline(cpu) || + !cpumask_equal(¤t->cpus_allowed, cpumask_of(cpu)) || + smp_processor_id() != cpu) { + if (kthread_should_stop()) + return 1; + local_bh_enable(); + schedule_timeout_uninterruptible(1); + if (!cpumask_equal(¤t->cpus_allowed, cpumask_of(cpu))) + set_cpus_allowed_ptr(current, cpumask_of(cpu)); + local_bh_disable(); + } + return 0; +} + +/* + * Per-CPU kernel thread that invokes RCU callbacks. This replaces the + * earlier RCU softirq. + */ +static int rcu_cpu_kthread(void *arg) +{ + int cpu = (int)(long)arg; + unsigned long flags; + int spincnt = 0; + wait_queue_head_t *wqp = &per_cpu(rcu_cpu_wq, cpu); + char work; + char *workp = &per_cpu(rcu_cpu_has_work, cpu); + + for (;;) { + wait_event_interruptible(*wqp, + *workp != 0 || kthread_should_stop()); + local_bh_disable(); + if (rcu_cpu_kthread_should_stop(cpu)) { + local_bh_enable(); + break; + } + local_irq_save(flags); + work = *workp; + *workp = 0; + local_irq_restore(flags); + if (work) + rcu_process_callbacks(); + local_bh_enable(); + if (*workp != 0) + spincnt++; + else + spincnt = 0; + if (spincnt > 10) { + rcu_yield(cpu); + spincnt = 0; + } + } + return 0; +} + +/* + * Spawn a per-CPU kthread, setting up affinity and priority. + * Because the CPU hotplug lock is held, no other CPU will be attempting + * to manipulate rcu_cpu_kthread_task. There might be another CPU + * attempting to access it during boot, but the locking in kthread_bind() + * will enforce sufficient ordering. + */ +static int __cpuinit rcu_spawn_one_cpu_kthread(int cpu) +{ + struct sched_param sp; + struct task_struct *t; + + if (!rcu_kthreads_spawnable || + per_cpu(rcu_cpu_kthread_task, cpu) != NULL) + return 0; + t = kthread_create(rcu_cpu_kthread, (void *)(long)cpu, "rcuc%d", cpu); + if (IS_ERR(t)) + return PTR_ERR(t); + kthread_bind(t, cpu); + WARN_ON_ONCE(per_cpu(rcu_cpu_kthread_task, cpu) != NULL); + per_cpu(rcu_cpu_kthread_task, cpu) = t; + wake_up_process(t); + sp.sched_priority = RCU_KTHREAD_PRIO; + sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); + return 0; +} + +/* + * Per-rcu_node kthread, which is in charge of waking up the per-CPU + * kthreads when needed. We ignore requests to wake up kthreads + * for offline CPUs, which is OK because force_quiescent_state() + * takes care of this case. + */ +static int rcu_node_kthread(void *arg) +{ + int cpu; + unsigned long flags; + unsigned long mask; + struct rcu_node *rnp = (struct rcu_node *)arg; + struct sched_param sp; + struct task_struct *t; + + for (;;) { + wait_event_interruptible(rnp->node_wq, rnp->wakemask != 0 || + kthread_should_stop()); + if (kthread_should_stop()) + break; + raw_spin_lock_irqsave(&rnp->lock, flags); + mask = rnp->wakemask; + rnp->wakemask = 0; + raw_spin_unlock_irqrestore(&rnp->lock, flags); + for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1) { + if ((mask & 0x1) == 0) + continue; + preempt_disable(); + t = per_cpu(rcu_cpu_kthread_task, cpu); + if (!cpu_online(cpu) || t == NULL) { + preempt_enable(); + continue; + } + per_cpu(rcu_cpu_has_work, cpu) = 1; + sp.sched_priority = RCU_KTHREAD_PRIO; + sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); + preempt_enable(); + } + } + return 0; +} + +/* + * Set the per-rcu_node kthread's affinity to cover all CPUs that are + * served by the rcu_node in question. + */ +static void rcu_node_kthread_setaffinity(struct rcu_node *rnp) +{ + cpumask_var_t cm; + int cpu; + unsigned long mask = rnp->qsmaskinit; + + if (rnp->node_kthread_task == NULL || + rnp->qsmaskinit == 0) + return; + if (!alloc_cpumask_var(&cm, GFP_KERNEL)) + return; + cpumask_clear(cm); + for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1) + if (mask & 0x1) + cpumask_set_cpu(cpu, cm); + set_cpus_allowed_ptr(rnp->node_kthread_task, cm); + free_cpumask_var(cm); +} + +/* + * Spawn a per-rcu_node kthread, setting priority and affinity. + */ +static int __cpuinit rcu_spawn_one_node_kthread(struct rcu_state *rsp, + struct rcu_node *rnp) +{ + int rnp_index = rnp - &rsp->node[0]; + struct sched_param sp; + struct task_struct *t; + + if (!rcu_kthreads_spawnable || + rnp->qsmaskinit == 0 || + rnp->node_kthread_task != NULL) + return 0; + t = kthread_create(rcu_node_kthread, (void *)rnp, "rcun%d", rnp_index); + if (IS_ERR(t)) + return PTR_ERR(t); + rnp->node_kthread_task = t; + wake_up_process(t); + sp.sched_priority = 99; + sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); + return 0; +} + +/* + * Spawn all kthreads -- called as soon as the scheduler is running. + */ +static int __init rcu_spawn_kthreads(void) +{ + int cpu; + struct rcu_node *rnp; + + rcu_kthreads_spawnable = 1; + for_each_possible_cpu(cpu) { + init_waitqueue_head(&per_cpu(rcu_cpu_wq, cpu)); + per_cpu(rcu_cpu_has_work, cpu) = 0; + if (cpu_online(cpu)) + (void)rcu_spawn_one_cpu_kthread(cpu); + } + rcu_for_each_leaf_node(&rcu_sched_state, rnp) { + init_waitqueue_head(&rnp->node_wq); + (void)rcu_spawn_one_node_kthread(&rcu_sched_state, rnp); + } + return 0; +} +early_initcall(rcu_spawn_kthreads); + static void __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), struct rcu_state *rsp) @@ -1771,6 +2085,19 @@ static void __cpuinit rcu_online_cpu(int cpu) rcu_preempt_init_percpu_data(cpu); } +static void __cpuinit rcu_online_kthreads(int cpu) +{ + struct rcu_data *rdp = per_cpu_ptr(rcu_sched_state.rda, cpu); + struct rcu_node *rnp = rdp->mynode; + + /* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */ + if (rcu_kthreads_spawnable) { + (void)rcu_spawn_one_cpu_kthread(cpu); + if (rnp->node_kthread_task == NULL) + (void)rcu_spawn_one_node_kthread(&rcu_sched_state, rnp); + } +} + /* * Handle CPU online/offline notification events. */ @@ -1778,11 +2105,17 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { long cpu = (long)hcpu; + struct rcu_data *rdp = per_cpu_ptr(rcu_sched_state.rda, cpu); + struct rcu_node *rnp = rdp->mynode; switch (action) { case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: rcu_online_cpu(cpu); + rcu_online_kthreads(cpu); + break; + case CPU_ONLINE: + rcu_node_kthread_setaffinity(rnp); break; case CPU_DYING: case CPU_DYING_FROZEN: @@ -1923,7 +2256,6 @@ void __init rcu_init(void) rcu_init_one(&rcu_sched_state, &rcu_sched_data); rcu_init_one(&rcu_bh_state, &rcu_bh_data); __rcu_init_preempt(); - open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); /* * We don't need protection against CPU-hotplug here because diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 5a439c180e69..c0213802d164 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -111,6 +111,7 @@ struct rcu_node { /* elements that need to drain to allow the */ /* current expedited grace period to */ /* complete (only for TREE_PREEMPT_RCU). */ + unsigned long wakemask; /* CPUs whose kthread needs to be awakened. */ unsigned long qsmaskinit; /* Per-GP initial value for qsmask & expmask. */ unsigned long grpmask; /* Mask to apply to parent qsmask. */ @@ -134,6 +135,13 @@ struct rcu_node { /* if there is no such task. If there */ /* is no current expedited grace period, */ /* then there can cannot be any such task. */ + struct task_struct *node_kthread_task; + /* kthread that takes care of this rcu_node */ + /* structure, for example, awakening the */ + /* per-CPU kthreads as needed. */ + wait_queue_head_t node_wq; + /* Wait queue on which to park the per-node */ + /* kthread. */ } ____cacheline_internodealigned_in_smp; /* diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 774f010a4619..b9bd69a5a4fe 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1206,7 +1206,7 @@ static DEFINE_PER_CPU(unsigned long, rcu_dyntick_holdoff); * * Because it is not legal to invoke rcu_process_callbacks() with irqs * disabled, we do one pass of force_quiescent_state(), then do a - * raise_softirq() to cause rcu_process_callbacks() to be invoked later. + * invoke_rcu_kthread() to cause rcu_process_callbacks() to be invoked later. * The per-cpu rcu_dyntick_drain variable controls the sequencing. */ int rcu_needs_cpu(int cpu) @@ -1257,7 +1257,7 @@ int rcu_needs_cpu(int cpu) /* If RCU callbacks are still pending, RCU still needs this CPU. */ if (c) - raise_softirq(RCU_SOFTIRQ); + invoke_rcu_kthread(); return c; } diff --git a/kernel/softirq.c b/kernel/softirq.c index 174f976c2874..13960170cad4 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -58,7 +58,7 @@ DEFINE_PER_CPU(struct task_struct *, ksoftirqd); char *softirq_to_name[NR_SOFTIRQS] = { "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL", - "TASKLET", "SCHED", "HRTIMER", "RCU" + "TASKLET", "SCHED", "HRTIMER" }; /* diff --git a/tools/perf/util/trace-event-parse.c b/tools/perf/util/trace-event-parse.c index 0a7ed5b5e281..1e88485c16a0 100644 --- a/tools/perf/util/trace-event-parse.c +++ b/tools/perf/util/trace-event-parse.c @@ -2187,7 +2187,6 @@ static const struct flag flags[] = { { "TASKLET_SOFTIRQ", 6 }, { "SCHED_SOFTIRQ", 7 }, { "HRTIMER_SOFTIRQ", 8 }, - { "RCU_SOFTIRQ", 9 }, { "HRTIMER_NORESTART", 0 }, { "HRTIMER_RESTART", 1 }, -- cgit v1.2.2 From 27f4d28057adf98750cf863c40baefb12f5b6d21 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 7 Feb 2011 12:47:15 -0800 Subject: rcu: priority boosting for TREE_PREEMPT_RCU Add priority boosting for TREE_PREEMPT_RCU, similar to that for TINY_PREEMPT_RCU. This is enabled by the default-off RCU_BOOST kernel parameter. The priority to which to boost preempted RCU readers is controlled by the RCU_BOOST_PRIO kernel parameter (defaulting to real-time priority 1) and the time to wait before boosting the readers who are blocking a given grace period is controlled by the RCU_BOOST_DELAY kernel parameter (defaulting to 500 milliseconds). Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- init/Kconfig | 2 +- kernel/rcutree.c | 115 ++++++++++++------ kernel/rcutree.h | 31 ++++- kernel/rcutree_plugin.h | 314 ++++++++++++++++++++++++++++++++++++++++++++++-- 4 files changed, 411 insertions(+), 51 deletions(-) diff --git a/init/Kconfig b/init/Kconfig index d886b1e9278e..2d964fa40f5b 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -485,7 +485,7 @@ config TREE_RCU_TRACE config RCU_BOOST bool "Enable RCU priority boosting" - depends on RT_MUTEXES && TINY_PREEMPT_RCU + depends on RT_MUTEXES && PREEMPT_RCU default n help This option boosts the priority of preempted RCU readers that diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 18e33313873e..28fd92a9e0d0 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -81,6 +81,8 @@ DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state); DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); +static struct rcu_state *rcu_state; + int rcu_scheduler_active __read_mostly; EXPORT_SYMBOL_GPL(rcu_scheduler_active); @@ -94,7 +96,7 @@ static DEFINE_PER_CPU(char, rcu_cpu_has_work); static char rcu_kthreads_spawnable; static void rcu_node_kthread_setaffinity(struct rcu_node *rnp); -static void invoke_rcu_kthread(void); +static void invoke_rcu_cpu_kthread(void); #define RCU_KTHREAD_PRIO 1 /* RT priority for per-CPU kthreads. */ @@ -791,6 +793,7 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) rnp->completed = rsp->completed; rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */ rcu_start_gp_per_cpu(rsp, rnp, rdp); + rcu_preempt_boost_start_gp(rnp); raw_spin_unlock_irqrestore(&rnp->lock, flags); return; } @@ -826,6 +829,7 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) rnp->completed = rsp->completed; if (rnp == rdp->mynode) rcu_start_gp_per_cpu(rsp, rnp, rdp); + rcu_preempt_boost_start_gp(rnp); raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ } @@ -882,7 +886,7 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, return; } rnp->qsmask &= ~mask; - if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) { + if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) { /* Other bits still set at this level, so done. */ raw_spin_unlock_irqrestore(&rnp->lock, flags); @@ -1089,8 +1093,11 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) t = rnp->node_kthread_task; if (t != NULL && rnp->qsmaskinit == 0) { - kthread_stop(t); + raw_spin_lock_irqsave(&rnp->lock, flags); rnp->node_kthread_task = NULL; + raw_spin_unlock_irqrestore(&rnp->lock, flags); + kthread_stop(t); + rcu_stop_boost_kthread(rnp); } else rcu_node_kthread_setaffinity(rnp); } @@ -1190,7 +1197,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) /* Re-raise the RCU softirq if there are callbacks remaining. */ if (cpu_has_callbacks_ready_to_invoke(rdp)) - invoke_rcu_kthread(); + invoke_rcu_cpu_kthread(); } /* @@ -1236,7 +1243,7 @@ void rcu_check_callbacks(int cpu, int user) } rcu_preempt_check_callbacks(cpu); if (rcu_pending(cpu)) - invoke_rcu_kthread(); + invoke_rcu_cpu_kthread(); } #ifdef CONFIG_SMP @@ -1244,6 +1251,8 @@ void rcu_check_callbacks(int cpu, int user) /* * Scan the leaf rcu_node structures, processing dyntick state for any that * have not yet encountered a quiescent state, using the function specified. + * Also initiate boosting for any threads blocked on the root rcu_node. + * * The caller must have suppressed start of new grace periods. */ static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *)) @@ -1262,6 +1271,7 @@ static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *)) return; } if (rnp->qsmask == 0) { + rcu_initiate_boost(rnp); raw_spin_unlock_irqrestore(&rnp->lock, flags); continue; } @@ -1280,6 +1290,11 @@ static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *)) } raw_spin_unlock_irqrestore(&rnp->lock, flags); } + rnp = rcu_get_root(rsp); + raw_spin_lock_irqsave(&rnp->lock, flags); + if (rnp->qsmask == 0) + rcu_initiate_boost(rnp); + raw_spin_unlock_irqrestore(&rnp->lock, flags); } /* @@ -1417,7 +1432,7 @@ static void rcu_process_callbacks(void) * the current CPU with interrupts disabled, the rcu_cpu_kthread_task * cannot disappear out from under us. */ -static void invoke_rcu_kthread(void) +static void invoke_rcu_cpu_kthread(void) { unsigned long flags; wait_queue_head_t *q; @@ -1435,25 +1450,34 @@ static void invoke_rcu_kthread(void) local_irq_restore(flags); } +/* + * Wake up the specified per-rcu_node-structure kthread. + * The caller must hold ->lock. + */ +static void invoke_rcu_node_kthread(struct rcu_node *rnp) +{ + struct task_struct *t; + + t = rnp->node_kthread_task; + if (t != NULL) + wake_up_process(t); +} + /* * Timer handler to initiate the waking up of per-CPU kthreads that * have yielded the CPU due to excess numbers of RCU callbacks. + * We wake up the per-rcu_node kthread, which in turn will wake up + * the booster kthread. */ static void rcu_cpu_kthread_timer(unsigned long arg) { unsigned long flags; - struct rcu_data *rdp = (struct rcu_data *)arg; + struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, arg); struct rcu_node *rnp = rdp->mynode; - struct task_struct *t; raw_spin_lock_irqsave(&rnp->lock, flags); rnp->wakemask |= rdp->grpmask; - t = rnp->node_kthread_task; - if (t == NULL) { - raw_spin_unlock_irqrestore(&rnp->lock, flags); - return; - } - wake_up_process(t); + invoke_rcu_node_kthread(rnp); raw_spin_unlock_irqrestore(&rnp->lock, flags); } @@ -1463,13 +1487,12 @@ static void rcu_cpu_kthread_timer(unsigned long arg) * remain preempted. Either way, we restore our real-time priority * before returning. */ -static void rcu_yield(int cpu) +static void rcu_yield(void (*f)(unsigned long), unsigned long arg) { - struct rcu_data *rdp = per_cpu_ptr(rcu_sched_state.rda, cpu); struct sched_param sp; struct timer_list yield_timer; - setup_timer_on_stack(&yield_timer, rcu_cpu_kthread_timer, (unsigned long)rdp); + setup_timer_on_stack(&yield_timer, f, arg); mod_timer(&yield_timer, jiffies + 2); sp.sched_priority = 0; sched_setscheduler_nocheck(current, SCHED_NORMAL, &sp); @@ -1540,7 +1563,7 @@ static int rcu_cpu_kthread(void *arg) else spincnt = 0; if (spincnt > 10) { - rcu_yield(cpu); + rcu_yield(rcu_cpu_kthread_timer, (unsigned long)cpu); spincnt = 0; } } @@ -1597,6 +1620,7 @@ static int rcu_node_kthread(void *arg) raw_spin_lock_irqsave(&rnp->lock, flags); mask = rnp->wakemask; rnp->wakemask = 0; + rcu_initiate_boost(rnp); raw_spin_unlock_irqrestore(&rnp->lock, flags); for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1) { if ((mask & 0x1) == 0) @@ -1618,7 +1642,8 @@ static int rcu_node_kthread(void *arg) /* * Set the per-rcu_node kthread's affinity to cover all CPUs that are - * served by the rcu_node in question. + * served by the rcu_node in question. The CPU hotplug lock is still + * held, so the value of rnp->qsmaskinit will be stable. */ static void rcu_node_kthread_setaffinity(struct rcu_node *rnp) { @@ -1626,8 +1651,7 @@ static void rcu_node_kthread_setaffinity(struct rcu_node *rnp) int cpu; unsigned long mask = rnp->qsmaskinit; - if (rnp->node_kthread_task == NULL || - rnp->qsmaskinit == 0) + if (rnp->node_kthread_task == NULL || mask == 0) return; if (!alloc_cpumask_var(&cm, GFP_KERNEL)) return; @@ -1636,31 +1660,40 @@ static void rcu_node_kthread_setaffinity(struct rcu_node *rnp) if (mask & 0x1) cpumask_set_cpu(cpu, cm); set_cpus_allowed_ptr(rnp->node_kthread_task, cm); + rcu_boost_kthread_setaffinity(rnp, cm); free_cpumask_var(cm); } /* * Spawn a per-rcu_node kthread, setting priority and affinity. + * Called during boot before online/offline can happen, or, if + * during runtime, with the main CPU-hotplug locks held. So only + * one of these can be executing at a time. */ static int __cpuinit rcu_spawn_one_node_kthread(struct rcu_state *rsp, struct rcu_node *rnp) { + unsigned long flags; int rnp_index = rnp - &rsp->node[0]; struct sched_param sp; struct task_struct *t; if (!rcu_kthreads_spawnable || - rnp->qsmaskinit == 0 || - rnp->node_kthread_task != NULL) + rnp->qsmaskinit == 0) return 0; - t = kthread_create(rcu_node_kthread, (void *)rnp, "rcun%d", rnp_index); - if (IS_ERR(t)) - return PTR_ERR(t); - rnp->node_kthread_task = t; - wake_up_process(t); - sp.sched_priority = 99; - sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); - return 0; + if (rnp->node_kthread_task == NULL) { + t = kthread_create(rcu_node_kthread, (void *)rnp, + "rcun%d", rnp_index); + if (IS_ERR(t)) + return PTR_ERR(t); + raw_spin_lock_irqsave(&rnp->lock, flags); + rnp->node_kthread_task = t; + raw_spin_unlock_irqrestore(&rnp->lock, flags); + wake_up_process(t); + sp.sched_priority = 99; + sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); + } + return rcu_spawn_one_boost_kthread(rsp, rnp, rnp_index); } /* @@ -1678,10 +1711,16 @@ static int __init rcu_spawn_kthreads(void) if (cpu_online(cpu)) (void)rcu_spawn_one_cpu_kthread(cpu); } - rcu_for_each_leaf_node(&rcu_sched_state, rnp) { - init_waitqueue_head(&rnp->node_wq); - (void)rcu_spawn_one_node_kthread(&rcu_sched_state, rnp); - } + rnp = rcu_get_root(rcu_state); + init_waitqueue_head(&rnp->node_wq); + rcu_init_boost_waitqueue(rnp); + (void)rcu_spawn_one_node_kthread(rcu_state, rnp); + if (NUM_RCU_NODES > 1) + rcu_for_each_leaf_node(rcu_state, rnp) { + init_waitqueue_head(&rnp->node_wq); + rcu_init_boost_waitqueue(rnp); + (void)rcu_spawn_one_node_kthread(rcu_state, rnp); + } return 0; } early_initcall(rcu_spawn_kthreads); @@ -2087,14 +2126,14 @@ static void __cpuinit rcu_online_cpu(int cpu) static void __cpuinit rcu_online_kthreads(int cpu) { - struct rcu_data *rdp = per_cpu_ptr(rcu_sched_state.rda, cpu); + struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu); struct rcu_node *rnp = rdp->mynode; /* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */ if (rcu_kthreads_spawnable) { (void)rcu_spawn_one_cpu_kthread(cpu); if (rnp->node_kthread_task == NULL) - (void)rcu_spawn_one_node_kthread(&rcu_sched_state, rnp); + (void)rcu_spawn_one_node_kthread(rcu_state, rnp); } } @@ -2105,7 +2144,7 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { long cpu = (long)hcpu; - struct rcu_data *rdp = per_cpu_ptr(rcu_sched_state.rda, cpu); + struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu); struct rcu_node *rnp = rdp->mynode; switch (action) { diff --git a/kernel/rcutree.h b/kernel/rcutree.h index c0213802d164..8db0cdc7f450 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -135,6 +135,24 @@ struct rcu_node { /* if there is no such task. If there */ /* is no current expedited grace period, */ /* then there can cannot be any such task. */ +#ifdef CONFIG_RCU_BOOST + struct list_head *boost_tasks; + /* Pointer to first task that needs to be */ + /* priority boosted, or NULL if no priority */ + /* boosting is needed for this rcu_node */ + /* structure. If there are no tasks */ + /* queued on this rcu_node structure that */ + /* are blocking the current grace period, */ + /* there can be no such task. */ + unsigned long boost_time; + /* When to start boosting (jiffies). */ + struct task_struct *boost_kthread_task; + /* kthread that takes care of priority */ + /* boosting for this rcu_node structure. */ + wait_queue_head_t boost_wq; + /* Wait queue on which to park the boost */ + /* kthread. */ +#endif /* #ifdef CONFIG_RCU_BOOST */ struct task_struct *node_kthread_task; /* kthread that takes care of this rcu_node */ /* structure, for example, awakening the */ @@ -365,7 +383,7 @@ DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data); static void rcu_bootup_announce(void); long rcu_batches_completed(void); static void rcu_preempt_note_context_switch(int cpu); -static int rcu_preempted_readers(struct rcu_node *rnp); +static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp); #ifdef CONFIG_HOTPLUG_CPU static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags); @@ -392,5 +410,16 @@ static void __cpuinit rcu_preempt_init_percpu_data(int cpu); static void rcu_preempt_send_cbs_to_online(void); static void __init __rcu_init_preempt(void); static void rcu_needs_cpu_flush(void); +static void __init rcu_init_boost_waitqueue(struct rcu_node *rnp); +static void rcu_initiate_boost(struct rcu_node *rnp); +static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, + cpumask_var_t cm); +static void rcu_preempt_boost_start_gp(struct rcu_node *rnp); +static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, + struct rcu_node *rnp, + int rnp_index); +#ifdef CONFIG_HOTPLUG_CPU +static void rcu_stop_boost_kthread(struct rcu_node *rnp); +#endif /* #ifdef CONFIG_HOTPLUG_CPU */ #endif /* #ifndef RCU_TREE_NONCORE */ diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index b9bd69a5a4fe..5964f82e2d96 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -66,6 +66,7 @@ static void __init rcu_bootup_announce_oddness(void) struct rcu_state rcu_preempt_state = RCU_STATE_INITIALIZER(rcu_preempt_state); DEFINE_PER_CPU(struct rcu_data, rcu_preempt_data); +static struct rcu_state *rcu_state = &rcu_preempt_state; static int rcu_preempted_readers_exp(struct rcu_node *rnp); @@ -179,6 +180,10 @@ static void rcu_preempt_note_context_switch(int cpu) if ((rnp->qsmask & rdp->grpmask) && rnp->gp_tasks != NULL) { list_add(&t->rcu_node_entry, rnp->gp_tasks->prev); rnp->gp_tasks = &t->rcu_node_entry; +#ifdef CONFIG_RCU_BOOST + if (rnp->boost_tasks != NULL) + rnp->boost_tasks = rnp->gp_tasks; +#endif /* #ifdef CONFIG_RCU_BOOST */ } else { list_add(&t->rcu_node_entry, &rnp->blkd_tasks); if (rnp->qsmask & rdp->grpmask) @@ -218,7 +223,7 @@ EXPORT_SYMBOL_GPL(__rcu_read_lock); * for the specified rcu_node structure. If the caller needs a reliable * answer, it must hold the rcu_node's ->lock. */ -static int rcu_preempted_readers(struct rcu_node *rnp) +static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp) { return rnp->gp_tasks != NULL; } @@ -236,7 +241,7 @@ static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags) unsigned long mask; struct rcu_node *rnp_p; - if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) { + if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) { raw_spin_unlock_irqrestore(&rnp->lock, flags); return; /* Still need more quiescent states! */ } @@ -325,7 +330,7 @@ static void rcu_read_unlock_special(struct task_struct *t) break; raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ } - empty = !rcu_preempted_readers(rnp); + empty = !rcu_preempt_blocked_readers_cgp(rnp); empty_exp = !rcu_preempted_readers_exp(rnp); smp_mb(); /* ensure expedited fastpath sees end of RCU c-s. */ np = rcu_next_node_entry(t, rnp); @@ -334,6 +339,10 @@ static void rcu_read_unlock_special(struct task_struct *t) rnp->gp_tasks = np; if (&t->rcu_node_entry == rnp->exp_tasks) rnp->exp_tasks = np; +#ifdef CONFIG_RCU_BOOST + if (&t->rcu_node_entry == rnp->boost_tasks) + rnp->boost_tasks = np; +#endif /* #ifdef CONFIG_RCU_BOOST */ t->rcu_blocked_node = NULL; /* @@ -346,6 +355,15 @@ static void rcu_read_unlock_special(struct task_struct *t) else rcu_report_unblock_qs_rnp(rnp, flags); +#ifdef CONFIG_RCU_BOOST + /* Unboost if we were boosted. */ + if (special & RCU_READ_UNLOCK_BOOSTED) { + t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_BOOSTED; + rt_mutex_unlock(t->rcu_boost_mutex); + t->rcu_boost_mutex = NULL; + } +#endif /* #ifdef CONFIG_RCU_BOOST */ + /* * If this was the last task on the expedited lists, * then we need to report up the rcu_node hierarchy. @@ -391,7 +409,7 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp) unsigned long flags; struct task_struct *t; - if (!rcu_preempted_readers(rnp)) + if (!rcu_preempt_blocked_readers_cgp(rnp)) return; raw_spin_lock_irqsave(&rnp->lock, flags); t = list_entry(rnp->gp_tasks, @@ -430,7 +448,7 @@ static void rcu_print_task_stall(struct rcu_node *rnp) { struct task_struct *t; - if (!rcu_preempted_readers(rnp)) + if (!rcu_preempt_blocked_readers_cgp(rnp)) return; t = list_entry(rnp->gp_tasks, struct task_struct, rcu_node_entry); @@ -460,7 +478,7 @@ static void rcu_preempt_stall_reset(void) */ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp) { - WARN_ON_ONCE(rcu_preempted_readers(rnp)); + WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp)); if (!list_empty(&rnp->blkd_tasks)) rnp->gp_tasks = rnp->blkd_tasks.next; WARN_ON_ONCE(rnp->qsmask); @@ -509,7 +527,7 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp, * absolutely necessary, but this is a good performance/complexity * tradeoff. */ - if (rcu_preempted_readers(rnp)) + if (rcu_preempt_blocked_readers_cgp(rnp)) retval |= RCU_OFL_TASKS_NORM_GP; if (rcu_preempted_readers_exp(rnp)) retval |= RCU_OFL_TASKS_EXP_GP; @@ -525,8 +543,22 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp, rnp_root->gp_tasks = rnp->gp_tasks; if (&t->rcu_node_entry == rnp->exp_tasks) rnp_root->exp_tasks = rnp->exp_tasks; +#ifdef CONFIG_RCU_BOOST + if (&t->rcu_node_entry == rnp->boost_tasks) + rnp_root->boost_tasks = rnp->boost_tasks; +#endif /* #ifdef CONFIG_RCU_BOOST */ raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */ } + +#ifdef CONFIG_RCU_BOOST + /* In case root is being boosted and leaf is not. */ + raw_spin_lock(&rnp_root->lock); /* irqs already disabled */ + if (rnp_root->boost_tasks != NULL && + rnp_root->boost_tasks != rnp_root->gp_tasks) + rnp_root->boost_tasks = rnp_root->gp_tasks; + raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */ +#endif /* #ifdef CONFIG_RCU_BOOST */ + rnp->gp_tasks = NULL; rnp->exp_tasks = NULL; return retval; @@ -684,6 +716,7 @@ sync_rcu_preempt_exp_init(struct rcu_state *rsp, struct rcu_node *rnp) raw_spin_lock(&rnp->lock); /* irqs already disabled */ if (!list_empty(&rnp->blkd_tasks)) { rnp->exp_tasks = rnp->blkd_tasks.next; + rcu_initiate_boost(rnp); must_wait = 1; } raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ @@ -830,6 +863,8 @@ void exit_rcu(void) #else /* #ifdef CONFIG_TREE_PREEMPT_RCU */ +static struct rcu_state *rcu_state = &rcu_sched_state; + /* * Tell them what RCU they are running. */ @@ -870,7 +905,7 @@ static void rcu_preempt_note_context_switch(int cpu) * Because preemptable RCU does not exist, there are never any preempted * RCU readers. */ -static int rcu_preempted_readers(struct rcu_node *rnp) +static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp) { return 0; } @@ -1034,6 +1069,263 @@ static void __init __rcu_init_preempt(void) #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ +#ifdef CONFIG_RCU_BOOST + +#include "rtmutex_common.h" + +/* + * Carry out RCU priority boosting on the task indicated by ->exp_tasks + * or ->boost_tasks, advancing the pointer to the next task in the + * ->blkd_tasks list. + * + * Note that irqs must be enabled: boosting the task can block. + * Returns 1 if there are more tasks needing to be boosted. + */ +static int rcu_boost(struct rcu_node *rnp) +{ + unsigned long flags; + struct rt_mutex mtx; + struct task_struct *t; + struct list_head *tb; + + if (rnp->exp_tasks == NULL && rnp->boost_tasks == NULL) + return 0; /* Nothing left to boost. */ + + raw_spin_lock_irqsave(&rnp->lock, flags); + + /* + * Recheck under the lock: all tasks in need of boosting + * might exit their RCU read-side critical sections on their own. + */ + if (rnp->exp_tasks == NULL && rnp->boost_tasks == NULL) { + raw_spin_unlock_irqrestore(&rnp->lock, flags); + return 0; + } + + /* + * Preferentially boost tasks blocking expedited grace periods. + * This cannot starve the normal grace periods because a second + * expedited grace period must boost all blocked tasks, including + * those blocking the pre-existing normal grace period. + */ + if (rnp->exp_tasks != NULL) + tb = rnp->exp_tasks; + else + tb = rnp->boost_tasks; + + /* + * We boost task t by manufacturing an rt_mutex that appears to + * be held by task t. We leave a pointer to that rt_mutex where + * task t can find it, and task t will release the mutex when it + * exits its outermost RCU read-side critical section. Then + * simply acquiring this artificial rt_mutex will boost task + * t's priority. (Thanks to tglx for suggesting this approach!) + * + * Note that task t must acquire rnp->lock to remove itself from + * the ->blkd_tasks list, which it will do from exit() if from + * nowhere else. We therefore are guaranteed that task t will + * stay around at least until we drop rnp->lock. Note that + * rnp->lock also resolves races between our priority boosting + * and task t's exiting its outermost RCU read-side critical + * section. + */ + t = container_of(tb, struct task_struct, rcu_node_entry); + rt_mutex_init_proxy_locked(&mtx, t); + t->rcu_boost_mutex = &mtx; + t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BOOSTED; + raw_spin_unlock_irqrestore(&rnp->lock, flags); + rt_mutex_lock(&mtx); /* Side effect: boosts task t's priority. */ + rt_mutex_unlock(&mtx); /* Keep lockdep happy. */ + + return rnp->exp_tasks != NULL || rnp->boost_tasks != NULL; +} + +/* + * Timer handler to initiate waking up of boost kthreads that + * have yielded the CPU due to excessive numbers of tasks to + * boost. We wake up the per-rcu_node kthread, which in turn + * will wake up the booster kthread. + */ +static void rcu_boost_kthread_timer(unsigned long arg) +{ + unsigned long flags; + struct rcu_node *rnp = (struct rcu_node *)arg; + + raw_spin_lock_irqsave(&rnp->lock, flags); + invoke_rcu_node_kthread(rnp); + raw_spin_unlock_irqrestore(&rnp->lock, flags); +} + +/* + * Priority-boosting kthread. One per leaf rcu_node and one for the + * root rcu_node. + */ +static int rcu_boost_kthread(void *arg) +{ + struct rcu_node *rnp = (struct rcu_node *)arg; + int spincnt = 0; + int more2boost; + + for (;;) { + wait_event_interruptible(rnp->boost_wq, rnp->boost_tasks || + rnp->exp_tasks || + kthread_should_stop()); + if (kthread_should_stop()) + break; + more2boost = rcu_boost(rnp); + if (more2boost) + spincnt++; + else + spincnt = 0; + if (spincnt > 10) { + rcu_yield(rcu_boost_kthread_timer, (unsigned long)rnp); + spincnt = 0; + } + } + return 0; +} + +/* + * Check to see if it is time to start boosting RCU readers that are + * blocking the current grace period, and, if so, tell the per-rcu_node + * kthread to start boosting them. If there is an expedited grace + * period in progress, it is always time to boost. + * + * The caller must hold rnp->lock. + */ +static void rcu_initiate_boost(struct rcu_node *rnp) +{ + struct task_struct *t; + + if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) + return; + if (rnp->exp_tasks != NULL || + (rnp->gp_tasks != NULL && + rnp->boost_tasks == NULL && + rnp->qsmask == 0 && + ULONG_CMP_GE(jiffies, rnp->boost_time))) { + if (rnp->exp_tasks == NULL) + rnp->boost_tasks = rnp->gp_tasks; + t = rnp->boost_kthread_task; + if (t != NULL) + wake_up_process(t); + } +} + +static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, + cpumask_var_t cm) +{ + unsigned long flags; + struct task_struct *t; + + raw_spin_lock_irqsave(&rnp->lock, flags); + t = rnp->boost_kthread_task; + if (t != NULL) + set_cpus_allowed_ptr(rnp->boost_kthread_task, cm); + raw_spin_unlock_irqrestore(&rnp->lock, flags); +} + +#define RCU_BOOST_DELAY_JIFFIES DIV_ROUND_UP(CONFIG_RCU_BOOST_DELAY * HZ, 1000) + +/* + * Do priority-boost accounting for the start of a new grace period. + */ +static void rcu_preempt_boost_start_gp(struct rcu_node *rnp) +{ + rnp->boost_time = jiffies + RCU_BOOST_DELAY_JIFFIES; +} + +/* + * Initialize the RCU-boost waitqueue. + */ +static void __init rcu_init_boost_waitqueue(struct rcu_node *rnp) +{ + init_waitqueue_head(&rnp->boost_wq); +} + +/* + * Create an RCU-boost kthread for the specified node if one does not + * already exist. We only create this kthread for preemptible RCU. + * Returns zero if all is well, a negated errno otherwise. + */ +static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, + struct rcu_node *rnp, + int rnp_index) +{ + unsigned long flags; + struct sched_param sp; + struct task_struct *t; + + if (&rcu_preempt_state != rsp) + return 0; + if (rnp->boost_kthread_task != NULL) + return 0; + t = kthread_create(rcu_boost_kthread, (void *)rnp, + "rcub%d", rnp_index); + if (IS_ERR(t)) + return PTR_ERR(t); + raw_spin_lock_irqsave(&rnp->lock, flags); + rnp->boost_kthread_task = t; + raw_spin_unlock_irqrestore(&rnp->lock, flags); + wake_up_process(t); + sp.sched_priority = RCU_KTHREAD_PRIO; + sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); + return 0; +} + +#ifdef CONFIG_HOTPLUG_CPU + +static void rcu_stop_boost_kthread(struct rcu_node *rnp) +{ + unsigned long flags; + struct task_struct *t; + + raw_spin_lock_irqsave(&rnp->lock, flags); + t = rnp->boost_kthread_task; + rnp->boost_kthread_task = NULL; + raw_spin_unlock_irqrestore(&rnp->lock, flags); + if (t != NULL) + kthread_stop(t); +} + +#endif /* #ifdef CONFIG_HOTPLUG_CPU */ + +#else /* #ifdef CONFIG_RCU_BOOST */ + +static void rcu_initiate_boost(struct rcu_node *rnp) +{ +} + +static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, + cpumask_var_t cm) +{ +} + +static void rcu_preempt_boost_start_gp(struct rcu_node *rnp) +{ +} + +static void __init rcu_init_boost_waitqueue(struct rcu_node *rnp) +{ +} + +static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, + struct rcu_node *rnp, + int rnp_index) +{ + return 0; +} + +#ifdef CONFIG_HOTPLUG_CPU + +static void rcu_stop_boost_kthread(struct rcu_node *rnp) +{ +} + +#endif /* #ifdef CONFIG_HOTPLUG_CPU */ + +#endif /* #else #ifdef CONFIG_RCU_BOOST */ + #ifndef CONFIG_SMP void synchronize_sched_expedited(void) @@ -1206,8 +1498,8 @@ static DEFINE_PER_CPU(unsigned long, rcu_dyntick_holdoff); * * Because it is not legal to invoke rcu_process_callbacks() with irqs * disabled, we do one pass of force_quiescent_state(), then do a - * invoke_rcu_kthread() to cause rcu_process_callbacks() to be invoked later. - * The per-cpu rcu_dyntick_drain variable controls the sequencing. + * invoke_rcu_cpu_kthread() to cause rcu_process_callbacks() to be invoked + * later. The per-cpu rcu_dyntick_drain variable controls the sequencing. */ int rcu_needs_cpu(int cpu) { @@ -1257,7 +1549,7 @@ int rcu_needs_cpu(int cpu) /* If RCU callbacks are still pending, RCU still needs this CPU. */ if (c) - invoke_rcu_kthread(); + invoke_rcu_cpu_kthread(); return c; } -- cgit v1.2.2 From 0f962a5e7277c34987b77dc82fc9aefcedc95e27 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 14 Apr 2011 12:13:53 -0700 Subject: rcu: Force per-rcu_node kthreads off of the outgoing CPU The scheduler has had some heartburn in the past when too many real-time kthreads were affinitied to the outgoing CPU. So, this commit lightens the load by forcing the per-rcu_node and the boost kthreads off of the outgoing CPU. Note that RCU's per-CPU kthread remains on the outgoing CPU until the bitter end, as it must in order to preserve correctness. Also avoid disabling hardirqs across calls to set_cpus_allowed_ptr(), given that this function can block. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 24 +++++++++++++++++++----- kernel/rcutree_plugin.h | 8 +++++--- 2 files changed, 24 insertions(+), 8 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 28fd92a9e0d0..51eef4193e7c 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -95,7 +95,7 @@ static DEFINE_PER_CPU(wait_queue_head_t, rcu_cpu_wq); static DEFINE_PER_CPU(char, rcu_cpu_has_work); static char rcu_kthreads_spawnable; -static void rcu_node_kthread_setaffinity(struct rcu_node *rnp); +static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu); static void invoke_rcu_cpu_kthread(void); #define RCU_KTHREAD_PRIO 1 /* RT priority for per-CPU kthreads. */ @@ -1099,7 +1099,7 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) kthread_stop(t); rcu_stop_boost_kthread(rnp); } else - rcu_node_kthread_setaffinity(rnp); + rcu_node_kthread_setaffinity(rnp, -1); } /* @@ -1644,8 +1644,12 @@ static int rcu_node_kthread(void *arg) * Set the per-rcu_node kthread's affinity to cover all CPUs that are * served by the rcu_node in question. The CPU hotplug lock is still * held, so the value of rnp->qsmaskinit will be stable. + * + * We don't include outgoingcpu in the affinity set, use -1 if there is + * no outgoing CPU. If there are no CPUs left in the affinity set, + * this function allows the kthread to execute on any CPU. */ -static void rcu_node_kthread_setaffinity(struct rcu_node *rnp) +static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu) { cpumask_var_t cm; int cpu; @@ -1657,8 +1661,14 @@ static void rcu_node_kthread_setaffinity(struct rcu_node *rnp) return; cpumask_clear(cm); for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1) - if (mask & 0x1) + if ((mask & 0x1) && cpu != outgoingcpu) cpumask_set_cpu(cpu, cm); + if (cpumask_weight(cm) == 0) { + cpumask_setall(cm); + for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++) + cpumask_clear_cpu(cpu, cm); + WARN_ON_ONCE(cpumask_weight(cm) == 0); + } set_cpus_allowed_ptr(rnp->node_kthread_task, cm); rcu_boost_kthread_setaffinity(rnp, cm); free_cpumask_var(cm); @@ -2154,7 +2164,11 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self, rcu_online_kthreads(cpu); break; case CPU_ONLINE: - rcu_node_kthread_setaffinity(rnp); + case CPU_DOWN_FAILED: + rcu_node_kthread_setaffinity(rnp, -1); + break; + case CPU_DOWN_PREPARE: + rcu_node_kthread_setaffinity(rnp, cpu); break; case CPU_DYING: case CPU_DYING_FROZEN: diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 5964f82e2d96..4e486255df63 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1212,17 +1212,19 @@ static void rcu_initiate_boost(struct rcu_node *rnp) } } +/* + * Set the affinity of the boost kthread. The CPU-hotplug locks are + * held, so no one should be messing with the existence of the boost + * kthread. + */ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, cpumask_var_t cm) { - unsigned long flags; struct task_struct *t; - raw_spin_lock_irqsave(&rnp->lock, flags); t = rnp->boost_kthread_task; if (t != NULL) set_cpus_allowed_ptr(rnp->boost_kthread_task, cm); - raw_spin_unlock_irqrestore(&rnp->lock, flags); } #define RCU_BOOST_DELAY_JIFFIES DIV_ROUND_UP(CONFIG_RCU_BOOST_DELAY * HZ, 1000) -- cgit v1.2.2 From e3995a25fa361ce987a7d0ade00b17e3151519d7 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 18 Apr 2011 15:31:26 -0700 Subject: rcu: put per-CPU kthread at non-RT priority during CPU hotplug operations If you are doing CPU hotplug operations, it is best not to have CPU-bound realtime tasks running CPU-bound on the outgoing CPU. So this commit makes per-CPU kthreads run at non-realtime priority during that time. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutree.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 51eef4193e7c..198e4df7d83e 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1463,6 +1463,30 @@ static void invoke_rcu_node_kthread(struct rcu_node *rnp) wake_up_process(t); } +/* + * Set the specified CPU's kthread to run RT or not, as specified by + * the to_rt argument. The CPU-hotplug locks are held, so the task + * is not going away. + */ +static void rcu_cpu_kthread_setrt(int cpu, int to_rt) +{ + int policy; + struct sched_param sp; + struct task_struct *t; + + t = per_cpu(rcu_cpu_kthread_task, cpu); + if (t == NULL) + return; + if (to_rt) { + policy = SCHED_FIFO; + sp.sched_priority = RCU_KTHREAD_PRIO; + } else { + policy = SCHED_NORMAL; + sp.sched_priority = 0; + } + sched_setscheduler_nocheck(t, policy, &sp); +} + /* * Timer handler to initiate the waking up of per-CPU kthreads that * have yielded the CPU due to excess numbers of RCU callbacks. @@ -2166,9 +2190,11 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self, case CPU_ONLINE: case CPU_DOWN_FAILED: rcu_node_kthread_setaffinity(rnp, -1); + rcu_cpu_kthread_setrt(cpu, 1); break; case CPU_DOWN_PREPARE: rcu_node_kthread_setaffinity(rnp, cpu); + rcu_cpu_kthread_setrt(cpu, 0); break; case CPU_DYING: case CPU_DYING_FROZEN: -- cgit v1.2.2 From 3acf4a9a3d63f23430f940842829175b0778a1b8 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 17 Apr 2011 23:45:23 -0700 Subject: rcu: avoid hammering sched with yet another bound RT kthread The scheduler does not appear to take kindly to having multiple real-time threads bound to a CPU that is going offline. So this commit is a temporary hack-around to avoid that happening. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- kernel/rcutorture.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index c224da41890c..4d256dba7d9b 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -163,11 +163,11 @@ static int stutter_pause_test; #endif int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT; -#ifdef CONFIG_RCU_BOOST +#if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) #define rcu_can_boost() 1 -#else /* #ifdef CONFIG_RCU_BOOST */ +#else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */ #define rcu_can_boost() 0 -#endif /* #else #ifdef CONFIG_RCU_BOOST */ +#endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */ static unsigned long boost_starttime; /* jiffies of next boost test start. */ DEFINE_MUTEX(boost_mutex); /* protect setting boost_starttime */ -- cgit v1.2.2 From 67b98dba474f293c389fc2b7254dcf7c0492e3bd Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 21 Feb 2011 13:31:55 -0800 Subject: rcu: eliminate unused boosting statistics The n_rcu_torture_boost_allocerror and n_rcu_torture_boost_afferror statistics are not actually incremented anymore, so eliminate them. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutorture.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 4d256dba7d9b..22b0e74e7d99 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -146,8 +146,6 @@ static atomic_t n_rcu_torture_mberror; static atomic_t n_rcu_torture_error; static long n_rcu_torture_boost_ktrerror; static long n_rcu_torture_boost_rterror; -static long n_rcu_torture_boost_allocerror; -static long n_rcu_torture_boost_afferror; static long n_rcu_torture_boost_failure; static long n_rcu_torture_boosts; static long n_rcu_torture_timers; @@ -1067,7 +1065,7 @@ rcu_torture_printk(char *page) cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG); cnt += sprintf(&page[cnt], "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d " - "rtmbe: %d rtbke: %ld rtbre: %ld rtbae: %ld rtbafe: %ld " + "rtmbe: %d rtbke: %ld rtbre: %ld " "rtbf: %ld rtb: %ld nt: %ld", rcu_torture_current, rcu_torture_current_version, @@ -1078,16 +1076,12 @@ rcu_torture_printk(char *page) atomic_read(&n_rcu_torture_mberror), n_rcu_torture_boost_ktrerror, n_rcu_torture_boost_rterror, - n_rcu_torture_boost_allocerror, - n_rcu_torture_boost_afferror, n_rcu_torture_boost_failure, n_rcu_torture_boosts, n_rcu_torture_timers); if (atomic_read(&n_rcu_torture_mberror) != 0 || n_rcu_torture_boost_ktrerror != 0 || n_rcu_torture_boost_rterror != 0 || - n_rcu_torture_boost_allocerror != 0 || - n_rcu_torture_boost_afferror != 0 || n_rcu_torture_boost_failure != 0) cnt += sprintf(&page[cnt], " !!!"); cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG); @@ -1486,8 +1480,6 @@ rcu_torture_init(void) atomic_set(&n_rcu_torture_error, 0); n_rcu_torture_boost_ktrerror = 0; n_rcu_torture_boost_rterror = 0; - n_rcu_torture_boost_allocerror = 0; - n_rcu_torture_boost_afferror = 0; n_rcu_torture_boost_failure = 0; n_rcu_torture_boosts = 0; for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) -- cgit v1.2.2 From 0ea1f2ebeb217d38770aebf91c4ecaa8e01b3305 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 22 Feb 2011 13:42:43 -0800 Subject: rcu: Add boosting to TREE_PREEMPT_RCU tracing Includes total number of tasks boosted, number boosted on behalf of each of normal and expedited grace periods, and statistics on attempts to initiate boosting that failed for various reasons. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutree.h | 19 ++++++++++++++ kernel/rcutree_plugin.h | 42 +++++++++++++++++++++++++++--- kernel/rcutree_trace.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 125 insertions(+), 4 deletions(-) diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 8db0cdc7f450..d49046c79c59 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -152,6 +152,25 @@ struct rcu_node { wait_queue_head_t boost_wq; /* Wait queue on which to park the boost */ /* kthread. */ + unsigned long n_tasks_boosted; + /* Total number of tasks boosted. */ + unsigned long n_exp_boosts; + /* Number of tasks boosted for expedited GP. */ + unsigned long n_normal_boosts; + /* Number of tasks boosted for normal GP. */ + unsigned long n_balk_blkd_tasks; + /* Refused to boost: no blocked tasks. */ + unsigned long n_balk_exp_gp_tasks; + /* Refused to boost: nothing blocking GP. */ + unsigned long n_balk_boost_tasks; + /* Refused to boost: already boosting. */ + unsigned long n_balk_notblocked; + /* Refused to boost: RCU RS CS still running. */ + unsigned long n_balk_notyet; + /* Refused to boost: not yet time. */ + unsigned long n_balk_nos; + /* Refused to boost: not sure why, though. */ + /* This can happen due to race conditions. */ #endif /* #ifdef CONFIG_RCU_BOOST */ struct task_struct *node_kthread_task; /* kthread that takes care of this rcu_node */ diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 4e486255df63..07d346445d12 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1073,6 +1073,33 @@ static void __init __rcu_init_preempt(void) #include "rtmutex_common.h" +#ifdef CONFIG_RCU_TRACE + +static void rcu_initiate_boost_trace(struct rcu_node *rnp) +{ + if (list_empty(&rnp->blkd_tasks)) + rnp->n_balk_blkd_tasks++; + else if (rnp->exp_tasks == NULL && rnp->gp_tasks == NULL) + rnp->n_balk_exp_gp_tasks++; + else if (rnp->gp_tasks != NULL && rnp->boost_tasks != NULL) + rnp->n_balk_boost_tasks++; + else if (rnp->gp_tasks != NULL && rnp->qsmask != 0) + rnp->n_balk_notblocked++; + else if (rnp->gp_tasks != NULL && + ULONG_CMP_GE(jiffies, rnp->boost_time)) + rnp->n_balk_notyet++; + else + rnp->n_balk_nos++; +} + +#else /* #ifdef CONFIG_RCU_TRACE */ + +static void rcu_initiate_boost_trace(struct rcu_node *rnp) +{ +} + +#endif /* #else #ifdef CONFIG_RCU_TRACE */ + /* * Carry out RCU priority boosting on the task indicated by ->exp_tasks * or ->boost_tasks, advancing the pointer to the next task in the @@ -1108,10 +1135,14 @@ static int rcu_boost(struct rcu_node *rnp) * expedited grace period must boost all blocked tasks, including * those blocking the pre-existing normal grace period. */ - if (rnp->exp_tasks != NULL) + if (rnp->exp_tasks != NULL) { tb = rnp->exp_tasks; - else + rnp->n_exp_boosts++; + } else { tb = rnp->boost_tasks; + rnp->n_normal_boosts++; + } + rnp->n_tasks_boosted++; /* * We boost task t by manufacturing an rt_mutex that appears to @@ -1197,8 +1228,10 @@ static void rcu_initiate_boost(struct rcu_node *rnp) { struct task_struct *t; - if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) + if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) { + rnp->n_balk_exp_gp_tasks++; return; + } if (rnp->exp_tasks != NULL || (rnp->gp_tasks != NULL && rnp->boost_tasks == NULL && @@ -1209,7 +1242,8 @@ static void rcu_initiate_boost(struct rcu_node *rnp) t = rnp->boost_kthread_task; if (t != NULL) wake_up_process(t); - } + } else + rcu_initiate_boost_trace(rnp); } /* diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index 1cedf94e2c4f..ead5736f99b5 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -157,6 +157,71 @@ static const struct file_operations rcudata_csv_fops = { .release = single_release, }; +#ifdef CONFIG_RCU_BOOST + +static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp) +{ + seq_printf(m, "%d:%d tasks=%c%c%c%c ntb=%lu neb=%lu nnb=%lu " + "j=%04x bt=%04x\n", + rnp->grplo, rnp->grphi, + "T."[list_empty(&rnp->blkd_tasks)], + "N."[!rnp->gp_tasks], + "E."[!rnp->exp_tasks], + "B."[!rnp->boost_tasks], + rnp->n_tasks_boosted, rnp->n_exp_boosts, + rnp->n_normal_boosts, + (int)(jiffies & 0xffff), + (int)(rnp->boost_time & 0xffff)); + seq_printf(m, "%s: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n", + " balk", + rnp->n_balk_blkd_tasks, + rnp->n_balk_exp_gp_tasks, + rnp->n_balk_boost_tasks, + rnp->n_balk_notblocked, + rnp->n_balk_notyet, + rnp->n_balk_nos); +} + +static int show_rcu_node_boost(struct seq_file *m, void *unused) +{ + struct rcu_node *rnp; + + rcu_for_each_leaf_node(&rcu_preempt_state, rnp) + print_one_rcu_node_boost(m, rnp); + return 0; +} + +static int rcu_node_boost_open(struct inode *inode, struct file *file) +{ + return single_open(file, show_rcu_node_boost, NULL); +} + +static const struct file_operations rcu_node_boost_fops = { + .owner = THIS_MODULE, + .open = rcu_node_boost_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +/* + * Create the rcuboost debugfs entry. Standard error return. + */ +static int rcu_boost_trace_create_file(struct dentry *rcudir) +{ + return !debugfs_create_file("rcuboost", 0444, rcudir, NULL, + &rcu_node_boost_fops); +} + +#else /* #ifdef CONFIG_RCU_BOOST */ + +static int rcu_boost_trace_create_file(struct dentry *rcudir) +{ + return 0; /* There cannot be an error if we didn't create it! */ +} + +#endif /* #else #ifdef CONFIG_RCU_BOOST */ + static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp) { unsigned long gpnum; @@ -315,6 +380,9 @@ static int __init rcutree_trace_init(void) if (!retval) goto free_out; + if (rcu_boost_trace_create_file(rcudir)) + goto free_out; + retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops); if (!retval) goto free_out; -- cgit v1.2.2 From 2fa218d8bbcff239302f9f36e19d7187077dd636 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 27 Mar 2011 21:37:58 -0700 Subject: rcu: Update RCU's trace.txt documentation for new format The trace.txt file had obsolete output for the debugfs rcu/rcudata file, so update it. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- Documentation/RCU/trace.txt | 65 ++++++++++++++++++++++++--------------------- 1 file changed, 34 insertions(+), 31 deletions(-) diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index 5a704ffd0bbc..13dbf9bccdbf 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -21,23 +21,23 @@ rcu_pending() function decided that there was core RCU work to do). The output of "cat rcu/rcudata" looks as follows: rcu_sched: - 0 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=10951/1/0 df=1101 of=0 ri=36 ql=0 b=10 - 1 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=16117/1/0 df=1015 of=0 ri=0 ql=0 b=10 - 2 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=1445/1/0 df=1839 of=0 ri=0 ql=0 b=10 - 3 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=6681/1/0 df=1545 of=0 ri=0 ql=0 b=10 - 4 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=1003/1/0 df=1992 of=0 ri=0 ql=0 b=10 - 5 c=17829 g=17830 pq=1 pqc=17829 qp=1 dt=3887/1/0 df=3331 of=0 ri=4 ql=2 b=10 - 6 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=859/1/0 df=3224 of=0 ri=0 ql=0 b=10 - 7 c=17829 g=17830 pq=0 pqc=17829 qp=1 dt=3761/1/0 df=1818 of=0 ri=0 ql=2 b=10 + 0!c=423090 g=423091 pq=1 pqc=423090 qp=1 dt=86475/1/0 df=16319 of=163 ri=1519 ql=0 b=10 ci=1460693 co=1648 ca=6448 + 1!c=423329 g=423330 pq=1 pqc=423329 qp=1 dt=90875/1/0 df=16231 of=157 ri=1249 ql=0 b=10 ci=1459002 co=1614 ca=3310 + 2!c=423370 g=423371 pq=1 pqc=423370 qp=1 dt=69661/1/0 df=16125 of=163 ri=1469 ql=0 b=10 ci=1610701 co=2015 ca=2378 + 3!c=422967 g=422968 pq=1 pqc=422967 qp=1 dt=70349/1/0 df=12528 of=163 ri=1450 ql=0 b=10 ci=1427543 co=1430 ca=897 + 4!c=423196 g=423197 pq=1 pqc=423196 qp=0 dt=38935/1/0 df=10959 of=177 ri=1657 ql=0 b=10 ci=1562249 co=1896 ca=533 + 5!c=422950 g=422951 pq=1 pqc=422950 qp=0 dt=25127/1/0 df=5895 of=167 ri=1549 ql=0 b=10 ci=1777260 co=2137 ca=274 + 6!c=423396 g=423397 pq=1 pqc=423396 qp=1 dt=22639/1/0 df=4590 of=149 ri=1572 ql=0 b=10 ci=1471186 co=1530 ca=243 + 7 c=460203 g=460203 pq=1 pqc=460202 qp=0 dt=937087/1/0 df=3298 of=149 ri=1584 ql=6 b=10 ci=4026154 co=1948 ca=135 rcu_bh: - 0 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=10951/1/0 df=0 of=0 ri=0 ql=0 b=10 - 1 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=16117/1/0 df=13 of=0 ri=0 ql=0 b=10 - 2 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=1445/1/0 df=15 of=0 ri=0 ql=0 b=10 - 3 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=6681/1/0 df=9 of=0 ri=0 ql=0 b=10 - 4 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=1003/1/0 df=15 of=0 ri=0 ql=0 b=10 - 5 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=3887/1/0 df=15 of=0 ri=0 ql=0 b=10 - 6 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=859/1/0 df=15 of=0 ri=0 ql=0 b=10 - 7 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=3761/1/0 df=15 of=0 ri=0 ql=0 b=10 + 0!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=86475/1/0 df=11 of=0 ri=0 ql=0 b=10 ci=112 co=0 ca=0 + 1!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=90875/1/0 df=15 of=0 ri=0 ql=0 b=10 ci=143 co=0 ca=0 + 2!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=69661/1/0 df=21 of=0 ri=1 ql=0 b=10 ci=88 co=0 ca=0 + 3!c=18446744073709551494 g=18446744073709551494 pq=1 pqc=18446744073709551493 qp=0 dt=70349/1/0 df=13 of=0 ri=0 ql=0 b=10 ci=100 co=0 ca=0 + 4!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=38935/1/0 df=17 of=0 ri=0 ql=0 b=10 ci=36 co=0 ca=0 + 5!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=25127/1/0 df=7 of=0 ri=0 ql=0 b=10 ci=32 co=0 ca=0 + 6!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=22639/1/0 df=9 of=0 ri=0 ql=0 b=10 ci=44 co=0 ca=0 + 7 c=182 g=182 pq=1 pqc=181 qp=0 dt=937087/1/0 df=14 of=0 ri=1 ql=0 b=10 ci=627 co=0 ca=0 The first section lists the rcu_data structures for rcu_sched, the second for rcu_bh. Note that CONFIG_TREE_PREEMPT_RCU kernels will have an @@ -52,17 +52,18 @@ o The number at the beginning of each line is the CPU number. substantially larger than the number of actual CPUs. o "c" is the count of grace periods that this CPU believes have - completed. CPUs in dynticks idle mode may lag quite a ways - behind, for example, CPU 4 under "rcu_sched" above, which has - slept through the past 25 RCU grace periods. It is not unusual - to see CPUs lagging by thousands of grace periods. + completed. Offlined CPUs and CPUs in dynticks idle mode may + lag quite a ways behind, for example, CPU 6 under "rcu_sched" + above, which has been offline through not quite 40,000 RCU grace + periods. It is not unusual to see CPUs lagging by thousands of + grace periods. o "g" is the count of grace periods that this CPU believes have - started. Again, CPUs in dynticks idle mode may lag behind. - If the "c" and "g" values are equal, this CPU has already - reported a quiescent state for the last RCU grace period that - it is aware of, otherwise, the CPU believes that it owes RCU a - quiescent state. + started. Again, offlined CPUs and CPUs in dynticks idle mode + may lag behind. If the "c" and "g" values are equal, this CPU + has already reported a quiescent state for the last RCU grace + period that it is aware of, otherwise, the CPU believes that it + owes RCU a quiescent state. o "pq" indicates that this CPU has passed through a quiescent state for the current grace period. It is possible for "pq" to be @@ -81,14 +82,16 @@ o "pqc" indicates which grace period the last-observed quiescent the next grace period! o "qp" indicates that RCU still expects a quiescent state from - this CPU. + this CPU. Offlined CPUs and CPUs in dyntick idle mode might + well have qp=1, which is OK: RCU is still ignoring them. o "dt" is the current value of the dyntick counter that is incremented when entering or leaving dynticks idle state, either by the - scheduler or by irq. The number after the first "/" is the - interrupt nesting depth when in dyntick-idle state, or one - greater than the interrupt-nesting depth otherwise. The number - after the second "/" is the NMI nesting depth. + scheduler or by irq. This number is even if the CPU is in + dyntick idle mode and odd otherwise. The number after the first + "/" is the interrupt nesting depth when in dyntick-idle state, + or one greater than the interrupt-nesting depth otherwise. + The number after the second "/" is the NMI nesting depth. This field is displayed only for CONFIG_NO_HZ kernels. @@ -100,7 +103,7 @@ o "df" is the number of times that some other CPU has forced a o "of" is the number of times that some other CPU has forced a quiescent state on behalf of this CPU due to this CPU being - offline. In a perfect world, this might neve happen, but it + offline. In a perfect world, this might never happen, but it turns out that offlining and onlining a CPU can take several grace periods, and so there is likely to be an extended period of time when RCU believes that the CPU is online when it really is not. -- cgit v1.2.2 From 0ac3d136b2e3cdf1161178223bc5da14a06241d0 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 28 Mar 2011 15:47:07 -0700 Subject: rcu: add callback-queue information to rcudata output This commit adds an indication of the state of the callback queue using a string of four characters following the "ql=" integer queue length. The first character is "N" if there are callbacks that have been queued that are not yet ready to be handled by the next grace period, or "." otherwise. The second character is "R" if there are callbacks queued that are ready to be handled by the next grace period, or "." otherwise. The third character is "W" if there are callbacks waiting for the current grace period, or "." otherwise. Finally, the fourth character is "D" if there are callbacks that have been handled by a prior grace period and are waiting to be invoked, or ".". Note that callbacks that are in the process of being invoked are not shown. These callbacks would have been removed from the rcu_data structure's list by rcu_do_batch() prior to being executed. (These callbacks are also not reflected in the "ql=" total, FWIW.) Also, document the new callback-queue trace information. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- Documentation/RCU/trace.txt | 58 ++++++++++++++++++++++++++++++++------------- kernel/rcutree_trace.c | 21 ++++++++++++++-- 2 files changed, 61 insertions(+), 18 deletions(-) diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index 13dbf9bccdbf..5aefd5fa7af5 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -21,23 +21,23 @@ rcu_pending() function decided that there was core RCU work to do). The output of "cat rcu/rcudata" looks as follows: rcu_sched: - 0!c=423090 g=423091 pq=1 pqc=423090 qp=1 dt=86475/1/0 df=16319 of=163 ri=1519 ql=0 b=10 ci=1460693 co=1648 ca=6448 - 1!c=423329 g=423330 pq=1 pqc=423329 qp=1 dt=90875/1/0 df=16231 of=157 ri=1249 ql=0 b=10 ci=1459002 co=1614 ca=3310 - 2!c=423370 g=423371 pq=1 pqc=423370 qp=1 dt=69661/1/0 df=16125 of=163 ri=1469 ql=0 b=10 ci=1610701 co=2015 ca=2378 - 3!c=422967 g=422968 pq=1 pqc=422967 qp=1 dt=70349/1/0 df=12528 of=163 ri=1450 ql=0 b=10 ci=1427543 co=1430 ca=897 - 4!c=423196 g=423197 pq=1 pqc=423196 qp=0 dt=38935/1/0 df=10959 of=177 ri=1657 ql=0 b=10 ci=1562249 co=1896 ca=533 - 5!c=422950 g=422951 pq=1 pqc=422950 qp=0 dt=25127/1/0 df=5895 of=167 ri=1549 ql=0 b=10 ci=1777260 co=2137 ca=274 - 6!c=423396 g=423397 pq=1 pqc=423396 qp=1 dt=22639/1/0 df=4590 of=149 ri=1572 ql=0 b=10 ci=1471186 co=1530 ca=243 - 7 c=460203 g=460203 pq=1 pqc=460202 qp=0 dt=937087/1/0 df=3298 of=149 ri=1584 ql=6 b=10 ci=4026154 co=1948 ca=135 + 0!c=423090 g=423091 pq=1 pqc=423090 qp=1 dt=86475/1/0 df=16319 of=163 ri=1519 ql=0 qs=.... b=10 ci=1460693 co=1648 ca=6448 + 1!c=423329 g=423330 pq=1 pqc=423329 qp=1 dt=90875/1/0 df=16231 of=157 ri=1249 ql=0 qs=.... b=10 ci=1459002 co=1614 ca=3310 + 2!c=423370 g=423371 pq=1 pqc=423370 qp=1 dt=69661/1/0 df=16125 of=163 ri=1469 ql=0 qs=.... b=10 ci=1610701 co=2015 ca=2378 + 3!c=422967 g=422968 pq=1 pqc=422967 qp=1 dt=70349/1/0 df=12528 of=163 ri=1450 ql=0 qs=.... b=10 ci=1427543 co=1430 ca=897 + 4!c=423196 g=423197 pq=1 pqc=423196 qp=0 dt=38935/1/0 df=10959 of=177 ri=1657 ql=0 qs=.... b=10 ci=1562249 co=1896 ca=533 + 5!c=422950 g=422951 pq=1 pqc=422950 qp=0 dt=25127/1/0 df=5895 of=167 ri=1549 ql=0 qs=.... b=10 ci=1777260 co=2137 ca=274 + 6!c=423396 g=423397 pq=1 pqc=423396 qp=1 dt=22639/1/0 df=4590 of=149 ri=1572 ql=0 qs=.... b=10 ci=1471186 co=1530 ca=243 + 7 c=460203 g=460203 pq=1 pqc=460202 qp=0 dt=937087/1/0 df=3298 of=149 ri=1584 ql=6 qs=N.W. b=10 ci=4026154 co=1948 ca=135 rcu_bh: - 0!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=86475/1/0 df=11 of=0 ri=0 ql=0 b=10 ci=112 co=0 ca=0 - 1!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=90875/1/0 df=15 of=0 ri=0 ql=0 b=10 ci=143 co=0 ca=0 - 2!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=69661/1/0 df=21 of=0 ri=1 ql=0 b=10 ci=88 co=0 ca=0 - 3!c=18446744073709551494 g=18446744073709551494 pq=1 pqc=18446744073709551493 qp=0 dt=70349/1/0 df=13 of=0 ri=0 ql=0 b=10 ci=100 co=0 ca=0 - 4!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=38935/1/0 df=17 of=0 ri=0 ql=0 b=10 ci=36 co=0 ca=0 - 5!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=25127/1/0 df=7 of=0 ri=0 ql=0 b=10 ci=32 co=0 ca=0 - 6!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=22639/1/0 df=9 of=0 ri=0 ql=0 b=10 ci=44 co=0 ca=0 - 7 c=182 g=182 pq=1 pqc=181 qp=0 dt=937087/1/0 df=14 of=0 ri=1 ql=0 b=10 ci=627 co=0 ca=0 + 0!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=86475/1/0 df=11 of=0 ri=0 ql=0 qs=.... b=10 ci=112 co=0 ca=0 + 1!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=90875/1/0 df=15 of=0 ri=0 ql=0 qs=.... b=10 ci=143 co=0 ca=0 + 2!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=69661/1/0 df=21 of=0 ri=1 ql=0 qs=.... b=10 ci=88 co=0 ca=0 + 3!c=18446744073709551494 g=18446744073709551494 pq=1 pqc=18446744073709551493 qp=0 dt=70349/1/0 df=13 of=0 ri=0 ql=0 qs=.... b=10 ci=100 co=0 ca=0 + 4!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=38935/1/0 df=17 of=0 ri=0 ql=0 qs=.... b=10 ci=36 co=0 ca=0 + 5!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=25127/1/0 df=7 of=0 ri=0 ql=0 qs=.... b=10 ci=32 co=0 ca=0 + 6!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=22639/1/0 df=9 of=0 ri=0 ql=0 qs=.... b=10 ci=44 co=0 ca=0 + 7 c=182 g=182 pq=1 pqc=181 qp=0 dt=937087/1/0 df=14 of=0 ri=1 ql=0 qs=.... b=10 ci=627 co=0 ca=0 The first section lists the rcu_data structures for rcu_sched, the second for rcu_bh. Note that CONFIG_TREE_PREEMPT_RCU kernels will have an @@ -120,6 +120,32 @@ o "ql" is the number of RCU callbacks currently residing on of what state they are in (new, waiting for grace period to start, waiting for grace period to end, ready to invoke). +o "qs" gives an indication of the state of the callback queue + with four characters: + + "N" Indicates that there are callbacks queued that are not + ready to be handled by the next grace period, and thus + will be handled by the grace period following the next + one. + + "R" Indicates that there are callbacks queued that are + ready to be handled by the next grace period. + + "W" Indicates that there are callbacks queued that are + waiting on the current grace period. + + "D" Indicates that there are callbacks queued that have + already been handled by a prior grace period, and are + thus waiting to be invoked. Note that callbacks in + the process of being invoked are not counted here. + Callbacks in the process of being invoked are those + that have been removed from the rcu_data structures + queues by rcu_do_batch(), but which have not yet been + invoked. + + If there are no callbacks in a given one of the above states, + the corresponding character is replaced by ".". + o "b" is the batch limit for this CPU. If more than this number of RCU callbacks is ready to invoke, then the remainder will be deferred. diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index ead5736f99b5..afd262f91262 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -64,7 +64,16 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) rdp->dynticks_fqs); #endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi); - seq_printf(m, " ql=%ld b=%ld", rdp->qlen, rdp->blimit); + seq_printf(m, " ql=%ld qs=%c%c%c%c b=%ld", + rdp->qlen, + ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] != + rdp->nxttail[RCU_NEXT_TAIL]], + ".R"[rdp->nxttail[RCU_WAIT_TAIL] != + rdp->nxttail[RCU_NEXT_READY_TAIL]], + ".W"[rdp->nxttail[RCU_DONE_TAIL] != + rdp->nxttail[RCU_WAIT_TAIL]], + ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]], + rdp->blimit); seq_printf(m, " ci=%lu co=%lu ca=%lu\n", rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted); } @@ -121,7 +130,15 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp) rdp->dynticks_fqs); #endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, ",%lu,%lu", rdp->offline_fqs, rdp->resched_ipi); - seq_printf(m, ",%ld,%ld", rdp->qlen, rdp->blimit); + seq_printf(m, ",%ld,\"%c%c%c%c\",%ld", rdp->qlen, + ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] != + rdp->nxttail[RCU_NEXT_TAIL]], + ".R"[rdp->nxttail[RCU_WAIT_TAIL] != + rdp->nxttail[RCU_NEXT_READY_TAIL]], + ".W"[rdp->nxttail[RCU_DONE_TAIL] != + rdp->nxttail[RCU_WAIT_TAIL]], + ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]], + rdp->blimit); seq_printf(m, ",%lu,%lu,%lu\n", rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted); } -- cgit v1.2.2 From d71df90eadfc35aa549ff9a850842673febca71f Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 29 Mar 2011 17:48:28 -0700 Subject: rcu: add tracing for RCU's kthread run states. Add tracing to help debugging situations when RCU's kthreads are not running but are supposed to be. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutree.c | 11 ++++++++++- kernel/rcutree.h | 11 +++++++++++ kernel/rcutree_plugin.h | 3 +++ kernel/rcutree_trace.c | 23 ++++++++++++++++++++--- 4 files changed, 44 insertions(+), 4 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 198e4df7d83e..d8917401cbbc 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -91,8 +91,9 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active); * handle all flavors of RCU. */ static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task); +DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status); static DEFINE_PER_CPU(wait_queue_head_t, rcu_cpu_wq); -static DEFINE_PER_CPU(char, rcu_cpu_has_work); +DEFINE_PER_CPU(char, rcu_cpu_has_work); static char rcu_kthreads_spawnable; static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu); @@ -1563,11 +1564,13 @@ static int rcu_cpu_kthread(void *arg) int cpu = (int)(long)arg; unsigned long flags; int spincnt = 0; + unsigned int *statusp = &per_cpu(rcu_cpu_kthread_status, cpu); wait_queue_head_t *wqp = &per_cpu(rcu_cpu_wq, cpu); char work; char *workp = &per_cpu(rcu_cpu_has_work, cpu); for (;;) { + *statusp = RCU_KTHREAD_WAITING; wait_event_interruptible(*wqp, *workp != 0 || kthread_should_stop()); local_bh_disable(); @@ -1575,6 +1578,7 @@ static int rcu_cpu_kthread(void *arg) local_bh_enable(); break; } + *statusp = RCU_KTHREAD_RUNNING; local_irq_save(flags); work = *workp; *workp = 0; @@ -1587,10 +1591,12 @@ static int rcu_cpu_kthread(void *arg) else spincnt = 0; if (spincnt > 10) { + *statusp = RCU_KTHREAD_YIELDING; rcu_yield(rcu_cpu_kthread_timer, (unsigned long)cpu); spincnt = 0; } } + *statusp = RCU_KTHREAD_STOPPED; return 0; } @@ -1637,10 +1643,12 @@ static int rcu_node_kthread(void *arg) struct task_struct *t; for (;;) { + rnp->node_kthread_status = RCU_KTHREAD_WAITING; wait_event_interruptible(rnp->node_wq, rnp->wakemask != 0 || kthread_should_stop()); if (kthread_should_stop()) break; + rnp->node_kthread_status = RCU_KTHREAD_RUNNING; raw_spin_lock_irqsave(&rnp->lock, flags); mask = rnp->wakemask; rnp->wakemask = 0; @@ -1661,6 +1669,7 @@ static int rcu_node_kthread(void *arg) preempt_enable(); } } + rnp->node_kthread_status = RCU_KTHREAD_STOPPED; return 0; } diff --git a/kernel/rcutree.h b/kernel/rcutree.h index d49046c79c59..67341dbebd95 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -89,6 +89,13 @@ struct rcu_dynticks { atomic_t dynticks; /* Even value for dynticks-idle, else odd. */ }; +/* RCU's kthread states for tracing. */ +#define RCU_KTHREAD_STOPPED 0 +#define RCU_KTHREAD_RUNNING 1 +#define RCU_KTHREAD_WAITING 2 +#define RCU_KTHREAD_YIELDING 3 +#define RCU_KTHREAD_MAX 3 + /* * Definition for node within the RCU grace-period-detection hierarchy. */ @@ -152,6 +159,8 @@ struct rcu_node { wait_queue_head_t boost_wq; /* Wait queue on which to park the boost */ /* kthread. */ + unsigned int boost_kthread_status; + /* State of boost_kthread_task for tracing. */ unsigned long n_tasks_boosted; /* Total number of tasks boosted. */ unsigned long n_exp_boosts; @@ -179,6 +188,8 @@ struct rcu_node { wait_queue_head_t node_wq; /* Wait queue on which to park the per-node */ /* kthread. */ + unsigned int node_kthread_status; + /* State of node_kthread_task for tracing. */ } ____cacheline_internodealigned_in_smp; /* diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 07d346445d12..22a6a46de7c6 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1198,11 +1198,13 @@ static int rcu_boost_kthread(void *arg) int more2boost; for (;;) { + rnp->boost_kthread_status = RCU_KTHREAD_WAITING; wait_event_interruptible(rnp->boost_wq, rnp->boost_tasks || rnp->exp_tasks || kthread_should_stop()); if (kthread_should_stop()) break; + rnp->boost_kthread_status = RCU_KTHREAD_RUNNING; more2boost = rcu_boost(rnp); if (more2boost) spincnt++; @@ -1213,6 +1215,7 @@ static int rcu_boost_kthread(void *arg) spincnt = 0; } } + rnp->boost_kthread_status = RCU_KTHREAD_STOPPED; return 0; } diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index afd262f91262..fc40e89a028c 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -46,6 +46,16 @@ #define RCU_TREE_NONCORE #include "rcutree.h" +DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status); +DECLARE_PER_CPU(char, rcu_cpu_has_work); + +static char convert_kthread_status(unsigned int kthread_status) +{ + if (kthread_status > RCU_KTHREAD_MAX) + return '?'; + return "SRWY"[kthread_status]; +} + static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) { if (!rdp->beenonline) @@ -64,7 +74,7 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) rdp->dynticks_fqs); #endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi); - seq_printf(m, " ql=%ld qs=%c%c%c%c b=%ld", + seq_printf(m, " ql=%ld qs=%c%c%c%c kt=%d/%c b=%ld", rdp->qlen, ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] != rdp->nxttail[RCU_NEXT_TAIL]], @@ -73,6 +83,9 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) ".W"[rdp->nxttail[RCU_DONE_TAIL] != rdp->nxttail[RCU_WAIT_TAIL]], ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]], + per_cpu(rcu_cpu_has_work, rdp->cpu), + convert_kthread_status(per_cpu(rcu_cpu_kthread_status, + rdp->cpu)), rdp->blimit); seq_printf(m, " ci=%lu co=%lu ca=%lu\n", rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted); @@ -130,7 +143,7 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp) rdp->dynticks_fqs); #endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, ",%lu,%lu", rdp->offline_fqs, rdp->resched_ipi); - seq_printf(m, ",%ld,\"%c%c%c%c\",%ld", rdp->qlen, + seq_printf(m, ",%ld,\"%c%c%c%c\",%d,\"%c\",%ld", rdp->qlen, ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] != rdp->nxttail[RCU_NEXT_TAIL]], ".R"[rdp->nxttail[RCU_WAIT_TAIL] != @@ -138,6 +151,9 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp) ".W"[rdp->nxttail[RCU_DONE_TAIL] != rdp->nxttail[RCU_WAIT_TAIL]], ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]], + per_cpu(rcu_cpu_has_work, rdp->cpu), + convert_kthread_status(per_cpu(rcu_cpu_kthread_status, + rdp->cpu)), rdp->blimit); seq_printf(m, ",%lu,%lu,%lu\n", rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted); @@ -178,13 +194,14 @@ static const struct file_operations rcudata_csv_fops = { static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp) { - seq_printf(m, "%d:%d tasks=%c%c%c%c ntb=%lu neb=%lu nnb=%lu " + seq_printf(m, "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu " "j=%04x bt=%04x\n", rnp->grplo, rnp->grphi, "T."[list_empty(&rnp->blkd_tasks)], "N."[!rnp->gp_tasks], "E."[!rnp->exp_tasks], "B."[!rnp->boost_tasks], + convert_kthread_status(rnp->boost_kthread_status), rnp->n_tasks_boosted, rnp->n_exp_boosts, rnp->n_normal_boosts, (int)(jiffies & 0xffff), -- cgit v1.2.2 From 4a29865689dbb87a02e3b0fff4a4ae5041273173 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 3 Apr 2011 21:33:51 -0700 Subject: rcu: make rcutorture version numbers available through debugfs It is not possible to accurately correlate rcutorture output with that of debugfs. This patch therefore adds a debugfs file that prints out the rcutorture version number, permitting easy correlation. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- include/linux/rcupdate.h | 13 ++++++++++++- include/linux/rcutree.h | 3 +++ kernel/rcutorture.c | 8 +++++--- kernel/rcutree.c | 37 +++++++++++++++++++++++++++++++++++++ kernel/rcutree_trace.c | 28 ++++++++++++++++++++++++++++ 5 files changed, 85 insertions(+), 4 deletions(-) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index ff422d2b7f90..9e169c2ba91f 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -47,6 +47,18 @@ extern int rcutorture_runnable; /* for sysctl */ #endif /* #ifdef CONFIG_RCU_TORTURE_TEST */ +#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU) +extern void rcutorture_record_test_transition(void); +extern void rcutorture_record_progress(unsigned long vernum); +#else +static inline void rcutorture_record_test_transition(void) +{ +} +static inline void rcutorture_record_progress(unsigned long vernum) +{ +} +#endif + #define UINT_CMP_GE(a, b) (UINT_MAX / 2 >= (a) - (b)) #define UINT_CMP_LT(a, b) (UINT_MAX / 2 < (a) - (b)) #define ULONG_CMP_GE(a, b) (ULONG_MAX / 2 >= (a) - (b)) @@ -68,7 +80,6 @@ extern void call_rcu_sched(struct rcu_head *head, extern void synchronize_sched(void); extern void rcu_barrier_bh(void); extern void rcu_barrier_sched(void); -extern int sched_expedited_torture_stats(char *page); static inline void __rcu_read_lock_bh(void) { diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 3a933482734a..284dad10c55b 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -58,9 +58,12 @@ static inline void synchronize_rcu_bh_expedited(void) extern void rcu_barrier(void); +extern unsigned long rcutorture_testseq; +extern unsigned long rcutorture_vernum; extern long rcu_batches_completed(void); extern long rcu_batches_completed_bh(void); extern long rcu_batches_completed_sched(void); + extern void rcu_force_quiescent_state(void); extern void rcu_bh_force_quiescent_state(void); extern void rcu_sched_force_quiescent_state(void); diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 22b0e74e7d99..c2f58ec24751 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -131,7 +131,7 @@ struct rcu_torture { static LIST_HEAD(rcu_torture_freelist); static struct rcu_torture __rcu *rcu_torture_current; -static long rcu_torture_current_version; +static unsigned long rcu_torture_current_version; static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN]; static DEFINE_SPINLOCK(rcu_torture_lock); static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) = @@ -884,7 +884,7 @@ rcu_torture_writer(void *arg) old_rp->rtort_pipe_count++; cur_ops->deferred_free(old_rp); } - rcu_torture_current_version++; + rcutorture_record_progress(++rcu_torture_current_version); oldbatch = cur_ops->completed(); rcu_stutter_wait("rcu_torture_writer"); } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP); @@ -1064,7 +1064,7 @@ rcu_torture_printk(char *page) } cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG); cnt += sprintf(&page[cnt], - "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d " + "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d " "rtmbe: %d rtbke: %ld rtbre: %ld " "rtbf: %ld rtb: %ld nt: %ld", rcu_torture_current, @@ -1325,6 +1325,7 @@ rcu_torture_cleanup(void) int i; mutex_lock(&fullstop_mutex); + rcutorture_record_test_transition(); if (fullstop == FULLSTOP_SHUTDOWN) { printk(KERN_WARNING /* but going down anyway, so... */ "Concurrent 'rmmod rcutorture' and shutdown illegal!\n"); @@ -1616,6 +1617,7 @@ rcu_torture_init(void) } } register_reboot_notifier(&rcutorture_shutdown_nb); + rcutorture_record_test_transition(); mutex_unlock(&fullstop_mutex); return 0; diff --git a/kernel/rcutree.c b/kernel/rcutree.c index d8917401cbbc..bb84deca3319 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -101,6 +101,18 @@ static void invoke_rcu_cpu_kthread(void); #define RCU_KTHREAD_PRIO 1 /* RT priority for per-CPU kthreads. */ +/* + * Track the rcutorture test sequence number and the update version + * number within a given test. The rcutorture_testseq is incremented + * on every rcutorture module load and unload, so has an odd value + * when a test is running. The rcutorture_vernum is set to zero + * when rcutorture starts and is incremented on each rcutorture update. + * These variables enable correlating rcutorture output with the + * RCU tracing information. + */ +unsigned long rcutorture_testseq; +unsigned long rcutorture_vernum; + /* * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s * permit this function to be invoked without holding the root rcu_node @@ -192,6 +204,31 @@ void rcu_bh_force_quiescent_state(void) } EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state); +/* + * Record the number of times rcutorture tests have been initiated and + * terminated. This information allows the debugfs tracing stats to be + * correlated to the rcutorture messages, even when the rcutorture module + * is being repeatedly loaded and unloaded. In other words, we cannot + * store this state in rcutorture itself. + */ +void rcutorture_record_test_transition(void) +{ + rcutorture_testseq++; + rcutorture_vernum = 0; +} +EXPORT_SYMBOL_GPL(rcutorture_record_test_transition); + +/* + * Record the number of writer passes through the current rcutorture test. + * This is also used to correlate debugfs tracing stats with the rcutorture + * messages. + */ +void rcutorture_record_progress(unsigned long vernum) +{ + rcutorture_vernum++; +} +EXPORT_SYMBOL_GPL(rcutorture_record_progress); + /* * Force a quiescent state for RCU-sched. */ diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index fc40e89a028c..3baa235786b5 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -394,6 +394,29 @@ static const struct file_operations rcu_pending_fops = { .release = single_release, }; +static int show_rcutorture(struct seq_file *m, void *unused) +{ + seq_printf(m, "rcutorture test sequence: %lu %s\n", + rcutorture_testseq >> 1, + (rcutorture_testseq & 0x1) ? "(test in progress)" : ""); + seq_printf(m, "rcutorture update version number: %lu\n", + rcutorture_vernum); + return 0; +} + +static int rcutorture_open(struct inode *inode, struct file *file) +{ + return single_open(file, show_rcutorture, NULL); +} + +static const struct file_operations rcutorture_fops = { + .owner = THIS_MODULE, + .open = rcutorture_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + static struct dentry *rcudir; static int __init rcutree_trace_init(void) @@ -430,6 +453,11 @@ static int __init rcutree_trace_init(void) NULL, &rcu_pending_fops); if (!retval) goto free_out; + + retval = debugfs_create_file("rcutorture", 0444, rcudir, + NULL, &rcutorture_fops); + if (!retval) + goto free_out; return 0; free_out: debugfs_remove_recursive(rcudir); -- cgit v1.2.2 From 90e6ac3657fd3b0446d585082000af3cf46439a7 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 6 Apr 2011 15:20:47 -0700 Subject: rcu: update tracing documentation for new rcutorture and rcuboost This commit documents the new debugfs rcu/rcutorture and rcu/rcuboost trace files. The description has been updated as suggested by Josh Triplett. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- Documentation/RCU/trace.txt | 186 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 161 insertions(+), 25 deletions(-) diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index 5aefd5fa7af5..40b530dd0fc7 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -10,34 +10,46 @@ for rcutree and next for rcutiny. CONFIG_TREE_RCU and CONFIG_TREE_PREEMPT_RCU debugfs Files and Formats -These implementations of RCU provides five debugfs files under the -top-level directory RCU: rcu/rcudata (which displays fields in struct -rcu_data), rcu/rcudata.csv (which is a .csv spreadsheet version of -rcu/rcudata), rcu/rcugp (which displays grace-period counters), -rcu/rcuhier (which displays the struct rcu_node hierarchy), and -rcu/rcu_pending (which displays counts of the reasons that the -rcu_pending() function decided that there was core RCU work to do). +These implementations of RCU provides several debugfs files under the +top-level directory "rcu": + +rcu/rcudata: + Displays fields in struct rcu_data. +rcu/rcudata.csv: + Comma-separated values spreadsheet version of rcudata. +rcu/rcugp: + Displays grace-period counters. +rcu/rcuhier: + Displays the struct rcu_node hierarchy. +rcu/rcu_pending: + Displays counts of the reasons rcu_pending() decided that RCU had + work to do. +rcu/rcutorture: + Displays rcutorture test progress. +rcu/rcuboost: + Displays RCU boosting statistics. Only present if + CONFIG_RCU_BOOST=y. The output of "cat rcu/rcudata" looks as follows: rcu_sched: - 0!c=423090 g=423091 pq=1 pqc=423090 qp=1 dt=86475/1/0 df=16319 of=163 ri=1519 ql=0 qs=.... b=10 ci=1460693 co=1648 ca=6448 - 1!c=423329 g=423330 pq=1 pqc=423329 qp=1 dt=90875/1/0 df=16231 of=157 ri=1249 ql=0 qs=.... b=10 ci=1459002 co=1614 ca=3310 - 2!c=423370 g=423371 pq=1 pqc=423370 qp=1 dt=69661/1/0 df=16125 of=163 ri=1469 ql=0 qs=.... b=10 ci=1610701 co=2015 ca=2378 - 3!c=422967 g=422968 pq=1 pqc=422967 qp=1 dt=70349/1/0 df=12528 of=163 ri=1450 ql=0 qs=.... b=10 ci=1427543 co=1430 ca=897 - 4!c=423196 g=423197 pq=1 pqc=423196 qp=0 dt=38935/1/0 df=10959 of=177 ri=1657 ql=0 qs=.... b=10 ci=1562249 co=1896 ca=533 - 5!c=422950 g=422951 pq=1 pqc=422950 qp=0 dt=25127/1/0 df=5895 of=167 ri=1549 ql=0 qs=.... b=10 ci=1777260 co=2137 ca=274 - 6!c=423396 g=423397 pq=1 pqc=423396 qp=1 dt=22639/1/0 df=4590 of=149 ri=1572 ql=0 qs=.... b=10 ci=1471186 co=1530 ca=243 - 7 c=460203 g=460203 pq=1 pqc=460202 qp=0 dt=937087/1/0 df=3298 of=149 ri=1584 ql=6 qs=N.W. b=10 ci=4026154 co=1948 ca=135 + 0!c=423090 g=423091 pq=1 pqc=423090 qp=1 dt=86475/1/0 df=16319 of=163 ri=1519 ql=0 qs=.... kt=0/W b=10 ci=1460693 co=1648 ca=6448 + 1!c=423329 g=423330 pq=1 pqc=423329 qp=1 dt=90875/1/0 df=16231 of=157 ri=1249 ql=0 qs=.... kt=0/W b=10 ci=1459002 co=1614 ca=3310 + 2!c=423370 g=423371 pq=1 pqc=423370 qp=1 dt=69661/1/0 df=16125 of=163 ri=1469 ql=0 qs=.... kt=0/W b=10 ci=1610701 co=2015 ca=2378 + 3!c=422967 g=422968 pq=1 pqc=422967 qp=1 dt=70349/1/0 df=12528 of=163 ri=1450 ql=0 qs=.... kt=0/W b=10 ci=1427543 co=1430 ca=897 + 4!c=423196 g=423197 pq=1 pqc=423196 qp=0 dt=38935/1/0 df=10959 of=177 ri=1657 ql=0 qs=.... kt=0/W b=10 ci=1562249 co=1896 ca=533 + 5!c=422950 g=422951 pq=1 pqc=422950 qp=0 dt=25127/1/0 df=5895 of=167 ri=1549 ql=0 qs=.... kt=0/W b=10 ci=1777260 co=2137 ca=274 + 6!c=423396 g=423397 pq=1 pqc=423396 qp=1 dt=22639/1/0 df=4590 of=149 ri=1572 ql=0 qs=.... kt=0/W b=10 ci=1471186 co=1530 ca=243 + 7 c=460203 g=460203 pq=1 pqc=460202 qp=0 dt=937087/1/0 df=3298 of=149 ri=1584 ql=6 qs=N.W. kt=0/W b=10 ci=4026154 co=1948 ca=135 rcu_bh: - 0!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=86475/1/0 df=11 of=0 ri=0 ql=0 qs=.... b=10 ci=112 co=0 ca=0 - 1!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=90875/1/0 df=15 of=0 ri=0 ql=0 qs=.... b=10 ci=143 co=0 ca=0 - 2!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=69661/1/0 df=21 of=0 ri=1 ql=0 qs=.... b=10 ci=88 co=0 ca=0 - 3!c=18446744073709551494 g=18446744073709551494 pq=1 pqc=18446744073709551493 qp=0 dt=70349/1/0 df=13 of=0 ri=0 ql=0 qs=.... b=10 ci=100 co=0 ca=0 - 4!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=38935/1/0 df=17 of=0 ri=0 ql=0 qs=.... b=10 ci=36 co=0 ca=0 - 5!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=25127/1/0 df=7 of=0 ri=0 ql=0 qs=.... b=10 ci=32 co=0 ca=0 - 6!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=22639/1/0 df=9 of=0 ri=0 ql=0 qs=.... b=10 ci=44 co=0 ca=0 - 7 c=182 g=182 pq=1 pqc=181 qp=0 dt=937087/1/0 df=14 of=0 ri=1 ql=0 qs=.... b=10 ci=627 co=0 ca=0 + 0!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=86475/1/0 df=11 of=0 ri=0 ql=0 qs=.... kt=0/W b=10 ci=112 co=0 ca=0 + 1!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=90875/1/0 df=15 of=0 ri=0 ql=0 qs=.... kt=0/W b=10 ci=143 co=0 ca=0 + 2!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=69661/1/0 df=21 of=0 ri=1 ql=0 qs=.... kt=0/W b=10 ci=88 co=0 ca=0 + 3!c=18446744073709551494 g=18446744073709551494 pq=1 pqc=18446744073709551493 qp=0 dt=70349/1/0 df=13 of=0 ri=0 ql=0 qs=.... kt=0/W b=10 ci=100 co=0 ca=0 + 4!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=38935/1/0 df=17 of=0 ri=0 ql=0 qs=.... kt=0/W b=10 ci=36 co=0 ca=0 + 5!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=25127/1/0 df=7 of=0 ri=0 ql=0 qs=.... kt=0/W b=10 ci=32 co=0 ca=0 + 6!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=22639/1/0 df=9 of=0 ri=0 ql=0 qs=.... kt=0/W b=10 ci=44 co=0 ca=0 + 7 c=182 g=182 pq=1 pqc=181 qp=0 dt=937087/1/0 df=14 of=0 ri=1 ql=0 qs=.... kt=0/W b=10 ci=627 co=0 ca=0 The first section lists the rcu_data structures for rcu_sched, the second for rcu_bh. Note that CONFIG_TREE_PREEMPT_RCU kernels will have an @@ -146,6 +158,23 @@ o "qs" gives an indication of the state of the callback queue If there are no callbacks in a given one of the above states, the corresponding character is replaced by ".". +o "kt" is the per-CPU kernel-thread state. The digit preceding + the slash is zero if there is no work pending and 1 otherwise. + The character after the slash is as follows: + + "S" The kernel thread is stopped, in other words, all + CPUs corresponding to this rcu_node structure are + offline. + + "R" The kernel thread is running. + + "W" The kernel thread is waiting because there is no work + for it to do. + + "Y" The kernel thread is yielding to avoid hogging CPU. + + "?" Unknown value, indicates a bug. + o "b" is the batch limit for this CPU. If more than this number of RCU callbacks is ready to invoke, then the remainder will be deferred. @@ -356,6 +385,113 @@ o "nn" is the number of times that this CPU needed nothing. Alert is due to short-circuit evaluation in rcu_pending(). +The output of "cat rcu/rcutorture" looks as follows: + +rcutorture test sequence: 0 (test in progress) +rcutorture update version number: 615 + +The first line shows the number of rcutorture tests that have completed +since boot. If a test is currently running, the "(test in progress)" +string will appear as shown above. The second line shows the number of +update cycles that the current test has started, or zero if there is +no test in progress. + + +The output of "cat rcu/rcuboost" looks as follows: + +0:5 tasks=.... kt=W ntb=0 neb=0 nnb=0 j=2f95 bt=300f + balk: nt=0 egt=989 bt=0 nb=0 ny=0 nos=16 +6:7 tasks=.... kt=W ntb=0 neb=0 nnb=0 j=2f95 bt=300f + balk: nt=0 egt=225 bt=0 nb=0 ny=0 nos=6 + +This information is output only for rcu_preempt. Each two-line entry +corresponds to a leaf rcu_node strcuture. The fields are as follows: + +o "n:m" is the CPU-number range for the corresponding two-line + entry. In the sample output above, the first entry covers + CPUs zero through five and the second entry covers CPUs 6 + and 7. + +o "tasks=TNEB" gives the state of the various segments of the + rnp->blocked_tasks list: + + "T" This indicates that there are some tasks that blocked + while running on one of the corresponding CPUs while + in an RCU read-side critical section. + + "N" This indicates that some of the blocked tasks are preventing + the current normal (non-expedited) grace period from + completing. + + "E" This indicates that some of the blocked tasks are preventing + the current expedited grace period from completing. + + "B" This indicates that some of the blocked tasks are in + need of RCU priority boosting. + + Each character is replaced with "." if the corresponding + condition does not hold. + +o "kt" is the state of the RCU priority-boosting kernel + thread associated with the corresponding rcu_node structure. + The state can be one of the following: + + "S" The kernel thread is stopped, in other words, all + CPUs corresponding to this rcu_node structure are + offline. + + "R" The kernel thread is running. + + "W" The kernel thread is waiting because there is no work + for it to do. + + "Y" The kernel thread is yielding to avoid hogging CPU. + + "?" Unknown value, indicates a bug. + +o "ntb" is the number of tasks boosted. + +o "neb" is the number of tasks boosted in order to complete an + expedited grace period. + +o "nnb" is the number of tasks boosted in order to complete a + normal (non-expedited) grace period. When boosting a task + that was blocking both an expedited and a normal grace period, + it is counted against the expedited total above. + +o "j" is the low-order 16 bits of the jiffies counter in + hexadecimal. + +o "bt" is the low-order 16 bits of the value that the jiffies + counter will have when we next start boosting, assuming that + the current grace period does not end beforehand. This is + also in hexadecimal. + +o "balk: nt" counts the number of times we didn't boost (in + other words, we balked) even though it was time to boost because + there were no blocked tasks to boost. This situation occurs + when there is one blocked task on one rcu_node structure and + none on some other rcu_node structure. + +o "egt" counts the number of times we balked because although + there were blocked tasks, none of them were blocking the + current grace period, whether expedited or otherwise. + +o "bt" counts the number of times we balked because boosting + had already been initiated for the current grace period. + +o "nb" counts the number of times we balked because there + was at least one task blocking the current non-expedited grace + period that never had blocked. If it is already running, it + just won't help to boost its priority! + +o "ny" counts the number of times we balked because it was + not yet time to start boosting. + +o "nos" counts the number of times we balked for other + reasons, e.g., the grace period ended first. + + CONFIG_TINY_RCU and CONFIG_TINY_PREEMPT_RCU debugfs Files and Formats These implementations of RCU provides a single debugfs file under the @@ -422,9 +558,9 @@ o "neb" is the number of expedited grace periods that have had o "nnb" is the number of normal grace periods that have had to resort to RCU priority boosting since boot. -o "j" is the low-order 12 bits of the jiffies counter in hexadecimal. +o "j" is the low-order 16 bits of the jiffies counter in hexadecimal. -o "bt" is the low-order 12 bits of the value that the jiffies counter +o "bt" is the low-order 16 bits of the value that the jiffies counter will have at the next time that boosting is scheduled to begin. o In the line beginning with "normal balk", the fields are as follows: -- cgit v1.2.2 From a9f4793d8900dc5dc09b3951bdcd4731290e06fe Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 2 May 2011 03:46:10 -0700 Subject: rcu: fix tracing bug thinko on boost-balk attribution The rcu_initiate_boost_trace() function mis-attributed refusals to initiate RCU priority boosting that were in fact due to its not yet being time to boost. This patch fixes the faulty comparison. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- kernel/rcutree_plugin.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 22a6a46de7c6..a21413d0581d 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1086,7 +1086,7 @@ static void rcu_initiate_boost_trace(struct rcu_node *rnp) else if (rnp->gp_tasks != NULL && rnp->qsmask != 0) rnp->n_balk_notblocked++; else if (rnp->gp_tasks != NULL && - ULONG_CMP_GE(jiffies, rnp->boost_time)) + ULONG_CMP_LT(jiffies, rnp->boost_time)) rnp->n_balk_notyet++; else rnp->n_balk_nos++; -- cgit v1.2.2 From 15ba0ba860871cf74b48b1bb47c26c91a66126f3 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 6 Apr 2011 16:01:16 -0700 Subject: rcu: add grace-period age and more kthread state to tracing This commit adds the age in jiffies of the current grace period along with the duration in jiffies of the longest grace period since boot to the rcu/rcugp debugfs file. It also adds an additional "O" state to kthread tracing to differentiate between the kthread waiting due to having nothing to do on the one hand and waiting due to being on the wrong CPU on the other hand. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- Documentation/RCU/trace.txt | 12 ++++++++++-- kernel/rcutree.c | 10 ++++++++++ kernel/rcutree.h | 7 +++++-- kernel/rcutree_trace.c | 37 +++++++++++++++++++++++++++++-------- 4 files changed, 54 insertions(+), 12 deletions(-) diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index 40b530dd0fc7..fd4bffb6e8c9 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -159,8 +159,8 @@ o "qs" gives an indication of the state of the callback queue the corresponding character is replaced by ".". o "kt" is the per-CPU kernel-thread state. The digit preceding - the slash is zero if there is no work pending and 1 otherwise. - The character after the slash is as follows: + the first slash is zero if there is no work pending and 1 + otherwise. The character between the slashes is as follows: "S" The kernel thread is stopped, in other words, all CPUs corresponding to this rcu_node structure are @@ -171,10 +171,18 @@ o "kt" is the per-CPU kernel-thread state. The digit preceding "W" The kernel thread is waiting because there is no work for it to do. + "O" The kernel thread is waiting because it has been + forced off of its designated CPU or because its + ->cpus_allowed mask permits it to run on other than + its designated CPU. + "Y" The kernel thread is yielding to avoid hogging CPU. "?" Unknown value, indicates a bug. + The number after the final slash is the CPU that the kthread + is actually running on. + o "b" is the batch limit for this CPU. If more than this number of RCU callbacks is ready to invoke, then the remainder will be deferred. diff --git a/kernel/rcutree.c b/kernel/rcutree.c index bb84deca3319..27b6d8de82f6 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -92,6 +92,7 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active); */ static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task); DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status); +DEFINE_PER_CPU(int, rcu_cpu_kthread_cpu); static DEFINE_PER_CPU(wait_queue_head_t, rcu_cpu_wq); DEFINE_PER_CPU(char, rcu_cpu_has_work); static char rcu_kthreads_spawnable; @@ -888,6 +889,8 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) __releases(rcu_get_root(rsp)->lock) { + unsigned long gp_duration; + WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); /* @@ -895,6 +898,9 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) * is seen before the assignment to rsp->completed. */ smp_mb(); /* See above block comment. */ + gp_duration = jiffies - rsp->gp_start; + if (gp_duration > rsp->gp_max) + rsp->gp_max = gp_duration; rsp->completed = rsp->gpnum; rsp->signaled = RCU_GP_IDLE; rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ @@ -1583,12 +1589,15 @@ static int rcu_cpu_kthread_should_stop(int cpu) smp_processor_id() != cpu) { if (kthread_should_stop()) return 1; + per_cpu(rcu_cpu_kthread_status, cpu) = RCU_KTHREAD_OFFCPU; + per_cpu(rcu_cpu_kthread_cpu, cpu) = raw_smp_processor_id(); local_bh_enable(); schedule_timeout_uninterruptible(1); if (!cpumask_equal(¤t->cpus_allowed, cpumask_of(cpu))) set_cpus_allowed_ptr(current, cpumask_of(cpu)); local_bh_disable(); } + per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu; return 0; } @@ -1656,6 +1665,7 @@ static int __cpuinit rcu_spawn_one_cpu_kthread(int cpu) if (IS_ERR(t)) return PTR_ERR(t); kthread_bind(t, cpu); + per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu; WARN_ON_ONCE(per_cpu(rcu_cpu_kthread_task, cpu) != NULL); per_cpu(rcu_cpu_kthread_task, cpu) = t; wake_up_process(t); diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 67341dbebd95..37502a27a072 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -93,8 +93,9 @@ struct rcu_dynticks { #define RCU_KTHREAD_STOPPED 0 #define RCU_KTHREAD_RUNNING 1 #define RCU_KTHREAD_WAITING 2 -#define RCU_KTHREAD_YIELDING 3 -#define RCU_KTHREAD_MAX 3 +#define RCU_KTHREAD_OFFCPU 3 +#define RCU_KTHREAD_YIELDING 4 +#define RCU_KTHREAD_MAX 4 /* * Definition for node within the RCU grace-period-detection hierarchy. @@ -383,6 +384,8 @@ struct rcu_state { /* but in jiffies. */ unsigned long jiffies_stall; /* Time at which to check */ /* for CPU stalls. */ + unsigned long gp_max; /* Maximum GP duration in */ + /* jiffies. */ char *name; /* Name of structure. */ }; diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index 3baa235786b5..564b8fef2a7e 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -47,13 +47,14 @@ #include "rcutree.h" DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status); +DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_cpu); DECLARE_PER_CPU(char, rcu_cpu_has_work); static char convert_kthread_status(unsigned int kthread_status) { if (kthread_status > RCU_KTHREAD_MAX) return '?'; - return "SRWY"[kthread_status]; + return "SRWOY"[kthread_status]; } static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) @@ -74,7 +75,7 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) rdp->dynticks_fqs); #endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi); - seq_printf(m, " ql=%ld qs=%c%c%c%c kt=%d/%c b=%ld", + seq_printf(m, " ql=%ld qs=%c%c%c%c kt=%d/%c/%d b=%ld", rdp->qlen, ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] != rdp->nxttail[RCU_NEXT_TAIL]], @@ -86,6 +87,7 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) per_cpu(rcu_cpu_has_work, rdp->cpu), convert_kthread_status(per_cpu(rcu_cpu_kthread_status, rdp->cpu)), + per_cpu(rcu_cpu_kthread_cpu, rdp->cpu), rdp->blimit); seq_printf(m, " ci=%lu co=%lu ca=%lu\n", rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted); @@ -312,16 +314,35 @@ static const struct file_operations rcuhier_fops = { .release = single_release, }; +static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp) +{ + unsigned long flags; + unsigned long completed; + unsigned long gpnum; + unsigned long gpage; + unsigned long gpmax; + struct rcu_node *rnp = &rsp->node[0]; + + raw_spin_lock_irqsave(&rnp->lock, flags); + completed = rsp->completed; + gpnum = rsp->gpnum; + if (rsp->completed == rsp->gpnum) + gpage = 0; + else + gpage = jiffies - rsp->gp_start; + gpmax = rsp->gp_max; + raw_spin_unlock_irqrestore(&rnp->lock, flags); + seq_printf(m, "%s: completed=%ld gpnum=%lu age=%ld max=%ld\n", + rsp->name, completed, gpnum, gpage, gpmax); +} + static int show_rcugp(struct seq_file *m, void *unused) { #ifdef CONFIG_TREE_PREEMPT_RCU - seq_printf(m, "rcu_preempt: completed=%ld gpnum=%lu\n", - rcu_preempt_state.completed, rcu_preempt_state.gpnum); + show_one_rcugp(m, &rcu_preempt_state); #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */ - seq_printf(m, "rcu_sched: completed=%ld gpnum=%lu\n", - rcu_sched_state.completed, rcu_sched_state.gpnum); - seq_printf(m, "rcu_bh: completed=%ld gpnum=%lu\n", - rcu_bh_state.completed, rcu_bh_state.gpnum); + show_one_rcugp(m, &rcu_sched_state); + show_one_rcugp(m, &rcu_bh_state); return 0; } -- cgit v1.2.2 From 5ece5bab3ed8594ce2c85c6c6e6b82109db36ca7 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 22 Apr 2011 18:08:51 -0700 Subject: rcu: Add forward-progress diagnostic for per-CPU kthreads Increment a per-CPU counter on each pass through rcu_cpu_kthread()'s service loop, and add it to the rcudata trace output. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- Documentation/RCU/trace.txt | 39 ++++++++++++++++++++++----------------- kernel/rcutree.c | 2 ++ kernel/rcutree_trace.c | 4 +++- 3 files changed, 27 insertions(+), 18 deletions(-) diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index fd4bffb6e8c9..8173cec473aa 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -33,23 +33,23 @@ rcu/rcuboost: The output of "cat rcu/rcudata" looks as follows: rcu_sched: - 0!c=423090 g=423091 pq=1 pqc=423090 qp=1 dt=86475/1/0 df=16319 of=163 ri=1519 ql=0 qs=.... kt=0/W b=10 ci=1460693 co=1648 ca=6448 - 1!c=423329 g=423330 pq=1 pqc=423329 qp=1 dt=90875/1/0 df=16231 of=157 ri=1249 ql=0 qs=.... kt=0/W b=10 ci=1459002 co=1614 ca=3310 - 2!c=423370 g=423371 pq=1 pqc=423370 qp=1 dt=69661/1/0 df=16125 of=163 ri=1469 ql=0 qs=.... kt=0/W b=10 ci=1610701 co=2015 ca=2378 - 3!c=422967 g=422968 pq=1 pqc=422967 qp=1 dt=70349/1/0 df=12528 of=163 ri=1450 ql=0 qs=.... kt=0/W b=10 ci=1427543 co=1430 ca=897 - 4!c=423196 g=423197 pq=1 pqc=423196 qp=0 dt=38935/1/0 df=10959 of=177 ri=1657 ql=0 qs=.... kt=0/W b=10 ci=1562249 co=1896 ca=533 - 5!c=422950 g=422951 pq=1 pqc=422950 qp=0 dt=25127/1/0 df=5895 of=167 ri=1549 ql=0 qs=.... kt=0/W b=10 ci=1777260 co=2137 ca=274 - 6!c=423396 g=423397 pq=1 pqc=423396 qp=1 dt=22639/1/0 df=4590 of=149 ri=1572 ql=0 qs=.... kt=0/W b=10 ci=1471186 co=1530 ca=243 - 7 c=460203 g=460203 pq=1 pqc=460202 qp=0 dt=937087/1/0 df=3298 of=149 ri=1584 ql=6 qs=N.W. kt=0/W b=10 ci=4026154 co=1948 ca=135 + 0 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=545/1/0 df=50 of=0 ri=0 ql=163 qs=NRW. kt=0/W/0 ktl=ebc3 b=10 ci=153737 co=0 ca=0 + 1 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=967/1/0 df=58 of=0 ri=0 ql=634 qs=NRW. kt=0/W/1 ktl=58c b=10 ci=191037 co=0 ca=0 + 2 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=1081/1/0 df=175 of=0 ri=0 ql=74 qs=N.W. kt=0/W/2 ktl=da94 b=10 ci=75991 co=0 ca=0 + 3 c=20942 g=20943 pq=1 pqc=20942 qp=1 dt=1846/0/0 df=404 of=0 ri=0 ql=0 qs=.... kt=0/W/3 ktl=d1cd b=10 ci=72261 co=0 ca=0 + 4 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=369/1/0 df=83 of=0 ri=0 ql=48 qs=N.W. kt=0/W/4 ktl=e0e7 b=10 ci=128365 co=0 ca=0 + 5 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=381/1/0 df=64 of=0 ri=0 ql=169 qs=NRW. kt=0/W/5 ktl=fb2f b=10 ci=164360 co=0 ca=0 + 6 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=1037/1/0 df=183 of=0 ri=0 ql=62 qs=N.W. kt=0/W/6 ktl=d2ad b=10 ci=65663 co=0 ca=0 + 7 c=20897 g=20897 pq=1 pqc=20896 qp=0 dt=1572/0/0 df=382 of=0 ri=0 ql=0 qs=.... kt=0/W/7 ktl=cf15 b=10 ci=75006 co=0 ca=0 rcu_bh: - 0!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=86475/1/0 df=11 of=0 ri=0 ql=0 qs=.... kt=0/W b=10 ci=112 co=0 ca=0 - 1!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=90875/1/0 df=15 of=0 ri=0 ql=0 qs=.... kt=0/W b=10 ci=143 co=0 ca=0 - 2!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=69661/1/0 df=21 of=0 ri=1 ql=0 qs=.... kt=0/W b=10 ci=88 co=0 ca=0 - 3!c=18446744073709551494 g=18446744073709551494 pq=1 pqc=18446744073709551493 qp=0 dt=70349/1/0 df=13 of=0 ri=0 ql=0 qs=.... kt=0/W b=10 ci=100 co=0 ca=0 - 4!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=38935/1/0 df=17 of=0 ri=0 ql=0 qs=.... kt=0/W b=10 ci=36 co=0 ca=0 - 5!c=18446744073709551494 g=18446744073709551494 pq=0 pqc=18446744073709551493 qp=1 dt=25127/1/0 df=7 of=0 ri=0 ql=0 qs=.... kt=0/W b=10 ci=32 co=0 ca=0 - 6!c=18446744073709551496 g=18446744073709551496 pq=1 pqc=18446744073709551495 qp=0 dt=22639/1/0 df=9 of=0 ri=0 ql=0 qs=.... kt=0/W b=10 ci=44 co=0 ca=0 - 7 c=182 g=182 pq=1 pqc=181 qp=0 dt=937087/1/0 df=14 of=0 ri=1 ql=0 qs=.... kt=0/W b=10 ci=627 co=0 ca=0 + 0 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=545/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/0 ktl=ebc3 b=10 ci=0 co=0 ca=0 + 1 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=967/1/0 df=3 of=0 ri=1 ql=0 qs=.... kt=0/W/1 ktl=58c b=10 ci=151 co=0 ca=0 + 2 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=1081/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/2 ktl=da94 b=10 ci=0 co=0 ca=0 + 3 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=1846/0/0 df=8 of=0 ri=1 ql=0 qs=.... kt=0/W/3 ktl=d1cd b=10 ci=0 co=0 ca=0 + 4 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=369/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/4 ktl=e0e7 b=10 ci=0 co=0 ca=0 + 5 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=381/1/0 df=4 of=0 ri=1 ql=0 qs=.... kt=0/W/5 ktl=fb2f b=10 ci=0 co=0 ca=0 + 6 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=1037/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/6 ktl=d2ad b=10 ci=0 co=0 ca=0 + 7 c=1474 g=1474 pq=1 pqc=1473 qp=0 dt=1572/0/0 df=8 of=0 ri=1 ql=0 qs=.... kt=0/W/7 ktl=cf15 b=10 ci=0 co=0 ca=0 The first section lists the rcu_data structures for rcu_sched, the second for rcu_bh. Note that CONFIG_TREE_PREEMPT_RCU kernels will have an @@ -160,7 +160,8 @@ o "qs" gives an indication of the state of the callback queue o "kt" is the per-CPU kernel-thread state. The digit preceding the first slash is zero if there is no work pending and 1 - otherwise. The character between the slashes is as follows: + otherwise. The character between the first pair of slashes is + as follows: "S" The kernel thread is stopped, in other words, all CPUs corresponding to this rcu_node structure are @@ -183,6 +184,10 @@ o "kt" is the per-CPU kernel-thread state. The digit preceding The number after the final slash is the CPU that the kthread is actually running on. +o "ktl" is the low-order 16 bits (in hexadecimal) of the count of + the number of times that this CPU's per-CPU kthread has gone + through its loop servicing invoke_rcu_cpu_kthread() requests. + o "b" is the batch limit for this CPU. If more than this number of RCU callbacks is ready to invoke, then the remainder will be deferred. diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 27b6d8de82f6..575d6414763e 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -93,6 +93,7 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active); static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task); DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status); DEFINE_PER_CPU(int, rcu_cpu_kthread_cpu); +DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); static DEFINE_PER_CPU(wait_queue_head_t, rcu_cpu_wq); DEFINE_PER_CPU(char, rcu_cpu_has_work); static char rcu_kthreads_spawnable; @@ -1625,6 +1626,7 @@ static int rcu_cpu_kthread(void *arg) break; } *statusp = RCU_KTHREAD_RUNNING; + per_cpu(rcu_cpu_kthread_loops, cpu)++; local_irq_save(flags); work = *workp; *workp = 0; diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index 564b8fef2a7e..9678cc3650f5 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -48,6 +48,7 @@ DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status); DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_cpu); +DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); DECLARE_PER_CPU(char, rcu_cpu_has_work); static char convert_kthread_status(unsigned int kthread_status) @@ -75,7 +76,7 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) rdp->dynticks_fqs); #endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi); - seq_printf(m, " ql=%ld qs=%c%c%c%c kt=%d/%c/%d b=%ld", + seq_printf(m, " ql=%ld qs=%c%c%c%c kt=%d/%c/%d ktl=%x b=%ld", rdp->qlen, ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] != rdp->nxttail[RCU_NEXT_TAIL]], @@ -88,6 +89,7 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) convert_kthread_status(per_cpu(rcu_cpu_kthread_status, rdp->cpu)), per_cpu(rcu_cpu_kthread_cpu, rdp->cpu), + per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff, rdp->blimit); seq_printf(m, " ci=%lu co=%lu ca=%lu\n", rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted); -- cgit v1.2.2 From fc2ecf7ec76c5ee150b83dcefc863fa03fd365fb Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Wed, 23 Feb 2011 09:42:14 -0800 Subject: rcu: Enable DEBUG_OBJECTS_RCU_HEAD from !PREEMPT The prohibition of DEBUG_OBJECTS_RCU_HEAD from !PREEMPT was due to the fixup actions. So just produce a warning from !PREEMPT. Signed-off-by: Mathieu Desnoyers Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcupdate.c | 26 +++++++++++++++++++++----- lib/Kconfig.debug | 2 +- 2 files changed, 22 insertions(+), 6 deletions(-) diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index f3240e987928..b54d6d18258c 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -142,7 +142,14 @@ static int rcuhead_fixup_init(void *addr, enum debug_obj_state state) * Ensure that queued callbacks are all executed. * If we detect that we are nested in a RCU read-side critical * section, we should simply fail, otherwise we would deadlock. + * In !PREEMPT configurations, there is no way to tell if we are + * in a RCU read-side critical section or not, so we never + * attempt any fixup and just print a warning. */ +#ifndef CONFIG_PREEMPT + WARN_ON(1); + return 0; +#endif if (rcu_preempt_depth() != 0 || preempt_count() != 0 || irqs_disabled()) { WARN_ON(1); @@ -184,7 +191,14 @@ static int rcuhead_fixup_activate(void *addr, enum debug_obj_state state) * Ensure that queued callbacks are all executed. * If we detect that we are nested in a RCU read-side critical * section, we should simply fail, otherwise we would deadlock. + * In !PREEMPT configurations, there is no way to tell if we are + * in a RCU read-side critical section or not, so we never + * attempt any fixup and just print a warning. */ +#ifndef CONFIG_PREEMPT + WARN_ON(1); + return 0; +#endif if (rcu_preempt_depth() != 0 || preempt_count() != 0 || irqs_disabled()) { WARN_ON(1); @@ -214,12 +228,14 @@ static int rcuhead_fixup_free(void *addr, enum debug_obj_state state) * Ensure that queued callbacks are all executed. * If we detect that we are nested in a RCU read-side critical * section, we should simply fail, otherwise we would deadlock. - * Note that the machinery to reliably determine whether - * or not we are in an RCU read-side critical section - * exists only in the preemptible RCU implementations - * (TINY_PREEMPT_RCU and TREE_PREEMPT_RCU), which is why - * DEBUG_OBJECTS_RCU_HEAD is disallowed if !PREEMPT. + * In !PREEMPT configurations, there is no way to tell if we are + * in a RCU read-side critical section or not, so we never + * attempt any fixup and just print a warning. */ +#ifndef CONFIG_PREEMPT + WARN_ON(1); + return 0; +#endif if (rcu_preempt_depth() != 0 || preempt_count() != 0 || irqs_disabled()) { WARN_ON(1); diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 93ce6de3300d..3aa278046d78 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -337,7 +337,7 @@ config DEBUG_OBJECTS_WORK config DEBUG_OBJECTS_RCU_HEAD bool "Debug RCU callbacks objects" - depends on DEBUG_OBJECTS && PREEMPT + depends on DEBUG_OBJECTS help Enable this to turn on debugging of RCU list heads (call_rcu() usage). -- cgit v1.2.2 From b0c9d7ff2793502650ad987c3f237d5fe5587a1e Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 29 Mar 2011 12:56:56 -0700 Subject: rcu: add DEBUG_OBJECTS_RCU_HEAD check for alignment Verify that rcu_head structures are aligned to a four-byte boundary. This check is enabled by CONFIG_DEBUG_OBJECTS_RCU_HEAD. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- include/linux/rcupdate.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 9e169c2ba91f..c7aeacf7fc98 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -785,6 +785,7 @@ extern struct debug_obj_descr rcuhead_debug_descr; static inline void debug_rcu_head_queue(struct rcu_head *head) { + WARN_ON_ONCE((unsigned long)head & 0x3); debug_object_activate(head, &rcuhead_debug_descr); debug_object_active_state(head, &rcuhead_debug_descr, STATE_RCU_HEAD_READY, -- cgit v1.2.2 From 561190e3b3db372403fb6a327b0121b4cae1b87e Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 30 Mar 2011 09:10:44 -0700 Subject: rcu: mark rcutorture boosting callback as being on-stack The CONFIG_DEBUG_OBJECTS_RCU_HEAD facility requires that on-stack RCU callbacks be flagged explicitly to debug-objects using the init_rcu_head_on_stack() and destroy_rcu_head_on_stack() functions. This commit applies those functions to the rcutorture code that tests RCU priority boosting. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutorture.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index c2f58ec24751..2e138db03382 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -749,6 +749,7 @@ static int rcu_torture_boost(void *arg) n_rcu_torture_boost_rterror++; } + init_rcu_head_on_stack(&rbi.rcu); /* Each pass through the following loop does one boost-test cycle. */ do { /* Wait for the next test interval. */ @@ -808,6 +809,7 @@ checkwait: rcu_stutter_wait("rcu_torture_boost"); /* Clean up and exit. */ VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping"); + destroy_rcu_head_on_stack(&rbi.rcu); rcutorture_shutdown_absorb("rcu_torture_boost"); while (!kthread_should_stop() || rbi.inflight) schedule_timeout_uninterruptible(1); -- cgit v1.2.2 From 108aae22339f445c134aeb48eca25df1014ab08d Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 23 Feb 2011 09:56:00 -0800 Subject: rcu: Use WARN_ON_ONCE for DEBUG_OBJECTS_RCU_HEAD warnings Avoid additional multiple-warning confusion in memory-corruption scenarios. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcupdate.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index b54d6d18258c..7784bd216b6a 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -147,12 +147,12 @@ static int rcuhead_fixup_init(void *addr, enum debug_obj_state state) * attempt any fixup and just print a warning. */ #ifndef CONFIG_PREEMPT - WARN_ON(1); + WARN_ON_ONCE(1); return 0; #endif if (rcu_preempt_depth() != 0 || preempt_count() != 0 || irqs_disabled()) { - WARN_ON(1); + WARN_ON_ONCE(1); return 0; } rcu_barrier(); @@ -196,12 +196,12 @@ static int rcuhead_fixup_activate(void *addr, enum debug_obj_state state) * attempt any fixup and just print a warning. */ #ifndef CONFIG_PREEMPT - WARN_ON(1); + WARN_ON_ONCE(1); return 0; #endif if (rcu_preempt_depth() != 0 || preempt_count() != 0 || irqs_disabled()) { - WARN_ON(1); + WARN_ON_ONCE(1); return 0; } rcu_barrier(); @@ -233,12 +233,12 @@ static int rcuhead_fixup_free(void *addr, enum debug_obj_state state) * attempt any fixup and just print a warning. */ #ifndef CONFIG_PREEMPT - WARN_ON(1); + WARN_ON_ONCE(1); return 0; #endif if (rcu_preempt_depth() != 0 || preempt_count() != 0 || irqs_disabled()) { - WARN_ON(1); + WARN_ON_ONCE(1); return 0; } rcu_barrier(); -- cgit v1.2.2 From f0a07aeaf8935b7e9ef8032ce6546169f143951c Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 23 Feb 2011 11:10:52 -0800 Subject: rcu: Switch to this_cpu() primitives This removes a couple of lines from invoke_rcu_cpu_kthread(), improving readability. Reported-by: Christoph Lameter Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutree.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 575d6414763e..27304bc15eca 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1480,18 +1480,14 @@ static void rcu_process_callbacks(void) static void invoke_rcu_cpu_kthread(void) { unsigned long flags; - wait_queue_head_t *q; - int cpu; local_irq_save(flags); - cpu = smp_processor_id(); - per_cpu(rcu_cpu_has_work, cpu) = 1; - if (per_cpu(rcu_cpu_kthread_task, cpu) == NULL) { + __this_cpu_write(rcu_cpu_has_work, 1); + if (__this_cpu_read(rcu_cpu_kthread_task) == NULL) { local_irq_restore(flags); return; } - q = &per_cpu(rcu_cpu_wq, cpu); - wake_up(q); + wake_up(&__get_cpu_var(rcu_cpu_wq)); local_irq_restore(flags); } -- cgit v1.2.2 From ddeb75814f09205df795121d9e373e82de7f2aca Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 23 Feb 2011 17:03:06 -0800 Subject: rcu: code cleanups in TINY_RCU priority boosting. Extraneous semicolon, bad comment, and fold INIT_LIST_HEAD() into list_del() to get list_del_init(). Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutiny_plugin.h | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h index 3cb8e362e883..0bc9f732d1a5 100644 --- a/kernel/rcutiny_plugin.h +++ b/kernel/rcutiny_plugin.h @@ -339,7 +339,7 @@ static void rcu_initiate_expedited_boost(void) raw_local_irq_restore(flags); } -#define RCU_BOOST_DELAY_JIFFIES DIV_ROUND_UP(CONFIG_RCU_BOOST_DELAY * HZ, 1000); +#define RCU_BOOST_DELAY_JIFFIES DIV_ROUND_UP(CONFIG_RCU_BOOST_DELAY * HZ, 1000) /* * Do priority-boost accounting for the start of a new grace period. @@ -418,7 +418,7 @@ static void rcu_preempt_cpu_qs(void) if (!rcu_preempt_gp_in_progress()) return; /* - * Check up on boosting. If there are no readers blocking the + * Check up on boosting. If there are readers blocking the * current grace period, leave. */ if (rcu_initiate_boost()) @@ -578,7 +578,7 @@ static void rcu_read_unlock_special(struct task_struct *t) empty = !rcu_preempt_blocked_readers_cgp(); empty_exp = rcu_preempt_ctrlblk.exp_tasks == NULL; np = rcu_next_node_entry(t); - list_del(&t->rcu_node_entry); + list_del_init(&t->rcu_node_entry); if (&t->rcu_node_entry == rcu_preempt_ctrlblk.gp_tasks) rcu_preempt_ctrlblk.gp_tasks = np; if (&t->rcu_node_entry == rcu_preempt_ctrlblk.exp_tasks) @@ -587,7 +587,6 @@ static void rcu_read_unlock_special(struct task_struct *t) if (&t->rcu_node_entry == rcu_preempt_ctrlblk.boost_tasks) rcu_preempt_ctrlblk.boost_tasks = np; #endif /* #ifdef CONFIG_RCU_BOOST */ - INIT_LIST_HEAD(&t->rcu_node_entry); /* * If this was the last task on the current list, and if -- cgit v1.2.2 From 203373c81b83e98da82836c4b8b5dd1e6fc9011f Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 24 Feb 2011 15:25:21 -0800 Subject: rcu: remove useless ->boosted_this_gp field The ->boosted_this_gp field is a holdover from an earlier design that was to carry out multiple boost operations in parallel. It is not required by the current design, which boosts one task at a time. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- kernel/rcutiny_plugin.h | 35 ++++------------------------------- 1 file changed, 4 insertions(+), 31 deletions(-) diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h index 0bc9f732d1a5..2b8d5293c5f4 100644 --- a/kernel/rcutiny_plugin.h +++ b/kernel/rcutiny_plugin.h @@ -100,7 +100,6 @@ struct rcu_preempt_ctrlblk { u8 completed; /* Last grace period completed. */ /* If all three are equal, RCU is idle. */ #ifdef CONFIG_RCU_BOOST - s8 boosted_this_gp; /* Has boosting already happened? */ unsigned long boost_time; /* When to start boosting (jiffies) */ #endif /* #ifdef CONFIG_RCU_BOOST */ #ifdef CONFIG_RCU_TRACE @@ -112,7 +111,6 @@ struct rcu_preempt_ctrlblk { unsigned long n_normal_balk_blkd_tasks; unsigned long n_normal_balk_gp_tasks; unsigned long n_normal_balk_boost_tasks; - unsigned long n_normal_balk_boosted; unsigned long n_normal_balk_notyet; unsigned long n_normal_balk_nos; unsigned long n_exp_balk_blkd_tasks; @@ -219,36 +217,19 @@ static void show_tiny_preempt_stats(struct seq_file *m) "N."[!rcu_preempt_ctrlblk.gp_tasks], "E."[!rcu_preempt_ctrlblk.exp_tasks]); #ifdef CONFIG_RCU_BOOST - seq_printf(m, " ttb=%c btg=", - "B."[!rcu_preempt_ctrlblk.boost_tasks]); - switch (rcu_preempt_ctrlblk.boosted_this_gp) { - case -1: - seq_puts(m, "exp"); - break; - case 0: - seq_puts(m, "no"); - break; - case 1: - seq_puts(m, "begun"); - break; - case 2: - seq_puts(m, "done"); - break; - default: - seq_printf(m, "?%d?", rcu_preempt_ctrlblk.boosted_this_gp); - } - seq_printf(m, " ntb=%lu neb=%lu nnb=%lu j=%04x bt=%04x\n", + seq_printf(m, "%sttb=%c ntb=%lu neb=%lu nnb=%lu j=%04x bt=%04x\n", + " ", + "B."[!rcu_preempt_ctrlblk.boost_tasks], rcu_preempt_ctrlblk.n_tasks_boosted, rcu_preempt_ctrlblk.n_exp_boosts, rcu_preempt_ctrlblk.n_normal_boosts, (int)(jiffies & 0xffff), (int)(rcu_preempt_ctrlblk.boost_time & 0xffff)); - seq_printf(m, " %s: nt=%lu gt=%lu bt=%lu b=%lu ny=%lu nos=%lu\n", + seq_printf(m, " %s: nt=%lu gt=%lu bt=%lu ny=%lu nos=%lu\n", "normal balk", rcu_preempt_ctrlblk.n_normal_balk_blkd_tasks, rcu_preempt_ctrlblk.n_normal_balk_gp_tasks, rcu_preempt_ctrlblk.n_normal_balk_boost_tasks, - rcu_preempt_ctrlblk.n_normal_balk_boosted, rcu_preempt_ctrlblk.n_normal_balk_notyet, rcu_preempt_ctrlblk.n_normal_balk_nos); seq_printf(m, " exp balk: bt=%lu nos=%lu\n", @@ -277,7 +258,6 @@ static int rcu_boost(void) if (rcu_preempt_ctrlblk.boost_tasks == NULL) return 0; /* Nothing to boost. */ raw_local_irq_save(flags); - rcu_preempt_ctrlblk.boosted_this_gp++; t = container_of(rcu_preempt_ctrlblk.boost_tasks, struct task_struct, rcu_node_entry); np = rcu_next_node_entry(t); @@ -287,7 +267,6 @@ static int rcu_boost(void) raw_local_irq_restore(flags); rt_mutex_lock(&mtx); RCU_TRACE(rcu_preempt_ctrlblk.n_tasks_boosted++); - rcu_preempt_ctrlblk.boosted_this_gp++; rt_mutex_unlock(&mtx); return rcu_preempt_ctrlblk.boost_tasks != NULL; } @@ -310,7 +289,6 @@ static int rcu_initiate_boost(void) } if (rcu_preempt_ctrlblk.gp_tasks != NULL && rcu_preempt_ctrlblk.boost_tasks == NULL && - rcu_preempt_ctrlblk.boosted_this_gp == 0 && ULONG_CMP_GE(jiffies, rcu_preempt_ctrlblk.boost_time)) { rcu_preempt_ctrlblk.boost_tasks = rcu_preempt_ctrlblk.gp_tasks; invoke_rcu_kthread(); @@ -331,7 +309,6 @@ static void rcu_initiate_expedited_boost(void) if (!list_empty(&rcu_preempt_ctrlblk.blkd_tasks)) { rcu_preempt_ctrlblk.boost_tasks = rcu_preempt_ctrlblk.blkd_tasks.next; - rcu_preempt_ctrlblk.boosted_this_gp = -1; invoke_rcu_kthread(); RCU_TRACE(rcu_preempt_ctrlblk.n_exp_boosts++); } else @@ -347,8 +324,6 @@ static void rcu_initiate_expedited_boost(void) static void rcu_preempt_boost_start_gp(void) { rcu_preempt_ctrlblk.boost_time = jiffies + RCU_BOOST_DELAY_JIFFIES; - if (rcu_preempt_ctrlblk.boosted_this_gp > 0) - rcu_preempt_ctrlblk.boosted_this_gp = 0; } #else /* #ifdef CONFIG_RCU_BOOST */ @@ -934,8 +909,6 @@ static void rcu_initiate_boost_trace(void) rcu_preempt_ctrlblk.n_normal_balk_gp_tasks++; else if (rcu_preempt_ctrlblk.boost_tasks != NULL) rcu_preempt_ctrlblk.n_normal_balk_boost_tasks++; - else if (rcu_preempt_ctrlblk.boosted_this_gp != 0) - rcu_preempt_ctrlblk.n_normal_balk_boosted++; else if (!ULONG_CMP_GE(jiffies, rcu_preempt_ctrlblk.boost_time)) rcu_preempt_ctrlblk.n_normal_balk_notyet++; else -- cgit v1.2.2 From 7e8b4c72344e0d904b0e3fa9fd2eb116f04b3d41 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 24 Feb 2011 19:26:21 -0800 Subject: rcu: Converge TINY_RCU expedited and normal boosting This applies a trick from TREE_RCU boosting to TINY_RCU, eliminating code and adding comments. The key point is that it is possible for the booster thread itself to work out whether there is a normal or expedited boost required based solely on local information. There is therefore no need for boost initiation to know or care what type of boosting is required. In addition, when boosting is complete for a given grace period, then by definition there cannot be any more boosting for that grace period. This allows eliminating yet more state and statistics. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutiny_plugin.h | 163 ++++++++++++++++++++++++++---------------------- 1 file changed, 89 insertions(+), 74 deletions(-) diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h index 2b8d5293c5f4..f259c676195f 100644 --- a/kernel/rcutiny_plugin.h +++ b/kernel/rcutiny_plugin.h @@ -106,15 +106,22 @@ struct rcu_preempt_ctrlblk { unsigned long n_grace_periods; #ifdef CONFIG_RCU_BOOST unsigned long n_tasks_boosted; + /* Total number of tasks boosted. */ unsigned long n_exp_boosts; + /* Number of tasks boosted for expedited GP. */ unsigned long n_normal_boosts; - unsigned long n_normal_balk_blkd_tasks; - unsigned long n_normal_balk_gp_tasks; - unsigned long n_normal_balk_boost_tasks; - unsigned long n_normal_balk_notyet; - unsigned long n_normal_balk_nos; - unsigned long n_exp_balk_blkd_tasks; - unsigned long n_exp_balk_nos; + /* Number of tasks boosted for normal GP. */ + unsigned long n_balk_blkd_tasks; + /* Refused to boost: no blocked tasks. */ + unsigned long n_balk_exp_gp_tasks; + /* Refused to boost: nothing blocking GP. */ + unsigned long n_balk_boost_tasks; + /* Refused to boost: already boosting. */ + unsigned long n_balk_notyet; + /* Refused to boost: not yet time. */ + unsigned long n_balk_nos; + /* Refused to boost: not sure why, though. */ + /* This can happen due to race conditions. */ #endif /* #ifdef CONFIG_RCU_BOOST */ #endif /* #ifdef CONFIG_RCU_TRACE */ }; @@ -199,7 +206,6 @@ static struct list_head *rcu_next_node_entry(struct task_struct *t) #ifdef CONFIG_RCU_BOOST static void rcu_initiate_boost_trace(void); -static void rcu_initiate_exp_boost_trace(void); #endif /* #ifdef CONFIG_RCU_BOOST */ /* @@ -225,16 +231,13 @@ static void show_tiny_preempt_stats(struct seq_file *m) rcu_preempt_ctrlblk.n_normal_boosts, (int)(jiffies & 0xffff), (int)(rcu_preempt_ctrlblk.boost_time & 0xffff)); - seq_printf(m, " %s: nt=%lu gt=%lu bt=%lu ny=%lu nos=%lu\n", - "normal balk", - rcu_preempt_ctrlblk.n_normal_balk_blkd_tasks, - rcu_preempt_ctrlblk.n_normal_balk_gp_tasks, - rcu_preempt_ctrlblk.n_normal_balk_boost_tasks, - rcu_preempt_ctrlblk.n_normal_balk_notyet, - rcu_preempt_ctrlblk.n_normal_balk_nos); - seq_printf(m, " exp balk: bt=%lu nos=%lu\n", - rcu_preempt_ctrlblk.n_exp_balk_blkd_tasks, - rcu_preempt_ctrlblk.n_exp_balk_nos); + seq_printf(m, "%s: nt=%lu egt=%lu bt=%lu ny=%lu nos=%lu\n", + " balk", + rcu_preempt_ctrlblk.n_balk_blkd_tasks, + rcu_preempt_ctrlblk.n_balk_exp_gp_tasks, + rcu_preempt_ctrlblk.n_balk_boost_tasks, + rcu_preempt_ctrlblk.n_balk_notyet, + rcu_preempt_ctrlblk.n_balk_nos); #endif /* #ifdef CONFIG_RCU_BOOST */ } @@ -252,23 +255,59 @@ static int rcu_boost(void) { unsigned long flags; struct rt_mutex mtx; - struct list_head *np; struct task_struct *t; + struct list_head *tb; - if (rcu_preempt_ctrlblk.boost_tasks == NULL) + if (rcu_preempt_ctrlblk.boost_tasks == NULL && + rcu_preempt_ctrlblk.exp_tasks == NULL) return 0; /* Nothing to boost. */ + raw_local_irq_save(flags); - t = container_of(rcu_preempt_ctrlblk.boost_tasks, struct task_struct, - rcu_node_entry); - np = rcu_next_node_entry(t); + + /* + * Recheck with irqs disabled: all tasks in need of boosting + * might exit their RCU read-side critical sections on their own + * if we are preempted just before disabling irqs. + */ + if (rcu_preempt_ctrlblk.boost_tasks == NULL && + rcu_preempt_ctrlblk.exp_tasks == NULL) { + raw_local_irq_restore(flags); + return 0; + } + + /* + * Preferentially boost tasks blocking expedited grace periods. + * This cannot starve the normal grace periods because a second + * expedited grace period must boost all blocked tasks, including + * those blocking the pre-existing normal grace period. + */ + if (rcu_preempt_ctrlblk.exp_tasks != NULL) { + tb = rcu_preempt_ctrlblk.exp_tasks; + RCU_TRACE(rcu_preempt_ctrlblk.n_exp_boosts++); + } else { + tb = rcu_preempt_ctrlblk.boost_tasks; + RCU_TRACE(rcu_preempt_ctrlblk.n_normal_boosts++); + } + RCU_TRACE(rcu_preempt_ctrlblk.n_tasks_boosted++); + + /* + * We boost task t by manufacturing an rt_mutex that appears to + * be held by task t. We leave a pointer to that rt_mutex where + * task t can find it, and task t will release the mutex when it + * exits its outermost RCU read-side critical section. Then + * simply acquiring this artificial rt_mutex will boost task + * t's priority. (Thanks to tglx for suggesting this approach!) + */ + t = container_of(tb, struct task_struct, rcu_node_entry); rt_mutex_init_proxy_locked(&mtx, t); t->rcu_boost_mutex = &mtx; t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BOOSTED; raw_local_irq_restore(flags); rt_mutex_lock(&mtx); - RCU_TRACE(rcu_preempt_ctrlblk.n_tasks_boosted++); - rt_mutex_unlock(&mtx); - return rcu_preempt_ctrlblk.boost_tasks != NULL; + rt_mutex_unlock(&mtx); /* Keep lockdep happy. */ + + return rcu_preempt_ctrlblk.boost_tasks != NULL || + rcu_preempt_ctrlblk.exp_tasks != NULL; } /* @@ -283,39 +322,24 @@ static int rcu_boost(void) */ static int rcu_initiate_boost(void) { - if (!rcu_preempt_blocked_readers_cgp()) { - RCU_TRACE(rcu_preempt_ctrlblk.n_normal_balk_blkd_tasks++); + if (!rcu_preempt_blocked_readers_cgp() && + rcu_preempt_ctrlblk.exp_tasks == NULL) { + RCU_TRACE(rcu_preempt_ctrlblk.n_balk_exp_gp_tasks++); return 0; } - if (rcu_preempt_ctrlblk.gp_tasks != NULL && - rcu_preempt_ctrlblk.boost_tasks == NULL && - ULONG_CMP_GE(jiffies, rcu_preempt_ctrlblk.boost_time)) { - rcu_preempt_ctrlblk.boost_tasks = rcu_preempt_ctrlblk.gp_tasks; + if (rcu_preempt_ctrlblk.exp_tasks != NULL || + (rcu_preempt_ctrlblk.gp_tasks != NULL && + rcu_preempt_ctrlblk.boost_tasks == NULL && + ULONG_CMP_GE(jiffies, rcu_preempt_ctrlblk.boost_time))) { + if (rcu_preempt_ctrlblk.exp_tasks == NULL) + rcu_preempt_ctrlblk.boost_tasks = + rcu_preempt_ctrlblk.gp_tasks; invoke_rcu_kthread(); - RCU_TRACE(rcu_preempt_ctrlblk.n_normal_boosts++); } else RCU_TRACE(rcu_initiate_boost_trace()); return 1; } -/* - * Initiate boosting for an expedited grace period. - */ -static void rcu_initiate_expedited_boost(void) -{ - unsigned long flags; - - raw_local_irq_save(flags); - if (!list_empty(&rcu_preempt_ctrlblk.blkd_tasks)) { - rcu_preempt_ctrlblk.boost_tasks = - rcu_preempt_ctrlblk.blkd_tasks.next; - invoke_rcu_kthread(); - RCU_TRACE(rcu_preempt_ctrlblk.n_exp_boosts++); - } else - RCU_TRACE(rcu_initiate_exp_boost_trace()); - raw_local_irq_restore(flags); -} - #define RCU_BOOST_DELAY_JIFFIES DIV_ROUND_UP(CONFIG_RCU_BOOST_DELAY * HZ, 1000) /* @@ -346,13 +370,6 @@ static int rcu_initiate_boost(void) return rcu_preempt_blocked_readers_cgp(); } -/* - * If there is no RCU priority boosting, we don't initiate expedited boosting. - */ -static void rcu_initiate_expedited_boost(void) -{ -} - /* * If there is no RCU priority boosting, nothing to do at grace-period start. */ @@ -786,13 +803,16 @@ void synchronize_rcu_expedited(void) rpcp->exp_tasks = rpcp->blkd_tasks.next; if (rpcp->exp_tasks == &rpcp->blkd_tasks) rpcp->exp_tasks = NULL; - local_irq_restore(flags); /* Wait for tail of ->blkd_tasks list to drain. */ - if (rcu_preempted_readers_exp()) - rcu_initiate_expedited_boost(); + if (!rcu_preempted_readers_exp()) + local_irq_restore(flags); + else { + rcu_initiate_boost(); + local_irq_restore(flags); wait_event(sync_rcu_preempt_exp_wq, !rcu_preempted_readers_exp()); + } /* Clean up and exit. */ barrier(); /* ensure expedited GP seen before counter increment. */ @@ -905,22 +925,17 @@ void __init rcu_scheduler_starting(void) static void rcu_initiate_boost_trace(void) { - if (rcu_preempt_ctrlblk.gp_tasks == NULL) - rcu_preempt_ctrlblk.n_normal_balk_gp_tasks++; + if (list_empty(&rcu_preempt_ctrlblk.blkd_tasks)) + rcu_preempt_ctrlblk.n_balk_blkd_tasks++; + else if (rcu_preempt_ctrlblk.gp_tasks == NULL && + rcu_preempt_ctrlblk.exp_tasks == NULL) + rcu_preempt_ctrlblk.n_balk_exp_gp_tasks++; else if (rcu_preempt_ctrlblk.boost_tasks != NULL) - rcu_preempt_ctrlblk.n_normal_balk_boost_tasks++; + rcu_preempt_ctrlblk.n_balk_boost_tasks++; else if (!ULONG_CMP_GE(jiffies, rcu_preempt_ctrlblk.boost_time)) - rcu_preempt_ctrlblk.n_normal_balk_notyet++; - else - rcu_preempt_ctrlblk.n_normal_balk_nos++; -} - -static void rcu_initiate_exp_boost_trace(void) -{ - if (list_empty(&rcu_preempt_ctrlblk.blkd_tasks)) - rcu_preempt_ctrlblk.n_exp_balk_blkd_tasks++; + rcu_preempt_ctrlblk.n_balk_notyet++; else - rcu_preempt_ctrlblk.n_exp_balk_nos++; + rcu_preempt_ctrlblk.n_balk_nos++; } #endif /* #ifdef CONFIG_RCU_BOOST */ -- cgit v1.2.2 From 13491a0ee1ef862b6c842132b6eb9c5e721af5ad Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 25 Feb 2011 11:37:59 -0800 Subject: rcu: call __rcu_read_unlock() in exit_rcu for tree RCU Using __rcu_read_lock() in place of rcu_read_lock() leaves any debug state as it really should be, namely with the lock still held. Signed-off-by: Lai Jiangshan Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutree_plugin.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index a21413d0581d..11b27f377b8b 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -858,7 +858,7 @@ void exit_rcu(void) if (t->rcu_read_lock_nesting == 0) return; t->rcu_read_lock_nesting = 1; - rcu_read_unlock(); + __rcu_read_unlock(); } #else /* #ifdef CONFIG_TREE_PREEMPT_RCU */ -- cgit v1.2.2 From 6cc68793e380bb51f447d8d02af873b7bc01f222 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 2 Mar 2011 13:15:15 -0800 Subject: rcu: fix spelling The "preemptible" spelling is preferable. May as well fix it. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutree.c | 10 ++++---- kernel/rcutree.h | 2 +- kernel/rcutree_plugin.h | 62 ++++++++++++++++++++++++------------------------- 3 files changed, 37 insertions(+), 37 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 27304bc15eca..b579e4f97210 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -290,8 +290,8 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp) return 1; } - /* If preemptable RCU, no point in sending reschedule IPI. */ - if (rdp->preemptable) + /* If preemptible RCU, no point in sending reschedule IPI. */ + if (rdp->preemptible) return 0; /* The CPU is online, so send it a reschedule IPI. */ @@ -1982,7 +1982,7 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) * or RCU-bh, force a local reschedule. */ rdp->n_rp_qs_pending++; - if (!rdp->preemptable && + if (!rdp->preemptible && ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1, jiffies)) set_need_resched(); @@ -2159,7 +2159,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) * that this CPU cannot possibly have any RCU callbacks in flight yet. */ static void __cpuinit -rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable) +rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible) { unsigned long flags; unsigned long mask; @@ -2171,7 +2171,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable) rdp->passed_quiesc = 0; /* We could be racing with new GP, */ rdp->qs_pending = 1; /* so set up to respond to current GP. */ rdp->beenonline = 1; /* We have now been online. */ - rdp->preemptable = preemptable; + rdp->preemptible = preemptible; rdp->qlen_last_fqs_check = 0; rdp->n_force_qs_snap = rsp->n_force_qs; rdp->blimit = blimit; diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 37502a27a072..a6a97171dac6 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -239,7 +239,7 @@ struct rcu_data { bool passed_quiesc; /* User-mode/idle loop etc. */ bool qs_pending; /* Core waits for quiesc state. */ bool beenonline; /* CPU online at least once. */ - bool preemptable; /* Preemptable RCU? */ + bool preemptible; /* Preemptible RCU? */ struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ unsigned long grpmask; /* Mask to apply to leaf qsmask. */ diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 11b27f377b8b..f629479d4b1f 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1,7 +1,7 @@ /* * Read-Copy Update mechanism for mutual exclusion (tree-based version) * Internal non-public definitions that provide either classic - * or preemptable semantics. + * or preemptible semantics. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -75,7 +75,7 @@ static int rcu_preempted_readers_exp(struct rcu_node *rnp); */ static void __init rcu_bootup_announce(void) { - printk(KERN_INFO "Preemptable hierarchical RCU implementation.\n"); + printk(KERN_INFO "Preemptible hierarchical RCU implementation.\n"); rcu_bootup_announce_oddness(); } @@ -108,7 +108,7 @@ void rcu_force_quiescent_state(void) EXPORT_SYMBOL_GPL(rcu_force_quiescent_state); /* - * Record a preemptable-RCU quiescent state for the specified CPU. Note + * Record a preemptible-RCU quiescent state for the specified CPU. Note * that this just means that the task currently running on the CPU is * not in a quiescent state. There might be any number of tasks blocked * while in an RCU read-side critical section. @@ -207,7 +207,7 @@ static void rcu_preempt_note_context_switch(int cpu) } /* - * Tree-preemptable RCU implementation for rcu_read_lock(). + * Tree-preemptible RCU implementation for rcu_read_lock(). * Just increment ->rcu_read_lock_nesting, shared state will be updated * if we block. */ @@ -376,7 +376,7 @@ static void rcu_read_unlock_special(struct task_struct *t) } /* - * Tree-preemptable RCU implementation for rcu_read_unlock(). + * Tree-preemptible RCU implementation for rcu_read_unlock(). * Decrement ->rcu_read_lock_nesting. If the result is zero (outermost * rcu_read_unlock()) and ->rcu_read_unlock_special is non-zero, then * invoke rcu_read_unlock_special() to clean up after a context switch @@ -565,7 +565,7 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp, } /* - * Do CPU-offline processing for preemptable RCU. + * Do CPU-offline processing for preemptible RCU. */ static void rcu_preempt_offline_cpu(int cpu) { @@ -594,7 +594,7 @@ static void rcu_preempt_check_callbacks(int cpu) } /* - * Process callbacks for preemptable RCU. + * Process callbacks for preemptible RCU. */ static void rcu_preempt_process_callbacks(void) { @@ -603,7 +603,7 @@ static void rcu_preempt_process_callbacks(void) } /* - * Queue a preemptable-RCU callback for invocation after a grace period. + * Queue a preemptible-RCU callback for invocation after a grace period. */ void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) { @@ -795,7 +795,7 @@ mb_ret: EXPORT_SYMBOL_GPL(synchronize_rcu_expedited); /* - * Check to see if there is any immediate preemptable-RCU-related work + * Check to see if there is any immediate preemptible-RCU-related work * to be done. */ static int rcu_preempt_pending(int cpu) @@ -805,7 +805,7 @@ static int rcu_preempt_pending(int cpu) } /* - * Does preemptable RCU need the CPU to stay out of dynticks mode? + * Does preemptible RCU need the CPU to stay out of dynticks mode? */ static int rcu_preempt_needs_cpu(int cpu) { @@ -822,7 +822,7 @@ void rcu_barrier(void) EXPORT_SYMBOL_GPL(rcu_barrier); /* - * Initialize preemptable RCU's per-CPU data. + * Initialize preemptible RCU's per-CPU data. */ static void __cpuinit rcu_preempt_init_percpu_data(int cpu) { @@ -830,7 +830,7 @@ static void __cpuinit rcu_preempt_init_percpu_data(int cpu) } /* - * Move preemptable RCU's callbacks from dying CPU to other online CPU. + * Move preemptible RCU's callbacks from dying CPU to other online CPU. */ static void rcu_preempt_send_cbs_to_online(void) { @@ -838,7 +838,7 @@ static void rcu_preempt_send_cbs_to_online(void) } /* - * Initialize preemptable RCU's state structures. + * Initialize preemptible RCU's state structures. */ static void __init __rcu_init_preempt(void) { @@ -846,7 +846,7 @@ static void __init __rcu_init_preempt(void) } /* - * Check for a task exiting while in a preemptable-RCU read-side + * Check for a task exiting while in a preemptible-RCU read-side * critical section, clean up if so. No need to issue warnings, * as debug_check_no_locks_held() already does this if lockdep * is enabled. @@ -894,7 +894,7 @@ void rcu_force_quiescent_state(void) EXPORT_SYMBOL_GPL(rcu_force_quiescent_state); /* - * Because preemptable RCU does not exist, we never have to check for + * Because preemptible RCU does not exist, we never have to check for * CPUs being in quiescent states. */ static void rcu_preempt_note_context_switch(int cpu) @@ -902,7 +902,7 @@ static void rcu_preempt_note_context_switch(int cpu) } /* - * Because preemptable RCU does not exist, there are never any preempted + * Because preemptible RCU does not exist, there are never any preempted * RCU readers. */ static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp) @@ -921,7 +921,7 @@ static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags) #endif /* #ifdef CONFIG_HOTPLUG_CPU */ /* - * Because preemptable RCU does not exist, we never have to check for + * Because preemptible RCU does not exist, we never have to check for * tasks blocked within RCU read-side critical sections. */ static void rcu_print_detail_task_stall(struct rcu_state *rsp) @@ -929,7 +929,7 @@ static void rcu_print_detail_task_stall(struct rcu_state *rsp) } /* - * Because preemptable RCU does not exist, we never have to check for + * Because preemptible RCU does not exist, we never have to check for * tasks blocked within RCU read-side critical sections. */ static void rcu_print_task_stall(struct rcu_node *rnp) @@ -945,7 +945,7 @@ static void rcu_preempt_stall_reset(void) } /* - * Because there is no preemptable RCU, there can be no readers blocked, + * Because there is no preemptible RCU, there can be no readers blocked, * so there is no need to check for blocked tasks. So check only for * bogus qsmask values. */ @@ -957,7 +957,7 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp) #ifdef CONFIG_HOTPLUG_CPU /* - * Because preemptable RCU does not exist, it never needs to migrate + * Because preemptible RCU does not exist, it never needs to migrate * tasks that were blocked within RCU read-side critical sections, and * such non-existent tasks cannot possibly have been blocking the current * grace period. @@ -970,7 +970,7 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp, } /* - * Because preemptable RCU does not exist, it never needs CPU-offline + * Because preemptible RCU does not exist, it never needs CPU-offline * processing. */ static void rcu_preempt_offline_cpu(int cpu) @@ -980,7 +980,7 @@ static void rcu_preempt_offline_cpu(int cpu) #endif /* #ifdef CONFIG_HOTPLUG_CPU */ /* - * Because preemptable RCU does not exist, it never has any callbacks + * Because preemptible RCU does not exist, it never has any callbacks * to check. */ static void rcu_preempt_check_callbacks(int cpu) @@ -988,7 +988,7 @@ static void rcu_preempt_check_callbacks(int cpu) } /* - * Because preemptable RCU does not exist, it never has any callbacks + * Because preemptible RCU does not exist, it never has any callbacks * to process. */ static void rcu_preempt_process_callbacks(void) @@ -997,7 +997,7 @@ static void rcu_preempt_process_callbacks(void) /* * Wait for an rcu-preempt grace period, but make it happen quickly. - * But because preemptable RCU does not exist, map to rcu-sched. + * But because preemptible RCU does not exist, map to rcu-sched. */ void synchronize_rcu_expedited(void) { @@ -1008,7 +1008,7 @@ EXPORT_SYMBOL_GPL(synchronize_rcu_expedited); #ifdef CONFIG_HOTPLUG_CPU /* - * Because preemptable RCU does not exist, there is never any need to + * Because preemptible RCU does not exist, there is never any need to * report on tasks preempted in RCU read-side critical sections during * expedited RCU grace periods. */ @@ -1020,7 +1020,7 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp) #endif /* #ifdef CONFIG_HOTPLUG_CPU */ /* - * Because preemptable RCU does not exist, it never has any work to do. + * Because preemptible RCU does not exist, it never has any work to do. */ static int rcu_preempt_pending(int cpu) { @@ -1028,7 +1028,7 @@ static int rcu_preempt_pending(int cpu) } /* - * Because preemptable RCU does not exist, it never needs any CPU. + * Because preemptible RCU does not exist, it never needs any CPU. */ static int rcu_preempt_needs_cpu(int cpu) { @@ -1036,7 +1036,7 @@ static int rcu_preempt_needs_cpu(int cpu) } /* - * Because preemptable RCU does not exist, rcu_barrier() is just + * Because preemptible RCU does not exist, rcu_barrier() is just * another name for rcu_barrier_sched(). */ void rcu_barrier(void) @@ -1046,7 +1046,7 @@ void rcu_barrier(void) EXPORT_SYMBOL_GPL(rcu_barrier); /* - * Because preemptable RCU does not exist, there is no per-CPU + * Because preemptible RCU does not exist, there is no per-CPU * data to initialize. */ static void __cpuinit rcu_preempt_init_percpu_data(int cpu) @@ -1054,14 +1054,14 @@ static void __cpuinit rcu_preempt_init_percpu_data(int cpu) } /* - * Because there is no preemptable RCU, there are no callbacks to move. + * Because there is no preemptible RCU, there are no callbacks to move. */ static void rcu_preempt_send_cbs_to_online(void) { } /* - * Because preemptable RCU does not exist, it need not be initialized. + * Because preemptible RCU does not exist, it need not be initialized. */ static void __init __rcu_init_preempt(void) { -- cgit v1.2.2 From 9ab1544eb4196ca8d05c433b2eb56f74496b1ee3 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 11:15:47 +0800 Subject: rcu: introduce kfree_rcu() Many rcu callbacks functions just call kfree() on the base structure. These functions are trivial, but their size adds up, and furthermore when they are used in a kernel module, that module must invoke the high-latency rcu_barrier() function at module-unload time. The kfree_rcu() function introduced by this commit addresses this issue. Rather than encoding a function address in the embedded rcu_head structure, kfree_rcu() instead encodes the offset of the rcu_head structure within the base structure. Because the functions are not allowed in the low-order 4096 bytes of kernel virtual memory, offsets up to 4095 bytes can be accommodated. If the offset is larger than 4095 bytes, a compile-time error will be generated in __kfree_rcu(). If this error is triggered, you can either fall back to use of call_rcu() or rearrange the structure to position the rcu_head structure into the first 4096 bytes. Note that the allowable offset might decrease in the future, for example, to allow something like kmem_cache_free_rcu(). The new kfree_rcu() function can replace code as follows: call_rcu(&p->rcu, simple_kfree_callback); where "simple_kfree_callback()" might be defined as follows: void simple_kfree_callback(struct rcu_head *p) { struct foo *q = container_of(p, struct foo, rcu); kfree(q); } with the following: kfree_rcu(&p->rcu, rcu); Note that the "rcu" is the name of a field in the structure being freed. The reason for using this rather than passing in a pointer to the base structure is that the above approach allows better type checking. This commit is based on earlier work by Lai Jiangshan and Manfred Spraul: Lai's V1 patch: http://lkml.org/lkml/2008/9/18/1 Manfred's patch: http://lkml.org/lkml/2009/1/2/115 Signed-off-by: Lai Jiangshan Signed-off-by: Manfred Spraul Signed-off-by: Paul E. McKenney Reviewed-by: David Howells Reviewed-by: Josh Triplett --- include/linux/rcupdate.h | 56 ++++++++++++++++++++++++++++++++++++++++++++++++ kernel/rcutiny.c | 2 +- kernel/rcutree.c | 2 +- 3 files changed, 58 insertions(+), 2 deletions(-) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index c7aeacf7fc98..99f9aa7c2804 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -809,4 +809,60 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head) } #endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ +static __always_inline bool __is_kfree_rcu_offset(unsigned long offset) +{ + return offset < 4096; +} + +static __always_inline +void __kfree_rcu(struct rcu_head *head, unsigned long offset) +{ + typedef void (*rcu_callback)(struct rcu_head *); + + BUILD_BUG_ON(!__builtin_constant_p(offset)); + + /* See the kfree_rcu() header comment. */ + BUILD_BUG_ON(!__is_kfree_rcu_offset(offset)); + + call_rcu(head, (rcu_callback)offset); +} + +extern void kfree(const void *); + +static inline void __rcu_reclaim(struct rcu_head *head) +{ + unsigned long offset = (unsigned long)head->func; + + if (__is_kfree_rcu_offset(offset)) + kfree((void *)head - offset); + else + head->func(head); +} + +/** + * kfree_rcu() - kfree an object after a grace period. + * @ptr: pointer to kfree + * @rcu_head: the name of the struct rcu_head within the type of @ptr. + * + * Many rcu callbacks functions just call kfree() on the base structure. + * These functions are trivial, but their size adds up, and furthermore + * when they are used in a kernel module, that module must invoke the + * high-latency rcu_barrier() function at module-unload time. + * + * The kfree_rcu() function handles this issue. Rather than encoding a + * function address in the embedded rcu_head structure, kfree_rcu() instead + * encodes the offset of the rcu_head structure within the base structure. + * Because the functions are not allowed in the low-order 4096 bytes of + * kernel virtual memory, offsets up to 4095 bytes can be accommodated. + * If the offset is larger than 4095 bytes, a compile-time error will + * be generated in __kfree_rcu(). If this error is triggered, you can + * either fall back to use of call_rcu() or rearrange the structure to + * position the rcu_head structure into the first 4096 bytes. + * + * Note that the allowable offset might decrease in the future, for example, + * to allow something like kmem_cache_free_rcu(). + */ +#define kfree_rcu(ptr, rcu_head) \ + __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head)) + #endif /* __LINUX_RCUPDATE_H */ diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index 0c343b9a46d5..4d60fbc9c64c 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -167,7 +167,7 @@ static void rcu_process_callbacks(struct rcu_ctrlblk *rcp) prefetch(next); debug_rcu_head_unqueue(list); local_bh_disable(); - list->func(list); + __rcu_reclaim(list); local_bh_enable(); list = next; RCU_TRACE(cb_count++); diff --git a/kernel/rcutree.c b/kernel/rcutree.c index b579e4f97210..2c07adb97088 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1206,7 +1206,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) next = list->next; prefetch(next); debug_rcu_head_unqueue(list); - list->func(list); + __rcu_reclaim(list); list = next; if (++count >= rdp->blimit) break; -- cgit v1.2.2 From baa1ae0c9f1c618bc60706efa75fef3508bcee58 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 26 Mar 2011 22:01:35 -0700 Subject: rcu: further lower priority in rcu_yield() Although rcu_yield() dropped from real-time to normal priority, there is always the possibility that the competing tasks have been niced. So nice to 19 in rcu_yield() to help ensure that other tasks have a better chance of running. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutree.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 2c07adb97088..fe85600ba8c2 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1561,6 +1561,7 @@ static void rcu_yield(void (*f)(unsigned long), unsigned long arg) mod_timer(&yield_timer, jiffies + 2); sp.sched_priority = 0; sched_setscheduler_nocheck(current, SCHED_NORMAL, &sp); + set_user_nice(current, 19); schedule(); sp.sched_priority = RCU_KTHREAD_PRIO; sched_setscheduler_nocheck(current, SCHED_FIFO, &sp); -- cgit v1.2.2 From 2655d57ef35aa327a2e58a1c5dc7b65c65003f4e Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 7 Apr 2011 22:47:23 -0700 Subject: rcu: prevent call_rcu() from diving into rcu core if irqs disabled This commit marks a first step towards making call_rcu() have real-time behavior. If irqs are disabled, don't dive into the RCU core. Later on, this new early exit will wake up the per-CPU kthread, which first must be modified to handle the cases involving callback storms. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutree.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index fe85600ba8c2..78923a50cdb2 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1839,6 +1839,13 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), /* Add the callback to our list. */ *rdp->nxttail[RCU_NEXT_TAIL] = head; rdp->nxttail[RCU_NEXT_TAIL] = &head->next; + rdp->qlen++; + + /* If interrupts were disabled, don't dive into RCU core. */ + if (irqs_disabled_flags(flags)) { + local_irq_restore(flags); + return; + } /* * Force the grace period if too many callbacks or too long waiting. @@ -1847,7 +1854,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), * invoking force_quiescent_state() if the newly enqueued callback * is the only one waiting for a grace period to complete. */ - if (unlikely(++rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) { + if (unlikely(rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) { /* Are we ignoring a completed grace period? */ rcu_process_gp_end(rsp, rdp); -- cgit v1.2.2 From b554d7de8d112fca4188da3bf0d7f8b56f42fb95 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 28 Apr 2011 07:23:45 +0200 Subject: rcu: optimize rcutiny rcu_sched_qs() currently calls local_irq_save()/local_irq_restore() up to three times. Remove irq masking from rcu_qsctr_help() / invoke_rcu_kthread() and do it once in rcu_sched_qs() / rcu_bh_qs() This generates smaller code as well. text data bss dec hex filename 2314 156 24 2494 9be kernel/rcutiny.old.o 2250 156 24 2430 97e kernel/rcutiny.new.o Fix an outdated comment for rcu_qsctr_help() Move invoke_rcu_kthread() definition before its use. Signed-off-by: Eric Dumazet Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutiny.c | 43 +++++++++++++++++++++---------------------- 1 file changed, 21 insertions(+), 22 deletions(-) diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index 4d60fbc9c64c..421abfd3641d 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -40,10 +40,10 @@ static struct task_struct *rcu_kthread_task; static DECLARE_WAIT_QUEUE_HEAD(rcu_kthread_wq); static unsigned long have_rcu_kthread_work; -static void invoke_rcu_kthread(void); /* Forward declarations for rcutiny_plugin.h. */ struct rcu_ctrlblk; +static void invoke_rcu_kthread(void); static void rcu_process_callbacks(struct rcu_ctrlblk *rcp); static int rcu_kthread(void *arg); static void __call_rcu(struct rcu_head *head, @@ -79,26 +79,31 @@ void rcu_exit_nohz(void) #endif /* #ifdef CONFIG_NO_HZ */ /* - * Helper function for rcu_qsctr_inc() and rcu_bh_qsctr_inc(). - * Also disable irqs to avoid confusion due to interrupt handlers + * Helper function for rcu_sched_qs() and rcu_bh_qs(). + * Also irqs are disabled to avoid confusion due to interrupt handlers * invoking call_rcu(). */ static int rcu_qsctr_help(struct rcu_ctrlblk *rcp) { - unsigned long flags; - - local_irq_save(flags); if (rcp->rcucblist != NULL && rcp->donetail != rcp->curtail) { rcp->donetail = rcp->curtail; - local_irq_restore(flags); return 1; } - local_irq_restore(flags); return 0; } +/* + * Wake up rcu_kthread() to process callbacks now eligible for invocation + * or to boost readers. + */ +static void invoke_rcu_kthread(void) +{ + have_rcu_kthread_work = 1; + wake_up(&rcu_kthread_wq); +} + /* * Record an rcu quiescent state. And an rcu_bh quiescent state while we * are at it, given that any rcu quiescent state is also an rcu_bh @@ -106,9 +111,13 @@ static int rcu_qsctr_help(struct rcu_ctrlblk *rcp) */ void rcu_sched_qs(int cpu) { + unsigned long flags; + + local_irq_save(flags); if (rcu_qsctr_help(&rcu_sched_ctrlblk) + rcu_qsctr_help(&rcu_bh_ctrlblk)) invoke_rcu_kthread(); + local_irq_restore(flags); } /* @@ -116,8 +125,12 @@ void rcu_sched_qs(int cpu) */ void rcu_bh_qs(int cpu) { + unsigned long flags; + + local_irq_save(flags); if (rcu_qsctr_help(&rcu_bh_ctrlblk)) invoke_rcu_kthread(); + local_irq_restore(flags); } /* @@ -207,20 +220,6 @@ static int rcu_kthread(void *arg) return 0; /* Not reached, but needed to shut gcc up. */ } -/* - * Wake up rcu_kthread() to process callbacks now eligible for invocation - * or to boost readers. - */ -static void invoke_rcu_kthread(void) -{ - unsigned long flags; - - local_irq_save(flags); - have_rcu_kthread_work = 1; - wake_up(&rcu_kthread_wq); - local_irq_restore(flags); -} - /* * Wait for a grace period to elapse. But it is illegal to invoke * synchronize_sched() from within an RCU read-side critical section. -- cgit v1.2.2 From bad6e1393cb505fe17747344a23666464daa3fa7 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 2 May 2011 23:40:04 -0700 Subject: rcu: get rid of signed overflow in check_cpu_stall() Signed integer overflow is undefined by the C standard, so move calculations to unsigned. Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 78923a50cdb2..b2fe2a273df2 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -581,21 +581,24 @@ static void print_cpu_stall(struct rcu_state *rsp) static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) { - long delta; + unsigned long j; + unsigned long js; struct rcu_node *rnp; if (rcu_cpu_stall_suppress) return; - delta = jiffies - ACCESS_ONCE(rsp->jiffies_stall); + j = ACCESS_ONCE(jiffies); + js = ACCESS_ONCE(rsp->jiffies_stall); rnp = rdp->mynode; - if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && delta >= 0) { + if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && ULONG_CMP_GE(j, js)) { /* We haven't checked in, so go dump stack. */ print_cpu_stall(rsp); - } else if (rcu_gp_in_progress(rsp) && delta >= RCU_STALL_RAT_DELAY) { + } else if (rcu_gp_in_progress(rsp) && + ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY)) { - /* They had two time units to dump stack, so complain. */ + /* They had a few time units to dump stack, so complain. */ print_other_cpu_stall(rsp); } } -- cgit v1.2.2 From 29ce831000081dd757d3116bf774aafffc4b6b20 Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Wed, 4 May 2011 16:31:03 +0300 Subject: rcu: provide rcu_virt_note_context_switch() function. Provide rcu_virt_note_context_switch() for vitalization use to note quiescent state during guest entry. Signed-off-by: Gleb Natapov Signed-off-by: Paul E. McKenney --- include/linux/rcutiny.h | 8 ++++++++ include/linux/rcutree.h | 10 ++++++++++ kernel/rcutree.c | 1 + 3 files changed, 19 insertions(+) diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 30ebd7c8d874..52b3e0281fd0 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -99,6 +99,14 @@ static inline void rcu_note_context_switch(int cpu) rcu_preempt_note_context_switch(); } +/* + * Take advantage of the fact that there is only one CPU, which + * allows us to ignore virtualization-based context switches. + */ +static inline void rcu_virt_note_context_switch(int cpu) +{ +} + /* * Return the number of grace periods. */ diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 284dad10c55b..e65d06634dd8 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -35,6 +35,16 @@ extern void rcu_note_context_switch(int cpu); extern int rcu_needs_cpu(int cpu); extern void rcu_cpu_stall_reset(void); +/* + * Note a virtualization-based context switch. This is simply a + * wrapper around rcu_note_context_switch(), which allows TINY_RCU + * to save a few bytes. + */ +static inline void rcu_virt_note_context_switch(int cpu) +{ + rcu_note_context_switch(cpu); +} + #ifdef CONFIG_TREE_PREEMPT_RCU extern void exit_rcu(void); diff --git a/kernel/rcutree.c b/kernel/rcutree.c index b2fe2a273df2..54ff7eb92819 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -157,6 +157,7 @@ void rcu_note_context_switch(int cpu) rcu_sched_qs(cpu); rcu_preempt_note_context_switch(cpu); } +EXPORT_SYMBOL_GPL(rcu_note_context_switch); #ifdef CONFIG_NO_HZ DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { -- cgit v1.2.2 From 1217ed1ba5c67393293dfb0f03c353b118dadeb4 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 4 May 2011 21:43:49 -0700 Subject: rcu: permit rcu_read_unlock() to be called while holding runqueue locks Avoid calling into the scheduler while holding core RCU locks. This allows rcu_read_unlock() to be called while holding the runqueue locks, but only as long as there was no chance of the RCU read-side critical section having been preempted. (Otherwise, if RCU priority boosting is enabled, rcu_read_unlock() might call into the scheduler in order to unboost itself, which might allows self-deadlock on the runqueue locks within the scheduler.) Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 44 ++++++++++------------------------ kernel/rcutree.h | 5 +--- kernel/rcutree_plugin.h | 64 ++++++++++++++++--------------------------------- 3 files changed, 34 insertions(+), 79 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 54ff7eb92819..5616b17e4a22 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1133,22 +1133,7 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) raw_spin_unlock_irqrestore(&rnp->lock, flags); if (need_report & RCU_OFL_TASKS_EXP_GP) rcu_report_exp_rnp(rsp, rnp); - - /* - * If there are no more online CPUs for this rcu_node structure, - * kill the rcu_node structure's kthread. Otherwise, adjust its - * affinity. - */ - t = rnp->node_kthread_task; - if (t != NULL && - rnp->qsmaskinit == 0) { - raw_spin_lock_irqsave(&rnp->lock, flags); - rnp->node_kthread_task = NULL; - raw_spin_unlock_irqrestore(&rnp->lock, flags); - kthread_stop(t); - rcu_stop_boost_kthread(rnp); - } else - rcu_node_kthread_setaffinity(rnp, -1); + rcu_node_kthread_setaffinity(rnp, -1); } /* @@ -1320,8 +1305,7 @@ static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *)) return; } if (rnp->qsmask == 0) { - rcu_initiate_boost(rnp); - raw_spin_unlock_irqrestore(&rnp->lock, flags); + rcu_initiate_boost(rnp, flags); /* releases rnp->lock */ continue; } cpu = rnp->grplo; @@ -1340,10 +1324,10 @@ static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *)) raw_spin_unlock_irqrestore(&rnp->lock, flags); } rnp = rcu_get_root(rsp); - raw_spin_lock_irqsave(&rnp->lock, flags); - if (rnp->qsmask == 0) - rcu_initiate_boost(rnp); - raw_spin_unlock_irqrestore(&rnp->lock, flags); + if (rnp->qsmask == 0) { + raw_spin_lock_irqsave(&rnp->lock, flags); + rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */ + } } /* @@ -1497,7 +1481,8 @@ static void invoke_rcu_cpu_kthread(void) /* * Wake up the specified per-rcu_node-structure kthread. - * The caller must hold ->lock. + * Because the per-rcu_node kthreads are immortal, we don't need + * to do anything to keep them alive. */ static void invoke_rcu_node_kthread(struct rcu_node *rnp) { @@ -1546,8 +1531,8 @@ static void rcu_cpu_kthread_timer(unsigned long arg) raw_spin_lock_irqsave(&rnp->lock, flags); rnp->wakemask |= rdp->grpmask; - invoke_rcu_node_kthread(rnp); raw_spin_unlock_irqrestore(&rnp->lock, flags); + invoke_rcu_node_kthread(rnp); } /* @@ -1694,16 +1679,12 @@ static int rcu_node_kthread(void *arg) for (;;) { rnp->node_kthread_status = RCU_KTHREAD_WAITING; - wait_event_interruptible(rnp->node_wq, rnp->wakemask != 0 || - kthread_should_stop()); - if (kthread_should_stop()) - break; + wait_event_interruptible(rnp->node_wq, rnp->wakemask != 0); rnp->node_kthread_status = RCU_KTHREAD_RUNNING; raw_spin_lock_irqsave(&rnp->lock, flags); mask = rnp->wakemask; rnp->wakemask = 0; - rcu_initiate_boost(rnp); - raw_spin_unlock_irqrestore(&rnp->lock, flags); + rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */ for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1) { if ((mask & 0x1) == 0) continue; @@ -1719,6 +1700,7 @@ static int rcu_node_kthread(void *arg) preempt_enable(); } } + /* NOTREACHED */ rnp->node_kthread_status = RCU_KTHREAD_STOPPED; return 0; } @@ -1738,7 +1720,7 @@ static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu) int cpu; unsigned long mask = rnp->qsmaskinit; - if (rnp->node_kthread_task == NULL || mask == 0) + if (rnp->node_kthread_task == NULL) return; if (!alloc_cpumask_var(&cm, GFP_KERNEL)) return; diff --git a/kernel/rcutree.h b/kernel/rcutree.h index a6a97171dac6..93d4a1c2e88b 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -444,15 +444,12 @@ static void rcu_preempt_send_cbs_to_online(void); static void __init __rcu_init_preempt(void); static void rcu_needs_cpu_flush(void); static void __init rcu_init_boost_waitqueue(struct rcu_node *rnp); -static void rcu_initiate_boost(struct rcu_node *rnp); +static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags); static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, cpumask_var_t cm); static void rcu_preempt_boost_start_gp(struct rcu_node *rnp); static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, struct rcu_node *rnp, int rnp_index); -#ifdef CONFIG_HOTPLUG_CPU -static void rcu_stop_boost_kthread(struct rcu_node *rnp); -#endif /* #ifdef CONFIG_HOTPLUG_CPU */ #endif /* #ifndef RCU_TREE_NONCORE */ diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index f629479d4b1f..ed339702481d 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -711,15 +711,17 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp) static void sync_rcu_preempt_exp_init(struct rcu_state *rsp, struct rcu_node *rnp) { + unsigned long flags; int must_wait = 0; - raw_spin_lock(&rnp->lock); /* irqs already disabled */ - if (!list_empty(&rnp->blkd_tasks)) { + raw_spin_lock_irqsave(&rnp->lock, flags); + if (list_empty(&rnp->blkd_tasks)) + raw_spin_unlock_irqrestore(&rnp->lock, flags); + else { rnp->exp_tasks = rnp->blkd_tasks.next; - rcu_initiate_boost(rnp); + rcu_initiate_boost(rnp, flags); /* releases rnp->lock */ must_wait = 1; } - raw_spin_unlock(&rnp->lock); /* irqs remain disabled */ if (!must_wait) rcu_report_exp_rnp(rsp, rnp); } @@ -1179,12 +1181,7 @@ static int rcu_boost(struct rcu_node *rnp) */ static void rcu_boost_kthread_timer(unsigned long arg) { - unsigned long flags; - struct rcu_node *rnp = (struct rcu_node *)arg; - - raw_spin_lock_irqsave(&rnp->lock, flags); - invoke_rcu_node_kthread(rnp); - raw_spin_unlock_irqrestore(&rnp->lock, flags); + invoke_rcu_node_kthread((struct rcu_node *)arg); } /* @@ -1200,10 +1197,7 @@ static int rcu_boost_kthread(void *arg) for (;;) { rnp->boost_kthread_status = RCU_KTHREAD_WAITING; wait_event_interruptible(rnp->boost_wq, rnp->boost_tasks || - rnp->exp_tasks || - kthread_should_stop()); - if (kthread_should_stop()) - break; + rnp->exp_tasks); rnp->boost_kthread_status = RCU_KTHREAD_RUNNING; more2boost = rcu_boost(rnp); if (more2boost) @@ -1215,7 +1209,7 @@ static int rcu_boost_kthread(void *arg) spincnt = 0; } } - rnp->boost_kthread_status = RCU_KTHREAD_STOPPED; + /* NOTREACHED */ return 0; } @@ -1225,14 +1219,17 @@ static int rcu_boost_kthread(void *arg) * kthread to start boosting them. If there is an expedited grace * period in progress, it is always time to boost. * - * The caller must hold rnp->lock. + * The caller must hold rnp->lock, which this function releases, + * but irqs remain disabled. The ->boost_kthread_task is immortal, + * so we don't need to worry about it going away. */ -static void rcu_initiate_boost(struct rcu_node *rnp) +static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags) { struct task_struct *t; if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) { rnp->n_balk_exp_gp_tasks++; + raw_spin_unlock_irqrestore(&rnp->lock, flags); return; } if (rnp->exp_tasks != NULL || @@ -1242,11 +1239,14 @@ static void rcu_initiate_boost(struct rcu_node *rnp) ULONG_CMP_GE(jiffies, rnp->boost_time))) { if (rnp->exp_tasks == NULL) rnp->boost_tasks = rnp->gp_tasks; + raw_spin_unlock_irqrestore(&rnp->lock, flags); t = rnp->boost_kthread_task; if (t != NULL) wake_up_process(t); - } else + } else { rcu_initiate_boost_trace(rnp); + raw_spin_unlock_irqrestore(&rnp->lock, flags); + } } /* @@ -1312,27 +1312,11 @@ static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, return 0; } -#ifdef CONFIG_HOTPLUG_CPU - -static void rcu_stop_boost_kthread(struct rcu_node *rnp) -{ - unsigned long flags; - struct task_struct *t; - - raw_spin_lock_irqsave(&rnp->lock, flags); - t = rnp->boost_kthread_task; - rnp->boost_kthread_task = NULL; - raw_spin_unlock_irqrestore(&rnp->lock, flags); - if (t != NULL) - kthread_stop(t); -} - -#endif /* #ifdef CONFIG_HOTPLUG_CPU */ - #else /* #ifdef CONFIG_RCU_BOOST */ -static void rcu_initiate_boost(struct rcu_node *rnp) +static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags) { + raw_spin_unlock_irqrestore(&rnp->lock, flags); } static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, @@ -1355,14 +1339,6 @@ static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, return 0; } -#ifdef CONFIG_HOTPLUG_CPU - -static void rcu_stop_boost_kthread(struct rcu_node *rnp) -{ -} - -#endif /* #ifdef CONFIG_HOTPLUG_CPU */ - #endif /* #else #ifdef CONFIG_RCU_BOOST */ #ifndef CONFIG_SMP -- cgit v1.2.2 From 30088ad815802f850f26114920ccf9effd4bc520 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 17:53:46 +0800 Subject: cgroup,rcu: convert call_rcu(free_css_set_rcu) to kfree_rcu() The rcu callback free_css_set_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(free_css_set_rcu). Signed-off-by: Lai Jiangshan Acked-by: Paul Menage Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/cgroup.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 25c7eb52de1a..d5160a83fb35 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -326,12 +326,6 @@ static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) return &css_set_table[index]; } -static void free_css_set_rcu(struct rcu_head *obj) -{ - struct css_set *cg = container_of(obj, struct css_set, rcu_head); - kfree(cg); -} - /* We don't maintain the lists running through each css_set to its * task until after the first call to cgroup_iter_start(). This * reduces the fork()/exit() overhead for people who have cgroups @@ -375,7 +369,7 @@ static void __put_css_set(struct css_set *cg, int taskexit) } write_unlock(&css_set_lock); - call_rcu(&cg->rcu_head, free_css_set_rcu); + kfree_rcu(cg, rcu_head); } /* -- cgit v1.2.2 From f2da1c40dc003939f616f27a103b2592f1424b07 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 17:55:16 +0800 Subject: cgroup,rcu: convert call_rcu(free_cgroup_rcu) to kfree_rcu() The rcu callback free_cgroup_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(free_cgroup_rcu). Signed-off-by: Lai Jiangshan Acked-by: Paul Menage Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/cgroup.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index d5160a83fb35..20451ce7195f 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -806,13 +806,6 @@ static int cgroup_call_pre_destroy(struct cgroup *cgrp) return ret; } -static void free_cgroup_rcu(struct rcu_head *obj) -{ - struct cgroup *cgrp = container_of(obj, struct cgroup, rcu_head); - - kfree(cgrp); -} - static void cgroup_diput(struct dentry *dentry, struct inode *inode) { /* is dentry a directory ? if so, kfree() associated cgroup */ @@ -850,7 +843,7 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode) */ BUG_ON(!list_empty(&cgrp->pidlists)); - call_rcu(&cgrp->rcu_head, free_cgroup_rcu); + kfree_rcu(cgrp, rcu_head); } iput(inode); } -- cgit v1.2.2 From 025cea99db3fb110ebc8ede5ff647833fab9574f Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 17:56:10 +0800 Subject: cgroup,rcu: convert call_rcu(__free_css_id_cb) to kfree_rcu() The rcu callback __free_css_id_cb() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(__free_css_id_cb). Signed-off-by: Lai Jiangshan Acked-by: Paul Menage Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/cgroup.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 20451ce7195f..909a35510af5 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4610,14 +4610,6 @@ bool css_is_ancestor(struct cgroup_subsys_state *child, return ret; } -static void __free_css_id_cb(struct rcu_head *head) -{ - struct css_id *id; - - id = container_of(head, struct css_id, rcu_head); - kfree(id); -} - void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) { struct css_id *id = css->id; @@ -4632,7 +4624,7 @@ void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) spin_lock(&ss->id_lock); idr_remove(&ss->idr, id->id); spin_unlock(&ss->id_lock); - call_rcu(&id->rcu_head, __free_css_id_cb); + kfree_rcu(id, rcu_head); } EXPORT_SYMBOL_GPL(free_css_id); -- cgit v1.2.2 From f5c8593c107500979909bd51c85e74bb2eaffbaa Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 17:57:04 +0800 Subject: net,rcu: convert call_rcu(tcf_common_free_rcu) to kfree_rcu() The rcu callback tcf_common_free_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(tcf_common_free_rcu). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/sched/act_api.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/net/sched/act_api.c b/net/sched/act_api.c index 14b42f4ad791..a606025814a1 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -26,11 +26,6 @@ #include #include -static void tcf_common_free_rcu(struct rcu_head *head) -{ - kfree(container_of(head, struct tcf_common, tcfc_rcu)); -} - void tcf_hash_destroy(struct tcf_common *p, struct tcf_hashinfo *hinfo) { unsigned int h = tcf_hash(p->tcfc_index, hinfo->hmask); @@ -47,7 +42,7 @@ void tcf_hash_destroy(struct tcf_common *p, struct tcf_hashinfo *hinfo) * gen_estimator est_timer() might access p->tcfc_lock * or bstats, wait a RCU grace period before freeing p */ - call_rcu(&p->tcfc_rcu, tcf_common_free_rcu); + kfree_rcu(p, tcfc_rcu); return; } } -- cgit v1.2.2 From 5957b1ac52c5fde2afe5d80abe2a1cb82a9b4f20 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 17:58:00 +0800 Subject: net,rcu: convert call_rcu(tcf_police_free_rcu) to kfree_rcu() [PATCH 05/17] net,rcu: convert call_rcu(tcf_police_free_rcu) to kfree_rcu() The rcu callback tcf_police_free_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(tcf_police_free_rcu). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/sched/act_police.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/net/sched/act_police.c b/net/sched/act_police.c index 8a1630774fd6..d6bcd64e91de 100644 --- a/net/sched/act_police.c +++ b/net/sched/act_police.c @@ -96,11 +96,6 @@ nla_put_failure: goto done; } -static void tcf_police_free_rcu(struct rcu_head *head) -{ - kfree(container_of(head, struct tcf_police, tcf_rcu)); -} - static void tcf_police_destroy(struct tcf_police *p) { unsigned int h = tcf_hash(p->tcf_index, POL_TAB_MASK); @@ -121,7 +116,7 @@ static void tcf_police_destroy(struct tcf_police *p) * gen_estimator est_timer() might access p->tcf_lock * or bstats, wait a RCU grace period before freeing p */ - call_rcu(&p->tcf_rcu, tcf_police_free_rcu); + kfree_rcu(p, tcf_rcu); return; } } -- cgit v1.2.2 From 38f57d1a4b4c13db92c7f6300a4e4ae70ff94d2b Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 17:59:14 +0800 Subject: net,rcu: convert call_rcu(in6_dev_finish_destroy_rcu) to kfree_rcu() The rcu callback in6_dev_finish_destroy_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(in6_dev_finish_destroy_rcu). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/ipv6/addrconf.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index a7bda0757053..c406f564b772 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -317,12 +317,6 @@ static void snmp6_free_dev(struct inet6_dev *idev) /* Nobody refers to this device, we may destroy it. */ -static void in6_dev_finish_destroy_rcu(struct rcu_head *head) -{ - struct inet6_dev *idev = container_of(head, struct inet6_dev, rcu); - kfree(idev); -} - void in6_dev_finish_destroy(struct inet6_dev *idev) { struct net_device *dev = idev->dev; @@ -339,7 +333,7 @@ void in6_dev_finish_destroy(struct inet6_dev *idev) return; } snmp6_free_dev(idev); - call_rcu(&idev->rcu, in6_dev_finish_destroy_rcu); + kfree_rcu(idev, rcu); } EXPORT_SYMBOL(in6_dev_finish_destroy); -- cgit v1.2.2 From e57859854aaac9b7ce0db3fe4959190a1a80b60a Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 18:00:14 +0800 Subject: net,rcu: convert call_rcu(inet6_ifa_finish_destroy_rcu) to kfree_rcu() The rcu callback inet6_ifa_finish_destroy_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(inet6_ifa_finish_destroy_rcu). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/ipv6/addrconf.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index c406f564b772..8f13d88d7dba 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -529,12 +529,6 @@ static int addrconf_fixup_forwarding(struct ctl_table *table, int *p, int old) } #endif -static void inet6_ifa_finish_destroy_rcu(struct rcu_head *head) -{ - struct inet6_ifaddr *ifp = container_of(head, struct inet6_ifaddr, rcu); - kfree(ifp); -} - /* Nobody refers to this ifaddr, destroy it */ void inet6_ifa_finish_destroy(struct inet6_ifaddr *ifp) { @@ -555,7 +549,7 @@ void inet6_ifa_finish_destroy(struct inet6_ifaddr *ifp) } dst_release(&ifp->rt->dst); - call_rcu(&ifp->rcu, inet6_ifa_finish_destroy_rcu); + kfree_rcu(ifp, rcu); } static void -- cgit v1.2.2 From 37b6b935e96e837ccc60812c03e9f92e7dce2e61 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 18:01:42 +0800 Subject: net,rcu: convert call_rcu(listeners_free_rcu) to kfree_rcu() The rcu callback listeners_free_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(listeners_free_rcu). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/netlink/af_netlink.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index c8f35b5d2ee9..5fe4f3b04ed3 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -1566,12 +1566,6 @@ netlink_kernel_release(struct sock *sk) } EXPORT_SYMBOL(netlink_kernel_release); - -static void listeners_free_rcu(struct rcu_head *head) -{ - kfree(container_of(head, struct listeners, rcu)); -} - int __netlink_change_ngroups(struct sock *sk, unsigned int groups) { struct listeners *new, *old; @@ -1588,7 +1582,7 @@ int __netlink_change_ngroups(struct sock *sk, unsigned int groups) memcpy(new->masks, old->masks, NLGRPSZ(tbl->groups)); rcu_assign_pointer(tbl->listeners, new); - call_rcu(&old->rcu, listeners_free_rcu); + kfree_rcu(old, rcu); } tbl->groups = groups; -- cgit v1.2.2 From 1231f0baa547a541a7481119323b7f964dda4788 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 18:05:02 +0800 Subject: net,rcu: convert call_rcu(sctp_local_addr_free) to kfree_rcu() The rcu callback sctp_local_addr_free() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(sctp_local_addr_free). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- include/net/sctp/sctp.h | 1 - net/sctp/bind_addr.c | 2 +- net/sctp/ipv6.c | 2 +- net/sctp/protocol.c | 9 +-------- 4 files changed, 3 insertions(+), 11 deletions(-) diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h index 505845ddb0be..01e094c6d0ae 100644 --- a/include/net/sctp/sctp.h +++ b/include/net/sctp/sctp.h @@ -115,7 +115,6 @@ * sctp/protocol.c */ extern struct sock *sctp_get_ctl_sock(void); -extern void sctp_local_addr_free(struct rcu_head *head); extern int sctp_copy_local_addr_list(struct sctp_bind_addr *, sctp_scope_t, gfp_t gfp, int flags); diff --git a/net/sctp/bind_addr.c b/net/sctp/bind_addr.c index faf71d179e46..3c06c87cd280 100644 --- a/net/sctp/bind_addr.c +++ b/net/sctp/bind_addr.c @@ -219,7 +219,7 @@ int sctp_del_bind_addr(struct sctp_bind_addr *bp, union sctp_addr *del_addr) } if (found) { - call_rcu(&addr->rcu, sctp_local_addr_free); + kfree_rcu(addr, rcu); SCTP_DBG_OBJCNT_DEC(addr); return 0; } diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c index 865ce7ba4e14..185fe058db11 100644 --- a/net/sctp/ipv6.c +++ b/net/sctp/ipv6.c @@ -123,7 +123,7 @@ static int sctp_inet6addr_event(struct notifier_block *this, unsigned long ev, } spin_unlock_bh(&sctp_local_addr_lock); if (found) - call_rcu(&addr->rcu, sctp_local_addr_free); + kfree_rcu(addr, rcu); break; } diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c index d5bf91d04f63..065d99958ced 100644 --- a/net/sctp/protocol.c +++ b/net/sctp/protocol.c @@ -230,13 +230,6 @@ static void sctp_free_local_addr_list(void) } } -void sctp_local_addr_free(struct rcu_head *head) -{ - struct sctp_sockaddr_entry *e = container_of(head, - struct sctp_sockaddr_entry, rcu); - kfree(e); -} - /* Copy the local addresses which are valid for 'scope' into 'bp'. */ int sctp_copy_local_addr_list(struct sctp_bind_addr *bp, sctp_scope_t scope, gfp_t gfp, int copy_flags) @@ -681,7 +674,7 @@ static int sctp_inetaddr_event(struct notifier_block *this, unsigned long ev, } spin_unlock_bh(&sctp_local_addr_lock); if (found) - call_rcu(&addr->rcu, sctp_local_addr_free); + kfree_rcu(addr, rcu); break; } -- cgit v1.2.2 From 217f18639bc18ba4bbb67481113037344c148938 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 18:08:58 +0800 Subject: net,rcu: convert call_rcu(ha_rcu_free) to kfree_rcu() The rcu callback ha_rcu_free() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(ha_rcu_free). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/core/dev_addr_lists.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/net/core/dev_addr_lists.c b/net/core/dev_addr_lists.c index 7b39f3ed2fda..e2e66939ed00 100644 --- a/net/core/dev_addr_lists.c +++ b/net/core/dev_addr_lists.c @@ -68,14 +68,6 @@ static int __hw_addr_add(struct netdev_hw_addr_list *list, unsigned char *addr, return __hw_addr_add_ex(list, addr, addr_len, addr_type, false); } -static void ha_rcu_free(struct rcu_head *head) -{ - struct netdev_hw_addr *ha; - - ha = container_of(head, struct netdev_hw_addr, rcu_head); - kfree(ha); -} - static int __hw_addr_del_ex(struct netdev_hw_addr_list *list, unsigned char *addr, int addr_len, unsigned char addr_type, bool global) @@ -94,7 +86,7 @@ static int __hw_addr_del_ex(struct netdev_hw_addr_list *list, if (--ha->refcount) return 0; list_del_rcu(&ha->list); - call_rcu(&ha->rcu_head, ha_rcu_free); + kfree_rcu(ha, rcu_head); list->count--; return 0; } @@ -197,7 +189,7 @@ void __hw_addr_flush(struct netdev_hw_addr_list *list) list_for_each_entry_safe(ha, tmp, &list->list, list) { list_del_rcu(&ha->list); - call_rcu(&ha->rcu_head, ha_rcu_free); + kfree_rcu(ha, rcu_head); } list->count = 0; } -- cgit v1.2.2 From 1e547757eca3c30eeeac526716e4ae833c2a9a2f Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 18:10:12 +0800 Subject: net,rcu: convert call_rcu(dn_dev_free_ifa_rcu) to kfree_rcu() The rcu callback dn_dev_free_ifa_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(dn_dev_free_ifa_rcu). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/decnet/dn_dev.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/net/decnet/dn_dev.c b/net/decnet/dn_dev.c index 0dcaa903e00e..4c27615340dc 100644 --- a/net/decnet/dn_dev.c +++ b/net/decnet/dn_dev.c @@ -332,14 +332,9 @@ static struct dn_ifaddr *dn_dev_alloc_ifa(void) return ifa; } -static void dn_dev_free_ifa_rcu(struct rcu_head *head) -{ - kfree(container_of(head, struct dn_ifaddr, rcu)); -} - static void dn_dev_free_ifa(struct dn_ifaddr *ifa) { - call_rcu(&ifa->rcu, dn_dev_free_ifa_rcu); + kfree_rcu(ifa, rcu); } static void dn_dev_del_ifa(struct dn_dev *dn_db, struct dn_ifaddr __rcu **ifap, int destroy) -- cgit v1.2.2 From 75ef0368d182785c7c5c06ac11081e31257a313e Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 18:11:46 +0800 Subject: net,act_police,rcu: remove rcu_barrier() There is no callback of this module maybe queued since we use kfree_rcu(), we can safely remove the rcu_barrier(). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/sched/act_police.c | 1 - 1 file changed, 1 deletion(-) diff --git a/net/sched/act_police.c b/net/sched/act_police.c index d6bcd64e91de..b3b9b32f4e00 100644 --- a/net/sched/act_police.c +++ b/net/sched/act_police.c @@ -396,7 +396,6 @@ static void __exit police_cleanup_module(void) { tcf_unregister_action(&act_police_ops); - rcu_barrier(); /* Wait for completion of call_rcu()'s (tcf_police_free_rcu) */ } module_init(police_init_module); -- cgit v1.2.2 From 3acb458c32293405cf68985b7b3ac5dc0a5e7929 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:11:07 +0800 Subject: security,rcu: convert call_rcu(user_update_rcu_disposal) to kfree_rcu() The rcu callback user_update_rcu_disposal() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(user_update_rcu_disposal). Signed-off-by: Lai Jiangshan Signed-off-by: Paul E. McKenney Acked-by: David Howells Reviewed-by: Josh Triplett --- security/keys/user_defined.c | 16 ++-------------- 1 file changed, 2 insertions(+), 14 deletions(-) diff --git a/security/keys/user_defined.c b/security/keys/user_defined.c index c6ca8662a468..f66baf44f32d 100644 --- a/security/keys/user_defined.c +++ b/security/keys/user_defined.c @@ -68,18 +68,6 @@ error: EXPORT_SYMBOL_GPL(user_instantiate); -/* - * dispose of the old data from an updated user defined key - */ -static void user_update_rcu_disposal(struct rcu_head *rcu) -{ - struct user_key_payload *upayload; - - upayload = container_of(rcu, struct user_key_payload, rcu); - - kfree(upayload); -} - /* * update a user defined key * - the key's semaphore is write-locked @@ -114,7 +102,7 @@ int user_update(struct key *key, const void *data, size_t datalen) key->expiry = 0; } - call_rcu(&zap->rcu, user_update_rcu_disposal); + kfree_rcu(zap, rcu); error: return ret; @@ -145,7 +133,7 @@ void user_revoke(struct key *key) if (upayload) { rcu_assign_pointer(key->payload.data, NULL); - call_rcu(&upayload->rcu, user_update_rcu_disposal); + kfree_rcu(upayload, rcu); } } -- cgit v1.2.2 From 4670994d150a86ebd53ab353a2af517c5465bfaf Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 11:42:11 +0800 Subject: net,rcu: convert call_rcu(fc_rport_free_rcu) to kfree_rcu() The rcu callback fc_rport_free_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(fc_rport_free_rcu). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/ipv4/fib_semantics.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-) diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index 641a5a2a9f9c..33e2c35b74b7 100644 --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -141,18 +141,8 @@ const struct fib_prop fib_props[RTN_MAX + 1] = { }, }; - /* Release a nexthop info record */ -static void free_fib_info_rcu(struct rcu_head *head) -{ - struct fib_info *fi = container_of(head, struct fib_info, rcu); - - if (fi->fib_metrics != (u32 *) dst_default_metrics) - kfree(fi->fib_metrics); - kfree(fi); -} - void free_fib_info(struct fib_info *fi) { if (fi->fib_dead == 0) { @@ -166,7 +156,7 @@ void free_fib_info(struct fib_info *fi) } endfor_nexthops(fi); fib_info_cnt--; release_net(fi->fib_net); - call_rcu(&fi->rcu, free_fib_info_rcu); + kfree_rcu(fi, rcu); } void fib_release_info(struct fib_info *fi) -- cgit v1.2.2 From bceb0f4512d448763fe98c9f37504c98bbebbed6 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 11:42:34 +0800 Subject: net,rcu: convert call_rcu(__leaf_info_free_rcu) to kfree_rcu() The rcu callback __leaf_info_free_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(__leaf_info_free_rcu). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/ipv4/fib_trie.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 5fe9b8b41df3..11d4d28190bd 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -350,14 +350,9 @@ static inline void free_leaf(struct leaf *l) call_rcu_bh(&l->rcu, __leaf_free_rcu); } -static void __leaf_info_free_rcu(struct rcu_head *head) -{ - kfree(container_of(head, struct leaf_info, rcu)); -} - static inline void free_leaf_info(struct leaf_info *leaf) { - call_rcu(&leaf->rcu, __leaf_info_free_rcu); + kfree_rcu(leaf, rcu); } static struct tnode *tnode_alloc(size_t size) -- cgit v1.2.2 From dad178fcd5b295f5f350a46a5eaf2f28e847bb5a Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 11:43:26 +0800 Subject: net,rcu: convert call_rcu(__gen_kill_estimator) to kfree_rcu() The rcu callback __gen_kill_estimator() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(__gen_kill_estimator). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/core/gen_estimator.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c index 7c2373321b74..43b03dd71e85 100644 --- a/net/core/gen_estimator.c +++ b/net/core/gen_estimator.c @@ -249,13 +249,6 @@ int gen_new_estimator(struct gnet_stats_basic_packed *bstats, } EXPORT_SYMBOL(gen_new_estimator); -static void __gen_kill_estimator(struct rcu_head *head) -{ - struct gen_estimator *e = container_of(head, - struct gen_estimator, e_rcu); - kfree(e); -} - /** * gen_kill_estimator - remove a rate estimator * @bstats: basic statistics @@ -279,7 +272,7 @@ void gen_kill_estimator(struct gnet_stats_basic_packed *bstats, write_unlock(&est_lock); list_del_rcu(&e->list); - call_rcu(&e->e_rcu, __gen_kill_estimator); + kfree_rcu(e, e_rcu); } spin_unlock_bh(&est_tree_lock); } -- cgit v1.2.2 From 42ea299d3f1941f8c3dbc1fe031d682f8ad45005 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 11:44:08 +0800 Subject: net,rcu: convert call_rcu(ip_mc_list_reclaim) to kfree_rcu() The rcu callback ip_mc_list_reclaim() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(ip_mc_list_reclaim). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/ipv4/igmp.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index 1fd3d9ce8398..f22f30e3f1af 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -149,17 +149,11 @@ static void ip_mc_clear_src(struct ip_mc_list *pmc); static int ip_mc_add_src(struct in_device *in_dev, __be32 *pmca, int sfmode, int sfcount, __be32 *psfsrc, int delta); - -static void ip_mc_list_reclaim(struct rcu_head *head) -{ - kfree(container_of(head, struct ip_mc_list, rcu)); -} - static void ip_ma_put(struct ip_mc_list *im) { if (atomic_dec_and_test(&im->refcnt)) { in_dev_put(im->interface); - call_rcu(&im->rcu, ip_mc_list_reclaim); + kfree_rcu(im, rcu); } } -- cgit v1.2.2 From 7519cce48fb0a314dac473bdfba203b787435857 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 11:44:46 +0800 Subject: net,rcu: convert call_rcu(ip_sf_socklist_reclaim) to kfree_rcu() The rcu callback ip_sf_socklist_reclaim() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(ip_sf_socklist_reclaim). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/ipv4/igmp.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index f22f30e3f1af..85a6e5d70632 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -1830,12 +1830,6 @@ done: } EXPORT_SYMBOL(ip_mc_join_group); -static void ip_sf_socklist_reclaim(struct rcu_head *rp) -{ - kfree(container_of(rp, struct ip_sf_socklist, rcu)); - /* sk_omem_alloc should have been decreased by the caller*/ -} - static int ip_mc_leave_src(struct sock *sk, struct ip_mc_socklist *iml, struct in_device *in_dev) { @@ -1852,7 +1846,7 @@ static int ip_mc_leave_src(struct sock *sk, struct ip_mc_socklist *iml, rcu_assign_pointer(iml->sflist, NULL); /* decrease mem now to avoid the memleak warning */ atomic_sub(IP_SFLSIZE(psf->sl_max), &sk->sk_omem_alloc); - call_rcu(&psf->rcu, ip_sf_socklist_reclaim); + kfree_rcu(psf, rcu); return err; } @@ -2020,7 +2014,7 @@ int ip_mc_source(int add, int omode, struct sock *sk, struct newpsl->sl_addr[i] = psl->sl_addr[i]; /* decrease mem now to avoid the memleak warning */ atomic_sub(IP_SFLSIZE(psl->sl_max), &sk->sk_omem_alloc); - call_rcu(&psl->rcu, ip_sf_socklist_reclaim); + kfree_rcu(psl, rcu); } rcu_assign_pointer(pmc->sflist, newpsl); psl = newpsl; @@ -2121,7 +2115,7 @@ int ip_mc_msfilter(struct sock *sk, struct ip_msfilter *msf, int ifindex) psl->sl_count, psl->sl_addr, 0); /* decrease mem now to avoid the memleak warning */ atomic_sub(IP_SFLSIZE(psl->sl_max), &sk->sk_omem_alloc); - call_rcu(&psl->rcu, ip_sf_socklist_reclaim); + kfree_rcu(psl, rcu); } else (void) ip_mc_del_src(in_dev, &msf->imsf_multiaddr, pmc->sfmode, 0, NULL, 0); -- cgit v1.2.2 From 10d50e748d983ff1003e0cf556ea17fa8f32c382 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 11:45:08 +0800 Subject: net,rcu: convert call_rcu(ip_mc_socklist_reclaim) to kfree_rcu() The rcu callback ip_mc_socklist_reclaim() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(ip_mc_socklist_reclaim). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/ipv4/igmp.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index 85a6e5d70632..8f62d66d0857 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -1850,14 +1850,6 @@ static int ip_mc_leave_src(struct sock *sk, struct ip_mc_socklist *iml, return err; } - -static void ip_mc_socklist_reclaim(struct rcu_head *rp) -{ - kfree(container_of(rp, struct ip_mc_socklist, rcu)); - /* sk_omem_alloc should have been decreased by the caller*/ -} - - /* * Ask a socket to leave a group. */ @@ -1897,7 +1889,7 @@ int ip_mc_leave_group(struct sock *sk, struct ip_mreqn *imr) rtnl_unlock(); /* decrease mem now to avoid the memleak warning */ atomic_sub(sizeof(*iml), &sk->sk_omem_alloc); - call_rcu(&iml->rcu, ip_mc_socklist_reclaim); + kfree_rcu(iml, rcu); return 0; } if (!in_dev) @@ -2312,7 +2304,7 @@ void ip_mc_drop_socket(struct sock *sk) ip_mc_dec_group(in_dev, iml->multi.imr_multiaddr.s_addr); /* decrease mem now to avoid the memleak warning */ atomic_sub(sizeof(*iml), &sk->sk_omem_alloc); - call_rcu(&iml->rcu, ip_mc_socklist_reclaim); + kfree_rcu(iml, rcu); } rtnl_unlock(); } -- cgit v1.2.2 From fa81c0e1d2d2176f1136c72c080c9ea4a98be347 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 11:39:43 +0800 Subject: net,rcu: convert call_rcu(free_dm_hw_stat) to kfree_rcu() The rcu callback free_dm_hw_stat() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(free_dm_hw_stat). Signed-off-by: Lai Jiangshan Acked-by: Neil Horman Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/core/drop_monitor.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c index 706502ff64aa..7f36b38e060f 100644 --- a/net/core/drop_monitor.c +++ b/net/core/drop_monitor.c @@ -207,14 +207,6 @@ static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi) rcu_read_unlock(); } - -static void free_dm_hw_stat(struct rcu_head *head) -{ - struct dm_hw_stat_delta *n; - n = container_of(head, struct dm_hw_stat_delta, rcu); - kfree(n); -} - static int set_all_monitor_traces(int state) { int rc = 0; @@ -245,7 +237,7 @@ static int set_all_monitor_traces(int state) list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) { if (new_stat->dev == NULL) { list_del_rcu(&new_stat->list); - call_rcu(&new_stat->rcu, free_dm_hw_stat); + kfree_rcu(new_stat, rcu); } } break; @@ -314,7 +306,7 @@ static int dropmon_net_event(struct notifier_block *ev_block, new_stat->dev = NULL; if (trace_state == TRACE_OFF) { list_del_rcu(&new_stat->list); - call_rcu(&new_stat->rcu, free_dm_hw_stat); + kfree_rcu(new_stat, rcu); break; } } -- cgit v1.2.2 From bcec8b6531d481ced35506517af69adb2399f2a4 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 11:57:21 +0800 Subject: ixgbe,rcu: convert call_rcu(ring_free_rcu) to kfree_rcu() The rcu callback ring_free_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(ring_free_rcu). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- drivers/net/ixgbe/ixgbe_main.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/drivers/net/ixgbe/ixgbe_main.c b/drivers/net/ixgbe/ixgbe_main.c index 6f8adc7f5d7c..e145f2c455cb 100644 --- a/drivers/net/ixgbe/ixgbe_main.c +++ b/drivers/net/ixgbe/ixgbe_main.c @@ -5100,11 +5100,6 @@ err_set_interrupt: return err; } -static void ring_free_rcu(struct rcu_head *head) -{ - kfree(container_of(head, struct ixgbe_ring, rcu)); -} - /** * ixgbe_clear_interrupt_scheme - Clear the current interrupt scheme settings * @adapter: board private structure to clear interrupt scheme on @@ -5126,7 +5121,7 @@ void ixgbe_clear_interrupt_scheme(struct ixgbe_adapter *adapter) /* ixgbe_get_stats64() might access this ring, we must wait * a grace period before freeing it. */ - call_rcu(&ring->rcu, ring_free_rcu); + kfree_rcu(ring, rcu); adapter->rx_ring[i] = NULL; } -- cgit v1.2.2 From 6e070aecd9e304264a6b8655f49aa7e6db0e55f2 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:00:07 +0800 Subject: macvlan,rcu: convert call_rcu(macvlan_port_rcu_free) to kfree_rcu() The rcu callback macvlan_port_rcu_free() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(macvlan_port_rcu_free). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- drivers/net/macvlan.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c index 78e34e9e4f00..d8e4e69ad0b9 100644 --- a/drivers/net/macvlan.c +++ b/drivers/net/macvlan.c @@ -603,21 +603,13 @@ static int macvlan_port_create(struct net_device *dev) return err; } -static void macvlan_port_rcu_free(struct rcu_head *head) -{ - struct macvlan_port *port; - - port = container_of(head, struct macvlan_port, rcu); - kfree(port); -} - static void macvlan_port_destroy(struct net_device *dev) { struct macvlan_port *port = macvlan_port_get(dev); dev->priv_flags &= ~IFF_MACVLAN_PORT; netdev_rx_handler_unregister(dev); - call_rcu(&port->rcu, macvlan_port_rcu_free); + kfree_rcu(port, rcu); } static int macvlan_validate(struct nlattr *tb[], struct nlattr *data[]) -- cgit v1.2.2 From e3cbf28fa61456bd2f0ba39846ffd905257eb4b0 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:00:50 +0800 Subject: net,rcu: convert call_rcu(ipv6_mc_socklist_reclaim) to kfree_rcu() The rcu callback ipv6_mc_socklist_reclaim() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(ipv6_mc_socklist_reclaim). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/ipv6/mcast.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index 76b893771e6e..f2d98ca7588a 100644 --- a/net/ipv6/mcast.c +++ b/net/ipv6/mcast.c @@ -201,10 +201,6 @@ int ipv6_sock_mc_join(struct sock *sk, int ifindex, const struct in6_addr *addr) return 0; } -static void ipv6_mc_socklist_reclaim(struct rcu_head *head) -{ - kfree(container_of(head, struct ipv6_mc_socklist, rcu)); -} /* * socket leave on multicast group */ @@ -239,7 +235,7 @@ int ipv6_sock_mc_drop(struct sock *sk, int ifindex, const struct in6_addr *addr) (void) ip6_mc_leave_src(sk, mc_lst, NULL); rcu_read_unlock(); atomic_sub(sizeof(*mc_lst), &sk->sk_omem_alloc); - call_rcu(&mc_lst->rcu, ipv6_mc_socklist_reclaim); + kfree_rcu(mc_lst, rcu); return 0; } } @@ -307,7 +303,7 @@ void ipv6_sock_mc_close(struct sock *sk) rcu_read_unlock(); atomic_sub(sizeof(*mc_lst), &sk->sk_omem_alloc); - call_rcu(&mc_lst->rcu, ipv6_mc_socklist_reclaim); + kfree_rcu(mc_lst, rcu); spin_lock(&ipv6_sk_mc_lock); } -- cgit v1.2.2 From f6f80238fab1ad19c44b4a12501528d50fc7fcd6 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:01:31 +0800 Subject: net,rcu: convert call_rcu(rps_map_release) to kfree_rcu() The rcu callback rps_map_release() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(rps_map_release). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/core/net-sysfs.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 5ceb257e860c..c410f2854c89 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -565,13 +565,6 @@ static ssize_t show_rps_map(struct netdev_rx_queue *queue, return len; } -static void rps_map_release(struct rcu_head *rcu) -{ - struct rps_map *map = container_of(rcu, struct rps_map, rcu); - - kfree(map); -} - static ssize_t store_rps_map(struct netdev_rx_queue *queue, struct rx_queue_attribute *attribute, const char *buf, size_t len) @@ -619,7 +612,7 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue, spin_unlock(&rps_map_lock); if (old_map) - call_rcu(&old_map->rcu, rps_map_release); + kfree_rcu(old_map, rcu); free_cpumask_var(mask); return len; @@ -728,7 +721,7 @@ static void rx_queue_release(struct kobject *kobj) map = rcu_dereference_raw(queue->rps_map); if (map) { RCU_INIT_POINTER(queue->rps_map, NULL); - call_rcu(&map->rcu, rps_map_release); + kfree_rcu(map, rcu); } flow_table = rcu_dereference_raw(queue->rps_flow_table); -- cgit v1.2.2 From edc86d8a1c824cca1df676f47fc713232885561f Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:02:20 +0800 Subject: net,rcu: convert call_rcu(xps_map_release) to kfree_rcu() The rcu callback xps_map_release() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(xps_map_release). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/core/net-sysfs.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index c410f2854c89..48ffc216c86f 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -891,13 +891,6 @@ static ssize_t show_xps_map(struct netdev_queue *queue, return len; } -static void xps_map_release(struct rcu_head *rcu) -{ - struct xps_map *map = container_of(rcu, struct xps_map, rcu); - - kfree(map); -} - static void xps_dev_maps_release(struct rcu_head *rcu) { struct xps_dev_maps *dev_maps = @@ -1002,7 +995,7 @@ static ssize_t store_xps_map(struct netdev_queue *queue, map = dev_maps ? xmap_dereference(dev_maps->cpu_map[cpu]) : NULL; if (map && xmap_dereference(new_dev_maps->cpu_map[cpu]) != map) - call_rcu(&map->rcu, xps_map_release); + kfree_rcu(map, rcu); if (new_dev_maps->cpu_map[cpu]) nonempty = 1; } @@ -1077,7 +1070,7 @@ static void netdev_queue_release(struct kobject *kobj) else { RCU_INIT_POINTER(dev_maps->cpu_map[i], NULL); - call_rcu(&map->rcu, xps_map_release); + kfree_rcu(map, rcu); map = NULL; } } -- cgit v1.2.2 From b55071eb6011413af3b9c434ae77dea8832069c8 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:02:47 +0800 Subject: net,rcu: convert call_rcu(xps_dev_maps_release) to kfree_rcu() The rcu callback xps_dev_maps_release() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(xps_dev_maps_release). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/core/net-sysfs.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 48ffc216c86f..80b2aad3b73d 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -891,14 +891,6 @@ static ssize_t show_xps_map(struct netdev_queue *queue, return len; } -static void xps_dev_maps_release(struct rcu_head *rcu) -{ - struct xps_dev_maps *dev_maps = - container_of(rcu, struct xps_dev_maps, rcu); - - kfree(dev_maps); -} - static DEFINE_MUTEX(xps_map_mutex); #define xmap_dereference(P) \ rcu_dereference_protected((P), lockdep_is_held(&xps_map_mutex)) @@ -1008,7 +1000,7 @@ static ssize_t store_xps_map(struct netdev_queue *queue, } if (dev_maps) - call_rcu(&dev_maps->rcu, xps_dev_maps_release); + kfree_rcu(dev_maps, rcu); netdev_queue_numa_node_write(queue, (numa_node >= 0) ? numa_node : NUMA_NO_NODE); @@ -1080,7 +1072,7 @@ static void netdev_queue_release(struct kobject *kobj) if (!nonempty) { RCU_INIT_POINTER(dev->xps_maps, NULL); - call_rcu(&dev_maps->rcu, xps_dev_maps_release); + kfree_rcu(dev_maps, rcu); } } -- cgit v1.2.2 From 690273fc70e94a07d70044881e5e52926301bcd3 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:03:19 +0800 Subject: security,rcu: convert call_rcu(sel_netif_free) to kfree_rcu() The rcu callback sel_netif_free() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(sel_netif_free). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- security/selinux/netif.c | 18 +----------------- 1 file changed, 1 insertion(+), 17 deletions(-) diff --git a/security/selinux/netif.c b/security/selinux/netif.c index d6095d63d831..58cc481c93d5 100644 --- a/security/selinux/netif.c +++ b/security/selinux/netif.c @@ -103,22 +103,6 @@ static int sel_netif_insert(struct sel_netif *netif) return 0; } -/** - * sel_netif_free - Frees an interface entry - * @p: the entry's RCU field - * - * Description: - * This function is designed to be used as a callback to the call_rcu() - * function so that memory allocated to a hash table interface entry can be - * released safely. - * - */ -static void sel_netif_free(struct rcu_head *p) -{ - struct sel_netif *netif = container_of(p, struct sel_netif, rcu_head); - kfree(netif); -} - /** * sel_netif_destroy - Remove an interface record from the table * @netif: the existing interface record @@ -131,7 +115,7 @@ static void sel_netif_destroy(struct sel_netif *netif) { list_del_rcu(&netif->list); sel_netif_total--; - call_rcu(&netif->rcu_head, sel_netif_free); + kfree_rcu(netif, rcu_head); } /** -- cgit v1.2.2 From c3b494209cc6084bd76d823d185a60ee5bd40b0d Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:03:56 +0800 Subject: net,rcu: convert call_rcu(netlbl_unlhsh_free_addr4) to kfree_rcu() The rcu callback netlbl_unlhsh_free_addr4() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(netlbl_unlhsh_free_addr4). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Acked-by: Paul Moore Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/netlabel/netlabel_unlabeled.c | 20 +------------------- 1 file changed, 1 insertion(+), 19 deletions(-) diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c index e2b0a680dd56..4e5ad90cc21c 100644 --- a/net/netlabel/netlabel_unlabeled.c +++ b/net/netlabel/netlabel_unlabeled.c @@ -153,24 +153,6 @@ static const struct nla_policy netlbl_unlabel_genl_policy[NLBL_UNLABEL_A_MAX + 1 * Unlabeled Connection Hash Table Functions */ -/** - * netlbl_unlhsh_free_addr4 - Frees an IPv4 address entry from the hash table - * @entry: the entry's RCU field - * - * Description: - * This function is designed to be used as a callback to the call_rcu() - * function so that memory allocated to a hash table address entry can be - * released safely. - * - */ -static void netlbl_unlhsh_free_addr4(struct rcu_head *entry) -{ - struct netlbl_unlhsh_addr4 *ptr; - - ptr = container_of(entry, struct netlbl_unlhsh_addr4, rcu); - kfree(ptr); -} - #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) /** * netlbl_unlhsh_free_addr6 - Frees an IPv6 address entry from the hash table @@ -568,7 +550,7 @@ static int netlbl_unlhsh_remove_addr4(struct net *net, if (entry == NULL) return -ENOENT; - call_rcu(&entry->rcu, netlbl_unlhsh_free_addr4); + kfree_rcu(entry, rcu); return 0; } -- cgit v1.2.2 From 6b2622328110b9c1094a4f644a6cdc9b6d5450ac Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:04:50 +0800 Subject: net,rcu: convert call_rcu(netlbl_unlhsh_free_addr6) to kfree_rcu() The rcu callback netlbl_unlhsh_free_addr6() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(netlbl_unlhsh_free_addr6). Signed-off-by: Lai Jiangshan Acked-by: Paul Moore Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/netlabel/netlabel_unlabeled.c | 22 +--------------------- 1 file changed, 1 insertion(+), 21 deletions(-) diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c index 4e5ad90cc21c..9c38658fba8b 100644 --- a/net/netlabel/netlabel_unlabeled.c +++ b/net/netlabel/netlabel_unlabeled.c @@ -153,26 +153,6 @@ static const struct nla_policy netlbl_unlabel_genl_policy[NLBL_UNLABEL_A_MAX + 1 * Unlabeled Connection Hash Table Functions */ -#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) -/** - * netlbl_unlhsh_free_addr6 - Frees an IPv6 address entry from the hash table - * @entry: the entry's RCU field - * - * Description: - * This function is designed to be used as a callback to the call_rcu() - * function so that memory allocated to a hash table address entry can be - * released safely. - * - */ -static void netlbl_unlhsh_free_addr6(struct rcu_head *entry) -{ - struct netlbl_unlhsh_addr6 *ptr; - - ptr = container_of(entry, struct netlbl_unlhsh_addr6, rcu); - kfree(ptr); -} -#endif /* IPv6 */ - /** * netlbl_unlhsh_free_iface - Frees an interface entry from the hash table * @entry: the entry's RCU field @@ -611,7 +591,7 @@ static int netlbl_unlhsh_remove_addr6(struct net *net, if (entry == NULL) return -ENOENT; - call_rcu(&entry->rcu, netlbl_unlhsh_free_addr6); + kfree_rcu(entry, rcu); return 0; } #endif /* IPv6 */ -- cgit v1.2.2 From 04d4dfed8e64f65d672502a614a4bb9093d1affd Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:06:32 +0800 Subject: net,rcu: convert call_rcu(net_generic_release) to kfree_rcu() The rcu callback net_generic_release() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(net_generic_release). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/core/net_namespace.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 3f860261c5ee..297bb9272240 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -27,14 +27,6 @@ EXPORT_SYMBOL(init_net); #define INITIAL_NET_GEN_PTRS 13 /* +1 for len +2 for rcu_head */ -static void net_generic_release(struct rcu_head *rcu) -{ - struct net_generic *ng; - - ng = container_of(rcu, struct net_generic, rcu); - kfree(ng); -} - static int net_assign_generic(struct net *net, int id, void *data) { struct net_generic *ng, *old_ng; @@ -68,7 +60,7 @@ static int net_assign_generic(struct net *net, int id, void *data) memcpy(&ng->ptr, &old_ng->ptr, old_ng->len * sizeof(void*)); rcu_assign_pointer(net->gen, ng); - call_rcu(&old_ng->rcu, net_generic_release); + kfree_rcu(old_ng, rcu); assign: ng->ptr[id - 1] = data; return 0; -- cgit v1.2.2 From 1f8d36a1869f5efae4fadf6baf01f02211040b97 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:07:09 +0800 Subject: net,rcu: convert call_rcu(__nf_ct_ext_free_rcu) to kfree_rcu() The rcu callback __nf_ct_ext_free_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(__nf_ct_ext_free_rcu). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/netfilter/nf_conntrack_extend.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/net/netfilter/nf_conntrack_extend.c b/net/netfilter/nf_conntrack_extend.c index 80a23ed62bb0..05ecdc281a53 100644 --- a/net/netfilter/nf_conntrack_extend.c +++ b/net/netfilter/nf_conntrack_extend.c @@ -68,12 +68,6 @@ nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id, gfp_t gfp) return (void *)(*ext) + off; } -static void __nf_ct_ext_free_rcu(struct rcu_head *head) -{ - struct nf_ct_ext *ext = container_of(head, struct nf_ct_ext, rcu); - kfree(ext); -} - void *__nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp) { struct nf_ct_ext *old, *new; @@ -114,7 +108,7 @@ void *__nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp) (void *)old + old->offset[i]); rcu_read_unlock(); } - call_rcu(&old->rcu, __nf_ct_ext_free_rcu); + kfree_rcu(old, rcu); ct->ext = new; } -- cgit v1.2.2 From cb796ff338db9f064f4ecb7d41898e8bedcad4d9 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:07:41 +0800 Subject: perf,rcu: convert call_rcu(free_ctx) to kfree_rcu() The rcu callback free_ctx() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(free_ctx). Signed-off-by: Lai Jiangshan Acked-by: Peter Zijlstra Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/perf_event.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 8e81a9860a0d..17a176f7ef11 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -586,14 +586,6 @@ static void get_ctx(struct perf_event_context *ctx) WARN_ON(!atomic_inc_not_zero(&ctx->refcount)); } -static void free_ctx(struct rcu_head *head) -{ - struct perf_event_context *ctx; - - ctx = container_of(head, struct perf_event_context, rcu_head); - kfree(ctx); -} - static void put_ctx(struct perf_event_context *ctx) { if (atomic_dec_and_test(&ctx->refcount)) { @@ -601,7 +593,7 @@ static void put_ctx(struct perf_event_context *ctx) put_ctx(ctx->parent_ctx); if (ctx->task) put_task_struct(ctx->task); - call_rcu(&ctx->rcu_head, free_ctx); + kfree_rcu(ctx, rcu_head); } } -- cgit v1.2.2 From fa4bbc4ca5795fbf1303b98c924e51a21a920f14 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:08:29 +0800 Subject: perf,rcu: convert call_rcu(swevent_hlist_release_rcu) to kfree_rcu() The rcu callback swevent_hlist_release_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(swevent_hlist_release_rcu). Signed-off-by: Lai Jiangshan Acked-by: Peter Zijlstra Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/perf_event.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 17a176f7ef11..b90d660fc875 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -5323,14 +5323,6 @@ swevent_hlist_deref(struct swevent_htable *swhash) lockdep_is_held(&swhash->hlist_mutex)); } -static void swevent_hlist_release_rcu(struct rcu_head *rcu_head) -{ - struct swevent_hlist *hlist; - - hlist = container_of(rcu_head, struct swevent_hlist, rcu_head); - kfree(hlist); -} - static void swevent_hlist_release(struct swevent_htable *swhash) { struct swevent_hlist *hlist = swevent_hlist_deref(swhash); @@ -5339,7 +5331,7 @@ static void swevent_hlist_release(struct swevent_htable *swhash) return; rcu_assign_pointer(swhash->swevent_hlist, NULL); - call_rcu(&hlist->rcu_head, swevent_hlist_release_rcu); + kfree_rcu(hlist, rcu_head); } static void swevent_hlist_put_cpu(struct perf_event *event, int cpu) -- cgit v1.2.2 From 7e113a9c759d1918fcbe456c5eb8890a4da62eaa Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:09:03 +0800 Subject: net,rcu: convert call_rcu(phonet_device_rcu_free) to kfree_rcu() The rcu callback phonet_device_rcu_free() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(phonet_device_rcu_free). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/phonet/pn_dev.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c index 947038ddd04c..1566672235dd 100644 --- a/net/phonet/pn_dev.c +++ b/net/phonet/pn_dev.c @@ -162,14 +162,6 @@ int phonet_address_add(struct net_device *dev, u8 addr) return err; } -static void phonet_device_rcu_free(struct rcu_head *head) -{ - struct phonet_device *pnd; - - pnd = container_of(head, struct phonet_device, rcu); - kfree(pnd); -} - int phonet_address_del(struct net_device *dev, u8 addr) { struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev)); @@ -188,7 +180,7 @@ int phonet_address_del(struct net_device *dev, u8 addr) mutex_unlock(&pndevs->lock); if (pnd) - call_rcu(&pnd->rcu, phonet_device_rcu_free); + kfree_rcu(pnd, rcu); return err; } -- cgit v1.2.2 From 61845220248c2368095158420b029683fad5570a Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:10:25 +0800 Subject: net,rcu: convert call_rcu(wq_free_rcu) to kfree_rcu() The rcu callback wq_free_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(wq_free_rcu). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/socket.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) diff --git a/net/socket.c b/net/socket.c index 310d16b1b3c9..c2ed7c95ce87 100644 --- a/net/socket.c +++ b/net/socket.c @@ -263,15 +263,6 @@ static struct inode *sock_alloc_inode(struct super_block *sb) return &ei->vfs_inode; } - - -static void wq_free_rcu(struct rcu_head *head) -{ - struct socket_wq *wq = container_of(head, struct socket_wq, rcu); - - kfree(wq); -} - static void sock_destroy_inode(struct inode *inode) { struct socket_alloc *ei; @@ -279,7 +270,7 @@ static void sock_destroy_inode(struct inode *inode) ei = container_of(inode, struct socket_alloc, vfs_inode); wq = rcu_dereference_protected(ei->socket.wq, 1); - call_rcu(&wq->rcu, wq_free_rcu); + kfree_rcu(wq, rcu); kmem_cache_free(sock_inode_cachep, ei); } -- cgit v1.2.2 From a74ce1425e4f6075de443274a5e917c84357eac4 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:14:15 +0800 Subject: net/mac80211,rcu: convert call_rcu(work_free_rcu) to kfree_rcu() The rcu callback work_free_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(work_free_rcu). Signed-off-by: Lai Jiangshan Acked-by: "John W. Linville" Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/mac80211/work.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/net/mac80211/work.c b/net/mac80211/work.c index e73c8cae036b..ac3549690b8e 100644 --- a/net/mac80211/work.c +++ b/net/mac80211/work.c @@ -65,17 +65,9 @@ static void run_again(struct ieee80211_local *local, mod_timer(&local->work_timer, timeout); } -static void work_free_rcu(struct rcu_head *head) -{ - struct ieee80211_work *wk = - container_of(head, struct ieee80211_work, rcu_head); - - kfree(wk); -} - void free_work(struct ieee80211_work *wk) { - call_rcu(&wk->rcu_head, work_free_rcu); + kfree_rcu(wk, rcu_head); } static int ieee80211_compatible_rates(const u8 *supp_rates, int supp_rates_len, -- cgit v1.2.2 From 88b4a0347a81539884df5ad535e10cf9fa87d8d4 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 18 Mar 2011 12:15:02 +0800 Subject: net,rcu: convert call_rcu(xt_osf_finger_free_rcu) to kfree_rcu() The rcu callback xt_osf_finger_free_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(xt_osf_finger_free_rcu). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- net/netfilter/xt_osf.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/net/netfilter/xt_osf.c b/net/netfilter/xt_osf.c index 4327e101c047..846f895cb656 100644 --- a/net/netfilter/xt_osf.c +++ b/net/netfilter/xt_osf.c @@ -62,13 +62,6 @@ static const struct nla_policy xt_osf_policy[OSF_ATTR_MAX + 1] = { [OSF_ATTR_FINGER] = { .len = sizeof(struct xt_osf_user_finger) }, }; -static void xt_osf_finger_free_rcu(struct rcu_head *rcu_head) -{ - struct xt_osf_finger *f = container_of(rcu_head, struct xt_osf_finger, rcu_head); - - kfree(f); -} - static int xt_osf_add_callback(struct sock *ctnl, struct sk_buff *skb, const struct nlmsghdr *nlh, const struct nlattr * const osf_attrs[]) @@ -133,7 +126,7 @@ static int xt_osf_remove_callback(struct sock *ctnl, struct sk_buff *skb, * We are protected by nfnl mutex. */ list_del_rcu(&sf->finger_entry); - call_rcu(&sf->rcu_head, xt_osf_finger_free_rcu); + kfree_rcu(sf, rcu_head); err = 0; break; @@ -414,7 +407,7 @@ static void __exit xt_osf_fini(void) list_for_each_entry_rcu(f, &xt_osf_fingers[i], finger_entry) { list_del_rcu(&f->finger_entry); - call_rcu(&f->rcu_head, xt_osf_finger_free_rcu); + kfree_rcu(f, rcu_head); } } rcu_read_unlock(); -- cgit v1.2.2 From 0744371aeba7a5004006c2309971ee026c0b2000 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 15 Mar 2011 18:02:42 +0800 Subject: net,rcu: convert call_rcu(kfree_tid_tx) to kfree_rcu() The rcu callback kfree_tid_tx() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(kfree_tid_tx). Signed-off-by: Lai Jiangshan Signed-off-by: Paul E. McKenney Cc: "John W. Linville" Cc: Johannes Berg Reviewed-by: Josh Triplett Acked-by: "David S. Miller" --- net/mac80211/agg-tx.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c index 63d852cb4ca2..53defafb9aae 100644 --- a/net/mac80211/agg-tx.c +++ b/net/mac80211/agg-tx.c @@ -136,14 +136,6 @@ void ieee80211_send_bar(struct ieee80211_sub_if_data *sdata, u8 *ra, u16 tid, u1 ieee80211_tx_skb(sdata, skb); } -static void kfree_tid_tx(struct rcu_head *rcu_head) -{ - struct tid_ampdu_tx *tid_tx = - container_of(rcu_head, struct tid_ampdu_tx, rcu_head); - - kfree(tid_tx); -} - int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid, enum ieee80211_back_parties initiator, bool tx) @@ -163,7 +155,7 @@ int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid, /* not even started yet! */ rcu_assign_pointer(sta->ampdu_mlme.tid_tx[tid], NULL); spin_unlock_bh(&sta->lock); - call_rcu(&tid_tx->rcu_head, kfree_tid_tx); + kfree_rcu(tid_tx, rcu_head); return 0; } @@ -322,7 +314,7 @@ void ieee80211_tx_ba_session_handle_start(struct sta_info *sta, int tid) spin_unlock_bh(&sta->lock); ieee80211_wake_queue_agg(local, tid); - call_rcu(&tid_tx->rcu_head, kfree_tid_tx); + kfree_rcu(tid_tx, rcu_head); return; } @@ -701,7 +693,7 @@ void ieee80211_stop_tx_ba_cb(struct ieee80211_vif *vif, u8 *ra, u8 tid) ieee80211_agg_splice_finish(local, tid); - call_rcu(&tid_tx->rcu_head, kfree_tid_tx); + kfree_rcu(tid_tx, rcu_head); unlock_sta: spin_unlock_bh(&sta->lock); -- cgit v1.2.2 From eb340b2f804860a51a0b92e35fd36742b6c2d6b7 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 1 May 2011 23:25:02 -0700 Subject: batman,rcu: convert call_rcu(gw_node_free_rcu) to kfree_rcu The RCU callback gw_node_free_rcu() just calls kfree(), so we can use kfree_rcu() instead of call_rcu(). Signed-off-by: Paul E. McKenney Cc: Marek Lindner Cc: Simon Wunderlich Acked-by: David S. Miller Reviewed-by: Josh Triplett Acked-by: Sven Eckelmann --- net/batman-adv/gateway_client.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c index 3cc43558cf9c..150b6ce23df3 100644 --- a/net/batman-adv/gateway_client.c +++ b/net/batman-adv/gateway_client.c @@ -28,18 +28,10 @@ #include #include -static void gw_node_free_rcu(struct rcu_head *rcu) -{ - struct gw_node *gw_node; - - gw_node = container_of(rcu, struct gw_node, rcu); - kfree(gw_node); -} - static void gw_node_free_ref(struct gw_node *gw_node) { if (atomic_dec_and_test(&gw_node->refcount)) - call_rcu(&gw_node->rcu, gw_node_free_rcu); + kfree_rcu(gw_node, rcu); } void *gw_get_selected(struct bat_priv *bat_priv) -- cgit v1.2.2 From ae179ae433bb4ef6b6179c5c1c7b6cc7dc01c670 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 1 May 2011 23:27:50 -0700 Subject: batman,rcu: convert call_rcu(neigh_node_free_rcu) to kfree() The RCU callback neigh_node_free_rcu() just calls kfree(), so we can use kfree_rcu() instead of call_rcu(). Signed-off-by: Paul E. McKenney Cc: Marek Lindner Cc: Simon Wunderlich Acked-by: David S. Miller Reviewed-by: Josh Triplett Acked-by: Sven Eckelmann --- net/batman-adv/originator.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c index 0b9133022d2d..ed23a5895d6c 100644 --- a/net/batman-adv/originator.c +++ b/net/batman-adv/originator.c @@ -56,18 +56,10 @@ err: return 0; } -static void neigh_node_free_rcu(struct rcu_head *rcu) -{ - struct neigh_node *neigh_node; - - neigh_node = container_of(rcu, struct neigh_node, rcu); - kfree(neigh_node); -} - void neigh_node_free_ref(struct neigh_node *neigh_node) { if (atomic_dec_and_test(&neigh_node->refcount)) - call_rcu(&neigh_node->rcu, neigh_node_free_rcu); + kfree_rcu(neigh_node, rcu); } struct neigh_node *create_neighbor(struct orig_node *orig_node, -- cgit v1.2.2 From 8e3572cff70ee19a0a1f2e2dde0bca0b7c8b54dc Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 2 May 2011 00:52:23 -0700 Subject: batman,rcu: convert call_rcu(softif_neigh_free_rcu) to kfree_rcu The RCU callback softif_neigh_free_rcu() just calls kfree(), so we can use kfree_rcu() instead of call_rcu(). Signed-off-by: Paul E. McKenney Cc: Marek Lindner Cc: Simon Wunderlich Acked-by: David S. Miller Reviewed-by: Josh Triplett Acked-by: Sven Eckelmann --- net/batman-adv/soft-interface.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c index 824e1f6e50f2..04efe022c13b 100644 --- a/net/batman-adv/soft-interface.c +++ b/net/batman-adv/soft-interface.c @@ -76,18 +76,10 @@ int my_skb_head_push(struct sk_buff *skb, unsigned int len) return 0; } -static void softif_neigh_free_rcu(struct rcu_head *rcu) -{ - struct softif_neigh *softif_neigh; - - softif_neigh = container_of(rcu, struct softif_neigh, rcu); - kfree(softif_neigh); -} - static void softif_neigh_free_ref(struct softif_neigh *softif_neigh) { if (atomic_dec_and_test(&softif_neigh->refcount)) - call_rcu(&softif_neigh->rcu, softif_neigh_free_rcu); + kfree_rcu(softif_neigh, rcu); } void softif_neigh_purge(struct bat_priv *bat_priv) -- cgit v1.2.2 From 11c476f31a0fabc6e604da5b09a6590b57c3fb20 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 2 May 2011 00:56:57 -0700 Subject: net,rcu: convert call_rcu(prl_entry_destroy_rcu) to kfree The RCU callback prl_entry_destroy_rcu() just calls kfree(), so we can use kfree_rcu() instead of call_rcu(). Signed-off-by: Paul E. McKenney Cc: Alexey Kuznetsov Cc: "Pekka Savola (ipv6)" Cc: James Morris Cc: Hideaki YOSHIFUJI Cc: Patrick McHardy Acked-by: David S. Miller Reviewed-by: Josh Triplett --- net/ipv6/sit.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index 43b33373adb2..5f35d595e4a5 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -401,11 +401,6 @@ out: return err; } -static void prl_entry_destroy_rcu(struct rcu_head *head) -{ - kfree(container_of(head, struct ip_tunnel_prl_entry, rcu_head)); -} - static void prl_list_destroy_rcu(struct rcu_head *head) { struct ip_tunnel_prl_entry *p, *n; @@ -433,7 +428,7 @@ ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a) p = &x->next) { if (x->addr == a->addr) { *p = x->next; - call_rcu(&x->rcu_head, prl_entry_destroy_rcu); + kfree_rcu(x, rcu_head); t->prl_count--; goto out; } -- cgit v1.2.2 From 80d02085d99039b3b7f3a73c8896226b0cb1ba07 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 12 May 2011 01:08:07 -0700 Subject: Revert "rcu: Decrease memory-barrier usage based on semi-formal proof" This reverts commit e59fb3120becfb36b22ddb8bd27d065d3cdca499. This reversion was due to (extreme) boot-time slowdowns on SPARC seen by Yinghai Lu and on x86 by Ingo . This is a non-trivial reversion due to intervening commits. Conflicts: Documentation/RCU/trace.txt kernel/rcutree.c Signed-off-by: Ingo Molnar --- Documentation/RCU/trace.txt | 17 ++++-- kernel/rcutree.c | 130 +++++++++++++++++++++++++------------------- kernel/rcutree.h | 9 ++- kernel/rcutree_plugin.h | 7 ++- kernel/rcutree_trace.c | 12 ++-- 5 files changed, 102 insertions(+), 73 deletions(-) diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index 8173cec473aa..c078ad48f7a1 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -99,11 +99,18 @@ o "qp" indicates that RCU still expects a quiescent state from o "dt" is the current value of the dyntick counter that is incremented when entering or leaving dynticks idle state, either by the - scheduler or by irq. This number is even if the CPU is in - dyntick idle mode and odd otherwise. The number after the first - "/" is the interrupt nesting depth when in dyntick-idle state, - or one greater than the interrupt-nesting depth otherwise. - The number after the second "/" is the NMI nesting depth. + scheduler or by irq. The number after the "/" is the interrupt + nesting depth when in dyntick-idle state, or one greater than + the interrupt-nesting depth otherwise. + + This field is displayed only for CONFIG_NO_HZ kernels. + +o "dn" is the current value of the dyntick counter that is incremented + when entering or leaving dynticks idle state via NMI. If both + the "dt" and "dn" values are even, then this CPU is in dynticks + idle mode and may be ignored by RCU. If either of these two + counters is odd, then RCU must be alert to the possibility of + an RCU read-side critical section running on this CPU. This field is displayed only for CONFIG_NO_HZ kernels. diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 5616b17e4a22..e486f7c3ffb8 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -162,7 +162,7 @@ EXPORT_SYMBOL_GPL(rcu_note_context_switch); #ifdef CONFIG_NO_HZ DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { .dynticks_nesting = 1, - .dynticks = ATOMIC_INIT(1), + .dynticks = 1, }; #endif /* #ifdef CONFIG_NO_HZ */ @@ -321,25 +321,13 @@ void rcu_enter_nohz(void) unsigned long flags; struct rcu_dynticks *rdtp; + smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ local_irq_save(flags); rdtp = &__get_cpu_var(rcu_dynticks); - if (--rdtp->dynticks_nesting) { - local_irq_restore(flags); - return; - } - /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ - smp_mb__before_atomic_inc(); /* See above. */ - atomic_inc(&rdtp->dynticks); - smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */ - WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); + rdtp->dynticks++; + rdtp->dynticks_nesting--; + WARN_ON_ONCE(rdtp->dynticks & 0x1); local_irq_restore(flags); - - /* If the interrupt queued a callback, get out of dyntick mode. */ - if (in_irq() && - (__get_cpu_var(rcu_sched_data).nxtlist || - __get_cpu_var(rcu_bh_data).nxtlist || - rcu_preempt_needs_cpu(smp_processor_id()))) - set_need_resched(); } /* @@ -355,16 +343,11 @@ void rcu_exit_nohz(void) local_irq_save(flags); rdtp = &__get_cpu_var(rcu_dynticks); - if (rdtp->dynticks_nesting++) { - local_irq_restore(flags); - return; - } - smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */ - atomic_inc(&rdtp->dynticks); - /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ - smp_mb__after_atomic_inc(); /* See above. */ - WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); + rdtp->dynticks++; + rdtp->dynticks_nesting++; + WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); local_irq_restore(flags); + smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ } /** @@ -378,15 +361,11 @@ void rcu_nmi_enter(void) { struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); - if (rdtp->dynticks_nmi_nesting == 0 && - (atomic_read(&rdtp->dynticks) & 0x1)) + if (rdtp->dynticks & 0x1) return; - rdtp->dynticks_nmi_nesting++; - smp_mb__before_atomic_inc(); /* Force delay from prior write. */ - atomic_inc(&rdtp->dynticks); - /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ - smp_mb__after_atomic_inc(); /* See above. */ - WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); + rdtp->dynticks_nmi++; + WARN_ON_ONCE(!(rdtp->dynticks_nmi & 0x1)); + smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ } /** @@ -400,14 +379,11 @@ void rcu_nmi_exit(void) { struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); - if (rdtp->dynticks_nmi_nesting == 0 || - --rdtp->dynticks_nmi_nesting != 0) + if (rdtp->dynticks & 0x1) return; - /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ - smp_mb__before_atomic_inc(); /* See above. */ - atomic_inc(&rdtp->dynticks); - smp_mb__after_atomic_inc(); /* Force delay to next write. */ - WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); + smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ + rdtp->dynticks_nmi++; + WARN_ON_ONCE(rdtp->dynticks_nmi & 0x1); } /** @@ -418,7 +394,13 @@ void rcu_nmi_exit(void) */ void rcu_irq_enter(void) { - rcu_exit_nohz(); + struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); + + if (rdtp->dynticks_nesting++) + return; + rdtp->dynticks++; + WARN_ON_ONCE(!(rdtp->dynticks & 0x1)); + smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ } /** @@ -430,7 +412,18 @@ void rcu_irq_enter(void) */ void rcu_irq_exit(void) { - rcu_enter_nohz(); + struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks); + + if (--rdtp->dynticks_nesting) + return; + smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ + rdtp->dynticks++; + WARN_ON_ONCE(rdtp->dynticks & 0x1); + + /* If the interrupt queued a callback, get out of dyntick mode. */ + if (__this_cpu_read(rcu_sched_data.nxtlist) || + __this_cpu_read(rcu_bh_data.nxtlist)) + set_need_resched(); } #ifdef CONFIG_SMP @@ -442,8 +435,19 @@ void rcu_irq_exit(void) */ static int dyntick_save_progress_counter(struct rcu_data *rdp) { - rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks); - return 0; + int ret; + int snap; + int snap_nmi; + + snap = rdp->dynticks->dynticks; + snap_nmi = rdp->dynticks->dynticks_nmi; + smp_mb(); /* Order sampling of snap with end of grace period. */ + rdp->dynticks_snap = snap; + rdp->dynticks_nmi_snap = snap_nmi; + ret = ((snap & 0x1) == 0) && ((snap_nmi & 0x1) == 0); + if (ret) + rdp->dynticks_fqs++; + return ret; } /* @@ -454,11 +458,16 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp) */ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) { - unsigned long curr; - unsigned long snap; + long curr; + long curr_nmi; + long snap; + long snap_nmi; - curr = (unsigned long)atomic_add_return(0, &rdp->dynticks->dynticks); - snap = (unsigned long)rdp->dynticks_snap; + curr = rdp->dynticks->dynticks; + snap = rdp->dynticks_snap; + curr_nmi = rdp->dynticks->dynticks_nmi; + snap_nmi = rdp->dynticks_nmi_snap; + smp_mb(); /* force ordering with cpu entering/leaving dynticks. */ /* * If the CPU passed through or entered a dynticks idle phase with @@ -468,7 +477,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) * read-side critical section that started before the beginning * of the current RCU grace period. */ - if ((curr & 0x1) == 0 || ULONG_CMP_GE(curr, snap + 2)) { + if ((curr != snap || (curr & 0x1) == 0) && + (curr_nmi != snap_nmi || (curr_nmi & 0x1) == 0)) { rdp->dynticks_fqs++; return 1; } @@ -897,12 +907,6 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) unsigned long gp_duration; WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); - - /* - * Ensure that all grace-period and pre-grace-period activity - * is seen before the assignment to rsp->completed. - */ - smp_mb(); /* See above block comment. */ gp_duration = jiffies - rsp->gp_start; if (gp_duration > rsp->gp_max) rsp->gp_max = gp_duration; @@ -1450,11 +1454,25 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp) */ static void rcu_process_callbacks(void) { + /* + * Memory references from any prior RCU read-side critical sections + * executed by the interrupted code must be seen before any RCU + * grace-period manipulations below. + */ + smp_mb(); /* See above block comment. */ + __rcu_process_callbacks(&rcu_sched_state, &__get_cpu_var(rcu_sched_data)); __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data)); rcu_preempt_process_callbacks(); + /* + * Memory references from any later RCU read-side critical sections + * executed by the interrupted code must be seen after any RCU + * grace-period manipulations above. + */ + smp_mb(); /* See above block comment. */ + /* If we are last CPU on way to dyntick-idle mode, accelerate it. */ rcu_needs_cpu_flush(); } diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 93d4a1c2e88b..257664815d5d 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -84,9 +84,11 @@ * Dynticks per-CPU state. */ struct rcu_dynticks { - int dynticks_nesting; /* Track irq/process nesting level. */ - int dynticks_nmi_nesting; /* Track NMI nesting level. */ - atomic_t dynticks; /* Even value for dynticks-idle, else odd. */ + int dynticks_nesting; /* Track nesting level, sort of. */ + int dynticks; /* Even value for dynticks-idle, else odd. */ + int dynticks_nmi; /* Even value for either dynticks-idle or */ + /* not in nmi handler, else odd. So this */ + /* remains even for nmi from irq handler. */ }; /* RCU's kthread states for tracing. */ @@ -282,6 +284,7 @@ struct rcu_data { /* 3) dynticks interface. */ struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ int dynticks_snap; /* Per-GP tracking for dynticks. */ + int dynticks_nmi_snap; /* Per-GP tracking for dynticks_nmi. */ #endif /* #ifdef CONFIG_NO_HZ */ /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index ed339702481d..3f6559a5f5cd 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1520,6 +1520,7 @@ int rcu_needs_cpu(int cpu) { int c = 0; int snap; + int snap_nmi; int thatcpu; /* Check for being in the holdoff period. */ @@ -1530,10 +1531,10 @@ int rcu_needs_cpu(int cpu) for_each_online_cpu(thatcpu) { if (thatcpu == cpu) continue; - snap = atomic_add_return(0, &per_cpu(rcu_dynticks, - thatcpu).dynticks); + snap = per_cpu(rcu_dynticks, thatcpu).dynticks; + snap_nmi = per_cpu(rcu_dynticks, thatcpu).dynticks_nmi; smp_mb(); /* Order sampling of snap with end of grace period. */ - if ((snap & 0x1) != 0) { + if (((snap & 0x1) != 0) || ((snap_nmi & 0x1) != 0)) { per_cpu(rcu_dyntick_drain, cpu) = 0; per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1; return rcu_needs_cpu_quick_check(cpu); diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index 9678cc3650f5..aa0fd72b4bc7 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -69,10 +69,10 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) rdp->passed_quiesc, rdp->passed_quiesc_completed, rdp->qs_pending); #ifdef CONFIG_NO_HZ - seq_printf(m, " dt=%d/%d/%d df=%lu", - atomic_read(&rdp->dynticks->dynticks), + seq_printf(m, " dt=%d/%d dn=%d df=%lu", + rdp->dynticks->dynticks, rdp->dynticks->dynticks_nesting, - rdp->dynticks->dynticks_nmi_nesting, + rdp->dynticks->dynticks_nmi, rdp->dynticks_fqs); #endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi); @@ -141,9 +141,9 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp) rdp->qs_pending); #ifdef CONFIG_NO_HZ seq_printf(m, ",%d,%d,%d,%lu", - atomic_read(&rdp->dynticks->dynticks), + rdp->dynticks->dynticks, rdp->dynticks->dynticks_nesting, - rdp->dynticks->dynticks_nmi_nesting, + rdp->dynticks->dynticks_nmi, rdp->dynticks_fqs); #endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, ",%lu,%lu", rdp->offline_fqs, rdp->resched_ipi); @@ -167,7 +167,7 @@ static int show_rcudata_csv(struct seq_file *m, void *unused) { seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pqc\",\"pq\","); #ifdef CONFIG_NO_HZ - seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\","); + seq_puts(m, "\"dt\",\"dt nesting\",\"dn\",\"df\","); #endif /* #ifdef CONFIG_NO_HZ */ seq_puts(m, "\"of\",\"ri\",\"ql\",\"b\",\"ci\",\"co\",\"ca\"\n"); #ifdef CONFIG_TREE_PREEMPT_RCU -- cgit v1.2.2