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* lockdep: fix debug_lock_allocPeter Zijlstra2008-08-11
| | | | | | | | | | | | | When we enable DEBUG_LOCK_ALLOC but do not enable PROVE_LOCKING and or LOCK_STAT, lock_alloc() and lock_release() turn into nops, even though we should be doing hlock checking (check=1). This causes a false warning and a lockdep self-disable. Rectify this. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep: handle chains involving classes defined in modulesRabin Vincent2008-08-11
| | | | | | | | | | | Solve this by marking the classes as unused and not printing information about the unused classes. Reported-by: Eric Sesterhenn <snakebyte@gmx.de> Signed-off-by: Rabin Vincent <rabin@rab.in> Acked-by: Huang Ying <ying.huang@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep: lock protection locksPeter Zijlstra2008-08-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On Fri, 2008-08-01 at 16:26 -0700, Linus Torvalds wrote: > On Fri, 1 Aug 2008, David Miller wrote: > > > > Taking more than a few locks of the same class at once is bad > > news and it's better to find an alternative method. > > It's not always wrong. > > If you can guarantee that anybody that takes more than one lock of a > particular class will always take a single top-level lock _first_, then > that's all good. You can obviously screw up and take the same lock _twice_ > (which will deadlock), but at least you cannot get into ABBA situations. > > So maybe the right thing to do is to just teach lockdep about "lock > protection locks". That would have solved the multi-queue issues for > networking too - all the actual network drivers would still have taken > just their single queue lock, but the one case that needs to take all of > them would have taken a separate top-level lock first. > > Never mind that the multi-queue locks were always taken in the same order: > it's never wrong to just have some top-level serialization, and anybody > who needs to take <n> locks might as well do <n+1>, because they sure as > hell aren't going to be on _any_ fastpaths. > > So the simplest solution really sounds like just teaching lockdep about > that one special case. It's not "nesting" exactly, although it's obviously > related to it. Do as Linus suggested. The lock protection lock is called nest_lock. Note that we still have the MAX_LOCK_DEPTH (48) limit to consider, so anything that spills that it still up shit creek. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep: shrink held_lock structureDave Jones2008-08-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | struct held_lock { u64 prev_chain_key; /* 0 8 */ struct lock_class * class; /* 8 8 */ long unsigned int acquire_ip; /* 16 8 */ struct lockdep_map * instance; /* 24 8 */ int irq_context; /* 32 4 */ int trylock; /* 36 4 */ int read; /* 40 4 */ int check; /* 44 4 */ int hardirqs_off; /* 48 4 */ /* size: 56, cachelines: 1 */ /* padding: 4 */ /* last cacheline: 56 bytes */ }; struct held_lock { u64 prev_chain_key; /* 0 8 */ long unsigned int acquire_ip; /* 8 8 */ struct lockdep_map * instance; /* 16 8 */ unsigned int class_idx:11; /* 24:21 4 */ unsigned int irq_context:2; /* 24:19 4 */ unsigned int trylock:1; /* 24:18 4 */ unsigned int read:2; /* 24:16 4 */ unsigned int check:2; /* 24:14 4 */ unsigned int hardirqs_off:1; /* 24:13 4 */ /* size: 32, cachelines: 1 */ /* padding: 4 */ /* bit_padding: 13 bits */ /* last cacheline: 32 bytes */ }; [mingo@elte.hu: shrunk hlock->class too] [peterz@infradead.org: fixup bit sizes] Signed-off-by: Dave Jones <davej@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
* lockdep: lock_set_subclass - reset a held lock's subclassPeter Zijlstra2008-08-11
| | | | | | | | | this can be used to reset a held lock's subclass, for arbitrary-depth iterated data structures such as trees or lists which have per-node locks. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep: fix combinatorial explosion in lock subgraph traversalDavid Miller2008-07-31
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When we traverse the graph, either forwards or backwards, we are interested in whether a certain property exists somewhere in a node reachable in the graph. Therefore it is never necessary to traverse through a node more than once to get a correct answer to the given query. Take advantage of this property using a global ID counter so that we need not clear all the markers in all the lock_class entries before doing a traversal. A new ID is choosen when we start to traverse, and we continue through a lock_class only if it's ID hasn't been marked with the new value yet. This short-circuiting is essential especially for high CPU count systems. The scheduler has a runqueue per cpu, and needs to take two runqueue locks at a time, which leads to long chains of backwards and forwards subgraphs from these runqueue lock nodes. Without the short-circuit implemented here, a graph traversal on a runqueue lock can take up to (1 << (N - 1)) checks on a system with N cpus. For anything more than 16 cpus or so, lockdep will eventually bring the machine to a complete standstill. Signed-off-by: David S. Miller <davem@davemloft.net> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Merge branch 'core/locking' of ↵Linus Torvalds2008-07-14
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core/locking' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: lockdep: fix kernel/fork.c warning lockdep: fix ftrace irq tracing false positive lockdep: remove duplicate definition of STATIC_LOCKDEP_MAP_INIT lockdep: add lock_class information to lock_chain and output it lockdep: add lock_class information to lock_chain and output it lockdep: output lock_class key instead of address for forward dependency output __mutex_lock_common: use signal_pending_state() mutex-debug: check mutex magic before owner Fixed up conflict in kernel/fork.c manually
| * lockdep: fix ftrace irq tracing false positiveIngo Molnar2008-07-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | fix this false positive: [ 0.020000] ------------[ cut here ]------------ [ 0.020000] WARNING: at kernel/lockdep.c:2718 check_flags+0x14a/0x170() [ 0.020000] Modules linked in: [ 0.020000] Pid: 0, comm: swapper Not tainted 2.6.26-tip-00343-gd7e5521-dirty #14486 [ 0.020000] [<c01312e4>] warn_on_slowpath+0x54/0x80 [ 0.020000] [<c067e451>] ? _spin_unlock_irqrestore+0x61/0x70 [ 0.020000] [<c0131bb1>] ? release_console_sem+0x201/0x210 [ 0.020000] [<c0143d65>] ? __kernel_text_address+0x35/0x40 [ 0.020000] [<c010562e>] ? dump_trace+0x5e/0x140 [ 0.020000] [<c01518b5>] ? __lock_acquire+0x245/0x820 [ 0.020000] [<c015063a>] check_flags+0x14a/0x170 [ 0.020000] [<c0151ed8>] ? lock_acquire+0x48/0xc0 [ 0.020000] [<c0151ee1>] lock_acquire+0x51/0xc0 [ 0.020000] [<c014a16c>] ? down+0x2c/0x40 [ 0.020000] [<c010a609>] ? sched_clock+0x9/0x10 [ 0.020000] [<c067e7b2>] _write_lock+0x32/0x60 [ 0.020000] [<c013797f>] ? request_resource+0x1f/0xb0 [ 0.020000] [<c013797f>] request_resource+0x1f/0xb0 [ 0.020000] [<c02f89ad>] vgacon_startup+0x2bd/0x3e0 [ 0.020000] [<c094d62a>] con_init+0x19/0x22f [ 0.020000] [<c0330c7c>] ? tty_register_ldisc+0x5c/0x70 [ 0.020000] [<c094cf49>] console_init+0x20/0x2e [ 0.020000] [<c092a969>] start_kernel+0x20c/0x379 [ 0.020000] [<c092a516>] ? unknown_bootoption+0x0/0x1f6 [ 0.020000] [<c092a099>] __init_begin+0x99/0xa1 [ 0.020000] ======================= [ 0.020000] ---[ end trace 4eaa2a86a8e2da22 ]--- [ 0.020000] possible reason: unannotated irqs-on. [ 0.020000] irq event stamp: 0 which occurs if CONFIG_TRACE_IRQFLAGS=y, CONFIG_DEBUG_LOCKDEP=y, but CONFIG_PROVE_LOCKING is disabled. Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * lockdep: add lock_class information to lock_chain and output itHuang, Ying2008-06-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It is based on x86/master branch of git-x86 tree, and has been tested on x86_64 platform. ChangeLog: v2: - Enclosing proc file system related code into CONFIG_PROVE_LOCKING. - Fix nr_chain_hlocks update code. Signed-off-by: Huang Ying <ying.huang@intel.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * lockdep: add lock_class information to lock_chain and output itHuang, Ying2008-06-20
| | | | | | | | | | | | | | | | | | | | | | | | This patch records array of lock_class into lock_chain, and export lock_chain information via /proc/lockdep_chains. It is based on x86/master branch of git-x86 tree, and has been tested on x86_64 platform. Signed-off-by: Huang Ying <ying.huang@intel.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | lockdep: update lockdep_recursion on graph_lockSteven Rostedt2008-05-23
| | | | | | | | | | | | | | | | | | | | | | With the introduction of ftrace, it is possible to recurse into the lockdep functions via the mcount call. To prevent possible lockups, updating the lockdep_recursion counter on grabbing the internal lockdep_lock should prevent deadlocks. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | ftrace: use Makefile to remove tracing from lockdepSteven Rostedt2008-05-23
| | | | | | | | | | | | | | | | | | | | This patch removes the "notrace" annotation from lockdep and adds the debugging files in the kernel director to those that should not be compiled with "-pg" mcount tracing. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | ftrace: lockdep notrace annotationsSteven Rostedt2008-05-23
| | | | | | | | | | | | | | | | | | Add notrace annotations to lockdep to keep ftrace from causing recursive problems with lock tracing and debugging. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | ftrace: trace irq disabled critical timingsSteven Rostedt2008-05-23
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds latency tracing for critical timings (how long interrupts are disabled for). "irqsoff" is added to /debugfs/tracing/available_tracers Note: tracing_max_latency also holds the max latency for irqsoff (in usecs). (default to large number so one must start latency tracing) tracing_thresh threshold (in usecs) to always print out if irqs off is detected to be longer than stated here. If irq_thresh is non-zero, then max_irq_latency is ignored. Here's an example of a trace with ftrace_enabled = 0 ======= preemption latency trace v1.1.5 on 2.6.24-rc7 Signed-off-by: Ingo Molnar <mingo@elte.hu> -------------------------------------------------------------------- latency: 100 us, #3/3, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2) ----------------- | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0) ----------------- => started at: _spin_lock_irqsave+0x2a/0xb7 => ended at: _spin_unlock_irqrestore+0x32/0x5f _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / swapper-0 1d.s3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000]) swapper-0 1d.s3 100us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1d.s3 100us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f) vim:ft=help ======= And this is a trace with ftrace_enabled == 1 ======= preemption latency trace v1.1.5 on 2.6.24-rc7 -------------------------------------------------------------------- latency: 102 us, #12/12, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2) ----------------- | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0) ----------------- => started at: _spin_lock_irqsave+0x2a/0xb7 => ended at: _spin_unlock_irqrestore+0x32/0x5f _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / swapper-0 1dNs3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000]) swapper-0 1dNs3 46us : e1000_read_phy_reg+0x16/0x225 [e1000] (e1000_update_stats+0x5e2/0x64c [e1000]) swapper-0 1dNs3 46us : e1000_swfw_sync_acquire+0x10/0x99 [e1000] (e1000_read_phy_reg+0x49/0x225 [e1000]) swapper-0 1dNs3 46us : e1000_get_hw_eeprom_semaphore+0x12/0xa6 [e1000] (e1000_swfw_sync_acquire+0x36/0x99 [e1000]) swapper-0 1dNs3 47us : __const_udelay+0x9/0x47 (e1000_read_phy_reg+0x116/0x225 [e1000]) swapper-0 1dNs3 47us+: __delay+0x9/0x50 (__const_udelay+0x45/0x47) swapper-0 1dNs3 97us : preempt_schedule+0xc/0x84 (__delay+0x4e/0x50) swapper-0 1dNs3 98us : e1000_swfw_sync_release+0xc/0x55 [e1000] (e1000_read_phy_reg+0x211/0x225 [e1000]) swapper-0 1dNs3 99us+: e1000_put_hw_eeprom_semaphore+0x9/0x35 [e1000] (e1000_swfw_sync_release+0x50/0x55 [e1000]) swapper-0 1dNs3 101us : _spin_unlock_irqrestore+0xe/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1dNs3 102us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1dNs3 102us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f) vim:ft=help ======= Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* Subject: lockdep: include all lock classes in all_lock_classesDale Farnsworth2008-02-25
| | | | | | | | | | | | | Add each lock class to the all_lock_classes list when it is first registered. Previously, lock classes were added to all_lock_classes when the lock class was first used. Since one of the uses of the list is to find unused locks, this didn't work well. Signed-off-by: Dale Farnsworth <dale@farnsworth.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasksIngo Molnar2008-01-25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | this patch extends the soft-lockup detector to automatically detect hung TASK_UNINTERRUPTIBLE tasks. Such hung tasks are printed the following way: ------------------> INFO: task prctl:3042 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message prctl D fd5e3793 0 3042 2997 f6050f38 00000046 00000001 fd5e3793 00000009 c06d8264 c06dae80 00000286 f6050f40 f6050f00 f7d34d90 f7d34fc8 c1e1be80 00000001 f6050000 00000000 f7e92d00 00000286 f6050f18 c0489d1a f6050f40 00006605 00000000 c0133a5b Call Trace: [<c04883a5>] schedule_timeout+0x6d/0x8b [<c04883d8>] schedule_timeout_uninterruptible+0x15/0x17 [<c0133a76>] msleep+0x10/0x16 [<c0138974>] sys_prctl+0x30/0x1e2 [<c0104c52>] sysenter_past_esp+0x5f/0xa5 ======================= 2 locks held by prctl/3042: #0: (&sb->s_type->i_mutex_key#5){--..}, at: [<c0197d11>] do_fsync+0x38/0x7a #1: (jbd_handle){--..}, at: [<c01ca3d2>] journal_start+0xc7/0xe9 <------------------ the current default timeout is 120 seconds. Such messages are printed up to 10 times per bootup. If the system has crashed already then the messages are not printed. if lockdep is enabled then all held locks are printed as well. this feature is a natural extension to the softlockup-detector (kernel locked up without scheduling) and to the NMI watchdog (kernel locked up with IRQs disabled). [ Gautham R Shenoy <ego@in.ibm.com>: CPU hotplug fixes. ] [ Andrew Morton <akpm@linux-foundation.org>: build warning fix. ] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
* lockdep: fix kernel crash on module unloadArjan van de Ven2008-01-24
| | | | | | | | | | | | | | | | | | | | Michael Wu noticed in his lkml post at http://marc.info/?l=linux-kernel&m=119396182726091&w=2 that certain wireless drivers ended up having their name in module memory, which would then crash the kernel on module unload. The patch he proposed was a bit clumsy in that it increased the size of a lockdep entry significantly; the patch below tries another approach, it checks, on module teardown, if the name of a class is in module space and then zaps the class. This is very similar to what we already do with keys that are in module space. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lockdep: fix internal double unlock during self-testNick Piggin2008-01-16
| | | | | | | | | | Lockdep, during self-test (when it was simulating double unlocks) was sometimes unconditionally unlocking a spinlock when it had not been locked. This won't work for ticket locks. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
* lockdep: make cli/sti annotation warnings clearerIngo Molnar2007-12-07
| | | | | | | make cli/sti annotation warnings easier to interpret. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
* lockdep: in_range() fixOleg Nesterov2007-12-05
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Torsten Kaiser wrote: | static inline int in_range(const void *start, const void *addr, const void *end) | { | return addr >= start && addr <= end; | } | This will return true, if addr is in the range of start (including) | to end (including). | | But debug_check_no_locks_freed() seems does: | const void *mem_to = mem_from + mem_len | -> mem_to is the last byte of the freed range, that fits in_range | lock_from = (void *)hlock->instance; | -> first byte of the lock | lock_to = (void *)(hlock->instance + 1); | -> first byte of the next lock, not last byte of the lock that is being checked! | | The test is: | if (!in_range(mem_from, lock_from, mem_to) && | !in_range(mem_from, lock_to, mem_to)) | continue; | So it tests, if the first byte of the lock is in the range that is freed ->OK | And if the first byte of the *next* lock is in the range that is freed | -> Not OK. We can also simplify in_range checks, we need only 2 comparisons, not 4. If the lock is not in memory range, it should be either at the left of range or at the right. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
* lockdep: fix debug_show_all_locks()Ingo Molnar2007-12-05
| | | | | | | | | | | | | | fix the oops that can be seen in: http://bugzilla.kernel.org/attachment.cgi?id=13828&action=view it is not safe to print the locks of running tasks. (even with this fix we have a small race - but this is a debug function after all.) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
* lockdep: fix a typo in the __lock_acquire commentGautham R Shenoy2007-10-28
| | | | | | | | Fix a typo in the __lock_acquire comment. Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Use helpers to obtain task pid in printksPavel Emelyanov2007-10-19
| | | | | | | | | | | | | | | | The task_struct->pid member is going to be deprecated, so start using the helpers (task_pid_nr/task_pid_vnr/task_pid_nr_ns) in the kernel. The first thing to start with is the pid, printed to dmesg - in this case we may safely use task_pid_nr(). Besides, printks produce more (much more) than a half of all the explicit pid usage. [akpm@linux-foundation.org: git-drm went and changed lots of stuff] Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Cc: Dave Airlie <airlied@linux.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* workqueue: debug flushing deadlocks with lockdepJohannes Berg2007-10-19
| | | | | | | | | | | | | | | | | | | | | | | | In the following scenario: code path 1: my_function() -> lock(L1); ...; flush_workqueue(); ... code path 2: run_workqueue() -> my_work() -> ...; lock(L1); ... you can get a deadlock when my_work() is queued or running but my_function() has acquired L1 already. This patch adds a pseudo-lock to each workqueue to make lockdep warn about this scenario. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Acked-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lockdep: syscall exit checkPeter Zijlstra2007-10-11
| | | | | | | | Provide a check to validate that we do not hold any locks when switching back to user-space. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep: fix mismatched lockdep_depth/curr_chain_hashGregory Haskins2007-10-11
| | | | | | | | | | | It is possible for the current->curr_chain_key to become inconsistent with the current index if the chain fails to validate. The end result is that future lock_acquire() operations may inadvertently fail to find a hit in the cache resulting in a new node being added to the graph for every acquire. Signed-off-by: Gregory Haskins <ghaskins@novell.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep debugging: give stacktrace for init_errorJohannes Berg2007-07-19
| | | | | | | | | | | | | | When I started adding support for lockdep to 64-bit powerpc, I got a lockdep_init_error and with this patch was able to pinpoint why and where to put lockdep_init(). Let's support this generally for others adding lockdep support to their architecture. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lockstat: measure lock bouncingPeter Zijlstra2007-07-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __acquire | lock _____ | \ | __contended | | | wait | _______/ |/ | __acquired | __release | unlock We measure acquisition and contention bouncing. This is done by recording a cpu stamp in each lock instance. Contention bouncing requires the cpu stamp to be set on acquisition. Hence we move __acquired into the generic path. __acquired is then used to measure acquisition bouncing by comparing the current cpu with the old stamp before replacing it. __contended is used to measure contention bouncing (only useful for preemptable locks) [akpm@linux-foundation.org: cleanups] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lockdep: various fixesPeter Zijlstra2007-07-19
| | | | | | | | | | | | | | - update the copyright notices - use the default hash function - fix a thinko in a BUILD_BUG_ON - add a WARN_ON to spot inconsitent naming - fix a termination issue in /proc/lock_stat [akpm@linux-foundation.org: cleanups] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lockstat: human readability tweaksPeter Zijlstra2007-07-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Present all this fancy new lock statistics information: *warning, _wide_ output ahead* (output edited for purpose of brevity) # cat /proc/lock_stat lock_stat version 0.1 ----------------------------------------------------------------------------------------------------------------------------------------------------------------- class name contentions waittime-min waittime-max waittime-total acquisitions holdtime-min holdtime-max holdtime-total ----------------------------------------------------------------------------------------------------------------------------------------------------------------- &inode->i_mutex: 14458 6.57 398832.75 2469412.23 6768876 0.34 11398383.65 339410830.89 --------------- &inode->i_mutex 4486 [<ffffffff802a08f9>] pipe_wait+0x86/0x8d &inode->i_mutex 0 [<ffffffff802a01e8>] pipe_write_fasync+0x29/0x5d &inode->i_mutex 0 [<ffffffff802a0e18>] pipe_read+0x74/0x3a5 &inode->i_mutex 0 [<ffffffff802a1a6a>] do_lookup+0x81/0x1ae ................................................................................................................................................................. &inode->i_data.tree_lock-W: 491 0.27 62.47 493.89 2477833 0.39 468.89 1146584.25 &inode->i_data.tree_lock-R: 65 0.44 4.27 48.78 26288792 0.36 184.62 10197458.24 -------------------------- &inode->i_data.tree_lock 46 [<ffffffff80277095>] __do_page_cache_readahead+0x69/0x24f &inode->i_data.tree_lock 31 [<ffffffff8026f9fb>] add_to_page_cache+0x31/0xba &inode->i_data.tree_lock 0 [<ffffffff802770ee>] __do_page_cache_readahead+0xc2/0x24f &inode->i_data.tree_lock 0 [<ffffffff8026f6e4>] find_get_page+0x1a/0x58 ................................................................................................................................................................. proc_inum_idr.lock: 0 0.00 0.00 0.00 36 0.00 65.60 148.26 proc_subdir_lock: 0 0.00 0.00 0.00 3049859 0.00 106.81 1563212.42 shrinker_rwsem-W: 0 0.00 0.00 0.00 5 0.00 1.73 3.68 shrinker_rwsem-R: 0 0.00 0.00 0.00 633 2.57 246.57 10909.76 'contentions' and 'acquisitions' are the number of such events measured (since the last reset). The waittime- and holdtime- (min, max, total) numbers are presented in microseconds. If there are any contention points, the lock class is presented in the block format (as i_mutex and tree_lock above), otherwise a single line of output is presented. The output is sorted on absolute number of contentions (read + write), this should get the worst offenders presented first, so that: # grep : /proc/lock_stat | head will quickly show who's bad. The stats can be reset using: # echo 0 > /proc/lock_stat [bunk@stusta.de: make 2 functions static] [akpm@linux-foundation.org: fix printk warning] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lockstat: core infrastructurePeter Zijlstra2007-07-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Introduce the core lock statistics code. Lock statistics provides lock wait-time and hold-time (as well as the count of corresponding contention and acquisitions events). Also, the first few call-sites that encounter contention are tracked. Lock wait-time is the time spent waiting on the lock. This provides insight into the locking scheme, that is, a heavily contended lock is indicative of a too coarse locking scheme. Lock hold-time is the duration the lock was held, this provides a reference for the wait-time numbers, so they can be put into perspective. 1) lock 2) ... do stuff .. unlock 3) The time between 1 and 2 is the wait-time. The time between 2 and 3 is the hold-time. The lockdep held-lock tracking code is reused, because it already collects locks into meaningful groups (classes), and because it is an existing infrastructure for lock instrumentation. Currently lockdep tracks lock acquisition with two hooks: lock() lock_acquire() _lock() ... code protected by lock ... unlock() lock_release() _unlock() We need to extend this with two more hooks, in order to measure contention. lock_contended() - used to measure contention events lock_acquired() - completion of the contention These are then placed the following way: lock() lock_acquire() if (!_try_lock()) lock_contended() _lock() lock_acquired() ... do locked stuff ... unlock() lock_release() _unlock() (Note: the try_lock() 'trick' is used to avoid instrumenting all platform dependent lock primitive implementations.) It is also possible to toggle the two lockdep features at runtime using: /proc/sys/kernel/prove_locking /proc/sys/kernel/lock_stat (esp. turning off the O(n^2) prove_locking functionaliy can help) [akpm@linux-foundation.org: build fixes] [akpm@linux-foundation.org: nuke unneeded ifdefs] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lockdep: reduce the ifdefferyPeter Zijlstra2007-07-19
| | | | | | | | | | Move code around to get fewer but larger #ifdef sections. Break some in-function #ifdefs out into their own functions. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lockdep: sanitise CONFIG_PROVE_LOCKINGPeter Zijlstra2007-07-19
| | | | | | | | | | | | Ensure that all of the lock dependency tracking code is under CONFIG_PROVE_LOCKING. This allows us to use the held lock tracking code for other purposes. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kallsyms: make KSYM_NAME_LEN include space for trailing '\0'Tejun Heo2007-07-17
| | | | | | | | | | | | | | | | | | | | | | | | KSYM_NAME_LEN is peculiar in that it does not include the space for the trailing '\0', forcing all users to use KSYM_NAME_LEN + 1 when allocating buffer. This is nonsense and error-prone. Moreover, when the caller forgets that it's very likely to subtly bite back by corrupting the stack because the last position of the buffer is always cleared to zero. This patch increments KSYM_NAME_LEN by one and updates code accordingly. * off-by-one bug in asm-powerpc/kprobes.h::kprobe_lookup_name() macro is fixed. * Where MODULE_NAME_LEN and KSYM_NAME_LEN were used together, MODULE_NAME_LEN was treated as if it didn't include space for the trailing '\0'. Fix it. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Paulo Marques <pmarques@grupopie.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lockdep: removed unused ip argument in mark_lock & mark_held_locksJarek Poplawski2007-05-08
| | | | | | | | | It looks like a remainder from designing... Signed-off-by: Jarek Poplawski <jarkao@o2.pl> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lockdep: lookup_chain_cache comment errataJarek Poplawski2007-05-08
| | | | | | | Signed-off-by: Jarek Poplawski <jarkao2@o2.pl> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Simplify kallsyms_lookup()Alexey Dobriyan2007-05-08
| | | | | | | | | | | | | | Several kallsyms_lookup() pass dummy arguments but only need, say, module's name. Make kallsyms_lookup() accept NULLs where possible. Also, makes picture clearer about what interfaces are needed for all symbol resolving business. Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> Cc: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* simplify the stacktrace codeChristoph Hellwig2007-05-08
| | | | | | | | | | | | | | | | | | | Simplify the stacktrace code: - remove the unused task argument to save_stack_trace, it's always current - remove the all_contexts flag, it's alwasy 0 Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Andi Kleen <ak@suse.de> Cc: Akinobu Mita <akinobu.mita@gmail.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] lockdep: debug_show_all_locks & debug_show_held_locks vs. debug_locksJarek Poplawski2007-03-22
| | | | | | | | | | | | | | | | | | | lockdep's data shouldn't be used when debug_locks == 0 because it's not updated after this, so it's more misleading than helpful. PS: probably lockdep's current-> fields should be reset after it turns debug_locks off: so, after printing a bug report, but before return from exported functions, but there are really a lot of these possibilities (e.g. after DEBUG_LOCKS_WARN_ON), so, something could be missed. (Of course direct use of this fields isn't recommended either.) Reported-by: Folkert van Heusden <folkert@vanheusden.com> Inspired-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Jarek Poplawski <jarkao2@o2.pl> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] fix section mismatch warning in lockdepSam Ravnborg2007-03-01
| | | | | | | | | | | | | | | | | | | | | lockdep_init() is marked __init but used in several places outside __init code. This causes following warnings: $ scripts/mod/modpost kernel/lockdep.o WARNING: kernel/built-in.o - Section mismatch: reference to .init.text:lockdep_init from .text.lockdep_init_map after 'lockdep_init_map' (at offset 0x105) WARNING: kernel/built-in.o - Section mismatch: reference to .init.text:lockdep_init from .text.lockdep_reset_lock after 'lockdep_reset_lock' (at offset 0x35) WARNING: kernel/built-in.o - Section mismatch: reference to .init.text:lockdep_init from .text.__lock_acquire after '__lock_acquire' (at offset 0xb2) The warnings are less obviously due to heavy inlining by gcc - this is not altered. Fix the section mismatch warnings by removing the __init marking, which seems obviously wrong. Signed-off-by: Sam Ravnborg <sam@ravnborg.org> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] lockdep: debug_locks check after check_chain_keyJarek Poplawski2007-02-20
| | | | | | | | | | In __lock_acquire check_chain_key can turn off debug_locks, so check is needed to assure proper return code. Signed-off-by: Jarek Poplawski <jarkao2@o2.pl> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] lockdep: add graph depth information to /proc/lockdepJason Baron2007-02-11
| | | | | | | | | | | | | | | | | | | Generate locking graph information into /proc/lockdep, for lock hierarchy documentation and visualization purposes. sample output: c089fd5c OPS: 138 FD: 14 BD: 1 --..: &tty->termios_mutex -> [c07a3430] tty_ldisc_lock -> [c07a37f0] &port_lock_key -> [c07afdc0] &rq->rq_lock_key#2 The lock classes listed are all the first-hop lock dependencies that lockdep has seen so far. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] lockdep: more unlock-on-error fixesJarek Poplawski2007-02-11
| | | | | | | | | | | | | | | | | | | | | | | | | - returns after DEBUG_LOCKS_WARN_ON added in 3 places - debug_locks checking after lookup_chain_cache() added in __lock_acquire() - locking for testing and changing global variable max_lockdep_depth added in __lock_acquire() From: Ingo Molnar <mingo@elte.hu> My __acquire_lock() cleanup introduced a locking bug: on SMP systems we'd release a non-owned graph lock. Fix this by moving the graph unlock back, and by leaving the max_lockdep_depth variable update possibly racy. (we dont care, it's just statistics) Also add some minimal debugging code to graph_unlock()/graph_lock(), which caught this locking bug. Signed-off-by: Jarek Poplawski <jarkao2@o2.pl> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] lockdep: printk warning fixAndrew Morton2006-12-30
| | | | | | | | | | kernel/lockdep.c: In function `lookup_chain_cache': kernel/lockdep.c:1339: warning: long long unsigned int format, u64 arg (arg 2) kernel/lockdep.c:1344: warning: long long unsigned int format, u64 arg (arg 2) Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] lockdep: fix possible races while disabling lock-debuggingIngo Molnar2006-12-13
| | | | | | | | | | | | | | | | | | | | Jarek Poplawski noticed that lockdep global state could be accessed in a racy way if one CPU did a lockdep assert (shutting lockdep down), while the other CPU would try to do something that changes its global state. This patch fixes those races and cleans up lockdep's internal locking by adding a graph_lock()/graph_unlock()/debug_locks_off_graph_unlock helpers. (Also note that as we all know the Linux kernel is, by definition, bug-free and perfect, so this code never triggers, so these fixes are highly theoretical. I wrote this patch for aesthetic reasons alone.) [akpm@osdl.org: build fix] [jarkao2@o2.pl: build fix's refix] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Jarek Poplawski <jarkao2@o2.pl> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] lockdep: print irq-trace info on assertsIngo Molnar2006-12-13
| | | | | | | | | | | | When we print an assert due to scheduling-in-atomic bugs, and if lockdep is enabled, then the IRQ tracing information of lockdep can be printed to pinpoint the code location that disabled interrupts. This saved me quite a bit of debugging time in cases where the backtrace did not identify the irq-disabling site well enough. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] lockdep: use chain hash on CONFIG_DEBUG_LOCKDEP tooIngo Molnar2006-12-13
| | | | | | | | | CONFIG_DEBUG_LOCKDEP is unacceptably slow because it does not utilize the chain-hash. Turn the chain-hash back on in this case too. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] lockdep: clean up VERY_VERBOSE defineIngo Molnar2006-12-13
| | | | | | | | | Cleanup: the VERY_VERBOSE define was unnecessarily dependent on #ifdef VERBOSE - while the VERBOSE switch is 0 or 1 (always defined). Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] lockdep: improve lockdep_reset()Ingo Molnar2006-12-13
| | | | | | | | | | Clear all the chains during lockdep_reset(). This fixes some locking-selftest false positives i saw on -rt. (never saw those on mainline though, but it could happen.) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] lockdep: improve verbose messagesIngo Molnar2006-12-13
| | | | | | | | | | Make verbose lockdep messages (off by default) more informative by printing out the hash chain key. (this patch was what helped me catch the earlier lockdep hash-collision bug) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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