aboutsummaryrefslogtreecommitdiffstats
path: root/kernel
diff options
context:
space:
mode:
Diffstat (limited to 'kernel')
-rw-r--r--kernel/Kconfig.preempt25
-rw-r--r--kernel/Makefile6
-rw-r--r--kernel/irq/manage.c12
-rw-r--r--kernel/lockdep.c27
-rw-r--r--kernel/printk.c2
-rw-r--r--kernel/rcupreempt.c10
-rw-r--r--kernel/rcupreempt_trace.c10
-rw-r--r--kernel/rcutorture.c66
-rw-r--r--kernel/rcutree.c1535
-rw-r--r--kernel/rcutree_trace.c271
-rw-r--r--kernel/resource.c9
-rw-r--r--kernel/softirq.c19
-rw-r--r--kernel/stacktrace.c11
13 files changed, 1927 insertions, 76 deletions
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index 9fdba03dc1f..bf987b95b35 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -52,28 +52,3 @@ config PREEMPT
52 52
53endchoice 53endchoice
54 54
55config PREEMPT_RCU
56 bool "Preemptible RCU"
57 depends on PREEMPT
58 default n
59 help
60 This option reduces the latency of the kernel by making certain
61 RCU sections preemptible. Normally RCU code is non-preemptible, if
62 this option is selected then read-only RCU sections become
63 preemptible. This helps latency, but may expose bugs due to
64 now-naive assumptions about each RCU read-side critical section
65 remaining on a given CPU through its execution.
66
67 Say N if you are unsure.
68
69config RCU_TRACE
70 bool "Enable tracing for RCU - currently stats in debugfs"
71 depends on PREEMPT_RCU
72 select DEBUG_FS
73 default y
74 help
75 This option provides tracing in RCU which presents stats
76 in debugfs for debugging RCU implementation.
77
78 Say Y here if you want to enable RCU tracing
79 Say N if you are unsure.
diff --git a/kernel/Makefile b/kernel/Makefile
index 19fad003b19..b4fdbbff5ec 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -74,10 +74,10 @@ obj-$(CONFIG_GENERIC_HARDIRQS) += irq/
74obj-$(CONFIG_SECCOMP) += seccomp.o 74obj-$(CONFIG_SECCOMP) += seccomp.o
75obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o 75obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
76obj-$(CONFIG_CLASSIC_RCU) += rcuclassic.o 76obj-$(CONFIG_CLASSIC_RCU) += rcuclassic.o
77obj-$(CONFIG_TREE_RCU) += rcutree.o
77obj-$(CONFIG_PREEMPT_RCU) += rcupreempt.o 78obj-$(CONFIG_PREEMPT_RCU) += rcupreempt.o
78ifeq ($(CONFIG_PREEMPT_RCU),y) 79obj-$(CONFIG_TREE_RCU_TRACE) += rcutree_trace.o
79obj-$(CONFIG_RCU_TRACE) += rcupreempt_trace.o 80obj-$(CONFIG_PREEMPT_RCU_TRACE) += rcupreempt_trace.o
80endif
81obj-$(CONFIG_RELAY) += relay.o 81obj-$(CONFIG_RELAY) += relay.o
82obj-$(CONFIG_SYSCTL) += utsname_sysctl.o 82obj-$(CONFIG_SYSCTL) += utsname_sysctl.o
83obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o 83obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 801addda3c4..e9d1c8205a3 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -673,6 +673,18 @@ int request_irq(unsigned int irq, irq_handler_t handler,
673 struct irq_desc *desc; 673 struct irq_desc *desc;
674 int retval; 674 int retval;
675 675
676 /*
677 * handle_IRQ_event() always ignores IRQF_DISABLED except for
678 * the _first_ irqaction (sigh). That can cause oopsing, but
679 * the behavior is classified as "will not fix" so we need to
680 * start nudging drivers away from using that idiom.
681 */
682 if ((irqflags & (IRQF_SHARED|IRQF_DISABLED))
683 == (IRQF_SHARED|IRQF_DISABLED))
684 pr_warning("IRQ %d/%s: IRQF_DISABLED is not "
685 "guaranteed on shared IRQs\n",
686 irq, devname);
687
676#ifdef CONFIG_LOCKDEP 688#ifdef CONFIG_LOCKDEP
677 /* 689 /*
678 * Lockdep wants atomic interrupt handlers: 690 * Lockdep wants atomic interrupt handlers:
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index e4bdda8dcf0..4fa6eeb4e8a 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -291,14 +291,12 @@ void lockdep_off(void)
291{ 291{
292 current->lockdep_recursion++; 292 current->lockdep_recursion++;
293} 293}
294
295EXPORT_SYMBOL(lockdep_off); 294EXPORT_SYMBOL(lockdep_off);
296 295
297void lockdep_on(void) 296void lockdep_on(void)
298{ 297{
299 current->lockdep_recursion--; 298 current->lockdep_recursion--;
300} 299}
301
302EXPORT_SYMBOL(lockdep_on); 300EXPORT_SYMBOL(lockdep_on);
303 301
304/* 302/*
@@ -580,7 +578,8 @@ static void print_lock_class_header(struct lock_class *class, int depth)
580/* 578/*
581 * printk all lock dependencies starting at <entry>: 579 * printk all lock dependencies starting at <entry>:
582 */ 580 */
583static void print_lock_dependencies(struct lock_class *class, int depth) 581static void __used
582print_lock_dependencies(struct lock_class *class, int depth)
584{ 583{
585 struct lock_list *entry; 584 struct lock_list *entry;
586 585
@@ -2512,7 +2511,6 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name,
2512 if (subclass) 2511 if (subclass)
2513 register_lock_class(lock, subclass, 1); 2512 register_lock_class(lock, subclass, 1);
2514} 2513}
2515
2516EXPORT_SYMBOL_GPL(lockdep_init_map); 2514EXPORT_SYMBOL_GPL(lockdep_init_map);
2517 2515
2518/* 2516/*
@@ -2693,8 +2691,9 @@ static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2693} 2691}
2694 2692
2695static int 2693static int
2696__lock_set_subclass(struct lockdep_map *lock, 2694__lock_set_class(struct lockdep_map *lock, const char *name,
2697 unsigned int subclass, unsigned long ip) 2695 struct lock_class_key *key, unsigned int subclass,
2696 unsigned long ip)
2698{ 2697{
2699 struct task_struct *curr = current; 2698 struct task_struct *curr = current;
2700 struct held_lock *hlock, *prev_hlock; 2699 struct held_lock *hlock, *prev_hlock;
@@ -2721,6 +2720,7 @@ __lock_set_subclass(struct lockdep_map *lock,
2721 return print_unlock_inbalance_bug(curr, lock, ip); 2720 return print_unlock_inbalance_bug(curr, lock, ip);
2722 2721
2723found_it: 2722found_it:
2723 lockdep_init_map(lock, name, key, 0);
2724 class = register_lock_class(lock, subclass, 0); 2724 class = register_lock_class(lock, subclass, 0);
2725 hlock->class_idx = class - lock_classes + 1; 2725 hlock->class_idx = class - lock_classes + 1;
2726 2726
@@ -2905,9 +2905,9 @@ static void check_flags(unsigned long flags)
2905#endif 2905#endif
2906} 2906}
2907 2907
2908void 2908void lock_set_class(struct lockdep_map *lock, const char *name,
2909lock_set_subclass(struct lockdep_map *lock, 2909 struct lock_class_key *key, unsigned int subclass,
2910 unsigned int subclass, unsigned long ip) 2910 unsigned long ip)
2911{ 2911{
2912 unsigned long flags; 2912 unsigned long flags;
2913 2913
@@ -2917,13 +2917,12 @@ lock_set_subclass(struct lockdep_map *lock,
2917 raw_local_irq_save(flags); 2917 raw_local_irq_save(flags);
2918 current->lockdep_recursion = 1; 2918 current->lockdep_recursion = 1;
2919 check_flags(flags); 2919 check_flags(flags);
2920 if (__lock_set_subclass(lock, subclass, ip)) 2920 if (__lock_set_class(lock, name, key, subclass, ip))
2921 check_chain_key(current); 2921 check_chain_key(current);
2922 current->lockdep_recursion = 0; 2922 current->lockdep_recursion = 0;
2923 raw_local_irq_restore(flags); 2923 raw_local_irq_restore(flags);
2924} 2924}
2925 2925EXPORT_SYMBOL_GPL(lock_set_class);
2926EXPORT_SYMBOL_GPL(lock_set_subclass);
2927 2926
2928/* 2927/*
2929 * We are not always called with irqs disabled - do that here, 2928 * We are not always called with irqs disabled - do that here,
@@ -2947,7 +2946,6 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2947 current->lockdep_recursion = 0; 2946 current->lockdep_recursion = 0;
2948 raw_local_irq_restore(flags); 2947 raw_local_irq_restore(flags);
2949} 2948}
2950
2951EXPORT_SYMBOL_GPL(lock_acquire); 2949EXPORT_SYMBOL_GPL(lock_acquire);
2952 2950
2953void lock_release(struct lockdep_map *lock, int nested, 2951void lock_release(struct lockdep_map *lock, int nested,
@@ -2965,7 +2963,6 @@ void lock_release(struct lockdep_map *lock, int nested,
2965 current->lockdep_recursion = 0; 2963 current->lockdep_recursion = 0;
2966 raw_local_irq_restore(flags); 2964 raw_local_irq_restore(flags);
2967} 2965}
2968
2969EXPORT_SYMBOL_GPL(lock_release); 2966EXPORT_SYMBOL_GPL(lock_release);
2970 2967
2971#ifdef CONFIG_LOCK_STAT 2968#ifdef CONFIG_LOCK_STAT
@@ -3450,7 +3447,6 @@ retry:
3450 if (unlock) 3447 if (unlock)
3451 read_unlock(&tasklist_lock); 3448 read_unlock(&tasklist_lock);
3452} 3449}
3453
3454EXPORT_SYMBOL_GPL(debug_show_all_locks); 3450EXPORT_SYMBOL_GPL(debug_show_all_locks);
3455 3451
3456/* 3452/*
@@ -3471,7 +3467,6 @@ void debug_show_held_locks(struct task_struct *task)
3471{ 3467{
3472 __debug_show_held_locks(task); 3468 __debug_show_held_locks(task);
3473} 3469}
3474
3475EXPORT_SYMBOL_GPL(debug_show_held_locks); 3470EXPORT_SYMBOL_GPL(debug_show_held_locks);
3476 3471
3477void lockdep_sys_exit(void) 3472void lockdep_sys_exit(void)
diff --git a/kernel/printk.c b/kernel/printk.c
index f492f1583d7..e651ab05655 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -662,7 +662,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
662 if (recursion_bug) { 662 if (recursion_bug) {
663 recursion_bug = 0; 663 recursion_bug = 0;
664 strcpy(printk_buf, recursion_bug_msg); 664 strcpy(printk_buf, recursion_bug_msg);
665 printed_len = sizeof(recursion_bug_msg); 665 printed_len = strlen(recursion_bug_msg);
666 } 666 }
667 /* Emit the output into the temporary buffer */ 667 /* Emit the output into the temporary buffer */
668 printed_len += vscnprintf(printk_buf + printed_len, 668 printed_len += vscnprintf(printk_buf + printed_len,
diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c
index 59236e8b9da..04982659875 100644
--- a/kernel/rcupreempt.c
+++ b/kernel/rcupreempt.c
@@ -551,6 +551,16 @@ void rcu_irq_exit(void)
551 } 551 }
552} 552}
553 553
554void rcu_nmi_enter(void)
555{
556 rcu_irq_enter();
557}
558
559void rcu_nmi_exit(void)
560{
561 rcu_irq_exit();
562}
563
554static void dyntick_save_progress_counter(int cpu) 564static void dyntick_save_progress_counter(int cpu)
555{ 565{
556 struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); 566 struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
diff --git a/kernel/rcupreempt_trace.c b/kernel/rcupreempt_trace.c
index 35c2d3360ec..7c2665cac17 100644
--- a/kernel/rcupreempt_trace.c
+++ b/kernel/rcupreempt_trace.c
@@ -149,12 +149,12 @@ static void rcupreempt_trace_sum(struct rcupreempt_trace *sp)
149 sp->done_length += cp->done_length; 149 sp->done_length += cp->done_length;
150 sp->done_add += cp->done_add; 150 sp->done_add += cp->done_add;
151 sp->done_remove += cp->done_remove; 151 sp->done_remove += cp->done_remove;
152 atomic_set(&sp->done_invoked, atomic_read(&cp->done_invoked)); 152 atomic_add(atomic_read(&cp->done_invoked), &sp->done_invoked);
153 sp->rcu_check_callbacks += cp->rcu_check_callbacks; 153 sp->rcu_check_callbacks += cp->rcu_check_callbacks;
154 atomic_set(&sp->rcu_try_flip_1, 154 atomic_add(atomic_read(&cp->rcu_try_flip_1),
155 atomic_read(&cp->rcu_try_flip_1)); 155 &sp->rcu_try_flip_1);
156 atomic_set(&sp->rcu_try_flip_e1, 156 atomic_add(atomic_read(&cp->rcu_try_flip_e1),
157 atomic_read(&cp->rcu_try_flip_e1)); 157 &sp->rcu_try_flip_e1);
158 sp->rcu_try_flip_i1 += cp->rcu_try_flip_i1; 158 sp->rcu_try_flip_i1 += cp->rcu_try_flip_i1;
159 sp->rcu_try_flip_ie1 += cp->rcu_try_flip_ie1; 159 sp->rcu_try_flip_ie1 += cp->rcu_try_flip_ie1;
160 sp->rcu_try_flip_g1 += cp->rcu_try_flip_g1; 160 sp->rcu_try_flip_g1 += cp->rcu_try_flip_g1;
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 85cb90588a5..b3106552210 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -39,6 +39,7 @@
39#include <linux/moduleparam.h> 39#include <linux/moduleparam.h>
40#include <linux/percpu.h> 40#include <linux/percpu.h>
41#include <linux/notifier.h> 41#include <linux/notifier.h>
42#include <linux/reboot.h>
42#include <linux/freezer.h> 43#include <linux/freezer.h>
43#include <linux/cpu.h> 44#include <linux/cpu.h>
44#include <linux/delay.h> 45#include <linux/delay.h>
@@ -108,7 +109,6 @@ struct rcu_torture {
108 int rtort_mbtest; 109 int rtort_mbtest;
109}; 110};
110 111
111static int fullstop = 0; /* stop generating callbacks at test end. */
112static LIST_HEAD(rcu_torture_freelist); 112static LIST_HEAD(rcu_torture_freelist);
113static struct rcu_torture *rcu_torture_current = NULL; 113static struct rcu_torture *rcu_torture_current = NULL;
114static long rcu_torture_current_version = 0; 114static long rcu_torture_current_version = 0;
@@ -136,6 +136,30 @@ static int stutter_pause_test = 0;
136#endif 136#endif
137int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT; 137int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
138 138
139#define FULLSTOP_SIGNALED 1 /* Bail due to signal. */
140#define FULLSTOP_CLEANUP 2 /* Orderly shutdown. */
141static int fullstop; /* stop generating callbacks at test end. */
142DEFINE_MUTEX(fullstop_mutex); /* protect fullstop transitions and */
143 /* spawning of kthreads. */
144
145/*
146 * Detect and respond to a signal-based shutdown.
147 */
148static int
149rcutorture_shutdown_notify(struct notifier_block *unused1,
150 unsigned long unused2, void *unused3)
151{
152 if (fullstop)
153 return NOTIFY_DONE;
154 if (signal_pending(current)) {
155 mutex_lock(&fullstop_mutex);
156 if (!ACCESS_ONCE(fullstop))
157 fullstop = FULLSTOP_SIGNALED;
158 mutex_unlock(&fullstop_mutex);
159 }
160 return NOTIFY_DONE;
161}
162
139/* 163/*
140 * Allocate an element from the rcu_tortures pool. 164 * Allocate an element from the rcu_tortures pool.
141 */ 165 */
@@ -199,11 +223,12 @@ rcu_random(struct rcu_random_state *rrsp)
199static void 223static void
200rcu_stutter_wait(void) 224rcu_stutter_wait(void)
201{ 225{
202 while (stutter_pause_test || !rcutorture_runnable) 226 while ((stutter_pause_test || !rcutorture_runnable) && !fullstop) {
203 if (rcutorture_runnable) 227 if (rcutorture_runnable)
204 schedule_timeout_interruptible(1); 228 schedule_timeout_interruptible(1);
205 else 229 else
206 schedule_timeout_interruptible(round_jiffies_relative(HZ)); 230 schedule_timeout_interruptible(round_jiffies_relative(HZ));
231 }
207} 232}
208 233
209/* 234/*
@@ -599,7 +624,7 @@ rcu_torture_writer(void *arg)
599 rcu_stutter_wait(); 624 rcu_stutter_wait();
600 } while (!kthread_should_stop() && !fullstop); 625 } while (!kthread_should_stop() && !fullstop);
601 VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping"); 626 VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
602 while (!kthread_should_stop()) 627 while (!kthread_should_stop() && fullstop != FULLSTOP_SIGNALED)
603 schedule_timeout_uninterruptible(1); 628 schedule_timeout_uninterruptible(1);
604 return 0; 629 return 0;
605} 630}
@@ -624,7 +649,7 @@ rcu_torture_fakewriter(void *arg)
624 } while (!kthread_should_stop() && !fullstop); 649 } while (!kthread_should_stop() && !fullstop);
625 650
626 VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping"); 651 VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
627 while (!kthread_should_stop()) 652 while (!kthread_should_stop() && fullstop != FULLSTOP_SIGNALED)
628 schedule_timeout_uninterruptible(1); 653 schedule_timeout_uninterruptible(1);
629 return 0; 654 return 0;
630} 655}
@@ -734,7 +759,7 @@ rcu_torture_reader(void *arg)
734 VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping"); 759 VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
735 if (irqreader && cur_ops->irqcapable) 760 if (irqreader && cur_ops->irqcapable)
736 del_timer_sync(&t); 761 del_timer_sync(&t);
737 while (!kthread_should_stop()) 762 while (!kthread_should_stop() && fullstop != FULLSTOP_SIGNALED)
738 schedule_timeout_uninterruptible(1); 763 schedule_timeout_uninterruptible(1);
739 return 0; 764 return 0;
740} 765}
@@ -831,7 +856,7 @@ rcu_torture_stats(void *arg)
831 do { 856 do {
832 schedule_timeout_interruptible(stat_interval * HZ); 857 schedule_timeout_interruptible(stat_interval * HZ);
833 rcu_torture_stats_print(); 858 rcu_torture_stats_print();
834 } while (!kthread_should_stop()); 859 } while (!kthread_should_stop() && !fullstop);
835 VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping"); 860 VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
836 return 0; 861 return 0;
837} 862}
@@ -899,7 +924,7 @@ rcu_torture_shuffle(void *arg)
899 do { 924 do {
900 schedule_timeout_interruptible(shuffle_interval * HZ); 925 schedule_timeout_interruptible(shuffle_interval * HZ);
901 rcu_torture_shuffle_tasks(); 926 rcu_torture_shuffle_tasks();
902 } while (!kthread_should_stop()); 927 } while (!kthread_should_stop() && !fullstop);
903 VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping"); 928 VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
904 return 0; 929 return 0;
905} 930}
@@ -914,10 +939,10 @@ rcu_torture_stutter(void *arg)
914 do { 939 do {
915 schedule_timeout_interruptible(stutter * HZ); 940 schedule_timeout_interruptible(stutter * HZ);
916 stutter_pause_test = 1; 941 stutter_pause_test = 1;
917 if (!kthread_should_stop()) 942 if (!kthread_should_stop() && !fullstop)
918 schedule_timeout_interruptible(stutter * HZ); 943 schedule_timeout_interruptible(stutter * HZ);
919 stutter_pause_test = 0; 944 stutter_pause_test = 0;
920 } while (!kthread_should_stop()); 945 } while (!kthread_should_stop() && !fullstop);
921 VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping"); 946 VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
922 return 0; 947 return 0;
923} 948}
@@ -934,12 +959,27 @@ rcu_torture_print_module_parms(char *tag)
934 stutter, irqreader); 959 stutter, irqreader);
935} 960}
936 961
962static struct notifier_block rcutorture_nb = {
963 .notifier_call = rcutorture_shutdown_notify,
964};
965
937static void 966static void
938rcu_torture_cleanup(void) 967rcu_torture_cleanup(void)
939{ 968{
940 int i; 969 int i;
941 970
942 fullstop = 1; 971 mutex_lock(&fullstop_mutex);
972 if (!fullstop) {
973 /* If being signaled, let it happen, then exit. */
974 mutex_unlock(&fullstop_mutex);
975 schedule_timeout_interruptible(10 * HZ);
976 if (cur_ops->cb_barrier != NULL)
977 cur_ops->cb_barrier();
978 return;
979 }
980 fullstop = FULLSTOP_CLEANUP;
981 mutex_unlock(&fullstop_mutex);
982 unregister_reboot_notifier(&rcutorture_nb);
943 if (stutter_task) { 983 if (stutter_task) {
944 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task"); 984 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
945 kthread_stop(stutter_task); 985 kthread_stop(stutter_task);
@@ -1015,6 +1055,8 @@ rcu_torture_init(void)
1015 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops, 1055 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
1016 &srcu_ops, &sched_ops, &sched_ops_sync, }; 1056 &srcu_ops, &sched_ops, &sched_ops_sync, };
1017 1057
1058 mutex_lock(&fullstop_mutex);
1059
1018 /* Process args and tell the world that the torturer is on the job. */ 1060 /* Process args and tell the world that the torturer is on the job. */
1019 for (i = 0; i < ARRAY_SIZE(torture_ops); i++) { 1061 for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1020 cur_ops = torture_ops[i]; 1062 cur_ops = torture_ops[i];
@@ -1024,6 +1066,7 @@ rcu_torture_init(void)
1024 if (i == ARRAY_SIZE(torture_ops)) { 1066 if (i == ARRAY_SIZE(torture_ops)) {
1025 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n", 1067 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
1026 torture_type); 1068 torture_type);
1069 mutex_unlock(&fullstop_mutex);
1027 return (-EINVAL); 1070 return (-EINVAL);
1028 } 1071 }
1029 if (cur_ops->init) 1072 if (cur_ops->init)
@@ -1146,9 +1189,12 @@ rcu_torture_init(void)
1146 goto unwind; 1189 goto unwind;
1147 } 1190 }
1148 } 1191 }
1192 register_reboot_notifier(&rcutorture_nb);
1193 mutex_unlock(&fullstop_mutex);
1149 return 0; 1194 return 0;
1150 1195
1151unwind: 1196unwind:
1197 mutex_unlock(&fullstop_mutex);
1152 rcu_torture_cleanup(); 1198 rcu_torture_cleanup();
1153 return firsterr; 1199 return firsterr;
1154} 1200}
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
new file mode 100644
index 00000000000..a342b032112
--- /dev/null
+++ b/kernel/rcutree.c
@@ -0,0 +1,1535 @@
1/*
2 * Read-Copy Update mechanism for mutual exclusion
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright IBM Corporation, 2008
19 *
20 * Authors: Dipankar Sarma <dipankar@in.ibm.com>
21 * Manfred Spraul <manfred@colorfullife.com>
22 * Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical version
23 *
24 * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
25 * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
26 *
27 * For detailed explanation of Read-Copy Update mechanism see -
28 * Documentation/RCU
29 */
30#include <linux/types.h>
31#include <linux/kernel.h>
32#include <linux/init.h>
33#include <linux/spinlock.h>
34#include <linux/smp.h>
35#include <linux/rcupdate.h>
36#include <linux/interrupt.h>
37#include <linux/sched.h>
38#include <asm/atomic.h>
39#include <linux/bitops.h>
40#include <linux/module.h>
41#include <linux/completion.h>
42#include <linux/moduleparam.h>
43#include <linux/percpu.h>
44#include <linux/notifier.h>
45#include <linux/cpu.h>
46#include <linux/mutex.h>
47#include <linux/time.h>
48
49#ifdef CONFIG_DEBUG_LOCK_ALLOC
50static struct lock_class_key rcu_lock_key;
51struct lockdep_map rcu_lock_map =
52 STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
53EXPORT_SYMBOL_GPL(rcu_lock_map);
54#endif
55
56/* Data structures. */
57
58#define RCU_STATE_INITIALIZER(name) { \
59 .level = { &name.node[0] }, \
60 .levelcnt = { \
61 NUM_RCU_LVL_0, /* root of hierarchy. */ \
62 NUM_RCU_LVL_1, \
63 NUM_RCU_LVL_2, \
64 NUM_RCU_LVL_3, /* == MAX_RCU_LVLS */ \
65 }, \
66 .signaled = RCU_SIGNAL_INIT, \
67 .gpnum = -300, \
68 .completed = -300, \
69 .onofflock = __SPIN_LOCK_UNLOCKED(&name.onofflock), \
70 .fqslock = __SPIN_LOCK_UNLOCKED(&name.fqslock), \
71 .n_force_qs = 0, \
72 .n_force_qs_ngp = 0, \
73}
74
75struct rcu_state rcu_state = RCU_STATE_INITIALIZER(rcu_state);
76DEFINE_PER_CPU(struct rcu_data, rcu_data);
77
78struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state);
79DEFINE_PER_CPU(struct rcu_data, rcu_bh_data);
80
81#ifdef CONFIG_NO_HZ
82DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks);
83#endif /* #ifdef CONFIG_NO_HZ */
84
85static int blimit = 10; /* Maximum callbacks per softirq. */
86static int qhimark = 10000; /* If this many pending, ignore blimit. */
87static int qlowmark = 100; /* Once only this many pending, use blimit. */
88
89static void force_quiescent_state(struct rcu_state *rsp, int relaxed);
90
91/*
92 * Return the number of RCU batches processed thus far for debug & stats.
93 */
94long rcu_batches_completed(void)
95{
96 return rcu_state.completed;
97}
98EXPORT_SYMBOL_GPL(rcu_batches_completed);
99
100/*
101 * Return the number of RCU BH batches processed thus far for debug & stats.
102 */
103long rcu_batches_completed_bh(void)
104{
105 return rcu_bh_state.completed;
106}
107EXPORT_SYMBOL_GPL(rcu_batches_completed_bh);
108
109/*
110 * Does the CPU have callbacks ready to be invoked?
111 */
112static int
113cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp)
114{
115 return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL];
116}
117
118/*
119 * Does the current CPU require a yet-as-unscheduled grace period?
120 */
121static int
122cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp)
123{
124 /* ACCESS_ONCE() because we are accessing outside of lock. */
125 return *rdp->nxttail[RCU_DONE_TAIL] &&
126 ACCESS_ONCE(rsp->completed) == ACCESS_ONCE(rsp->gpnum);
127}
128
129/*
130 * Return the root node of the specified rcu_state structure.
131 */
132static struct rcu_node *rcu_get_root(struct rcu_state *rsp)
133{
134 return &rsp->node[0];
135}
136
137#ifdef CONFIG_SMP
138
139/*
140 * If the specified CPU is offline, tell the caller that it is in
141 * a quiescent state. Otherwise, whack it with a reschedule IPI.
142 * Grace periods can end up waiting on an offline CPU when that
143 * CPU is in the process of coming online -- it will be added to the
144 * rcu_node bitmasks before it actually makes it online. The same thing
145 * can happen while a CPU is in the process of coming online. Because this
146 * race is quite rare, we check for it after detecting that the grace
147 * period has been delayed rather than checking each and every CPU
148 * each and every time we start a new grace period.
149 */
150static int rcu_implicit_offline_qs(struct rcu_data *rdp)
151{
152 /*
153 * If the CPU is offline, it is in a quiescent state. We can
154 * trust its state not to change because interrupts are disabled.
155 */
156 if (cpu_is_offline(rdp->cpu)) {
157 rdp->offline_fqs++;
158 return 1;
159 }
160
161 /* The CPU is online, so send it a reschedule IPI. */
162 if (rdp->cpu != smp_processor_id())
163 smp_send_reschedule(rdp->cpu);
164 else
165 set_need_resched();
166 rdp->resched_ipi++;
167 return 0;
168}
169
170#endif /* #ifdef CONFIG_SMP */
171
172#ifdef CONFIG_NO_HZ
173static DEFINE_RATELIMIT_STATE(rcu_rs, 10 * HZ, 5);
174
175/**
176 * rcu_enter_nohz - inform RCU that current CPU is entering nohz
177 *
178 * Enter nohz mode, in other words, -leave- the mode in which RCU
179 * read-side critical sections can occur. (Though RCU read-side
180 * critical sections can occur in irq handlers in nohz mode, a possibility
181 * handled by rcu_irq_enter() and rcu_irq_exit()).
182 */
183void rcu_enter_nohz(void)
184{
185 unsigned long flags;
186 struct rcu_dynticks *rdtp;
187
188 smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
189 local_irq_save(flags);
190 rdtp = &__get_cpu_var(rcu_dynticks);
191 rdtp->dynticks++;
192 rdtp->dynticks_nesting--;
193 WARN_ON_RATELIMIT(rdtp->dynticks & 0x1, &rcu_rs);
194 local_irq_restore(flags);
195}
196
197/*
198 * rcu_exit_nohz - inform RCU that current CPU is leaving nohz
199 *
200 * Exit nohz mode, in other words, -enter- the mode in which RCU
201 * read-side critical sections normally occur.
202 */
203void rcu_exit_nohz(void)
204{
205 unsigned long flags;
206 struct rcu_dynticks *rdtp;
207
208 local_irq_save(flags);
209 rdtp = &__get_cpu_var(rcu_dynticks);
210 rdtp->dynticks++;
211 rdtp->dynticks_nesting++;
212 WARN_ON_RATELIMIT(!(rdtp->dynticks & 0x1), &rcu_rs);
213 local_irq_restore(flags);
214 smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
215}
216
217/**
218 * rcu_nmi_enter - inform RCU of entry to NMI context
219 *
220 * If the CPU was idle with dynamic ticks active, and there is no
221 * irq handler running, this updates rdtp->dynticks_nmi to let the
222 * RCU grace-period handling know that the CPU is active.
223 */
224void rcu_nmi_enter(void)
225{
226 struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks);
227
228 if (rdtp->dynticks & 0x1)
229 return;
230 rdtp->dynticks_nmi++;
231 WARN_ON_RATELIMIT(!(rdtp->dynticks_nmi & 0x1), &rcu_rs);
232 smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
233}
234
235/**
236 * rcu_nmi_exit - inform RCU of exit from NMI context
237 *
238 * If the CPU was idle with dynamic ticks active, and there is no
239 * irq handler running, this updates rdtp->dynticks_nmi to let the
240 * RCU grace-period handling know that the CPU is no longer active.
241 */
242void rcu_nmi_exit(void)
243{
244 struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks);
245
246 if (rdtp->dynticks & 0x1)
247 return;
248 smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
249 rdtp->dynticks_nmi++;
250 WARN_ON_RATELIMIT(rdtp->dynticks_nmi & 0x1, &rcu_rs);
251}
252
253/**
254 * rcu_irq_enter - inform RCU of entry to hard irq context
255 *
256 * If the CPU was idle with dynamic ticks active, this updates the
257 * rdtp->dynticks to let the RCU handling know that the CPU is active.
258 */
259void rcu_irq_enter(void)
260{
261 struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks);
262
263 if (rdtp->dynticks_nesting++)
264 return;
265 rdtp->dynticks++;
266 WARN_ON_RATELIMIT(!(rdtp->dynticks & 0x1), &rcu_rs);
267 smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
268}
269
270/**
271 * rcu_irq_exit - inform RCU of exit from hard irq context
272 *
273 * If the CPU was idle with dynamic ticks active, update the rdp->dynticks
274 * to put let the RCU handling be aware that the CPU is going back to idle
275 * with no ticks.
276 */
277void rcu_irq_exit(void)
278{
279 struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks);
280
281 if (--rdtp->dynticks_nesting)
282 return;
283 smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
284 rdtp->dynticks++;
285 WARN_ON_RATELIMIT(rdtp->dynticks & 0x1, &rcu_rs);
286
287 /* If the interrupt queued a callback, get out of dyntick mode. */
288 if (__get_cpu_var(rcu_data).nxtlist ||
289 __get_cpu_var(rcu_bh_data).nxtlist)
290 set_need_resched();
291}
292
293/*
294 * Record the specified "completed" value, which is later used to validate
295 * dynticks counter manipulations. Specify "rsp->completed - 1" to
296 * unconditionally invalidate any future dynticks manipulations (which is
297 * useful at the beginning of a grace period).
298 */
299static void dyntick_record_completed(struct rcu_state *rsp, long comp)
300{
301 rsp->dynticks_completed = comp;
302}
303
304#ifdef CONFIG_SMP
305
306/*
307 * Recall the previously recorded value of the completion for dynticks.
308 */
309static long dyntick_recall_completed(struct rcu_state *rsp)
310{
311 return rsp->dynticks_completed;
312}
313
314/*
315 * Snapshot the specified CPU's dynticks counter so that we can later
316 * credit them with an implicit quiescent state. Return 1 if this CPU
317 * is already in a quiescent state courtesy of dynticks idle mode.
318 */
319static int dyntick_save_progress_counter(struct rcu_data *rdp)
320{
321 int ret;
322 int snap;
323 int snap_nmi;
324
325 snap = rdp->dynticks->dynticks;
326 snap_nmi = rdp->dynticks->dynticks_nmi;
327 smp_mb(); /* Order sampling of snap with end of grace period. */
328 rdp->dynticks_snap = snap;
329 rdp->dynticks_nmi_snap = snap_nmi;
330 ret = ((snap & 0x1) == 0) && ((snap_nmi & 0x1) == 0);
331 if (ret)
332 rdp->dynticks_fqs++;
333 return ret;
334}
335
336/*
337 * Return true if the specified CPU has passed through a quiescent
338 * state by virtue of being in or having passed through an dynticks
339 * idle state since the last call to dyntick_save_progress_counter()
340 * for this same CPU.
341 */
342static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
343{
344 long curr;
345 long curr_nmi;
346 long snap;
347 long snap_nmi;
348
349 curr = rdp->dynticks->dynticks;
350 snap = rdp->dynticks_snap;
351 curr_nmi = rdp->dynticks->dynticks_nmi;
352 snap_nmi = rdp->dynticks_nmi_snap;
353 smp_mb(); /* force ordering with cpu entering/leaving dynticks. */
354
355 /*
356 * If the CPU passed through or entered a dynticks idle phase with
357 * no active irq/NMI handlers, then we can safely pretend that the CPU
358 * already acknowledged the request to pass through a quiescent
359 * state. Either way, that CPU cannot possibly be in an RCU
360 * read-side critical section that started before the beginning
361 * of the current RCU grace period.
362 */
363 if ((curr != snap || (curr & 0x1) == 0) &&
364 (curr_nmi != snap_nmi || (curr_nmi & 0x1) == 0)) {
365 rdp->dynticks_fqs++;
366 return 1;
367 }
368
369 /* Go check for the CPU being offline. */
370 return rcu_implicit_offline_qs(rdp);
371}
372
373#endif /* #ifdef CONFIG_SMP */
374
375#else /* #ifdef CONFIG_NO_HZ */
376
377static void dyntick_record_completed(struct rcu_state *rsp, long comp)
378{
379}
380
381#ifdef CONFIG_SMP
382
383/*
384 * If there are no dynticks, then the only way that a CPU can passively
385 * be in a quiescent state is to be offline. Unlike dynticks idle, which
386 * is a point in time during the prior (already finished) grace period,
387 * an offline CPU is always in a quiescent state, and thus can be
388 * unconditionally applied. So just return the current value of completed.
389 */
390static long dyntick_recall_completed(struct rcu_state *rsp)
391{
392 return rsp->completed;
393}
394
395static int dyntick_save_progress_counter(struct rcu_data *rdp)
396{
397 return 0;
398}
399
400static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
401{
402 return rcu_implicit_offline_qs(rdp);
403}
404
405#endif /* #ifdef CONFIG_SMP */
406
407#endif /* #else #ifdef CONFIG_NO_HZ */
408
409#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
410
411static void record_gp_stall_check_time(struct rcu_state *rsp)
412{
413 rsp->gp_start = jiffies;
414 rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_CHECK;
415}
416
417static void print_other_cpu_stall(struct rcu_state *rsp)
418{
419 int cpu;
420 long delta;
421 unsigned long flags;
422 struct rcu_node *rnp = rcu_get_root(rsp);
423 struct rcu_node *rnp_cur = rsp->level[NUM_RCU_LVLS - 1];
424 struct rcu_node *rnp_end = &rsp->node[NUM_RCU_NODES];
425
426 /* Only let one CPU complain about others per time interval. */
427
428 spin_lock_irqsave(&rnp->lock, flags);
429 delta = jiffies - rsp->jiffies_stall;
430 if (delta < RCU_STALL_RAT_DELAY || rsp->gpnum == rsp->completed) {
431 spin_unlock_irqrestore(&rnp->lock, flags);
432 return;
433 }
434 rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK;
435 spin_unlock_irqrestore(&rnp->lock, flags);
436
437 /* OK, time to rat on our buddy... */
438
439 printk(KERN_ERR "INFO: RCU detected CPU stalls:");
440 for (; rnp_cur < rnp_end; rnp_cur++) {
441 if (rnp_cur->qsmask == 0)
442 continue;
443 for (cpu = 0; cpu <= rnp_cur->grphi - rnp_cur->grplo; cpu++)
444 if (rnp_cur->qsmask & (1UL << cpu))
445 printk(" %d", rnp_cur->grplo + cpu);
446 }
447 printk(" (detected by %d, t=%ld jiffies)\n",
448 smp_processor_id(), (long)(jiffies - rsp->gp_start));
449 force_quiescent_state(rsp, 0); /* Kick them all. */
450}
451
452static void print_cpu_stall(struct rcu_state *rsp)
453{
454 unsigned long flags;
455 struct rcu_node *rnp = rcu_get_root(rsp);
456
457 printk(KERN_ERR "INFO: RCU detected CPU %d stall (t=%lu jiffies)\n",
458 smp_processor_id(), jiffies - rsp->gp_start);
459 dump_stack();
460 spin_lock_irqsave(&rnp->lock, flags);
461 if ((long)(jiffies - rsp->jiffies_stall) >= 0)
462 rsp->jiffies_stall =
463 jiffies + RCU_SECONDS_TILL_STALL_RECHECK;
464 spin_unlock_irqrestore(&rnp->lock, flags);
465 set_need_resched(); /* kick ourselves to get things going. */
466}
467
468static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
469{
470 long delta;
471 struct rcu_node *rnp;
472
473 delta = jiffies - rsp->jiffies_stall;
474 rnp = rdp->mynode;
475 if ((rnp->qsmask & rdp->grpmask) && delta >= 0) {
476
477 /* We haven't checked in, so go dump stack. */
478 print_cpu_stall(rsp);
479
480 } else if (rsp->gpnum != rsp->completed &&
481 delta >= RCU_STALL_RAT_DELAY) {
482
483 /* They had two time units to dump stack, so complain. */
484 print_other_cpu_stall(rsp);
485 }
486}
487
488#else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
489
490static void record_gp_stall_check_time(struct rcu_state *rsp)
491{
492}
493
494static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
495{
496}
497
498#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
499
500/*
501 * Update CPU-local rcu_data state to record the newly noticed grace period.
502 * This is used both when we started the grace period and when we notice
503 * that someone else started the grace period.
504 */
505static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp)
506{
507 rdp->qs_pending = 1;
508 rdp->passed_quiesc = 0;
509 rdp->gpnum = rsp->gpnum;
510 rdp->n_rcu_pending_force_qs = rdp->n_rcu_pending +
511 RCU_JIFFIES_TILL_FORCE_QS;
512}
513
514/*
515 * Did someone else start a new RCU grace period start since we last
516 * checked? Update local state appropriately if so. Must be called
517 * on the CPU corresponding to rdp.
518 */
519static int
520check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp)
521{
522 unsigned long flags;
523 int ret = 0;
524
525 local_irq_save(flags);
526 if (rdp->gpnum != rsp->gpnum) {
527 note_new_gpnum(rsp, rdp);
528 ret = 1;
529 }
530 local_irq_restore(flags);
531 return ret;
532}
533
534/*
535 * Start a new RCU grace period if warranted, re-initializing the hierarchy
536 * in preparation for detecting the next grace period. The caller must hold
537 * the root node's ->lock, which is released before return. Hard irqs must
538 * be disabled.
539 */
540static void
541rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
542 __releases(rcu_get_root(rsp)->lock)
543{
544 struct rcu_data *rdp = rsp->rda[smp_processor_id()];
545 struct rcu_node *rnp = rcu_get_root(rsp);
546 struct rcu_node *rnp_cur;
547 struct rcu_node *rnp_end;
548
549 if (!cpu_needs_another_gp(rsp, rdp)) {
550 spin_unlock_irqrestore(&rnp->lock, flags);
551 return;
552 }
553
554 /* Advance to a new grace period and initialize state. */
555 rsp->gpnum++;
556 rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */
557 rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
558 rdp->n_rcu_pending_force_qs = rdp->n_rcu_pending +
559 RCU_JIFFIES_TILL_FORCE_QS;
560 record_gp_stall_check_time(rsp);
561 dyntick_record_completed(rsp, rsp->completed - 1);
562 note_new_gpnum(rsp, rdp);
563
564 /*
565 * Because we are first, we know that all our callbacks will
566 * be covered by this upcoming grace period, even the ones
567 * that were registered arbitrarily recently.
568 */
569 rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
570 rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
571
572 /* Special-case the common single-level case. */
573 if (NUM_RCU_NODES == 1) {
574 rnp->qsmask = rnp->qsmaskinit;
575 spin_unlock_irqrestore(&rnp->lock, flags);
576 return;
577 }
578
579 spin_unlock(&rnp->lock); /* leave irqs disabled. */
580
581
582 /* Exclude any concurrent CPU-hotplug operations. */
583 spin_lock(&rsp->onofflock); /* irqs already disabled. */
584
585 /*
586 * Set the quiescent-state-needed bits in all the non-leaf RCU
587 * nodes for all currently online CPUs. This operation relies
588 * on the layout of the hierarchy within the rsp->node[] array.
589 * Note that other CPUs will access only the leaves of the
590 * hierarchy, which still indicate that no grace period is in
591 * progress. In addition, we have excluded CPU-hotplug operations.
592 *
593 * We therefore do not need to hold any locks. Any required
594 * memory barriers will be supplied by the locks guarding the
595 * leaf rcu_nodes in the hierarchy.
596 */
597
598 rnp_end = rsp->level[NUM_RCU_LVLS - 1];
599 for (rnp_cur = &rsp->node[0]; rnp_cur < rnp_end; rnp_cur++)
600 rnp_cur->qsmask = rnp_cur->qsmaskinit;
601
602 /*
603 * Now set up the leaf nodes. Here we must be careful. First,
604 * we need to hold the lock in order to exclude other CPUs, which
605 * might be contending for the leaf nodes' locks. Second, as
606 * soon as we initialize a given leaf node, its CPUs might run
607 * up the rest of the hierarchy. We must therefore acquire locks
608 * for each node that we touch during this stage. (But we still
609 * are excluding CPU-hotplug operations.)
610 *
611 * Note that the grace period cannot complete until we finish
612 * the initialization process, as there will be at least one
613 * qsmask bit set in the root node until that time, namely the
614 * one corresponding to this CPU.
615 */
616 rnp_end = &rsp->node[NUM_RCU_NODES];
617 rnp_cur = rsp->level[NUM_RCU_LVLS - 1];
618 for (; rnp_cur < rnp_end; rnp_cur++) {
619 spin_lock(&rnp_cur->lock); /* irqs already disabled. */
620 rnp_cur->qsmask = rnp_cur->qsmaskinit;
621 spin_unlock(&rnp_cur->lock); /* irqs already disabled. */
622 }
623
624 rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */
625 spin_unlock_irqrestore(&rsp->onofflock, flags);
626}
627
628/*
629 * Advance this CPU's callbacks, but only if the current grace period
630 * has ended. This may be called only from the CPU to whom the rdp
631 * belongs.
632 */
633static void
634rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp)
635{
636 long completed_snap;
637 unsigned long flags;
638
639 local_irq_save(flags);
640 completed_snap = ACCESS_ONCE(rsp->completed); /* outside of lock. */
641
642 /* Did another grace period end? */
643 if (rdp->completed != completed_snap) {
644
645 /* Advance callbacks. No harm if list empty. */
646 rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL];
647 rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL];
648 rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
649
650 /* Remember that we saw this grace-period completion. */
651 rdp->completed = completed_snap;
652 }
653 local_irq_restore(flags);
654}
655
656/*
657 * Similar to cpu_quiet(), for which it is a helper function. Allows
658 * a group of CPUs to be quieted at one go, though all the CPUs in the
659 * group must be represented by the same leaf rcu_node structure.
660 * That structure's lock must be held upon entry, and it is released
661 * before return.
662 */
663static void
664cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
665 unsigned long flags)
666 __releases(rnp->lock)
667{
668 /* Walk up the rcu_node hierarchy. */
669 for (;;) {
670 if (!(rnp->qsmask & mask)) {
671
672 /* Our bit has already been cleared, so done. */
673 spin_unlock_irqrestore(&rnp->lock, flags);
674 return;
675 }
676 rnp->qsmask &= ~mask;
677 if (rnp->qsmask != 0) {
678
679 /* Other bits still set at this level, so done. */
680 spin_unlock_irqrestore(&rnp->lock, flags);
681 return;
682 }
683 mask = rnp->grpmask;
684 if (rnp->parent == NULL) {
685
686 /* No more levels. Exit loop holding root lock. */
687
688 break;
689 }
690 spin_unlock_irqrestore(&rnp->lock, flags);
691 rnp = rnp->parent;
692 spin_lock_irqsave(&rnp->lock, flags);
693 }
694
695 /*
696 * Get here if we are the last CPU to pass through a quiescent
697 * state for this grace period. Clean up and let rcu_start_gp()
698 * start up the next grace period if one is needed. Note that
699 * we still hold rnp->lock, as required by rcu_start_gp(), which
700 * will release it.
701 */
702 rsp->completed = rsp->gpnum;
703 rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]);
704 rcu_start_gp(rsp, flags); /* releases rnp->lock. */
705}
706
707/*
708 * Record a quiescent state for the specified CPU, which must either be
709 * the current CPU or an offline CPU. The lastcomp argument is used to
710 * make sure we are still in the grace period of interest. We don't want
711 * to end the current grace period based on quiescent states detected in
712 * an earlier grace period!
713 */
714static void
715cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
716{
717 unsigned long flags;
718 unsigned long mask;
719 struct rcu_node *rnp;
720
721 rnp = rdp->mynode;
722 spin_lock_irqsave(&rnp->lock, flags);
723 if (lastcomp != ACCESS_ONCE(rsp->completed)) {
724
725 /*
726 * Someone beat us to it for this grace period, so leave.
727 * The race with GP start is resolved by the fact that we
728 * hold the leaf rcu_node lock, so that the per-CPU bits
729 * cannot yet be initialized -- so we would simply find our
730 * CPU's bit already cleared in cpu_quiet_msk() if this race
731 * occurred.
732 */
733 rdp->passed_quiesc = 0; /* try again later! */
734 spin_unlock_irqrestore(&rnp->lock, flags);
735 return;
736 }
737 mask = rdp->grpmask;
738 if ((rnp->qsmask & mask) == 0) {
739 spin_unlock_irqrestore(&rnp->lock, flags);
740 } else {
741 rdp->qs_pending = 0;
742
743 /*
744 * This GP can't end until cpu checks in, so all of our
745 * callbacks can be processed during the next GP.
746 */
747 rdp = rsp->rda[smp_processor_id()];
748 rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
749
750 cpu_quiet_msk(mask, rsp, rnp, flags); /* releases rnp->lock */
751 }
752}
753
754/*
755 * Check to see if there is a new grace period of which this CPU
756 * is not yet aware, and if so, set up local rcu_data state for it.
757 * Otherwise, see if this CPU has just passed through its first
758 * quiescent state for this grace period, and record that fact if so.
759 */
760static void
761rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
762{
763 /* If there is now a new grace period, record and return. */
764 if (check_for_new_grace_period(rsp, rdp))
765 return;
766
767 /*
768 * Does this CPU still need to do its part for current grace period?
769 * If no, return and let the other CPUs do their part as well.
770 */
771 if (!rdp->qs_pending)
772 return;
773
774 /*
775 * Was there a quiescent state since the beginning of the grace
776 * period? If no, then exit and wait for the next call.
777 */
778 if (!rdp->passed_quiesc)
779 return;
780
781 /* Tell RCU we are done (but cpu_quiet() will be the judge of that). */
782 cpu_quiet(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed);
783}
784
785#ifdef CONFIG_HOTPLUG_CPU
786
787/*
788 * Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy
789 * and move all callbacks from the outgoing CPU to the current one.
790 */
791static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
792{
793 int i;
794 unsigned long flags;
795 long lastcomp;
796 unsigned long mask;
797 struct rcu_data *rdp = rsp->rda[cpu];
798 struct rcu_data *rdp_me;
799 struct rcu_node *rnp;
800
801 /* Exclude any attempts to start a new grace period. */
802 spin_lock_irqsave(&rsp->onofflock, flags);
803
804 /* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */
805 rnp = rdp->mynode;
806 mask = rdp->grpmask; /* rnp->grplo is constant. */
807 do {
808 spin_lock(&rnp->lock); /* irqs already disabled. */
809 rnp->qsmaskinit &= ~mask;
810 if (rnp->qsmaskinit != 0) {
811 spin_unlock(&rnp->lock); /* irqs already disabled. */
812 break;
813 }
814 mask = rnp->grpmask;
815 spin_unlock(&rnp->lock); /* irqs already disabled. */
816 rnp = rnp->parent;
817 } while (rnp != NULL);
818 lastcomp = rsp->completed;
819
820 spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
821
822 /* Being offline is a quiescent state, so go record it. */
823 cpu_quiet(cpu, rsp, rdp, lastcomp);
824
825 /*
826 * Move callbacks from the outgoing CPU to the running CPU.
827 * Note that the outgoing CPU is now quiscent, so it is now
828 * (uncharacteristically) safe to access it rcu_data structure.
829 * Note also that we must carefully retain the order of the
830 * outgoing CPU's callbacks in order for rcu_barrier() to work
831 * correctly. Finally, note that we start all the callbacks
832 * afresh, even those that have passed through a grace period
833 * and are therefore ready to invoke. The theory is that hotplug
834 * events are rare, and that if they are frequent enough to
835 * indefinitely delay callbacks, you have far worse things to
836 * be worrying about.
837 */
838 rdp_me = rsp->rda[smp_processor_id()];
839 if (rdp->nxtlist != NULL) {
840 *rdp_me->nxttail[RCU_NEXT_TAIL] = rdp->nxtlist;
841 rdp_me->nxttail[RCU_NEXT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
842 rdp->nxtlist = NULL;
843 for (i = 0; i < RCU_NEXT_SIZE; i++)
844 rdp->nxttail[i] = &rdp->nxtlist;
845 rdp_me->qlen += rdp->qlen;
846 rdp->qlen = 0;
847 }
848 local_irq_restore(flags);
849}
850
851/*
852 * Remove the specified CPU from the RCU hierarchy and move any pending
853 * callbacks that it might have to the current CPU. This code assumes
854 * that at least one CPU in the system will remain running at all times.
855 * Any attempt to offline -all- CPUs is likely to strand RCU callbacks.
856 */
857static void rcu_offline_cpu(int cpu)
858{
859 __rcu_offline_cpu(cpu, &rcu_state);
860 __rcu_offline_cpu(cpu, &rcu_bh_state);
861}
862
863#else /* #ifdef CONFIG_HOTPLUG_CPU */
864
865static void rcu_offline_cpu(int cpu)
866{
867}
868
869#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
870
871/*
872 * Invoke any RCU callbacks that have made it to the end of their grace
873 * period. Thottle as specified by rdp->blimit.
874 */
875static void rcu_do_batch(struct rcu_data *rdp)
876{
877 unsigned long flags;
878 struct rcu_head *next, *list, **tail;
879 int count;
880
881 /* If no callbacks are ready, just return.*/
882 if (!cpu_has_callbacks_ready_to_invoke(rdp))
883 return;
884
885 /*
886 * Extract the list of ready callbacks, disabling to prevent
887 * races with call_rcu() from interrupt handlers.
888 */
889 local_irq_save(flags);
890 list = rdp->nxtlist;
891 rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL];
892 *rdp->nxttail[RCU_DONE_TAIL] = NULL;
893 tail = rdp->nxttail[RCU_DONE_TAIL];
894 for (count = RCU_NEXT_SIZE - 1; count >= 0; count--)
895 if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL])
896 rdp->nxttail[count] = &rdp->nxtlist;
897 local_irq_restore(flags);
898
899 /* Invoke callbacks. */
900 count = 0;
901 while (list) {
902 next = list->next;
903 prefetch(next);
904 list->func(list);
905 list = next;
906 if (++count >= rdp->blimit)
907 break;
908 }
909
910 local_irq_save(flags);
911
912 /* Update count, and requeue any remaining callbacks. */
913 rdp->qlen -= count;
914 if (list != NULL) {
915 *tail = rdp->nxtlist;
916 rdp->nxtlist = list;
917 for (count = 0; count < RCU_NEXT_SIZE; count++)
918 if (&rdp->nxtlist == rdp->nxttail[count])
919 rdp->nxttail[count] = tail;
920 else
921 break;
922 }
923
924 /* Reinstate batch limit if we have worked down the excess. */
925 if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark)
926 rdp->blimit = blimit;
927
928 local_irq_restore(flags);
929
930 /* Re-raise the RCU softirq if there are callbacks remaining. */
931 if (cpu_has_callbacks_ready_to_invoke(rdp))
932 raise_softirq(RCU_SOFTIRQ);
933}
934
935/*
936 * Check to see if this CPU is in a non-context-switch quiescent state
937 * (user mode or idle loop for rcu, non-softirq execution for rcu_bh).
938 * Also schedule the RCU softirq handler.
939 *
940 * This function must be called with hardirqs disabled. It is normally
941 * invoked from the scheduling-clock interrupt. If rcu_pending returns
942 * false, there is no point in invoking rcu_check_callbacks().
943 */
944void rcu_check_callbacks(int cpu, int user)
945{
946 if (user ||
947 (idle_cpu(cpu) && !in_softirq() &&
948 hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
949
950 /*
951 * Get here if this CPU took its interrupt from user
952 * mode or from the idle loop, and if this is not a
953 * nested interrupt. In this case, the CPU is in
954 * a quiescent state, so count it.
955 *
956 * No memory barrier is required here because both
957 * rcu_qsctr_inc() and rcu_bh_qsctr_inc() reference
958 * only CPU-local variables that other CPUs neither
959 * access nor modify, at least not while the corresponding
960 * CPU is online.
961 */
962
963 rcu_qsctr_inc(cpu);
964 rcu_bh_qsctr_inc(cpu);
965
966 } else if (!in_softirq()) {
967
968 /*
969 * Get here if this CPU did not take its interrupt from
970 * softirq, in other words, if it is not interrupting
971 * a rcu_bh read-side critical section. This is an _bh
972 * critical section, so count it.
973 */
974
975 rcu_bh_qsctr_inc(cpu);
976 }
977 raise_softirq(RCU_SOFTIRQ);
978}
979
980#ifdef CONFIG_SMP
981
982/*
983 * Scan the leaf rcu_node structures, processing dyntick state for any that
984 * have not yet encountered a quiescent state, using the function specified.
985 * Returns 1 if the current grace period ends while scanning (possibly
986 * because we made it end).
987 */
988static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp,
989 int (*f)(struct rcu_data *))
990{
991 unsigned long bit;
992 int cpu;
993 unsigned long flags;
994 unsigned long mask;
995 struct rcu_node *rnp_cur = rsp->level[NUM_RCU_LVLS - 1];
996 struct rcu_node *rnp_end = &rsp->node[NUM_RCU_NODES];
997
998 for (; rnp_cur < rnp_end; rnp_cur++) {
999 mask = 0;
1000 spin_lock_irqsave(&rnp_cur->lock, flags);
1001 if (rsp->completed != lastcomp) {
1002 spin_unlock_irqrestore(&rnp_cur->lock, flags);
1003 return 1;
1004 }
1005 if (rnp_cur->qsmask == 0) {
1006 spin_unlock_irqrestore(&rnp_cur->lock, flags);
1007 continue;
1008 }
1009 cpu = rnp_cur->grplo;
1010 bit = 1;
1011 for (; cpu <= rnp_cur->grphi; cpu++, bit <<= 1) {
1012 if ((rnp_cur->qsmask & bit) != 0 && f(rsp->rda[cpu]))
1013 mask |= bit;
1014 }
1015 if (mask != 0 && rsp->completed == lastcomp) {
1016
1017 /* cpu_quiet_msk() releases rnp_cur->lock. */
1018 cpu_quiet_msk(mask, rsp, rnp_cur, flags);
1019 continue;
1020 }
1021 spin_unlock_irqrestore(&rnp_cur->lock, flags);
1022 }
1023 return 0;
1024}
1025
1026/*
1027 * Force quiescent states on reluctant CPUs, and also detect which
1028 * CPUs are in dyntick-idle mode.
1029 */
1030static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
1031{
1032 unsigned long flags;
1033 long lastcomp;
1034 struct rcu_data *rdp = rsp->rda[smp_processor_id()];
1035 struct rcu_node *rnp = rcu_get_root(rsp);
1036 u8 signaled;
1037
1038 if (ACCESS_ONCE(rsp->completed) == ACCESS_ONCE(rsp->gpnum))
1039 return; /* No grace period in progress, nothing to force. */
1040 if (!spin_trylock_irqsave(&rsp->fqslock, flags)) {
1041 rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */
1042 return; /* Someone else is already on the job. */
1043 }
1044 if (relaxed &&
1045 (long)(rsp->jiffies_force_qs - jiffies) >= 0 &&
1046 (rdp->n_rcu_pending_force_qs - rdp->n_rcu_pending) >= 0)
1047 goto unlock_ret; /* no emergency and done recently. */
1048 rsp->n_force_qs++;
1049 spin_lock(&rnp->lock);
1050 lastcomp = rsp->completed;
1051 signaled = rsp->signaled;
1052 rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
1053 rdp->n_rcu_pending_force_qs = rdp->n_rcu_pending +
1054 RCU_JIFFIES_TILL_FORCE_QS;
1055 if (lastcomp == rsp->gpnum) {
1056 rsp->n_force_qs_ngp++;
1057 spin_unlock(&rnp->lock);
1058 goto unlock_ret; /* no GP in progress, time updated. */
1059 }
1060 spin_unlock(&rnp->lock);
1061 switch (signaled) {
1062 case RCU_GP_INIT:
1063
1064 break; /* grace period still initializing, ignore. */
1065
1066 case RCU_SAVE_DYNTICK:
1067
1068 if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK)
1069 break; /* So gcc recognizes the dead code. */
1070
1071 /* Record dyntick-idle state. */
1072 if (rcu_process_dyntick(rsp, lastcomp,
1073 dyntick_save_progress_counter))
1074 goto unlock_ret;
1075
1076 /* Update state, record completion counter. */
1077 spin_lock(&rnp->lock);
1078 if (lastcomp == rsp->completed) {
1079 rsp->signaled = RCU_FORCE_QS;
1080 dyntick_record_completed(rsp, lastcomp);
1081 }
1082 spin_unlock(&rnp->lock);
1083 break;
1084
1085 case RCU_FORCE_QS:
1086
1087 /* Check dyntick-idle state, send IPI to laggarts. */
1088 if (rcu_process_dyntick(rsp, dyntick_recall_completed(rsp),
1089 rcu_implicit_dynticks_qs))
1090 goto unlock_ret;
1091
1092 /* Leave state in case more forcing is required. */
1093
1094 break;
1095 }
1096unlock_ret:
1097 spin_unlock_irqrestore(&rsp->fqslock, flags);
1098}
1099
1100#else /* #ifdef CONFIG_SMP */
1101
1102static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
1103{
1104 set_need_resched();
1105}
1106
1107#endif /* #else #ifdef CONFIG_SMP */
1108
1109/*
1110 * This does the RCU processing work from softirq context for the
1111 * specified rcu_state and rcu_data structures. This may be called
1112 * only from the CPU to whom the rdp belongs.
1113 */
1114static void
1115__rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
1116{
1117 unsigned long flags;
1118
1119 /*
1120 * If an RCU GP has gone long enough, go check for dyntick
1121 * idle CPUs and, if needed, send resched IPIs.
1122 */
1123 if ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0 ||
1124 (rdp->n_rcu_pending_force_qs - rdp->n_rcu_pending) < 0)
1125 force_quiescent_state(rsp, 1);
1126
1127 /*
1128 * Advance callbacks in response to end of earlier grace
1129 * period that some other CPU ended.
1130 */
1131 rcu_process_gp_end(rsp, rdp);
1132
1133 /* Update RCU state based on any recent quiescent states. */
1134 rcu_check_quiescent_state(rsp, rdp);
1135
1136 /* Does this CPU require a not-yet-started grace period? */
1137 if (cpu_needs_another_gp(rsp, rdp)) {
1138 spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags);
1139 rcu_start_gp(rsp, flags); /* releases above lock */
1140 }
1141
1142 /* If there are callbacks ready, invoke them. */
1143 rcu_do_batch(rdp);
1144}
1145
1146/*
1147 * Do softirq processing for the current CPU.
1148 */
1149static void rcu_process_callbacks(struct softirq_action *unused)
1150{
1151 /*
1152 * Memory references from any prior RCU read-side critical sections
1153 * executed by the interrupted code must be seen before any RCU
1154 * grace-period manipulations below.
1155 */
1156 smp_mb(); /* See above block comment. */
1157
1158 __rcu_process_callbacks(&rcu_state, &__get_cpu_var(rcu_data));
1159 __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data));
1160
1161 /*
1162 * Memory references from any later RCU read-side critical sections
1163 * executed by the interrupted code must be seen after any RCU
1164 * grace-period manipulations above.
1165 */
1166 smp_mb(); /* See above block comment. */
1167}
1168
1169static void
1170__call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
1171 struct rcu_state *rsp)
1172{
1173 unsigned long flags;
1174 struct rcu_data *rdp;
1175
1176 head->func = func;
1177 head->next = NULL;
1178
1179 smp_mb(); /* Ensure RCU update seen before callback registry. */
1180
1181 /*
1182 * Opportunistically note grace-period endings and beginnings.
1183 * Note that we might see a beginning right after we see an
1184 * end, but never vice versa, since this CPU has to pass through
1185 * a quiescent state betweentimes.
1186 */
1187 local_irq_save(flags);
1188 rdp = rsp->rda[smp_processor_id()];
1189 rcu_process_gp_end(rsp, rdp);
1190 check_for_new_grace_period(rsp, rdp);
1191
1192 /* Add the callback to our list. */
1193 *rdp->nxttail[RCU_NEXT_TAIL] = head;
1194 rdp->nxttail[RCU_NEXT_TAIL] = &head->next;
1195
1196 /* Start a new grace period if one not already started. */
1197 if (ACCESS_ONCE(rsp->completed) == ACCESS_ONCE(rsp->gpnum)) {
1198 unsigned long nestflag;
1199 struct rcu_node *rnp_root = rcu_get_root(rsp);
1200
1201 spin_lock_irqsave(&rnp_root->lock, nestflag);
1202 rcu_start_gp(rsp, nestflag); /* releases rnp_root->lock. */
1203 }
1204
1205 /* Force the grace period if too many callbacks or too long waiting. */
1206 if (unlikely(++rdp->qlen > qhimark)) {
1207 rdp->blimit = LONG_MAX;
1208 force_quiescent_state(rsp, 0);
1209 } else if ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0 ||
1210 (rdp->n_rcu_pending_force_qs - rdp->n_rcu_pending) < 0)
1211 force_quiescent_state(rsp, 1);
1212 local_irq_restore(flags);
1213}
1214
1215/*
1216 * Queue an RCU callback for invocation after a grace period.
1217 */
1218void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
1219{
1220 __call_rcu(head, func, &rcu_state);
1221}
1222EXPORT_SYMBOL_GPL(call_rcu);
1223
1224/*
1225 * Queue an RCU for invocation after a quicker grace period.
1226 */
1227void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
1228{
1229 __call_rcu(head, func, &rcu_bh_state);
1230}
1231EXPORT_SYMBOL_GPL(call_rcu_bh);
1232
1233/*
1234 * Check to see if there is any immediate RCU-related work to be done
1235 * by the current CPU, for the specified type of RCU, returning 1 if so.
1236 * The checks are in order of increasing expense: checks that can be
1237 * carried out against CPU-local state are performed first. However,
1238 * we must check for CPU stalls first, else we might not get a chance.
1239 */
1240static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
1241{
1242 rdp->n_rcu_pending++;
1243
1244 /* Check for CPU stalls, if enabled. */
1245 check_cpu_stall(rsp, rdp);
1246
1247 /* Is the RCU core waiting for a quiescent state from this CPU? */
1248 if (rdp->qs_pending)
1249 return 1;
1250
1251 /* Does this CPU have callbacks ready to invoke? */
1252 if (cpu_has_callbacks_ready_to_invoke(rdp))
1253 return 1;
1254
1255 /* Has RCU gone idle with this CPU needing another grace period? */
1256 if (cpu_needs_another_gp(rsp, rdp))
1257 return 1;
1258
1259 /* Has another RCU grace period completed? */
1260 if (ACCESS_ONCE(rsp->completed) != rdp->completed) /* outside of lock */
1261 return 1;
1262
1263 /* Has a new RCU grace period started? */
1264 if (ACCESS_ONCE(rsp->gpnum) != rdp->gpnum) /* outside of lock */
1265 return 1;
1266
1267 /* Has an RCU GP gone long enough to send resched IPIs &c? */
1268 if (ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum) &&
1269 ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0 ||
1270 (rdp->n_rcu_pending_force_qs - rdp->n_rcu_pending) < 0))
1271 return 1;
1272
1273 /* nothing to do */
1274 return 0;
1275}
1276
1277/*
1278 * Check to see if there is any immediate RCU-related work to be done
1279 * by the current CPU, returning 1 if so. This function is part of the
1280 * RCU implementation; it is -not- an exported member of the RCU API.
1281 */
1282int rcu_pending(int cpu)
1283{
1284 return __rcu_pending(&rcu_state, &per_cpu(rcu_data, cpu)) ||
1285 __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu));
1286}
1287
1288/*
1289 * Check to see if any future RCU-related work will need to be done
1290 * by the current CPU, even if none need be done immediately, returning
1291 * 1 if so. This function is part of the RCU implementation; it is -not-
1292 * an exported member of the RCU API.
1293 */
1294int rcu_needs_cpu(int cpu)
1295{
1296 /* RCU callbacks either ready or pending? */
1297 return per_cpu(rcu_data, cpu).nxtlist ||
1298 per_cpu(rcu_bh_data, cpu).nxtlist;
1299}
1300
1301/*
1302 * Initialize a CPU's per-CPU RCU data. We take this "scorched earth"
1303 * approach so that we don't have to worry about how long the CPU has
1304 * been gone, or whether it ever was online previously. We do trust the
1305 * ->mynode field, as it is constant for a given struct rcu_data and
1306 * initialized during early boot.
1307 *
1308 * Note that only one online or offline event can be happening at a given
1309 * time. Note also that we can accept some slop in the rsp->completed
1310 * access due to the fact that this CPU cannot possibly have any RCU
1311 * callbacks in flight yet.
1312 */
1313static void
1314rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
1315{
1316 unsigned long flags;
1317 int i;
1318 long lastcomp;
1319 unsigned long mask;
1320 struct rcu_data *rdp = rsp->rda[cpu];
1321 struct rcu_node *rnp = rcu_get_root(rsp);
1322
1323 /* Set up local state, ensuring consistent view of global state. */
1324 spin_lock_irqsave(&rnp->lock, flags);
1325 lastcomp = rsp->completed;
1326 rdp->completed = lastcomp;
1327 rdp->gpnum = lastcomp;
1328 rdp->passed_quiesc = 0; /* We could be racing with new GP, */
1329 rdp->qs_pending = 1; /* so set up to respond to current GP. */
1330 rdp->beenonline = 1; /* We have now been online. */
1331 rdp->passed_quiesc_completed = lastcomp - 1;
1332 rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
1333 rdp->nxtlist = NULL;
1334 for (i = 0; i < RCU_NEXT_SIZE; i++)
1335 rdp->nxttail[i] = &rdp->nxtlist;
1336 rdp->qlen = 0;
1337 rdp->blimit = blimit;
1338#ifdef CONFIG_NO_HZ
1339 rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
1340#endif /* #ifdef CONFIG_NO_HZ */
1341 rdp->cpu = cpu;
1342 spin_unlock(&rnp->lock); /* irqs remain disabled. */
1343
1344 /*
1345 * A new grace period might start here. If so, we won't be part
1346 * of it, but that is OK, as we are currently in a quiescent state.
1347 */
1348
1349 /* Exclude any attempts to start a new GP on large systems. */
1350 spin_lock(&rsp->onofflock); /* irqs already disabled. */
1351
1352 /* Add CPU to rcu_node bitmasks. */
1353 rnp = rdp->mynode;
1354 mask = rdp->grpmask;
1355 do {
1356 /* Exclude any attempts to start a new GP on small systems. */
1357 spin_lock(&rnp->lock); /* irqs already disabled. */
1358 rnp->qsmaskinit |= mask;
1359 mask = rnp->grpmask;
1360 spin_unlock(&rnp->lock); /* irqs already disabled. */
1361 rnp = rnp->parent;
1362 } while (rnp != NULL && !(rnp->qsmaskinit & mask));
1363
1364 spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
1365
1366 /*
1367 * A new grace period might start here. If so, we will be part of
1368 * it, and its gpnum will be greater than ours, so we will
1369 * participate. It is also possible for the gpnum to have been
1370 * incremented before this function was called, and the bitmasks
1371 * to not be filled out until now, in which case we will also
1372 * participate due to our gpnum being behind.
1373 */
1374
1375 /* Since it is coming online, the CPU is in a quiescent state. */
1376 cpu_quiet(cpu, rsp, rdp, lastcomp);
1377 local_irq_restore(flags);
1378}
1379
1380static void __cpuinit rcu_online_cpu(int cpu)
1381{
1382#ifdef CONFIG_NO_HZ
1383 struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
1384
1385 rdtp->dynticks_nesting = 1;
1386 rdtp->dynticks |= 1; /* need consecutive #s even for hotplug. */
1387 rdtp->dynticks_nmi = (rdtp->dynticks_nmi + 1) & ~0x1;
1388#endif /* #ifdef CONFIG_NO_HZ */
1389 rcu_init_percpu_data(cpu, &rcu_state);
1390 rcu_init_percpu_data(cpu, &rcu_bh_state);
1391 open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
1392}
1393
1394/*
1395 * Handle CPU online/offline notifcation events.
1396 */
1397static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
1398 unsigned long action, void *hcpu)
1399{
1400 long cpu = (long)hcpu;
1401
1402 switch (action) {
1403 case CPU_UP_PREPARE:
1404 case CPU_UP_PREPARE_FROZEN:
1405 rcu_online_cpu(cpu);
1406 break;
1407 case CPU_DEAD:
1408 case CPU_DEAD_FROZEN:
1409 case CPU_UP_CANCELED:
1410 case CPU_UP_CANCELED_FROZEN:
1411 rcu_offline_cpu(cpu);
1412 break;
1413 default:
1414 break;
1415 }
1416 return NOTIFY_OK;
1417}
1418
1419/*
1420 * Compute the per-level fanout, either using the exact fanout specified
1421 * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT.
1422 */
1423#ifdef CONFIG_RCU_FANOUT_EXACT
1424static void __init rcu_init_levelspread(struct rcu_state *rsp)
1425{
1426 int i;
1427
1428 for (i = NUM_RCU_LVLS - 1; i >= 0; i--)
1429 rsp->levelspread[i] = CONFIG_RCU_FANOUT;
1430}
1431#else /* #ifdef CONFIG_RCU_FANOUT_EXACT */
1432static void __init rcu_init_levelspread(struct rcu_state *rsp)
1433{
1434 int ccur;
1435 int cprv;
1436 int i;
1437
1438 cprv = NR_CPUS;
1439 for (i = NUM_RCU_LVLS - 1; i >= 0; i--) {
1440 ccur = rsp->levelcnt[i];
1441 rsp->levelspread[i] = (cprv + ccur - 1) / ccur;
1442 cprv = ccur;
1443 }
1444}
1445#endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */
1446
1447/*
1448 * Helper function for rcu_init() that initializes one rcu_state structure.
1449 */
1450static void __init rcu_init_one(struct rcu_state *rsp)
1451{
1452 int cpustride = 1;
1453 int i;
1454 int j;
1455 struct rcu_node *rnp;
1456
1457 /* Initialize the level-tracking arrays. */
1458
1459 for (i = 1; i < NUM_RCU_LVLS; i++)
1460 rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1];
1461 rcu_init_levelspread(rsp);
1462
1463 /* Initialize the elements themselves, starting from the leaves. */
1464
1465 for (i = NUM_RCU_LVLS - 1; i >= 0; i--) {
1466 cpustride *= rsp->levelspread[i];
1467 rnp = rsp->level[i];
1468 for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) {
1469 spin_lock_init(&rnp->lock);
1470 rnp->qsmask = 0;
1471 rnp->qsmaskinit = 0;
1472 rnp->grplo = j * cpustride;
1473 rnp->grphi = (j + 1) * cpustride - 1;
1474 if (rnp->grphi >= NR_CPUS)
1475 rnp->grphi = NR_CPUS - 1;
1476 if (i == 0) {
1477 rnp->grpnum = 0;
1478 rnp->grpmask = 0;
1479 rnp->parent = NULL;
1480 } else {
1481 rnp->grpnum = j % rsp->levelspread[i - 1];
1482 rnp->grpmask = 1UL << rnp->grpnum;
1483 rnp->parent = rsp->level[i - 1] +
1484 j / rsp->levelspread[i - 1];
1485 }
1486 rnp->level = i;
1487 }
1488 }
1489}
1490
1491/*
1492 * Helper macro for __rcu_init(). To be used nowhere else!
1493 * Assigns leaf node pointers into each CPU's rcu_data structure.
1494 */
1495#define RCU_DATA_PTR_INIT(rsp, rcu_data) \
1496do { \
1497 rnp = (rsp)->level[NUM_RCU_LVLS - 1]; \
1498 j = 0; \
1499 for_each_possible_cpu(i) { \
1500 if (i > rnp[j].grphi) \
1501 j++; \
1502 per_cpu(rcu_data, i).mynode = &rnp[j]; \
1503 (rsp)->rda[i] = &per_cpu(rcu_data, i); \
1504 } \
1505} while (0)
1506
1507static struct notifier_block __cpuinitdata rcu_nb = {
1508 .notifier_call = rcu_cpu_notify,
1509};
1510
1511void __init __rcu_init(void)
1512{
1513 int i; /* All used by RCU_DATA_PTR_INIT(). */
1514 int j;
1515 struct rcu_node *rnp;
1516
1517 printk(KERN_WARNING "Experimental hierarchical RCU implementation.\n");
1518#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
1519 printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n");
1520#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
1521 rcu_init_one(&rcu_state);
1522 RCU_DATA_PTR_INIT(&rcu_state, rcu_data);
1523 rcu_init_one(&rcu_bh_state);
1524 RCU_DATA_PTR_INIT(&rcu_bh_state, rcu_bh_data);
1525
1526 for_each_online_cpu(i)
1527 rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, (void *)(long)i);
1528 /* Register notifier for non-boot CPUs */
1529 register_cpu_notifier(&rcu_nb);
1530 printk(KERN_WARNING "Experimental hierarchical RCU init done.\n");
1531}
1532
1533module_param(blimit, int, 0);
1534module_param(qhimark, int, 0);
1535module_param(qlowmark, int, 0);
diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
new file mode 100644
index 00000000000..d6db3e83782
--- /dev/null
+++ b/kernel/rcutree_trace.c
@@ -0,0 +1,271 @@
1/*
2 * Read-Copy Update tracing for classic implementation
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright IBM Corporation, 2008
19 *
20 * Papers: http://www.rdrop.com/users/paulmck/RCU
21 *
22 * For detailed explanation of Read-Copy Update mechanism see -
23 * Documentation/RCU
24 *
25 */
26#include <linux/types.h>
27#include <linux/kernel.h>
28#include <linux/init.h>
29#include <linux/spinlock.h>
30#include <linux/smp.h>
31#include <linux/rcupdate.h>
32#include <linux/interrupt.h>
33#include <linux/sched.h>
34#include <asm/atomic.h>
35#include <linux/bitops.h>
36#include <linux/module.h>
37#include <linux/completion.h>
38#include <linux/moduleparam.h>
39#include <linux/percpu.h>
40#include <linux/notifier.h>
41#include <linux/cpu.h>
42#include <linux/mutex.h>
43#include <linux/debugfs.h>
44#include <linux/seq_file.h>
45
46static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
47{
48 if (!rdp->beenonline)
49 return;
50 seq_printf(m, "%3d%cc=%ld g=%ld pq=%d pqc=%ld qp=%d rpfq=%ld rp=%x",
51 rdp->cpu,
52 cpu_is_offline(rdp->cpu) ? '!' : ' ',
53 rdp->completed, rdp->gpnum,
54 rdp->passed_quiesc, rdp->passed_quiesc_completed,
55 rdp->qs_pending,
56 rdp->n_rcu_pending_force_qs - rdp->n_rcu_pending,
57 (int)(rdp->n_rcu_pending & 0xffff));
58#ifdef CONFIG_NO_HZ
59 seq_printf(m, " dt=%d/%d dn=%d df=%lu",
60 rdp->dynticks->dynticks,
61 rdp->dynticks->dynticks_nesting,
62 rdp->dynticks->dynticks_nmi,
63 rdp->dynticks_fqs);
64#endif /* #ifdef CONFIG_NO_HZ */
65 seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi);
66 seq_printf(m, " ql=%ld b=%ld\n", rdp->qlen, rdp->blimit);
67}
68
69#define PRINT_RCU_DATA(name, func, m) \
70 do { \
71 int _p_r_d_i; \
72 \
73 for_each_possible_cpu(_p_r_d_i) \
74 func(m, &per_cpu(name, _p_r_d_i)); \
75 } while (0)
76
77static int show_rcudata(struct seq_file *m, void *unused)
78{
79 seq_puts(m, "rcu:\n");
80 PRINT_RCU_DATA(rcu_data, print_one_rcu_data, m);
81 seq_puts(m, "rcu_bh:\n");
82 PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data, m);
83 return 0;
84}
85
86static int rcudata_open(struct inode *inode, struct file *file)
87{
88 return single_open(file, show_rcudata, NULL);
89}
90
91static struct file_operations rcudata_fops = {
92 .owner = THIS_MODULE,
93 .open = rcudata_open,
94 .read = seq_read,
95 .llseek = seq_lseek,
96 .release = single_release,
97};
98
99static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
100{
101 if (!rdp->beenonline)
102 return;
103 seq_printf(m, "%d,%s,%ld,%ld,%d,%ld,%d,%ld,%ld",
104 rdp->cpu,
105 cpu_is_offline(rdp->cpu) ? "\"Y\"" : "\"N\"",
106 rdp->completed, rdp->gpnum,
107 rdp->passed_quiesc, rdp->passed_quiesc_completed,
108 rdp->qs_pending,
109 rdp->n_rcu_pending_force_qs - rdp->n_rcu_pending,
110 rdp->n_rcu_pending);
111#ifdef CONFIG_NO_HZ
112 seq_printf(m, ",%d,%d,%d,%lu",
113 rdp->dynticks->dynticks,
114 rdp->dynticks->dynticks_nesting,
115 rdp->dynticks->dynticks_nmi,
116 rdp->dynticks_fqs);
117#endif /* #ifdef CONFIG_NO_HZ */
118 seq_printf(m, ",%lu,%lu", rdp->offline_fqs, rdp->resched_ipi);
119 seq_printf(m, ",%ld,%ld\n", rdp->qlen, rdp->blimit);
120}
121
122static int show_rcudata_csv(struct seq_file *m, void *unused)
123{
124 seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pqc\",\"pq\",\"rpfq\",\"rp\",");
125#ifdef CONFIG_NO_HZ
126 seq_puts(m, "\"dt\",\"dt nesting\",\"dn\",\"df\",");
127#endif /* #ifdef CONFIG_NO_HZ */
128 seq_puts(m, "\"of\",\"ri\",\"ql\",\"b\"\n");
129 seq_puts(m, "\"rcu:\"\n");
130 PRINT_RCU_DATA(rcu_data, print_one_rcu_data_csv, m);
131 seq_puts(m, "\"rcu_bh:\"\n");
132 PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data_csv, m);
133 return 0;
134}
135
136static int rcudata_csv_open(struct inode *inode, struct file *file)
137{
138 return single_open(file, show_rcudata_csv, NULL);
139}
140
141static struct file_operations rcudata_csv_fops = {
142 .owner = THIS_MODULE,
143 .open = rcudata_csv_open,
144 .read = seq_read,
145 .llseek = seq_lseek,
146 .release = single_release,
147};
148
149static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
150{
151 int level = 0;
152 struct rcu_node *rnp;
153
154 seq_printf(m, "c=%ld g=%ld s=%d jfq=%ld j=%x "
155 "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu\n",
156 rsp->completed, rsp->gpnum, rsp->signaled,
157 (long)(rsp->jiffies_force_qs - jiffies),
158 (int)(jiffies & 0xffff),
159 rsp->n_force_qs, rsp->n_force_qs_ngp,
160 rsp->n_force_qs - rsp->n_force_qs_ngp,
161 rsp->n_force_qs_lh);
162 for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < NUM_RCU_NODES; rnp++) {
163 if (rnp->level != level) {
164 seq_puts(m, "\n");
165 level = rnp->level;
166 }
167 seq_printf(m, "%lx/%lx %d:%d ^%d ",
168 rnp->qsmask, rnp->qsmaskinit,
169 rnp->grplo, rnp->grphi, rnp->grpnum);
170 }
171 seq_puts(m, "\n");
172}
173
174static int show_rcuhier(struct seq_file *m, void *unused)
175{
176 seq_puts(m, "rcu:\n");
177 print_one_rcu_state(m, &rcu_state);
178 seq_puts(m, "rcu_bh:\n");
179 print_one_rcu_state(m, &rcu_bh_state);
180 return 0;
181}
182
183static int rcuhier_open(struct inode *inode, struct file *file)
184{
185 return single_open(file, show_rcuhier, NULL);
186}
187
188static struct file_operations rcuhier_fops = {
189 .owner = THIS_MODULE,
190 .open = rcuhier_open,
191 .read = seq_read,
192 .llseek = seq_lseek,
193 .release = single_release,
194};
195
196static int show_rcugp(struct seq_file *m, void *unused)
197{
198 seq_printf(m, "rcu: completed=%ld gpnum=%ld\n",
199 rcu_state.completed, rcu_state.gpnum);
200 seq_printf(m, "rcu_bh: completed=%ld gpnum=%ld\n",
201 rcu_bh_state.completed, rcu_bh_state.gpnum);
202 return 0;
203}
204
205static int rcugp_open(struct inode *inode, struct file *file)
206{
207 return single_open(file, show_rcugp, NULL);
208}
209
210static struct file_operations rcugp_fops = {
211 .owner = THIS_MODULE,
212 .open = rcugp_open,
213 .read = seq_read,
214 .llseek = seq_lseek,
215 .release = single_release,
216};
217
218static struct dentry *rcudir, *datadir, *datadir_csv, *hierdir, *gpdir;
219static int __init rcuclassic_trace_init(void)
220{
221 rcudir = debugfs_create_dir("rcu", NULL);
222 if (!rcudir)
223 goto out;
224
225 datadir = debugfs_create_file("rcudata", 0444, rcudir,
226 NULL, &rcudata_fops);
227 if (!datadir)
228 goto free_out;
229
230 datadir_csv = debugfs_create_file("rcudata.csv", 0444, rcudir,
231 NULL, &rcudata_csv_fops);
232 if (!datadir_csv)
233 goto free_out;
234
235 gpdir = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
236 if (!gpdir)
237 goto free_out;
238
239 hierdir = debugfs_create_file("rcuhier", 0444, rcudir,
240 NULL, &rcuhier_fops);
241 if (!hierdir)
242 goto free_out;
243 return 0;
244free_out:
245 if (datadir)
246 debugfs_remove(datadir);
247 if (datadir_csv)
248 debugfs_remove(datadir_csv);
249 if (gpdir)
250 debugfs_remove(gpdir);
251 debugfs_remove(rcudir);
252out:
253 return 1;
254}
255
256static void __exit rcuclassic_trace_cleanup(void)
257{
258 debugfs_remove(datadir);
259 debugfs_remove(datadir_csv);
260 debugfs_remove(gpdir);
261 debugfs_remove(hierdir);
262 debugfs_remove(rcudir);
263}
264
265
266module_init(rcuclassic_trace_init);
267module_exit(rcuclassic_trace_cleanup);
268
269MODULE_AUTHOR("Paul E. McKenney");
270MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
271MODULE_LICENSE("GPL");
diff --git a/kernel/resource.c b/kernel/resource.c
index 4337063663e..e633106b12f 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -853,6 +853,15 @@ int iomem_map_sanity_check(resource_size_t addr, unsigned long size)
853 if (PFN_DOWN(p->start) <= PFN_DOWN(addr) && 853 if (PFN_DOWN(p->start) <= PFN_DOWN(addr) &&
854 PFN_DOWN(p->end) >= PFN_DOWN(addr + size - 1)) 854 PFN_DOWN(p->end) >= PFN_DOWN(addr + size - 1))
855 continue; 855 continue;
856 /*
857 * if a resource is "BUSY", it's not a hardware resource
858 * but a driver mapping of such a resource; we don't want
859 * to warn for those; some drivers legitimately map only
860 * partial hardware resources. (example: vesafb)
861 */
862 if (p->flags & IORESOURCE_BUSY)
863 continue;
864
856 printk(KERN_WARNING "resource map sanity check conflict: " 865 printk(KERN_WARNING "resource map sanity check conflict: "
857 "0x%llx 0x%llx 0x%llx 0x%llx %s\n", 866 "0x%llx 0x%llx 0x%llx 0x%llx %s\n",
858 (unsigned long long)addr, 867 (unsigned long long)addr,
diff --git a/kernel/softirq.c b/kernel/softirq.c
index e7c69a720d6..466e75ce271 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -102,20 +102,6 @@ void local_bh_disable(void)
102 102
103EXPORT_SYMBOL(local_bh_disable); 103EXPORT_SYMBOL(local_bh_disable);
104 104
105void __local_bh_enable(void)
106{
107 WARN_ON_ONCE(in_irq());
108
109 /*
110 * softirqs should never be enabled by __local_bh_enable(),
111 * it always nests inside local_bh_enable() sections:
112 */
113 WARN_ON_ONCE(softirq_count() == SOFTIRQ_OFFSET);
114
115 sub_preempt_count(SOFTIRQ_OFFSET);
116}
117EXPORT_SYMBOL_GPL(__local_bh_enable);
118
119/* 105/*
120 * Special-case - softirqs can safely be enabled in 106 * Special-case - softirqs can safely be enabled in
121 * cond_resched_softirq(), or by __do_softirq(), 107 * cond_resched_softirq(), or by __do_softirq(),
@@ -269,6 +255,7 @@ void irq_enter(void)
269{ 255{
270 int cpu = smp_processor_id(); 256 int cpu = smp_processor_id();
271 257
258 rcu_irq_enter();
272 if (idle_cpu(cpu) && !in_interrupt()) { 259 if (idle_cpu(cpu) && !in_interrupt()) {
273 __irq_enter(); 260 __irq_enter();
274 tick_check_idle(cpu); 261 tick_check_idle(cpu);
@@ -295,9 +282,9 @@ void irq_exit(void)
295 282
296#ifdef CONFIG_NO_HZ 283#ifdef CONFIG_NO_HZ
297 /* Make sure that timer wheel updates are propagated */ 284 /* Make sure that timer wheel updates are propagated */
298 if (!in_interrupt() && idle_cpu(smp_processor_id()) && !need_resched())
299 tick_nohz_stop_sched_tick(0);
300 rcu_irq_exit(); 285 rcu_irq_exit();
286 if (idle_cpu(smp_processor_id()) && !in_interrupt() && !need_resched())
287 tick_nohz_stop_sched_tick(0);
301#endif 288#endif
302 preempt_enable_no_resched(); 289 preempt_enable_no_resched();
303} 290}
diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index 94b527ef1d1..eb212f8f8bc 100644
--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -6,6 +6,7 @@
6 * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> 6 * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
7 */ 7 */
8#include <linux/sched.h> 8#include <linux/sched.h>
9#include <linux/kernel.h>
9#include <linux/module.h> 10#include <linux/module.h>
10#include <linux/kallsyms.h> 11#include <linux/kallsyms.h>
11#include <linux/stacktrace.h> 12#include <linux/stacktrace.h>
@@ -24,3 +25,13 @@ void print_stack_trace(struct stack_trace *trace, int spaces)
24} 25}
25EXPORT_SYMBOL_GPL(print_stack_trace); 26EXPORT_SYMBOL_GPL(print_stack_trace);
26 27
28/*
29 * Architectures that do not implement save_stack_trace_tsk get this
30 * weak alias and a once-per-bootup warning (whenever this facility
31 * is utilized - for example by procfs):
32 */
33__weak void
34save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
35{
36 WARN_ONCE(1, KERN_INFO "save_stack_trace_tsk() not implemented yet.\n");
37}
generated by cgit v1.2.2 (git 2.25.0) at 2026-03-15 16:24:20 -0400