From 3427445afd26bd2395f29241319283a93f362cd0 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 24 Sep 2014 10:18:56 +0200 Subject: [PATCH] sched: Exclude cond_resched() from nested sleep test cond_resched() is a preemption point, not strictly a blocking primitive, so exclude it from the ->state test. In particular, preemption preserves task_struct::state. Signed-off-by: Peter Zijlstra (Intel) Cc: tglx@linutronix.de Cc: ilya.dryomov@inktank.com Cc: umgwanakikbuti@gmail.com Cc: oleg@redhat.com Cc: Alex Elder Cc: Andrew Morton Cc: Axel Lin Cc: Daniel Borkmann Cc: Dave Jones Cc: Jason Baron Cc: Linus Torvalds Cc: Rusty Russell Cc: Steven Rostedt Link: http://lkml.kernel.org/r/20140924082242.656559952@infradead.org Signed-off-by: Ingo Molnar --- include/linux/kernel.h | 3 +++ include/linux/sched.h | 6 +++--- kernel/sched/core.c | 12 +++++++++--- 3 files changed, 15 insertions(+), 6 deletions(-) diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 5068a0d9fecd..446d76a87ba1 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -162,6 +162,7 @@ extern int _cond_resched(void); #endif #ifdef CONFIG_DEBUG_ATOMIC_SLEEP + void ___might_sleep(const char *file, int line, int preempt_offset); void __might_sleep(const char *file, int line, int preempt_offset); /** * might_sleep - annotation for functions that can sleep @@ -177,6 +178,8 @@ extern int _cond_resched(void); do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0) # define sched_annotate_sleep() __set_current_state(TASK_RUNNING) #else + static inline void ___might_sleep(const char *file, int line, + int preempt_offset) { } static inline void __might_sleep(const char *file, int line, int preempt_offset) { } # define might_sleep() do { might_resched(); } while (0) diff --git a/include/linux/sched.h b/include/linux/sched.h index 4648e07f7d6f..4400ddc2fe73 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2806,7 +2806,7 @@ static inline int signal_pending_state(long state, struct task_struct *p) extern int _cond_resched(void); #define cond_resched() ({ \ - __might_sleep(__FILE__, __LINE__, 0); \ + ___might_sleep(__FILE__, __LINE__, 0); \ _cond_resched(); \ }) @@ -2819,14 +2819,14 @@ extern int __cond_resched_lock(spinlock_t *lock); #endif #define cond_resched_lock(lock) ({ \ - __might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET); \ + ___might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET);\ __cond_resched_lock(lock); \ }) extern int __cond_resched_softirq(void); #define cond_resched_softirq() ({ \ - __might_sleep(__FILE__, __LINE__, SOFTIRQ_DISABLE_OFFSET); \ + ___might_sleep(__FILE__, __LINE__, SOFTIRQ_DISABLE_OFFSET); \ __cond_resched_softirq(); \ }) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 5b4b96b27cd7..b9f78f12ac22 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7296,8 +7296,6 @@ static inline int preempt_count_equals(int preempt_offset) void __might_sleep(const char *file, int line, int preempt_offset) { - static unsigned long prev_jiffy; /* ratelimiting */ - /* * Blocking primitives will set (and therefore destroy) current->state, * since we will exit with TASK_RUNNING make sure we enter with it, @@ -7311,6 +7309,14 @@ void __might_sleep(const char *file, int line, int preempt_offset) (void *)current->task_state_change)) __set_current_state(TASK_RUNNING); + ___might_sleep(file, line, preempt_offset); +} +EXPORT_SYMBOL(__might_sleep); + +void ___might_sleep(const char *file, int line, int preempt_offset) +{ + static unsigned long prev_jiffy; /* ratelimiting */ + rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */ if ((preempt_count_equals(preempt_offset) && !irqs_disabled() && !is_idle_task(current)) || @@ -7340,7 +7346,7 @@ void __might_sleep(const char *file, int line, int preempt_offset) #endif dump_stack(); } -EXPORT_SYMBOL(__might_sleep); +EXPORT_SYMBOL(___might_sleep); #endif #ifdef CONFIG_MAGIC_SYSRQ