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Commit 3427445a authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

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: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: oleg@redhat.com
Cc: Alex Elder <alex.elder@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Axel Lin <axel.lin@ingics.com>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20140924082242.656559952@infradead.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 8eb23b9f

include/linux/kernel.h

+3 −0
Original line number Diff line number Diff line
@@ -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)

include/linux/sched.h

+3 −3
Original line number Diff line number Diff line
@@ -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();					\

})

kernel/sched/core.c

+9 −3
Original line number Diff line number Diff line
@@ -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