Commit 613afbf8 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
Browse files

sched: Pull up the might_sleep() check into cond_resched() 



might_sleep() is called late-ish in cond_resched(), after the
need_resched()/preempt enabled/system running tests are
checked.

It's better to check the sleeps while atomic earlier and not
depend on some environment datas that reduce the chances to
detect a problem.

Also define cond_resched_*() helpers as macros, so that the
FILE/LINE reported in the sleeping while atomic warning
displays the real origin and not sched.h

Changes in v2:

 - Call __might_sleep() directly instead of might_sleep() which
   may call cond_resched()

 - Turn cond_resched() into a macro so that the file:line
   couple reported refers to the caller of cond_resched() and
   not __cond_resched() itself.

Changes in v3:

 - Also propagate this __might_sleep() pull up to
   cond_resched_lock() and cond_resched_softirq()

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1247725694-6082-6-git-send-email-fweisbec@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 6f80bd98

fs/dcache.c

+1 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 
#include <linux/swap.h>

#include <linux/bootmem.h>

#include <linux/fs_struct.h>

#include <linux/hardirq.h>

#include "internal.h"



int sysctl_vfs_cache_pressure __read_mostly = 100;

include/linux/sched.h

+19 −10
Original line number Diff line number Diff line
@@ -2286,17 +2286,26 @@ static inline int need_resched(void) 
 */

extern int _cond_resched(void);



static inline int cond_resched(void)

{

	return _cond_resched();

}

#define cond_resched() ({			\

	__might_sleep(__FILE__, __LINE__, 0);	\

	_cond_resched();			\

})



extern int cond_resched_lock(spinlock_t * lock);

extern int cond_resched_softirq(void);

static inline int cond_resched_bkl(void)

{

	return _cond_resched();

}

extern int __cond_resched_lock(spinlock_t *lock);



#define cond_resched_lock(lock) ({				\

	__might_sleep(__FILE__, __LINE__, PREEMPT_OFFSET);	\

	__cond_resched_lock(lock);				\

})



extern int __cond_resched_softirq(void);



#define cond_resched_softirq() ({				\

	__might_sleep(__FILE__, __LINE__, SOFTIRQ_OFFSET);	\

	__cond_resched_softirq();				\

})



#define cond_resched_bkl()	cond_resched()



/*

 * Does a critical section need to be broken due to another

kernel/sched.c

+5 −7
Original line number Diff line number Diff line
@@ -6610,8 +6610,6 @@ static inline int should_resched(void) 


static void __cond_resched(void)

{

	__might_sleep(__FILE__, __LINE__, 0);



	add_preempt_count(PREEMPT_ACTIVE);

	schedule();

	sub_preempt_count(PREEMPT_ACTIVE);
@@ -6628,14 +6626,14 @@ int __sched _cond_resched(void) 
EXPORT_SYMBOL(_cond_resched);



/*

 * cond_resched_lock() - if a reschedule is pending, drop the given lock,

 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,

 * call schedule, and on return reacquire the lock.

 *

 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level

 * operations here to prevent schedule() from being called twice (once via

 * spin_unlock(), once by hand).

 */

int cond_resched_lock(spinlock_t *lock)

int __cond_resched_lock(spinlock_t *lock)

{

	int resched = should_resched();

	int ret = 0;
@@ -6651,9 +6649,9 @@ int cond_resched_lock(spinlock_t *lock) 
	}

	return ret;

}

EXPORT_SYMBOL(cond_resched_lock);

EXPORT_SYMBOL(__cond_resched_lock);



int __sched cond_resched_softirq(void)

int __sched __cond_resched_softirq(void)

{

	BUG_ON(!in_softirq());
@@ -6665,7 +6663,7 @@ int __sched cond_resched_softirq(void) 
	}

	return 0;

}

EXPORT_SYMBOL(cond_resched_softirq);

EXPORT_SYMBOL(__cond_resched_softirq);



/**

 * yield - yield the current processor to other threads.

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