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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: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1247725694-6082-6-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Frederic Weisbecker 2009-07-16 15:44:29 +02:00 committed by Ingo Molnar
parent 6f80bd985f
commit 613afbf832
3 changed files with 25 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
fs/dcache.c
View File

@ -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;

29
include/linux/sched.h
View File

@ -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

12
kernel/sched.c
View File

@ -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.