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sched: Add a preempt count base offset to __might_sleep()

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Add a preempt count base offset to compare against the current
preempt level count. It prepares to pull up the might_sleep
check from cond_resched() to cond_resched_lock() and
cond_resched_bh().

For these two helpers, we need to respectively ensure that once
we'll unlock the given spinlock / reenable local softirqs, we
will reach a sleepable state.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
[ Move and rename preempt_count_equals() ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1247725694-6082-4-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 e09758fae8
commit e4aafea2d4
2 changed files with 14 additions and 7 deletions
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6
include/linux/kernel.h
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@ -125,7 +125,7 @@ extern int _cond_resched(void);
#endif
#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
void __might_sleep(char *file, int line);
void __might_sleep(char *file, int line, int preempt_offset);
/**
* might_sleep - annotation for functions that can sleep
*
@ -137,9 +137,9 @@ extern int _cond_resched(void);
* supposed to.
*/
# define might_sleep() \
do { __might_sleep(__FILE__, __LINE__); might_resched(); } while (0)
do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
#else
static inline void __might_sleep(char *file, int line) { }
static inline void __might_sleep(char *file, int line, int preempt_offset) { }
# define might_sleep() do { might_resched(); } while (0)
#endif

15
kernel/sched.c
View File

@ -6610,7 +6610,7 @@ static inline int should_resched(void)
static void __cond_resched(void)
{
__might_sleep(__FILE__, __LINE__);
__might_sleep(__FILE__, __LINE__, 0);
add_preempt_count(PREEMPT_ACTIVE);
schedule();
@ -9429,13 +9429,20 @@ void __init sched_init(void)
}
#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
void __might_sleep(char *file, int line)
static inline int preempt_count_equals(int preempt_offset)
{
int nested = preempt_count() & ~PREEMPT_ACTIVE;
return (nested == PREEMPT_INATOMIC_BASE + preempt_offset);
}
void __might_sleep(char *file, int line, int preempt_offset)
{
#ifdef in_atomic
static unsigned long prev_jiffy; /* ratelimiting */
if ((!in_atomic() && !irqs_disabled()) ||
system_state != SYSTEM_RUNNING || oops_in_progress)
if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) ||
system_state != SYSTEM_RUNNING || oops_in_progress)
return;
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
return;