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[PATCH] fix cond_resched() fix 

In cond_resched_lock() it calls __resched_legal() before dropping the spin
lock.  __resched_legal() will always finds the preempt_count non-zero and
will prevent the call to __cond_resched().

The attached patch adds a parameter to __resched_legal() with the expected
preempt_count value.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jim Houston 2006-07-30 03:03:39 -07:00 committed by Linus Torvalds
parent 6ea24f9ad1
commit 2d7d253548
1 changed files with 5 additions and 5 deletions
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10
kernel/sched.c
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@ -4456,9 +4456,9 @@ asmlinkage long sys_sched_yield(void)
return 0;
}
static inline int __resched_legal(void)
static inline int __resched_legal(int expected_preempt_count)
{
if (unlikely(preempt_count()))
if (unlikely(preempt_count() != expected_preempt_count))
return 0;
if (unlikely(system_state != SYSTEM_RUNNING))
return 0;
@ -4484,7 +4484,7 @@ static void __cond_resched(void)
int __sched cond_resched(void)
{
if (need_resched() && __resched_legal()) {
if (need_resched() && __resched_legal(0)) {
__cond_resched();
return 1;
}
@ -4510,7 +4510,7 @@ int cond_resched_lock(spinlock_t *lock)
ret = 1;
spin_lock(lock);
}
if (need_resched() && __resched_legal()) {
if (need_resched() && __resched_legal(1)) {
spin_release(&lock->dep_map, 1, _THIS_IP_);
_raw_spin_unlock(lock);
preempt_enable_no_resched();
@ -4526,7 +4526,7 @@ int __sched cond_resched_softirq(void)
{
BUG_ON(!in_softirq());
if (need_resched() && __resched_legal()) {
if (need_resched() && __resched_legal(0)) {
raw_local_irq_disable();
_local_bh_enable();
raw_local_irq_enable();