[PATCH] cond_resched(): fix bogus might_sleep() warning

5bbcfd90 · Ingo Molnar <[email protected]> · 2005-07-07 17:57:04 -07:00

The BKS might be reacquired before we have dropped PREEMPT_ACTIVE, which
could trigger a second could trigger a second cond_resched() call.  Bug
found by Hirofumi Ogawa.

Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: 5bbcfd9000887c0da7d57cc7b3ac869fc0dd5aa9
Parents: a4014d8f

Changes

1 files changed · +7 −0

File	Status	Add	Del	Content
kernel/sched.c	modified	+7	−0	View file

kernel/sched.c

View file

diff --git a/kernel/sched.c b/kernel/sched.c
index 5f2182d..4107db0 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3877,6 +3877,13 @@ asmlinkage long sys_sched_yield(void)
 
 static inline void __cond_resched(void)
 {
+	/*
+	 * The BKS might be reacquired before we have dropped
+	 * PREEMPT_ACTIVE, which could trigger a second
+	 * cond_resched() call.
+	 */
+	if (unlikely(preempt_count()))
+		return;
 	do {
 		add_preempt_count(PREEMPT_ACTIVE);
 		schedule();