Commit 716a4234 authored Jul 24, 2009 by Frederic Weisbecker Committed by Ingo Molnar Aug 02, 2009

sched: Fix cond_resched_lock() in !CONFIG_PREEMPT



The might_sleep() test inside cond_resched_lock() assumes the
spinlock is held and then preemption is disabled. This is true
with CONFIG_PREEMPT but the preempt_count() doesn't change
otherwise.

Check by starting from the appropriate preempt offset depending
on the config.

Reported-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1248458723-12146-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent a004cd42

include/linux/sched.h

+7 −1

Original line number	Diff line number	Diff line
		@@ -2293,8 +2293,14 @@ extern int _cond_resched(void);

		extern int __cond_resched_lock(spinlock_t *lock);

		#ifdef CONFIG_PREEMPT
		#define PREEMPT_LOCK_OFFSET PREEMPT_OFFSET
		#else
		#define PREEMPT_LOCK_OFFSET 0
		#endif

		#define cond_resched_lock(lock) ({ \
		__might_sleep(__FILE__, __LINE__, PREEMPT_OFFSET); \
		__might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET); \
		__cond_resched_lock(lock); \
		})

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