[PATCH] Conditionally check expected_preempt_count in __resched_legal()
Commit 2d7d253548
("fix cond_resched() fix")
introduced an 'expected_preempt_count' parameter to __resched_legal() to
fix a bug where it was returning a false negative when called from
cond_resched_lock() and preemption was enabled.
Unfortunately this broke things for when preemption is disabled.
preempt_count() will always return zero, thus failing the check against any
value of expected_preempt_count not equal to zero. cond_resched_lock() for
example, passes an expected_preempt_count value of 1.
So fix the fix for the cond_resched() fix by skipping the check of
preempt_count() against expected_preempt_count when preemption is disabled.
Credit should go to Sunil Mushran for spotting the bug during testing.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
parent
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@ -4619,8 +4619,10 @@ asmlinkage long sys_sched_yield(void)
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static inline int __resched_legal(int expected_preempt_count)
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static inline int __resched_legal(int expected_preempt_count)
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{
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{
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#ifdef CONFIG_PREEMPT
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if (unlikely(preempt_count() != expected_preempt_count))
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if (unlikely(preempt_count() != expected_preempt_count))
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return 0;
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return 0;
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#endif
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if (unlikely(system_state != SYSTEM_RUNNING))
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if (unlikely(system_state != SYSTEM_RUNNING))
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return 0;
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return 0;
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return 1;
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return 1;
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