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| author | Andrew Morton <akpm@linux-foundation.org> | 2009-09-19 20:55:44 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-09-20 20:00:32 +0200 |
| commit | 89f19f04dc72363d912fd007a399cb10310eff6e (patch) | |
| tree | daa64e5de98a668eed4a2ceeb6ca95c478be4053 /kernel/trace | |
| parent | sched: Re-add lost cpu_allowed check to sched_fair.c::select_task_rq_fair() (diff) | |
| download | linux-89f19f04dc72363d912fd007a399cb10310eff6e.tar.xz linux-89f19f04dc72363d912fd007a399cb10310eff6e.zip | |
sched: Fix raciness in runqueue_is_locked()
runqueue_is_locked() is unavoidably racy due to a poor interface design.
It does
cpu = get_cpu()
ret = some_perpcu_thing(cpu);
put_cpu(cpu);
return ret;
Its return value is unreliable.
Fix.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <200909191855.n8JItiko022148@imap1.linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index fd52a19dd172..420232a1fbba 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -275,12 +275,18 @@ static DEFINE_SPINLOCK(tracing_start_lock); */ void trace_wake_up(void) { + int cpu; + + if (trace_flags & TRACE_ITER_BLOCK) + return; /* * The runqueue_is_locked() can fail, but this is the best we * have for now: */ - if (!(trace_flags & TRACE_ITER_BLOCK) && !runqueue_is_locked()) + cpu = get_cpu(); + if (!runqueue_is_locked(cpu)) wake_up(&trace_wait); + put_cpu(); } static int __init set_buf_size(char *str) |