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perf: Avoid race between cpu hotplug and installing event

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perf_event_open() requires the cpu on which to install event is online,
but the cpu can go offline after perf_event_open checks that. Add a
get_online_cpus()/put_online_cpus() pair to avoid the race.

Signed-off-by: Zheng Yan <zheng.z.yan@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1339741902-8449-3-git-send-email-zheng.z.yan@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Yan, Zheng 2012-06-15 14:31:31 +08:00 committed by Ingo Molnar
parent 4b4969b144
commit fbfc623f82
1 changed files with 5 additions and 0 deletions
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5
kernel/events/core.c
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@ -6252,6 +6252,8 @@ SYSCALL_DEFINE5(perf_event_open,
}
}
get_online_cpus();
event = perf_event_alloc(&attr, cpu, task, group_leader, NULL,
NULL, NULL);
if (IS_ERR(event)) {
@ -6391,6 +6393,8 @@ SYSCALL_DEFINE5(perf_event_open,
perf_unpin_context(ctx);
mutex_unlock(&ctx->mutex);
put_online_cpus();
event->owner = current;
mutex_lock(&current->perf_event_mutex);
@ -6419,6 +6423,7 @@ err_context:
err_alloc:
free_event(event);
err_task:
put_online_cpus();
if (task)
put_task_struct(task);
err_group_fd: