Re: [PATCH 3.4 43/91] perf: Fix a race condition in perf_remove_from_context()

[Sukadev Bhattiprolu]

lizf@xxxxxxxxxx [lizf@xxxxxxxxxx] wrote:
| From: Cong Wang <cwang@xxxxxxxxxxxxxxxx>
| 
| 3.4.105-rc1 review patch.  If anyone has any objections, please let me know.
| 
<snip>
| 
| diff --git a/kernel/events/core.c b/kernel/events/core.c
| index 685ce46..c958be1 100644
| --- a/kernel/events/core.c
| +++ b/kernel/events/core.c
| @@ -1702,6 +1702,16 @@ retry:
|  	 */
|  	if (ctx->is_active) {
|  		raw_spin_unlock_irq(&ctx->lock);
| +		/*
| +		 * Reload the task pointer, it might have been changed by
| +		 * a concurrent perf_event_context_sched_out().
| +		 */
| +		task = ctx->task;
| +		/*
| +		 * Reload the task pointer, it might have been changed by
| +		 * a concurrent perf_event_context_sched_out().
| +		 */
| +		task = ctx->task;

Something wrong in the way the patch was applied ?
The lines are identical...

The original commit, 3577af70, has the change applied in two
places: perf_event_disable() and perf_remove_from_context().

|  		goto retry;
|  	}
| 
| -- 
| 1.9.1
| 
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