Re: [RFC v2 5/7] perf: add a pmu capability for "exclusive" events

[Alexander Shishkin]

Peter Zijlstra <peterz@xxxxxxxxxxxxx> writes:

> On Wed, Jun 11, 2014 at 06:41:48PM +0300, Alexander Shishkin wrote:
>> +static bool exclusive_event_ok(struct perf_event *event,
>> +			      struct perf_event_context *ctx)
>> +{
>> +	struct perf_event *iter_event;
>> +
>> +	if (!(event->pmu->capabilities & PERF_PMU_CAP_EXCLUSIVE))
>> +		return true;
>> +
>> +	list_for_each_entry(iter_event, &ctx->event_list, event_entry) {
>> +		if (exclusive_event_match(iter_event, event))
>> +			return false;
>> +	}
>
> This list iteration needs either rcu or ctx->lock or ctx->mutex, and the
> two callsites below don't have either afaict.

True, this needs to be done before perf_install_in_context() under the
same ctx->mutex. Thanks!

Regards,
--
Alex
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