Messages in this thread | | | Date | Wed, 6 Jan 2016 13:56:56 -0500 | Subject | Re: [tip:perf/core] perf: Fix race in perf_event_exec() | From | Eric Dumazet <> |
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On Wed, Jan 6, 2016 at 1:46 PM, tip-bot for Peter Zijlstra <tipbot@zytor.com> wrote:
> > This is because context switches can swap the task_struct::perf_event_ctxp[] > pointer around. Therefore you have to either disable preemption when looking > at current, or hold ctx->lock. >
> > void perf_event_exec(void) > { > - struct perf_event_context *ctx; > int ctxn; > > rcu_read_lock();
Do we still need this rcu_read_lock(), if perf_event_enable_on_exec() uses local_irq_save( ?
> - for_each_task_context_nr(ctxn) { > - ctx = current->perf_event_ctxp[ctxn]; > - if (!ctx) > - continue; > - > - perf_event_enable_on_exec(ctx); > - } > + for_each_task_context_nr(ctxn) > + perf_event_enable_on_exec(ctxn); > rcu_read_unlock(); > } >
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