From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754974Ab1KCHlR (ORCPT ); Thu, 3 Nov 2011 03:41:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:63503 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752121Ab1KCHlQ (ORCPT ); Thu, 3 Nov 2011 03:41:16 -0400 Date: Thu, 3 Nov 2011 09:41:04 +0200 From: Gleb Natapov To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo Subject: Re: [PATCH] perf: do not set task_ctx pointer in cpuctx if there is no events in the context Message-ID: <20111103074104.GG14726@redhat.com> References: <20111023171033.GI17571@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111023171033.GI17571@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ingo, Peter can you look into this please. On Sun, Oct 23, 2011 at 07:10:33PM +0200, Gleb Natapov wrote: > Do not set task_ctx pointer during sched_in if there is no > events associated with the context. Otherwise if during task > execution total number of events in the system will become zero > perf_event_context_sched_out() will not be called and cpuctx->task_ctx > will be left with a stale value. > > Signed-off-by: Gleb Natapov > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 0f85778..68b13ee 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -2172,7 +2172,8 @@ static void perf_event_context_sched_in(struct perf_event_context *ctx, > > perf_event_sched_in(cpuctx, ctx, task); > > - cpuctx->task_ctx = ctx; > + if (ctx->nr_events) > + cpuctx->task_ctx = ctx; > > perf_pmu_enable(ctx->pmu); > perf_ctx_unlock(cpuctx, ctx); > -- > Gleb. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Gleb.