From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756611Ab1CWVTJ (ORCPT ); Wed, 23 Mar 2011 17:19:09 -0400 Received: from hera.kernel.org ([140.211.167.34]:35790 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756190Ab1CWVTH (ORCPT ); Wed, 23 Mar 2011 17:19:07 -0400 Date: Wed, 23 Mar 2011 21:18:45 GMT From: tip-bot for Stephane Eranian Cc: linux-kernel@vger.kernel.org, eranian@google.com, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, eranian@google.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <20110323150306.GA1580@quad> References: <20110323150306.GA1580@quad> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] perf_events: Fix stale ->cgrp pointer in update_cgrp_time_from_cpuctx() Message-ID: Git-Commit-ID: 68cacd29167b1926d237bd1b153aa2a990201729 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Wed, 23 Mar 2011 21:18:45 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 68cacd29167b1926d237bd1b153aa2a990201729 Gitweb: http://git.kernel.org/tip/68cacd29167b1926d237bd1b153aa2a990201729 Author: Stephane Eranian AuthorDate: Wed, 23 Mar 2011 16:03:06 +0100 Committer: Ingo Molnar CommitDate: Wed, 23 Mar 2011 16:07:22 +0100 perf_events: Fix stale ->cgrp pointer in update_cgrp_time_from_cpuctx() This patch solves a stale pointer problem in update_cgrp_time_from_cpuctx(). The cpuctx->cgrp was not cleared on all possible event exit paths, including: close() perf_release() perf_release_kernel() list_del_event() This patch fixes list_del_event() to clear cpuctx->cgrp when there are no cgroup events left in the context. [ This second version makes the code compile when CONFIG_CGROUP_PERF is not enabled. We unconditionally define perf_cpu_context->cgrp. ] Signed-off-by: Stephane Eranian Cc: peterz@infradead.org Cc: perfmon2-devel@lists.sf.net Cc: paulus@samba.org Cc: davem@davemloft.net LKML-Reference: <20110323150306.GA1580@quad> Signed-off-by: Ingo Molnar --- include/linux/perf_event.h | 2 -- kernel/perf_event.c | 12 +++++++++++- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index f495c01..311b4dc 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -938,9 +938,7 @@ struct perf_cpu_context { struct list_head rotation_list; int jiffies_interval; struct pmu *active_pmu; -#ifdef CONFIG_CGROUP_PERF struct perf_cgroup *cgrp; -#endif }; struct perf_output_handle { diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 3472bb1..0c71422 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -941,6 +941,7 @@ static void perf_group_attach(struct perf_event *event) static void list_del_event(struct perf_event *event, struct perf_event_context *ctx) { + struct perf_cpu_context *cpuctx; /* * We can have double detach due to exit/hot-unplug + close. */ @@ -949,8 +950,17 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) event->attach_state &= ~PERF_ATTACH_CONTEXT; - if (is_cgroup_event(event)) + if (is_cgroup_event(event)) { ctx->nr_cgroups--; + cpuctx = __get_cpu_context(ctx); + /* + * if there are no more cgroup events + * then cler cgrp to avoid stale pointer + * in update_cgrp_time_from_cpuctx() + */ + if (!ctx->nr_cgroups) + cpuctx->cgrp = NULL; + } ctx->nr_events--; if (event->attr.inherit_stat)