From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751556AbZKZRwL (ORCPT ); Thu, 26 Nov 2009 12:52:11 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751009AbZKZRwK (ORCPT ); Thu, 26 Nov 2009 12:52:10 -0500 Received: from hera.kernel.org ([140.211.167.34]:46840 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750846AbZKZRwJ (ORCPT ); Thu, 26 Nov 2009 12:52:09 -0500 Date: Thu, 26 Nov 2009 17:51:35 GMT From: tip-bot for Stephane Eranian Cc: linux-kernel@vger.kernel.org, paulus@samba.org, eranian@google.com, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, eranian@google.com, paulus@samba.org, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <4b0eb9ce.0508d00a.573b.ffffeab6@mx.google.com> References: <4b0eb9ce.0508d00a.573b.ffffeab6@mx.google.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] perf_events: Fix read() bogus counts when in error state Message-ID: Git-Commit-ID: b2e74a265ded1a185f762ebaab967e9e0d008dd8 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: b2e74a265ded1a185f762ebaab967e9e0d008dd8 Gitweb: http://git.kernel.org/tip/b2e74a265ded1a185f762ebaab967e9e0d008dd8 Author: Stephane Eranian AuthorDate: Thu, 26 Nov 2009 09:24:30 -0800 Committer: Ingo Molnar CommitDate: Thu, 26 Nov 2009 18:49:59 +0100 perf_events: Fix read() bogus counts when in error state When a pinned group cannot be scheduled it goes into error state. Normally a group cannot go out of error state without being explicitly re-enabled or disabled. There was a bug in per-thread mode, whereby upon termination of the thread, the group would transition from error to off leading to bogus counts and timing information returned by read(). Fix it by clearing the error state. Signed-off-by: Stephane Eranian Acked-by: Peter Zijlstra Cc: Paul Mackerras Cc: perfmon2-devel@lists.sourceforge.net LKML-Reference: <4b0eb9ce.0508d00a.573b.ffffeab6@mx.google.com> Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 11 ++++++++++- 1 files changed, 10 insertions(+), 1 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index f8c7939..0b9ca2d 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -338,7 +338,16 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) event->group_leader->nr_siblings--; update_event_times(event); - event->state = PERF_EVENT_STATE_OFF; + + /* + * If event was in error state, then keep it + * that way, otherwise bogus counts will be + * returned on read(). The only way to get out + * of error state is by explicit re-enabling + * of the event + */ + if (event->state > PERF_EVENT_STATE_OFF) + event->state = PERF_EVENT_STATE_OFF; /* * If this was a group event with sibling events then