From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756821Ab0FCRz2 (ORCPT ); Thu, 3 Jun 2010 13:55:28 -0400 Received: from hera.kernel.org ([140.211.167.34]:45916 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752931Ab0FCRzX (ORCPT ); Thu, 3 Jun 2010 13:55:23 -0400 Date: Thu, 3 Jun 2010 17:54:48 GMT From: tip-bot for Peter Zijlstra Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, fweisbec@gmail.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, fweisbec@gmail.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <1275557609.27810.35218.camel@twins> References: <1275557609.27810.35218.camel@twins> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] perf: Fix crash in swevents Message-ID: Git-Commit-ID: c6df8d5ab87a246942d138321e1721edbb69f6e1 X-Mailer: tip-git-log-daemon 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]); Thu, 03 Jun 2010 17:54:50 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: c6df8d5ab87a246942d138321e1721edbb69f6e1 Gitweb: http://git.kernel.org/tip/c6df8d5ab87a246942d138321e1721edbb69f6e1 Author: Peter Zijlstra AuthorDate: Thu, 3 Jun 2010 11:21:20 +0200 Committer: Ingo Molnar CommitDate: Thu, 3 Jun 2010 17:03:08 +0200 perf: Fix crash in swevents Frederic reported that because swevents handling doesn't disable IRQs anymore, we can get a recursion of perf_adjust_period(), once from overflow handling and once from the tick. If both call ->disable, we get a double hlist_del_rcu() and trigger a LIST_POISON2 dereference. Since we don't actually need to stop/start a swevent to re-programm the hardware (lack of hardware to program), simply nop out these callbacks for the swevent pmu. Reported-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra LKML-Reference: <1275557609.27810.35218.camel@twins> Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 24 +++++++++++++++--------- 1 files changed, 15 insertions(+), 9 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 858f56f..31d6afe 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -4055,13 +4055,6 @@ static void perf_swevent_overflow(struct perf_event *event, u64 overflow, } } -static void perf_swevent_unthrottle(struct perf_event *event) -{ - /* - * Nothing to do, we already reset hwc->interrupts. - */ -} - static void perf_swevent_add(struct perf_event *event, u64 nr, int nmi, struct perf_sample_data *data, struct pt_regs *regs) @@ -4276,11 +4269,22 @@ static void perf_swevent_disable(struct perf_event *event) hlist_del_rcu(&event->hlist_entry); } +static void perf_swevent_void(struct perf_event *event) +{ +} + +static int perf_swevent_int(struct perf_event *event) +{ + return 0; +} + static const struct pmu perf_ops_generic = { .enable = perf_swevent_enable, .disable = perf_swevent_disable, + .start = perf_swevent_int, + .stop = perf_swevent_void, .read = perf_swevent_read, - .unthrottle = perf_swevent_unthrottle, + .unthrottle = perf_swevent_void, /* hwc->interrupts already reset */ }; /* @@ -4561,8 +4565,10 @@ static int swevent_hlist_get(struct perf_event *event) static const struct pmu perf_ops_tracepoint = { .enable = perf_trace_enable, .disable = perf_trace_disable, + .start = perf_swevent_int, + .stop = perf_swevent_void, .read = perf_swevent_read, - .unthrottle = perf_swevent_unthrottle, + .unthrottle = perf_swevent_void, }; static int perf_tp_filter_match(struct perf_event *event,