From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755296Ab0EUL3K (ORCPT ); Fri, 21 May 2010 07:29:10 -0400 Received: from hera.kernel.org ([140.211.167.34]:58537 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753490Ab0EUL3F (ORCPT ); Fri, 21 May 2010 07:29:05 -0400 Date: Fri, 21 May 2010 11:28:31 GMT From: tip-bot for Peter Zijlstra Cc: linux-kernel@vger.kernel.org, paulus@samba.org, acme@redhat.com, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, efault@gmx.de, fweisbec@gmail.com, rostedt@goodmis.org, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, acme@redhat.com, paulus@samba.org, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, efault@gmx.de, fweisbec@gmail.com, rostedt@goodmis.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <20100521090710.528215873@chello.nl> References: <20100521090710.528215873@chello.nl> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] perf: Ensure that IOC_OUTPUT isn't used to create multi-writer buffers Message-ID: Git-Commit-ID: 0f139300c9057c16b5833a4636b715b104fe0baa 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]); Fri, 21 May 2010 11:28:31 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 0f139300c9057c16b5833a4636b715b104fe0baa Gitweb: http://git.kernel.org/tip/0f139300c9057c16b5833a4636b715b104fe0baa Author: Peter Zijlstra AuthorDate: Thu, 20 May 2010 14:35:15 +0200 Committer: Ingo Molnar CommitDate: Fri, 21 May 2010 11:37:57 +0200 perf: Ensure that IOC_OUTPUT isn't used to create multi-writer buffers Since we want to ensure buffers only have a single writer, we must avoid creating one with multiple. Signed-off-by: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker Cc: Paul Mackerras Cc: Mike Galbraith Cc: Steven Rostedt LKML-Reference: <20100521090710.528215873@chello.nl> Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 19 +++++++++++++++++++ 1 files changed, 19 insertions(+), 0 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 3f2cc31..7a93252 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -4920,6 +4920,13 @@ static int perf_event_set_output(struct perf_event *event, int output_fd) int fput_needed = 0; int ret = -EINVAL; + /* + * Don't allow output of inherited per-task events. This would + * create performance issues due to cross cpu access. + */ + if (event->cpu == -1 && event->attr.inherit) + return -EINVAL; + if (!output_fd) goto set; @@ -4940,6 +4947,18 @@ static int perf_event_set_output(struct perf_event *event, int output_fd) if (event->data) goto out; + /* + * Don't allow cross-cpu buffers + */ + if (output_event->cpu != event->cpu) + goto out; + + /* + * If its not a per-cpu buffer, it must be the same task. + */ + if (output_event->cpu == -1 && output_event->ctx != event->ctx) + goto out; + atomic_long_inc(&output_file->f_count); set: