From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758450Ab0ERRRL (ORCPT ); Tue, 18 May 2010 13:17:11 -0400 Received: from hera.kernel.org ([140.211.167.34]:60706 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753350Ab0ERRRG (ORCPT ); Tue, 18 May 2010 13:17:06 -0400 Date: Tue, 18 May 2010 17:16:38 GMT From: tip-bot for Peter Zijlstra Cc: linux-kernel@vger.kernel.org, acme@redhat.com, paulus@samba.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, efault@gmx.de, fweisbec@gmail.com, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, paulus@samba.org, acme@redhat.com, linux-kernel@vger.kernel.org, fweisbec@gmail.com, a.p.zijlstra@chello.nl, efault@gmx.de, tglx@linutronix.de, mingo@elte.hu In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] perf: Disallow mmap() on per-task inherited events Message-ID: Git-Commit-ID: c7920614cebbf269a7c8397ff959a8dcf727465c 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]); Tue, 18 May 2010 17:16:38 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: c7920614cebbf269a7c8397ff959a8dcf727465c Gitweb: http://git.kernel.org/tip/c7920614cebbf269a7c8397ff959a8dcf727465c Author: Peter Zijlstra AuthorDate: Tue, 18 May 2010 10:33:24 +0200 Committer: Ingo Molnar CommitDate: Tue, 18 May 2010 18:35:48 +0200 perf: Disallow mmap() on per-task inherited events Since we now have working per-task-per-cpu events for a while, disallow mmap() on per-task inherited events. Those things were a performance problem anyway, and doing away with it allows us to optimize the buffer somewhat by assuming there is only a single writer. Signed-off-by: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker LKML-Reference: Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 6ae6218..ff5d430 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -2593,6 +2593,14 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) long user_extra, extra; int ret = 0; + /* + * Don't allow mmap() of inherited per-task counters. This would + * create a performance issue due to all children writing to the + * same buffer. + */ + if (event->cpu == -1 && event->attr.inherit) + return -EINVAL; + if (!(vma->vm_flags & VM_SHARED)) return -EINVAL;