From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757167Ab1CaMmS (ORCPT ); Thu, 31 Mar 2011 08:42:18 -0400 Received: from hera.kernel.org ([140.211.167.34]:56825 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753008Ab1CaMmQ (ORCPT ); Thu, 31 Mar 2011 08:42:16 -0400 Date: Thu, 31 Mar 2011 12:41:57 GMT From: tip-bot for Peter Zijlstra Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, jolsa@redhat.com, tglx@linutronix.de, oleg@redhat.com, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, jolsa@redhat.com, tglx@linutronix.de, oleg@redhat.com, mingo@elte.hu In-Reply-To: <1301520405.4859.213.camel@twins> References: <1301520405.4859.213.camel@twins> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] perf: Fix task context scheduling Message-ID: Git-Commit-ID: ab711fe08297de1485fff0a366e6db8828cafd6a 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]); Thu, 31 Mar 2011 12:41:57 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: ab711fe08297de1485fff0a366e6db8828cafd6a Gitweb: http://git.kernel.org/tip/ab711fe08297de1485fff0a366e6db8828cafd6a Author: Peter Zijlstra AuthorDate: Thu, 31 Mar 2011 10:29:26 +0200 Committer: Ingo Molnar CommitDate: Thu, 31 Mar 2011 13:02:55 +0200 perf: Fix task context scheduling Jiri reported: | | - once an event is created by sys_perf_event_open, task context | is created and it stays even if the event is closed, until the | task is finished ... thats what I see in code and I assume it's | correct | | - when the task opens event, perf_sched_events jump label is | incremented and following callbacks are started from scheduler | | __perf_event_task_sched_in | __perf_event_task_sched_out | | These callback *in/out set/unset cpuctx->task_ctx value to the | task context. | | - close is called on event on CPU 0: | - the task is scheduled on CPU 0 | - __perf_event_task_sched_in is called | - cpuctx->task_ctx is set | - perf_sched_events jump label is decremented and == 0 | - __perf_event_task_sched_out is not called | - cpuctx->task_ctx on CPU 0 stays set | | - exit is called on CPU 1: | - the task is scheduled on CPU 1 | - perf_event_exit_task is called | - task_ctx_sched_out unsets cpuctx->task_ctx on CPU 1 | - put_ctx destroys the context | | - another call of perf_rotate_context on CPU 0 will use invalid | task_ctx pointer, and eventualy panic. | Cure this the simplest possibly way by partially reverting the jump_label optimization for the sched_out case. Reported-and-tested-by: Jiri Olsa Signed-off-by: Peter Zijlstra Cc: Oleg Nesterov Cc: # .37+ LKML-Reference: <1301520405.4859.213.camel@twins> Signed-off-by: Ingo Molnar --- include/linux/perf_event.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 311b4dc..04d75a8 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1086,7 +1086,7 @@ void perf_event_task_sched_out(struct task_struct *task, struct task_struct *nex { perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, NULL, 0); - COND_STMT(&perf_sched_events, __perf_event_task_sched_out(task, next)); + __perf_event_task_sched_out(task, next); } extern void perf_event_mmap(struct vm_area_struct *vma);