From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753132Ab1ASSaV (ORCPT ); Wed, 19 Jan 2011 13:30:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52496 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752356Ab1ASSaT (ORCPT ); Wed, 19 Jan 2011 13:30:19 -0500 Date: Wed, 19 Jan 2011 19:22:28 +0100 From: Oleg Nesterov To: Alan Stern , Arnaldo Carvalho de Melo , Frederic Weisbecker , Ingo Molnar , Paul Mackerras , Peter Zijlstra , Prasad , Roland McGrath Cc: linux-kernel@vger.kernel.org Subject: [PATCH 2/2] perf: fix perf_event_init_task()/perf_event_free_task() interaction Message-ID: <20110119182228.GC12183@redhat.com> References: <20101108145647.GA3426@redhat.com> <20101108145725.GA3434@redhat.com> <20110119182141.GA12183@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110119182141.GA12183@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org perf_event_init_task() should clear child->perf_event_ctxp[] before anything else. Otherwise, if perf_event_init_context(perf_hw_context) fails, perf_event_free_task() can free perf_event_ctxp[perf_sw_context] copied from parent->perf_event_ctxp[] by dup_task_struct(). Also move the initialization of perf_event_mutex and perf_event_list from perf_event_init_context() to perf_event_init_context(). Signed-off-by: Oleg Nesterov --- kernel/perf_event.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) --- git/kernel/perf_event.c~4_perf_event_init_task 2011-01-19 17:41:16.000000000 +0100 +++ git/kernel/perf_event.c 2011-01-19 18:49:23.000000000 +0100 @@ -6446,11 +6446,6 @@ int perf_event_init_context(struct task_ unsigned long flags; int ret = 0; - child->perf_event_ctxp[ctxn] = NULL; - - mutex_init(&child->perf_event_mutex); - INIT_LIST_HEAD(&child->perf_event_list); - if (likely(!parent->perf_event_ctxp[ctxn])) return 0; @@ -6540,6 +6535,10 @@ int perf_event_init_task(struct task_str { int ctxn, ret; + memset(child->perf_event_ctxp, 0, sizeof(child->perf_event_ctxp)); + mutex_init(&child->perf_event_mutex); + INIT_LIST_HEAD(&child->perf_event_list); + for_each_task_context_nr(ctxn) { ret = perf_event_init_context(child, ctxn); if (ret)