Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752807AbZIYBYi (ORCPT ); Thu, 24 Sep 2009 21:24:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751613AbZIYBYg (ORCPT ); Thu, 24 Sep 2009 21:24:36 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:63219 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751568AbZIYBYf (ORCPT ); Thu, 24 Sep 2009 21:24:35 -0400 Message-ID: <4ABC1B9E.50109@cn.fujitsu.com> Date: Fri, 25 Sep 2009 09:23:42 +0800 From: Xiao Guangrong User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Peter Zijlstra CC: Ingo Molnar , Paul Mackerras , LKML Subject: Re: [PATCH 2/2] perf_counter: optimize for perf_event_init_task() References: <4AB88F06.10900@cn.fujitsu.com> <19128.39768.149110.673711@cargo.ozlabs.ibm.com> <4AB98BB0.6020202@cn.fujitsu.com> <19129.38627.94363.857137@cargo.ozlabs.ibm.com> <4AB9D7FA.5040707@cn.fujitsu.com> <4AB9D8B1.4020000@cn.fujitsu.com> <1253695389.7695.124.camel@twins> In-Reply-To: <1253695389.7695.124.camel@twins> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1346 Lines: 43 Peter Zijlstra wrote: > On Wed, 2009-09-23 at 16:13 +0800, Xiao Guangrong wrote: >> We can traverse ctx->group_list to get all group leader, it should be safe >> since we hold ctx->mutex > > I don't think we need that WARN_ON_ONCE there. > I'll remove it Thanks, Xiao >> Signed-off-by: Xiao Guangrong >> --- >> kernel/perf_event.c | 5 ++--- >> 1 files changed, 2 insertions(+), 3 deletions(-) >> >> diff --git a/kernel/perf_event.c b/kernel/perf_event.c >> index 9ca975a..4e6e822 100644 >> --- a/kernel/perf_event.c >> +++ b/kernel/perf_event.c >> @@ -4786,9 +4786,8 @@ int perf_event_init_task(struct task_struct *child) >> * We dont have to disable NMIs - we are only looking at >> * the list, not manipulating it: >> */ >> - list_for_each_entry_rcu(event, &parent_ctx->event_list, event_entry) { >> - if (event != event->group_leader) >> - continue; >> + list_for_each_entry(event, &parent_ctx->group_list, group_entry) { >> + WARN_ON_ONCE(event != event->group_leader); >> >> if (!event->attr.inherit) { >> inherited_all = 0; > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/