From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753551Ab1KWLkG (ORCPT ); Wed, 23 Nov 2011 06:40:06 -0500 Received: from merlin.infradead.org ([205.233.59.134]:54195 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753122Ab1KWLkE convert rfc822-to-8bit (ORCPT ); Wed, 23 Nov 2011 06:40:04 -0500 Message-ID: <1322048382.14799.41.camel@twins> Subject: Re: [PATCH v2 5/5] perf: Enable applicable siblings when group leader is enable-on-exec From: Peter Zijlstra To: Deng-Cheng Zhu Cc: "Barzilay, Eyal" , "Fortuna, Zenon" , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo , "ralf@linux-mips.org" , LKML Date: Wed, 23 Nov 2011 12:39:42 +0100 In-Reply-To: <4ECC6AAC.4010504@mips.com> References: <1321932601-21128-1-git-send-email-dczhu@mips.com> ,<1321959115.5148.22.camel@twins> ,<1321969559.14799.7.camel@twins> <1321971798.14799.12.camel@twins> <4ECC6AAC.4010504@mips.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.2.1- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2011-11-23 at 11:38 +0800, Deng-Cheng Zhu wrote: > + list_for_each_entry_rcu(event, &ctx->event_list, event_entry) { > + ret = event_enable_on_exec(event, ctx); > + if (ret) > + enabled = 1; > + } > + > list_for_each_entry(event, &ctx->pinned_groups, group_entry) { > ret = event_enable_on_exec(event, ctx); > if (ret) This isn't correct either, in this case you should then remove the other two iterations of pinned/flexible group lists. Also your use of list_for_each_entry_rcu() is incorrect, either you then should also use rcu_read_lock(), or its not needed and not use the _rcu list primitive at all. Now since event_list is modified under ctx->lock, and we hold that lock no fancy stuff is needed and we can do without. --- Subject: perf: Fix enable_on_exec for sibling events From: Peter Zijlstra Date: Tue Nov 22 11:25:43 CET 2011 Deng-Cheng Zhu reported that sibling events that were created disabled with enable_on_exec would never get enabled. Iterate all events instead of the group lists. Reported-by: Deng-Cheng Zhu Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/n/tip-299rxrpmmle8hp3spyxfo202@git.kernel.org --- kernel/events/core.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) Index: linux-2.6/kernel/events/core.c =================================================================== --- linux-2.6.orig/kernel/events/core.c +++ linux-2.6/kernel/events/core.c @@ -2494,13 +2494,7 @@ static void perf_event_enable_on_exec(st raw_spin_lock(&ctx->lock); task_ctx_sched_out(ctx); - list_for_each_entry(event, &ctx->pinned_groups, group_entry) { - ret = event_enable_on_exec(event, ctx); - if (ret) - enabled = 1; - } - - list_for_each_entry(event, &ctx->flexible_groups, group_entry) { + list_for_each_entry(event, &ctx->event_list, group_entry) { ret = event_enable_on_exec(event, ctx); if (ret) enabled = 1;