From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754974AbbIHORW (ORCPT ); Tue, 8 Sep 2015 10:17:22 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:41361 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754346AbbIHORV (ORCPT ); Tue, 8 Sep 2015 10:17:21 -0400 Message-ID: <55EEEDEB.3080508@oracle.com> Date: Tue, 08 Sep 2015 10:17:15 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Steven Rostedt CC: Minfei Huang , mingo@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ftrace: allow dumping traces without tracking trace started cpus References: <1441385156-27279-1-git-send-email-sasha.levin@oracle.com> <20150906092016.GA20381@dhcp-128-25.nay.redhat.com> <55EC4DD7.80208@oracle.com> <20150908101344.09656618@gandalf.local.home> In-Reply-To: <20150908101344.09656618@gandalf.local.home> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/08/2015 10:13 AM, Steven Rostedt wrote: > On Sun, 06 Sep 2015 10:29:43 -0400 > Sasha Levin wrote: > > >>> So it is safe to call the function cpumask_test_cpu without doing >>> checking. >> >> Can you point me to exactly where trace_init_global_iter() initializes >> iter->started? > > Wouldn't the better solution be to initialize it in that function, > instead of checking if it is NULL? I think that's the true fix. > "started" should not be ignored. Yes, I agree that it would be nicer if we init it rather than ignore it, but I wanted to avoid trying to do an extra allocation on this path since it usually happens when the system oopsed, so allocations might be reliable and we want to get the ftrace buffer out as reliably as we can. Thanks, Sasha