From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932748Ab3GRCUu (ORCPT ); Wed, 17 Jul 2013 22:20:50 -0400 Received: from mail7.hitachi.co.jp ([133.145.228.42]:36285 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754791Ab3GRCUt (ORCPT ); Wed, 17 Jul 2013 22:20:49 -0400 Message-ID: <51E750F4.5070200@hitachi.com> Date: Thu, 18 Jul 2013 11:20:36 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 5.2; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Oleg Nesterov Cc: Steven Rostedt , Peter Zijlstra , Frederic Weisbecker , linux-kernel@vger.kernel.org, Ingo Molnar , Arnaldo Carvalho de Melo , Andrew Morton , jovi.zhangwei@huawei.com, Jiri Olsa , Srikar Dronamraju Subject: Re: [RFC PATCH V2] tracing: Check f_dentry before accessing event_file/call in inode->i_private References: <20130705003223.GA4981@redhat.com> <20130709075519.2583.96462.stgit@mhiramat-M0-7522> <20130715181659.GA18505@redhat.com> <51E5FD33.4040604@hitachi.com> <20130717145148.GB7358@redhat.com> In-Reply-To: <20130717145148.GB7358@redhat.com> 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 (2013/07/17 23:51), Oleg Nesterov wrote: > On 07/17, Masami Hiramatsu wrote: >> >> (2013/07/16 3:16), Oleg Nesterov wrote: >>> On 07/09, Masami Hiramatsu wrote: >>>> >>>> To avoid this, when opening events/*/*/enable, we have to ensure >>>> the dentry of the file is not unlinked yet, under event_mutex >>>> is locked. >>> >>> Probably this can work, but I am starting to think that this ref >>> count becomes toooooo complex.... >> >> Oleg, I agree that is a bit complex way to fix but it can fix. >> >> However, I think we should fix bugs first, because there are bugs. >> I don't like to leave a bug in the kernel as it is, while we re- >> start discussing new approach... > > And I am trying to fix the same problems, just _I think_ there is > another and simpler approach. I see. I also just feel uncomfortable with leaving obvious bugs, like as having ants in my pants :) >> So, I'd like to suggest you getting these fixes into ftrace as >> first-aid treatment, and discuss your new series. > > Well, perhaps you are right... But this TRACE_EVENT_FL_REF_MASK code > is new too, it is not that we only need a small fixlets to finish it. Would you mean that TRACE_EVENT_FL_REF_MASK may also have some problems? > So I think that it makes sense to discuss the alternatives before we > decide what exactly we should do. Your approach is also interesting for me, indeed. However, it is so different from current one. I think you should clarify what bug you would like to solve and how. And we should clarify what ants^H^H^H^H bugs we have found in ftrace too. ;) Thank you, -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com