Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759625AbaGDBA7 (ORCPT ); Thu, 3 Jul 2014 21:00:59 -0400 Received: from mail4.hitachi.co.jp ([133.145.228.5]:55857 "EHLO mail4.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755088AbaGDBA6 (ORCPT ); Thu, 3 Jul 2014 21:00:58 -0400 Message-ID: <53B5FCC3.8010303@hitachi.com> Date: Fri, 04 Jul 2014 10:00:51 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Namhyung Kim Cc: Oleg Nesterov , Steven Rostedt , Srikar Dronamraju , Tom Zanussi , "zhangwei(Jovi)" , linux-kernel@vger.kernel.org, "yrl.pp-manager.tt@hitachi.com" Subject: Re: probe_event_disable()->synchronize_sched() References: <20140627170116.GA18298@redhat.com> <20140627170136.GA18319@redhat.com> <87k37z54lu.fsf@sejong.aot.lge.com> <20140630184828.GA24594@redhat.com> <20140701193147.GA32492@redhat.com> <53B4EE21.2040203@hitachi.com> <87lhsa51kg.fsf@sejong.aot.lge.com> In-Reply-To: <87lhsa51kg.fsf@sejong.aot.lge.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2014/07/03 16:44), Namhyung Kim wrote: > Hi Masami, > > On Thu, 03 Jul 2014 14:46:09 +0900, Masami Hiramatsu wrote: >> One possible scenario is here; someone disables an event and tries to remove >> it (both will be done by different syscalls). If we don't synchronize >> the first disabling, the event flag set disabled, but the event itself >> is not disabled. Thus event handler is still possible to be running >> somewhere when it is removed. > > But, IIUC both of disable and remove path are protected by event_mutex. > So one cannot see the case of disabled event flag but enabled event, no? No, the flag is not protect the trace event handler itself. I meant that running handlers and the flag was not synchronized. Thank you, -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com -- 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/