Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755691Ab0K2SQ3 (ORCPT ); Mon, 29 Nov 2010 13:16:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51372 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755357Ab0K2SQ2 (ORCPT ); Mon, 29 Nov 2010 13:16:28 -0500 Date: Mon, 29 Nov 2010 19:08:54 +0100 From: Oleg Nesterov To: Michael Holzheu Cc: Shailabh Nagar , Andrew Morton , Peter Zijlstra , John stultz , Thomas Gleixner , Balbir Singh , Martin Schwidefsky , Heiko Carstens , Roland McGrath , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [patch 4/4] taskstats: Export "cdata_acct" with taskstats Message-ID: <20101129180854.GA21217@redhat.com> References: <20101119201108.269346583@linux.vnet.ibm.com> <20101119201144.871656307@linux.vnet.ibm.com> <20101125132639.GB25836@redhat.com> <1290705675.1941.73.camel@holzheu-laptop> <20101129164329.GA16648@redhat.com> <1291049917.1935.14.camel@holzheu-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1291049917.1935.14.camel@holzheu-laptop> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1129 Lines: 31 On 11/29, Michael Holzheu wrote: > > Hello Oleg, > > On Mon, 2010-11-29 at 17:43 +0100, Oleg Nesterov wrote: > > > I just did it like it is done in e.g. fs/proc/base.c (proc_pid_limits). > > > Can we remove the locking there, too? > > > > We can certainly remove more siglock's which were previously > > needed to access ->signal. > > > > This particular one is just wrong. We need task_lock(group_leader) > > to read signal->rlim atomically. However, it is not trivial to do > > this correctly. Probably we should ignore this minor problem. > > > > In any case, this ->siglock buys nothing today. > > But at least to get the two values cutime and cstime consistent we need > the siglock? There could be a parallel update for > tsk->signal->cutime/cstime, while the taskstats are created, no? I guess you mean 4/4 you sent. Probably you are right, I'll try to look tomorrow. Oleg. -- 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/