Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754163Ab0BHRRh (ORCPT ); Mon, 8 Feb 2010 12:17:37 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60210 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753791Ab0BHRRg (ORCPT ); Mon, 8 Feb 2010 12:17:36 -0500 Date: Mon, 8 Feb 2010 18:16:44 +0100 From: Oleg Nesterov To: Thomas Gleixner Cc: Tetsuo Handa , linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, linux-security-module@vger.kernel.org Subject: Re: [PATCH] Update comment on find_task_by_pid_ns Message-ID: <20100208171643.GA19230@redhat.com> References: <20091210001308.247025548@linutronix.de> <20091210004703.029784964@linutronix.de> <20091210142036.GA8226@redhat.com> <200912110008.BEJ00511.FVOJLtSMOFHOQF@I-love.SAKURA.ne.jp> <201002082130.JDC57339.OHOVJFQtFSLFMO@I-love.SAKURA.ne.jp> <20100208132101.GA7129@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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: 1060 Lines: 37 On 02/08, Thomas Gleixner wrote: > > On Mon, 8 Feb 2010, Oleg Nesterov wrote: > > > IOW, if we change copy_process() > > > > --- kernel/fork.c > > +++ kernel/fork.c > > @@ -1304,8 +1304,11 @@ static struct task_struct *copy_process( > > return p; > > > > bad_fork_free_pid: > > - if (pid != &init_struct_pid) > > + if (pid != &init_struct_pid) { > > + read_lock(&tasklist_lock); > > free_pid(pid); > > + read_unlock(&tasklist_lock); > > + } > > bad_fork_cleanup_io: > > if (p->io_context) > > exit_io_context(p); > > > > then find_task_by_pid_ns/etc could be used under tasklist safely even > > with PREEMPT_RCU. > > We try to get rid of the read_lock sites of tasklist_lock, so please > let's not think about adding more :) Yes, yes, I agree. I didn't mean this patch makes sense. 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/