Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938225AbXHLTou (ORCPT ); Sun, 12 Aug 2007 15:44:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S937569AbXHLTol (ORCPT ); Sun, 12 Aug 2007 15:44:41 -0400 Received: from x346.tv-sign.ru ([89.108.83.215]:59339 "EHLO mail.screens.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S937364AbXHLTok (ORCPT ); Sun, 12 Aug 2007 15:44:40 -0400 Date: Sun, 12 Aug 2007 23:44:55 +0400 From: Oleg Nesterov To: Thomas Gleixner Cc: Andrew Morton , Ingo Molnar , linux-kernel@vger.kernel.org, stable@kernel.org Subject: Re: [PATCH 2/4] posix-timers: fix creation race Message-ID: <20070812194455.GA113@tv-sign.ru> References: <20070812170522.GA4299@tv-sign.ru> <1186945555.12828.89.camel@chaos> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1186945555.12828.89.camel@chaos> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1942 Lines: 50 On 08/12, Thomas Gleixner wrote: > > On Sun, 2007-08-12 at 21:05 +0400, Oleg Nesterov wrote: > > sys_timer_create() sets ->it_process and unlocks ->siglock, then checks > > tmr->it_sigev_notify to define if get_task_struct() is needed. > > > > We already passed ->it_id to the caller, another thread can delete this > > timer and free its memory in between. > > > > As a minimal fix, move this code under ->siglock, sys_timer_delete() takes > > it too before calling release_posix_timer(). A proper serialization would > > be to take ->it_lock, we add a partly initialized timer on posix_timers_id, > > not good. > > > > Signed-off-by: Oleg Nesterov > > Acked-by: Thomas Gleixner Oooh, thanks, but... > > --- t/kernel/posix-timers.c~2_CREATE 2007-08-12 17:59:17.000000000 +0400 > > +++ t/kernel/posix-timers.c 2007-08-12 18:11:33.000000000 +0400 > > @@ -547,13 +547,12 @@ sys_timer_create(const clockid_t which_c > > new_timer->it_process = process; > > list_add(&new_timer->list, > > &process->signal->posix_timers); > > - spin_unlock_irqrestore(&process->sighand->siglock, flags); > > if (new_timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) > > get_task_struct(process); > > } else { > > - spin_unlock_irqrestore(&process->sighand->siglock, flags); > > process = NULL; > > } > > + spin_unlock_irqrestore(&process->sighand->siglock, flags); i'll resend this patch tomorrow. We can't do spin_unlock_irqrestore(&process->...) if we set process = NULL above. This all needs a cleanup anyway. The PF_EXITING check and related comment are bogus. Other patches do not depend on this one. 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/