From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH] atm: clip timer race Date: Thu, 13 Apr 2006 10:26:30 -0700 Message-ID: <20060413102630.7748f7b3@localhost.localdomain> References: <20060412105545.3b089dd8@localhost.localdomain> <20060412124533.14e0c4ff@localhost.localdomain> <20060412200015.GA19878@gondor.apana.org.au> <20060412131527.71f42d58@localhost.localdomain> <20060412202551.GA20085@gondor.apana.org.au> <20060412145254.4dd21be6@localhost.localdomain> <20060412154214.1dd4117d@localhost.localdomain> <20060413124534.GA25333@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, chas@cmf.nrl.navy.mil, linux-atm-general@lists.sourceforge.net, netdev@vger.kernel.org Return-path: Received: from smtp.osdl.org ([65.172.181.4]:21136 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S932134AbWDMR1h (ORCPT ); Thu, 13 Apr 2006 13:27:37 -0400 To: Herbert Xu In-Reply-To: <20060413124534.GA25333@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, 13 Apr 2006 22:45:34 +1000 Herbert Xu wrote: > On Wed, Apr 12, 2006 at 03:42:14PM -0700, Stephen Hemminger wrote: > > By inspection, the clip idle timer code is racy on SMP. > > Here is a safe version of timer management. > > Untested, I don't have ATM hardware. > > Good catch Stephen. > > > - if (start_timer == 0) > > - del_timer(&idle_timer); > > + del_timer_sync(&idle_timer); > > I don't think this is enough though since this timer is one of those > self-rescheduling timers. You need to provide some sort of a flag > for it to stop scheduling itself and synchronise it properly. Arp and neighbor table have the same rescheduling bug. > Of course this is an existing bug but we might as well squash it > before we forget about it. > > Cheers,