From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750798AbWDVBDX (ORCPT ); Fri, 21 Apr 2006 21:03:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750826AbWDVBDX (ORCPT ); Fri, 21 Apr 2006 21:03:23 -0400 Received: from e36.co.us.ibm.com ([32.97.110.154]:47032 "EHLO e36.co.us.ibm.com") by vger.kernel.org with ESMTP id S1750798AbWDVBDW (ORCPT ); Fri, 21 Apr 2006 21:03:22 -0400 Date: Fri, 21 Apr 2006 20:03:21 -0500 To: utz.bacher@de.ibm.com, Arnd Bergmann , Maxim Shchetynin , linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2]: Spider ethernet driver -- protect chain head Message-ID: <20060422010321.GO7242@austin.ibm.com> References: <20060421232942.GG7242@austin.ibm.com> <20060421234551.GI7242@austin.ibm.com> <20060422001140.GA12826@gate.ebshome.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060422001140.GA12826@gate.ebshome.net> User-Agent: Mutt/1.5.9i From: linas@austin.ibm.com (Linas Vepstas) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 21, 2006 at 05:11:40PM -0700, Eugene Surovegin wrote: > On Fri, Apr 21, 2006 at 06:45:51PM -0500, Linas Vepstas wrote: > > Prevent a potential race. If two threads are both calling > > the transmit routine, both can potentially try to grab the > > same dma descriptor. Serialize access to the head of the > > tx ring with spinlocks. > > Two threads cannot be in spider_net_xmit() simultaneosuly because > hard_start_xmit entry point is already protected by net_device > xmit_lock, see Documentation/net/netdevices.txt Ahh, thank you. I was wondering why I never semmed to see this this happen in "real life". --linas