From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755392AbYDGUMQ (ORCPT ); Mon, 7 Apr 2008 16:12:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752167AbYDGUMD (ORCPT ); Mon, 7 Apr 2008 16:12:03 -0400 Received: from ozlabs.org ([203.10.76.45]:51203 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752046AbYDGUMB (ORCPT ); Mon, 7 Apr 2008 16:12:01 -0400 From: Rusty Russell To: virtualization@lists.linux-foundation.org Subject: Re: [PATCH] virtio: remove overzealous BUG_ON. Date: Tue, 8 Apr 2008 06:09:12 +1000 User-Agent: KMail/1.9.9 Cc: Anthony Liguori , virtualization@lists.osdl.org, Linus Torvalds , linux-kernel@vger.kernel.org References: <200804071430.28399.rusty__35361.6672721275$1207542780$gmane$org@rustcorp.com.au> <47FA26A0.3020701@codemonkey.ws> In-Reply-To: <47FA26A0.3020701@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200804080609.12891.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday 07 April 2008 23:50:24 Anthony Liguori wrote: > Rusty Russell wrote: > > The 'disable_cb' callback is designed as an optimization to tell the host > > we don't need callbacks now. As it is not reliable, the debug check is > > overzealous: it can happen on two CPUs at the same time. Document this. > > > > Even if it were reliable, the virtio_net driver doesn't disable > > callbacks on transmit so the START_USE/END_USE debugging reentrance > > protection can be easily tripped even on UP. > > > > Thanks to Balaji Rao for the bug report and testing. > > I think the printk() in start_xmit should be removed too (or at least > rate limited). Yep, please send patch. I'm about to jump on a plane, so consider this a pre-canned ack. Thanks, Rusty.