From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758230AbYDGNui (ORCPT ); Mon, 7 Apr 2008 09:50:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754623AbYDGNu3 (ORCPT ); Mon, 7 Apr 2008 09:50:29 -0400 Received: from py-out-1112.google.com ([64.233.166.180]:35642 "EHLO py-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752291AbYDGNu3 (ORCPT ); Mon, 7 Apr 2008 09:50:29 -0400 Message-ID: <47FA26A0.3020701@codemonkey.ws> Date: Mon, 07 Apr 2008 08:50:24 -0500 From: Anthony Liguori User-Agent: Thunderbird 2.0.0.12 (X11/20080227) MIME-Version: 1.0 Newsgroups: gmane.linux.kernel.virtualization To: Rusty Russell CC: Balaji Rao , Linus Torvalds , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH] virtio: remove overzealous BUG_ON. References: <200804071430.28399.rusty__35361.6672721275$1207542780$gmane$org@rustcorp.com.au> In-Reply-To: <200804071430.28399.rusty__35361.6672721275$1207542780$gmane$org@rustcorp.com.au> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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). Regards, Anthony Liguori