From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758674AbYCUQdX (ORCPT ); Fri, 21 Mar 2008 12:33:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752512AbYCUQdP (ORCPT ); Fri, 21 Mar 2008 12:33:15 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:40172 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751325AbYCUQdO (ORCPT ); Fri, 21 Mar 2008 12:33:14 -0400 Date: Fri, 21 Mar 2008 17:32:54 +0100 From: Ingo Molnar To: Jeff Garzik Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [patch] forcedeth: fix locking bug with netconsole Message-ID: <20080321163252.GA1034@elte.hu> References: <20080321155213.GA22755@elte.hu> <47E3DDD1.2010601@pobox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47E3DDD1.2010601@pobox.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Jeff Garzik wrote: > Ingo Molnar wrote: >> Subject: forcedeth: fix locking bug with netconsole >> From: Ingo Molnar >> >> while using netconsole on forcedeth, lockdep noticed the following >> locking bug: > [...] >> the fix is to disable/restore irqs instead of disable/enable. > > So we make _the_ TX fast path slower, to accomodate a path that is > rarely executed? no strong opinion but a single PCI mmio access far outweighs any flags save/restore, so i'd not fight about something like that. I've never seen flags save/restore costs show up in NMI-driven profiles that had networking load. Ingo