Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261685AbTILFZV (ORCPT ); Fri, 12 Sep 2003 01:25:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261689AbTILFZV (ORCPT ); Fri, 12 Sep 2003 01:25:21 -0400 Received: from [63.205.85.133] ([63.205.85.133]:44275 "EHLO gaz.sfgoth.com") by vger.kernel.org with ESMTP id S261685AbTILFZQ (ORCPT ); Fri, 12 Sep 2003 01:25:16 -0400 Date: Thu, 11 Sep 2003 22:33:35 -0700 From: Mitchell Blank Jr To: Matt Mackall , linux-kernel@vger.kernel.org Cc: mc@cs.stanford.edu Subject: Re: [PATCH 2/3] netpoll: netconsole Message-ID: <20030912053335.GJ41254@gaz.sfgoth.com> References: <20030910074256.GD4489@waste.org.suse.lists.linux.kernel> <20030910082435.GG4489@waste.org> <20030910082908.GE29485@wotan.suse.de> <20030910090121.GH4489@waste.org> <20030910160002.GB84652@gaz.sfgoth.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030910160002.GB84652@gaz.sfgoth.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1297 Lines: 27 Mitchell Blank Jr wrote: > The netconsole problem is only if the net driver calls printk() with > its spinlock held (but when not called from netconsole). Then printk() > won't know that it's unsafe to re-enter the network driver. BTW, this isn't neccesarily a netconsole-only thing. For instance, has anyone ever audited all of the serial and lp drivers to make sure that nothing they call can call printk() while holding a lock? This sounds fairly serious - we could have any number of simple error cases that would cause a deadlock with the right "console=" setting. It'd be interesting if we could do something like: 1. For every function that appears as a "struct console -> write()" call, follow every possible code path and make a list of every lock that they can try to acquire exclusively. 2. Then scan the entire code base see if we ever call can printk() while holding that same lock. I'm cc:'ing the Stanford Checker team... maybe they'd be interested in adding something like this to their automated tests. -Mitch - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/