From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755518Ab2IXMyv (ORCPT ); Mon, 24 Sep 2012 08:54:51 -0400 Received: from mail-oa0-f46.google.com ([209.85.219.46]:33227 "EHLO mail-oa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751997Ab2IXMys (ORCPT ); Mon, 24 Sep 2012 08:54:48 -0400 MIME-Version: 1.0 X-Originating-IP: [2001:998:22:0:c685:8ff:fe10:f3d8] In-Reply-To: <1348489478.11847.55.camel@twins> References: <1347923013-4253-1-git-send-email-daniel.vetter@ffwll.ch> <1347923013-4253-2-git-send-email-daniel.vetter@ffwll.ch> <1348489027.11847.53.camel@twins> <1348489478.11847.55.camel@twins> Date: Mon, 24 Sep 2012 14:54:47 +0200 Message-ID: Subject: Re: [PATCH 2/2] [RESEND] console: implement lockdep support for console_lock From: Daniel Vetter To: Peter Zijlstra Cc: LKML , DRI Development , Dave Airlie , Thomas Gleixner , Alan Cox Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 24, 2012 at 2:24 PM, Peter Zijlstra wrote: > On Mon, 2012-09-24 at 14:17 +0200, Peter Zijlstra wrote: >> On Tue, 2012-09-18 at 01:03 +0200, Daniel Vetter wrote: >> > - In the printk code there's a special trylock, only used to kick off >> > the logbuffer printk'ing in console_unlock. But all that happens >> > while lockdep is disable (since printk does a few other evil >> > tricks). So no issue there, either. >> >> Not particularly evil, just plain broken. >> >> See this series: >> >> http://marc.info/?l=linux-kernel&m=132446644123326&w=2 >> >> In particular see patches 1-4. The problem with lockdep is that lockdep >> uses printk and printk's recursion stuff is utterly broken. >> >> Console drivers being on crack simply doesn't help :-) Note that I would >> never recommend drm/ksm to anybody who really cares about their console >> output. I've read through the patches and I'm hoping you don't volunteer me to pick these up ... ;-) But there doesn't seem to be anything that would get worse through this lockdep annotation patch, right? > Also, don't cross-post with a subscribe only list. Sorry, forgot about this, I'll try to fix this - we really need an intel-gfx that's open to people not subscribed to it. Thanks, Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch