From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753794Ab1LNHBI (ORCPT ); Wed, 14 Dec 2011 02:01:08 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:47015 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753617Ab1LNHBF (ORCPT ); Wed, 14 Dec 2011 02:01:05 -0500 Date: Wed, 14 Dec 2011 07:59:10 +0100 From: Ingo Molnar To: Peter Zijlstra Cc: Greg KH , "Theodore Ts'o" , Linus Torvalds , Alan Cox , linux-kernel Subject: Re: printk() vs tty_io Message-ID: <20111214065910.GA25775@elte.hu> References: <1323804803.9082.40.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1323804803.9082.40.camel@twins> User-Agent: Mutt/1.5.21 (2010-09-15) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes 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 * Peter Zijlstra wrote: > Hi tty folks, > > I've been poking at reducing the constraints on printk(), like make it > work under rq->lock etc.. > > Aside from a fwd port of the patch that abuses the > console_sem.lock: https://lkml.org/lkml/2011/6/9/298 and a few > other not so very pretty patches, I ran into the following > lockdep splat (using a not so very pretty lockdep > early_printk() patch): btw., would be nice to also somehow realeasify those debug hacks to preserve them for eternity - doing all lockdep output as earlyprintk while keeping printks working is a great way to debug printk() itself. Those printk lockups also took a *lot* of time for me to bisect. Thanks, Ingo