Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755662Ab1DDUm4 (ORCPT ); Mon, 4 Apr 2011 16:42:56 -0400 Received: from mail-yw0-f46.google.com ([209.85.213.46]:61805 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755640Ab1DDUmz convert rfc822-to-8bit (ORCPT ); Mon, 4 Apr 2011 16:42:55 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=pOqptJLokh2JFMN6l+tpGq4oTsXZ0HND3lDrjZ0WhEU3NNUu2YsBjdMRB57zHT/r3h CclSkiOVDfbv6DxYaHAe1BAEJjbvDojgYBtA3IYeuxqyZYvHX3LY4t/KFwUk08Rj69xy UETD9PCjSN5OePy9TOxq/U+vicCgz5z3cGaZo= MIME-Version: 1.0 In-Reply-To: References: <20110404194230.GA8785@sucs.org> Date: Tue, 5 Apr 2011 00:42:54 +0400 Message-ID: Subject: Re: [REGRESSION] 2.6.39-rc1: f23eb2b breaks console output From: Alexander Beregalov To: Linus Torvalds Cc: Sitsofe Wheeler , Linux Kernel Mailing List , Greg KH , Alan Cox Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1707 Lines: 39 On 4 April 2011 23:59, Linus Torvalds wrote: > On Mon, Apr 4, 2011 at 12:42 PM, Sitsofe Wheeler wrote: >> On Mon, Apr 04, 2011 at 11:15:10PM +0400, Alexander Beregalov wrote: >>> >>> commit f23eb2b2b28547fc70df82dd5049eb39bec5ba12 tty: stop using >>> "delayed_work" in the tty layer >>> breaks console output for me. >> >> Same here - doing a dmesg in an xterm makes the machine hang for about >> 10 seconds and latencytop whinges that a raw SCSI command took 4000ms to >> complete (uniprocessor x86 EeePC 900). >> >> Additionally, you won't see this problem if you have CONFIG_PREEMPT set >> but as my config has CONFIG_PREEMPT_VOLUNTARY=y I do see this problem. >> Reverting f23eb2b2b28547fc70df82dd5049eb39bec5ba12 fixed the problem for >> me too. > > Does this patch make a difference? Yes, it works on top of 2.6.39-rc1-00184-g78fca1b9 Thanks > > The tty ldisc flushing code had this crazy "reflush if we're full" > logic, which was apparently hiding a problem in N_TTY handling where > it wouldn't wake things up when the receive-room was opened up again. > > When I made it not do timers, the "reflush" logic basically made for > an infinite loop (before, it used to instead basically poll for the > event on each timer tick instead). > > The attached patch removes the reflush logic, and makes N_TTY instead > wake up the work when opening up the receive buffer again. > >               Linus > -- 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/