Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754205Ab0FGTux (ORCPT ); Mon, 7 Jun 2010 15:50:53 -0400 Received: from waste.org ([173.11.57.241]:49473 "EHLO waste.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751512Ab0FGTuw (ORCPT ); Mon, 7 Jun 2010 15:50:52 -0400 Subject: Re: [PATCH] netconsole: queue console messages to send later From: Matt Mackall To: Flavio Leitner Cc: netdev@vger.kernel.org, David Miller , Cong Wang , Jay Vosburgh , Flavio Leitner , Andy Gospodarek , Neil Horman , Jeff Moyer , Stephen Hemminger , lkml , bridge@lists.linux-foundation.org, bonding-devel@lists.sourceforge.net In-Reply-To: <1275938692-26997-1-git-send-email-fleitner@redhat.com> References: <24059.1275417767@death.nxdomain.ibm.com> <1275938692-26997-1-git-send-email-fleitner@redhat.com> Content-Type: text/plain; charset="UTF-8" Date: Mon, 07 Jun 2010 14:50:48 -0500 Message-ID: <1275940248.26597.70.camel@calx> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1235 Lines: 29 On Mon, 2010-06-07 at 16:24 -0300, Flavio Leitner wrote: > There are some networking drivers that hold a lock in the > transmit path. Therefore, if a console message is printed > after that, netconsole will push it through the transmit path, > resulting in a deadlock. This is an ongoing pain we've known about since before introducing the netpoll code to the tree. My take has always been that any form of queueing is contrary to the goal of netpoll: timely delivery of messages even during machine-killing situations like oopses. There may never be a second chance to deliver the message as the machine may be locked solid. And there may be no other way to get the message out of the box in such situations. Adding queueing is a throwing-the-baby-out-with-the-bathwater fix. I think Dave agrees with me here, and I believe he's said in the past that drivers trying to print messages in such contexts should be considered buggy. -- Mathematics is the supreme nostalgia of our time. -- 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/