Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965026AbVJ1AsP (ORCPT ); Thu, 27 Oct 2005 20:48:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965027AbVJ1AsP (ORCPT ); Thu, 27 Oct 2005 20:48:15 -0400 Received: from mail.ocs.com.au ([202.147.117.210]:11462 "EHLO mail.ocs.com.au") by vger.kernel.org with ESMTP id S965026AbVJ1AsO (ORCPT ); Thu, 27 Oct 2005 20:48:14 -0400 X-Mailer: exmh version 2.6.3_20040314 03/14/2004 with nmh-1.1 From: Keith Owens To: sekharan@us.ibm.com Cc: Alan Stern , Kernel development list Subject: Re: Notifier chains are unsafe In-reply-to: Your message of "Thu, 27 Oct 2005 16:02:08 MST." <1130454128.3586.268.camel@linuxchandra> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Fri, 28 Oct 2005 10:48:00 +1000 Message-ID: <6933.1130460480@ocs3.ocs.com.au> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 982 Lines: 21 On Thu, 27 Oct 2005 16:02:08 -0700, Chandra Seetharaman wrote: >On Thu, 2005-10-27 at 17:21 -0400, Alan Stern wrote: >> The other problem is that you violated Keith's statement that >> notifier_call_chain shouldn't take any locks. On the other hand, if we > >I would interpret Keith's comment like this: callout should not be >called with any locks held (because that would limit the callouts from >blocking). We should be able to call notifier_call_chain() from any context. That includes oops, panic, NMI and other unmaskable machine check events. If you can call notifier_call_chain() from an unmaskable context then it follows that the callbacks cannot take any locks. Locks are not safe in NMI context. - 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/