Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759913AbXIZOjU (ORCPT ); Wed, 26 Sep 2007 10:39:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754208AbXIZOjM (ORCPT ); Wed, 26 Sep 2007 10:39:12 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:32893 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753491AbXIZOjL (ORCPT ); Wed, 26 Sep 2007 10:39:11 -0400 Date: Wed, 26 Sep 2007 10:39:06 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Tejun Heo cc: Jonathan Corbet , , , , , , Subject: Re: [PATCH 1/4] module: implement module_inhibit_unload() In-Reply-To: <46F996AD.2070107@gmail.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1031 Lines: 24 On Wed, 26 Sep 2007, Tejun Heo wrote: > >> Hmmm... I might be missing something here. Who else can wake up a > >> thread in uninterruptible sleep? > > > > In principle, anything can. There has never been any guarantee in the > > kernel that a task sleeping on a waitqueue will remain asleep until > > the waitqueue is signalled. That's part of the reason why things like > > __wait_event() are coded as loops. > > Hmmm... I always thought the queue was because the condition can change > inbetween waking up and actually running. For example, if the condition > is !(queue empty), another task can enter the critical section and > consume the element which triggered wake up before the woken up task do. That's the other part of the reason for using a loop. :-) Alan Stern - 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/