From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756336AbYEHI0J (ORCPT ); Thu, 8 May 2008 04:26:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752801AbYEHIZ4 (ORCPT ); Thu, 8 May 2008 04:25:56 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:50593 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752774AbYEHIZz (ORCPT ); Thu, 8 May 2008 04:25:55 -0400 Date: Thu, 8 May 2008 01:25:03 -0700 From: Andrew Morton To: Daniel Walker Cc: linux-kernel@vger.kernel.org, Pierre Peiffer Subject: Re: futex: priority wakeup miss ordering Message-Id: <20080508012503.0d023cdc.akpm@linux-foundation.org> In-Reply-To: <1210195378.17132.237.camel@localhost.localdomain> References: <1210195378.17132.237.camel@localhost.localdomain> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 07 May 2008 14:22:58 -0700 Daniel Walker wrote: > > > from commit ec92d08292d3e9b0823eba138a4564d2d39f25c7 > > The wakeup ordering should be in priority order. However if the priority > of a task is modified while it's waiting on the futex you will get an > out of order wakeup. > > If you use a priority inheriting mutex this is correct. It's because the > rtmutex hooks into sched_setscheduler to catch any priority changes, > then re-queues with the new priority.. But the futex doesn't have this > hook. > > Was this intentionally left out of this priority wake up patch? I > thought I would let you know in case you had a specific reason for not > handling this.. > Pierre is no longer @bull.net.