From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754776AbYEGVXT (ORCPT ); Wed, 7 May 2008 17:23:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752074AbYEGVXB (ORCPT ); Wed, 7 May 2008 17:23:01 -0400 Received: from gateway-1237.mvista.com ([63.81.120.158]:1936 "EHLO gateway-1237.mvista.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752030AbYEGVXA (ORCPT ); Wed, 7 May 2008 17:23:00 -0400 Subject: futex: priority wakeup miss ordering From: Daniel Walker To: Pierre Peiffer Cc: linux-kernel@vger.kernel.org Content-Type: text/plain Date: Wed, 07 May 2008 14:22:58 -0700 Message-Id: <1210195378.17132.237.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.12.3 (2.12.3-3.fc8) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.. Daniel