From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759243Ab2JYITc (ORCPT ); Thu, 25 Oct 2012 04:19:32 -0400 Received: from mga01.intel.com ([192.55.52.88]:27472 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753349Ab2JYIT2 (ORCPT ); Thu, 25 Oct 2012 04:19:28 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.80,646,1344236400"; d="scan'208";a="238184021" Message-ID: <5088F5D0.7010604@linux.intel.com> Date: Thu, 25 Oct 2012 01:18:24 -0700 From: Darren Hart User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121016 Thunderbird/16.0.1 MIME-Version: 1.0 To: Thomas Gleixner CC: Siddhesh Poyarekar , LKML , Ingo Molnar , Peter Zijlstra Subject: Re: [PATCH] [RESEND 2] Take over futex of dead task only if FUTEX_WAITERS is not set References: <1350876034-22023-1-git-send-email-siddhesh.poyarekar@gmail.com> <5086A3D1.7080709@linux.intel.com> <5088C10C.80503@linux.intel.com> In-Reply-To: X-Enigmail-Version: 1.4.5 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/25/2012 01:14 AM, Thomas Gleixner wrote: > On Wed, 24 Oct 2012, Darren Hart wrote: >> On 10/23/2012 01:29 PM, Thomas Gleixner wrote: > Nah. I'm just too paranoid to apply any futex patch w/o understanding > the root cause of it. Darn, if I only could remember how that stale > waiters bit issue got inflicted .... Stale waiters happens in userspace for non-pi mutexes and there we make one extra FUTEX_WAKE syscall just in case. The futex value policy is much more rigid with PI obviously, so I wasn't aware this could happen there. -- Darren Hart Intel Open Source Technology Center Yocto Project - Technical Lead - Linux Kernel