Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935437Ab2JXSI1 (ORCPT ); Wed, 24 Oct 2012 14:08:27 -0400 Received: from www.linutronix.de ([62.245.132.108]:52531 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935380Ab2JXSIZ (ORCPT ); Wed, 24 Oct 2012 14:08:25 -0400 Date: Wed, 24 Oct 2012 20:08:18 +0200 (CEST) From: Thomas Gleixner To: Siddhesh Poyarekar cc: Darren Hart , LKML , Ingo Molnar , Peter Zijlstra Subject: Re: [PATCH] [RESEND 2] Take over futex of dead task only if FUTEX_WAITERS is not set In-Reply-To: Message-ID: References: <1350876034-22023-1-git-send-email-siddhesh.poyarekar@gmail.com> <5086A3D1.7080709@linux.intel.com> User-Agent: Alpine 2.02 (LFD 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 904 Lines: 25 On Wed, 24 Oct 2012, Siddhesh Poyarekar wrote: > > Now there is a different solution to that problem. Do not look at the > > user space value at all and enforce a lookup of possibly available > > pi_state. If pi_state can be found, then the new incoming locker T3 > > blocks on that pi_state and legitimately races with T2 to acquire the > > rt_mutex and the pi_state and therefor the proper ownership of the > > user space futex. > > That works. Thanks for the detailed explanation too. Thanks for the reproducer and finding the trouble spot in the first place! I'll queue that if Darren has no objections and mark it for stable as well. Thanks, tglx -- 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/