Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751421AbWBQTz0 (ORCPT ); Fri, 17 Feb 2006 14:55:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750898AbWBQTz0 (ORCPT ); Fri, 17 Feb 2006 14:55:26 -0500 Received: from allen.werkleitz.de ([80.190.251.108]:32900 "EHLO allen.werkleitz.de") by vger.kernel.org with ESMTP id S1751580AbWBQTzY (ORCPT ); Fri, 17 Feb 2006 14:55:24 -0500 Date: Fri, 17 Feb 2006 20:55:15 +0100 From: Johannes Stezenbach To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Ulrich Drepper , Thomas Gleixner , Arjan van de Ven , David Singleton , Andrew Morton Message-ID: <20060217195515.GA12501@linuxtv.org> Mail-Followup-To: Johannes Stezenbach , Ingo Molnar , linux-kernel@vger.kernel.org, Ulrich Drepper , Thomas Gleixner , Arjan van de Ven , David Singleton , Andrew Morton References: <20060215151711.GA31569@elte.hu> <20060216145823.GA25759@linuxtv.org> <20060216172007.GB29151@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060216172007.GB29151@elte.hu> User-Agent: Mutt/1.5.11+cvs20060126 X-SA-Exim-Connect-IP: 84.190.141.209 Subject: Re: [patch 0/5] lightweight robust futexes: -V1 X-SA-Exim-Version: 4.2 (built Thu, 03 Mar 2005 10:44:12 +0100) X-SA-Exim-Scanned: Yes (on allen.werkleitz.de) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1382 Lines: 37 On Thu, Feb 16, 2006, Ingo Molnar wrote: > > * Johannes Stezenbach wrote: > > > Anyway: If a process can trash its robust futext list and then die > > with a segfault, why are the futexes still robust? In this case the > > kernel has no way to wake up waiters with FUTEX_OWNER_DEAD, or does > > it? > > that's memory corruption - which robust futexes do not (and cannot) > solve. Robustness is mostly about handling sudden death (e.g. which is > due to oom, or is due to a user killing the task, or due to the > application crashing in some non-memory-corrupting way), but it cannot > handle all possible failure modes. Hm, OK, from reading this and the other threads on this topic I get: - there is a tradeoff between speed and robustness - the focus for "robust futexes" is on speed (else they wouldn't deserve to be called futexes) - thus it is acceptable if they are just 99% robust That's OK, but IMHO it wouldn't hurt to clearly spell it out in the documentation. However, this leaves the question: Is there a slower, but 100% robust alternative on Linux for applications which need it? Johannes - 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/