Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932090AbXAFTMK (ORCPT ); Sat, 6 Jan 2007 14:12:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932086AbXAFTMK (ORCPT ); Sat, 6 Jan 2007 14:12:10 -0500 Received: from smtp.osdl.org ([65.172.181.24]:36183 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932092AbXAFTMJ (ORCPT ); Sat, 6 Jan 2007 14:12:09 -0500 Date: Sat, 6 Jan 2007 11:11:17 -0800 From: Andrew Morton To: vatsa@in.ibm.com Cc: Oleg Nesterov , David Howells , Christoph Hellwig , Ingo Molnar , Linus Torvalds , linux-kernel@vger.kernel.org, Gautham shenoy Subject: Re: [PATCH] fix-flush_workqueue-vs-cpu_dead-race-update Message-Id: <20070106111117.54bb2307.akpm@osdl.org> In-Reply-To: <20070106163851.GA13579@in.ibm.com> References: <20061217223416.GA6872@tv-sign.ru> <20061218162701.a3b5bfda.akpm@osdl.org> <20061219004319.GA821@tv-sign.ru> <20070104113214.GA30377@in.ibm.com> <20070104142936.GA179@tv-sign.ru> <20070104091850.c1feee76.akpm@osdl.org> <20070106151036.GA951@tv-sign.ru> <20070106154506.GC24274@in.ibm.com> <20070106163035.GA2948@tv-sign.ru> <20070106163851.GA13579@in.ibm.com> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1140 Lines: 25 On Sat, 6 Jan 2007 22:08:51 +0530 Srivatsa Vaddagiri wrote: > This workqueue problem has exposed a classic example of how > tough/miserable it can be to write hotplug safe code w/o something like > lock_cpu_hotplug() ..Are you still inclined towards banning it? :) I don't ban stuff - I just advocate ;) I would still prefer that we not try to invent a new magical lock, but yes, the current approach is looking troublesome. > FYI, the lock_cpu_hotplug() rewrite proposed by Gautham at > http://lkml.org/lkml/2006/10/26/65 may still need refinement to avoid > all the kind of deadlocks we have unearthed with workqueue example. I > can review that design with Gautham if there is some interest to > revive lock_cpu_hotplug() .. Has anyone thought seriously about using the process freezer in the cpu-down/cpu-up paths? That way we don't need to lock anything anywhere? - 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/