Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161026AbWBYQSu (ORCPT ); Sat, 25 Feb 2006 11:18:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964771AbWBYQSu (ORCPT ); Sat, 25 Feb 2006 11:18:50 -0500 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:62131 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S964773AbWBYQSt (ORCPT ); Sat, 25 Feb 2006 11:18:49 -0500 To: Oleg Nesterov Cc: Andrew Morton , linux-kernel@vger.kernel.org, Ingo Molnar , "Paul E. McKenney" , David Howells Subject: Re: [PATCH 2/6] relax sig_needs_tasklist() References: <43FCEE08.7923E800@tv-sign.ru> From: ebiederm@xmission.com (Eric W. Biederman) Date: Sat, 25 Feb 2006 09:17:22 -0700 In-Reply-To: <43FCEE08.7923E800@tv-sign.ru> (Oleg Nesterov's message of "Thu, 23 Feb 2006 02:04:40 +0300") Message-ID: User-Agent: Gnus/5.1007 (Gnus v5.10.7) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 888 Lines: 27 Oleg Nesterov writes: > handle_stop_signal() does not need tasklist_lock for > SIG_KERNEL_STOP_MASK signals anymore. Small question. If I read the code correctly the only thing handle_stop_signal needs the tasklist_lock for is to protect task->parent, for the do_notify_parent_cldstop(...) case. If this is correct. I think I see a path to kill read_lock(&tasklist_lock) completely. - Protect task->parent with the rcu_read_lock && task_lock(). - Use the rcu forms of list_add/list_del on the tasklist. - replace read_lock(&tasklist_lock) with rcu_read_lock(). - Make tasklist_lock a simple spin lock. Comments? Eric - 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/