Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965079AbWHUMma (ORCPT ); Mon, 21 Aug 2006 08:42:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965080AbWHUMma (ORCPT ); Mon, 21 Aug 2006 08:42:30 -0400 Received: from filfla-vlan276.msk.corbina.net ([213.234.233.49]:16089 "EHLO screens.ru") by vger.kernel.org with ESMTP id S965083AbWHUMmT (ORCPT ); Mon, 21 Aug 2006 08:42:19 -0400 Date: Mon, 21 Aug 2006 21:06:21 +0400 From: Oleg Nesterov To: Andrew Morton Cc: Ingo Molnar , Thomas Gleixner , Steven Rostedt , linux-kernel@vger.kernel.org Subject: [PATCH 2/3] futex_find_get_task: don't take tasklist_lock Message-ID: <20060821170621.GA1643@oleg> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 981 Lines: 33 It is ok to do find_task_by_pid() + get_task_struct() under rcu_read_lock(), we cand drop tasklist_lock. Note that testing of ->exit_state is racy with or without tasklist anyway. Signed-off-by: Oleg Nesterov --- 2.6.18-rc4/kernel/futex.c~2_ffgt 2006-08-21 20:32:48.000000000 +0400 +++ 2.6.18-rc4/kernel/futex.c 2006-08-21 20:41:15.000000000 +0400 @@ -389,7 +389,7 @@ static struct task_struct * futex_find_g { struct task_struct *p; - read_lock(&tasklist_lock); + rcu_read_lock(); p = find_task_by_pid(pid); if (!p) goto out_unlock; @@ -403,7 +403,7 @@ static struct task_struct * futex_find_g } get_task_struct(p); out_unlock: - read_unlock(&tasklist_lock); + rcu_read_unlock(); return p; } - 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/