Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751024AbWHMMj4 (ORCPT ); Sun, 13 Aug 2006 08:39:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751162AbWHMMj4 (ORCPT ); Sun, 13 Aug 2006 08:39:56 -0400 Received: from filfla-vlan276.msk.corbina.net ([213.234.233.49]:54146 "EHLO screens.ru") by vger.kernel.org with ESMTP id S1751024AbWHMMj4 (ORCPT ); Sun, 13 Aug 2006 08:39:56 -0400 Date: Sun, 13 Aug 2006 21:03:40 +0400 From: Oleg Nesterov To: Andrew Morton Cc: Ingo Molnar , Thomas Gleixner , Steven Rostedt , linux-kernel@vger.kernel.org Subject: [PATCH] do_sched_setscheduler: don't take tasklist_lock Message-ID: <20060813170340.GA1913@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: 1073 Lines: 36 We don't need to take tasklist_lock or disable irqs for find_task_by_pid() + get_task_struct(). Use RCU locks instead. Signed-off-by: Oleg Nesterov --- 2.6.18-rc3/kernel/sched.c~1_dss 2006-07-16 01:53:08.000000000 +0400 +++ 2.6.18-rc3/kernel/sched.c 2006-08-13 20:19:02.000000000 +0400 @@ -4156,14 +4156,15 @@ do_sched_setscheduler(pid_t pid, int pol return -EINVAL; if (copy_from_user(&lparam, param, sizeof(struct sched_param))) return -EFAULT; - read_lock_irq(&tasklist_lock); + + rcu_read_lock(); p = find_process_by_pid(pid); - if (!p) { - read_unlock_irq(&tasklist_lock); + if (p) + get_task_struct(p); + rcu_read_unlock(); + if (!p) return -ESRCH; - } - get_task_struct(p); - read_unlock_irq(&tasklist_lock); + retval = sched_setscheduler(p, policy, &lparam); put_task_struct(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/