Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261578AbVCSR1n (ORCPT ); Sat, 19 Mar 2005 12:27:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262644AbVCSR07 (ORCPT ); Sat, 19 Mar 2005 12:26:59 -0500 Received: from mail.tv-sign.ru ([213.234.233.51]:37286 "EHLO several.ru") by vger.kernel.org with ESMTP id S261578AbVCSRZK (ORCPT ); Sat, 19 Mar 2005 12:25:10 -0500 Message-ID: <423C6FD1.748BCC89@tv-sign.ru> Date: Sat, 19 Mar 2005 21:30:41 +0300 From: Oleg Nesterov X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.2.20 i686) X-Accept-Language: en MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Christoph Lameter , Andrew Morton Subject: [PATCH 4/5] timers: remove memory barriers 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: 1281 Lines: 37 del_timer() and __run_timers() use smp_wmb() before clearing timer's pending flag. It was needed because __mod_timer() did not locked old_base if the timer is not pending, so __mod_timer()->internal_add_timer() can race with del_timer()->list_del(). With the previous patch these functions are serialized through base->lock, so the barrier can be killed. Still needed in del_timer_sync(), because it clears ->_base. Signed-off-by: Oleg Nesterov --- 2.6.12-rc1/kernel/timer.c~4_BARR 2005-03-19 22:26:50.000000000 +0300 +++ 2.6.12-rc1/kernel/timer.c 2005-03-19 22:28:34.000000000 +0300 @@ -337,8 +337,6 @@ repeat: goto repeat; } list_del(&timer->entry); - /* Need to make sure that anybody who sees a NULL base also sees the list ops */ - smp_wmb(); __set_base(timer, base, 0); spin_unlock_irqrestore(&base->lock, flags); @@ -496,7 +494,6 @@ repeat: list_del(&timer->entry); set_running_timer(base, timer); - smp_wmb(); __set_base(timer, base, 0); spin_unlock_irq(&base->lock); { - 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/