From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756664AbYCaNQW (ORCPT ); Mon, 31 Mar 2008 09:16:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754948AbYCaNQN (ORCPT ); Mon, 31 Mar 2008 09:16:13 -0400 Received: from tomts10.bellnexxia.net ([209.226.175.54]:63815 "EHLO tomts10-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753582AbYCaNQM (ORCPT ); Mon, 31 Mar 2008 09:16:12 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvoEACqB8EdMQWoK/2dsb2JhbACBWqdMghw Date: Mon, 31 Mar 2008 09:16:09 -0400 From: Mathieu Desnoyers To: "Paul E. McKenney" , Andrew Morton , linux-kernel@vger.kernel.org Subject: [PATCH for 2.6.25] Markers - use synchronize_sched() Message-ID: <20080331131609.GA22207@Krystal> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 09:13:43 up 31 days, 9:24, 6 users, load average: 1.36, 0.75, 0.56 User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use synchronize_sched before calling call_rcu in CONFIG_PREEMPT_RCU until we have call_rcu_sched and rcu_barrier_sched in mainline. It will slow down the marker operations in CONFIG_PREEMPT_RCU, but it fixes the current race against the preempt_disable/enable() protected code paths. Paul, is this ok ? It would be good to get this in for 2.6.25 final. Signed-off-by: Mathieu Desnoyers CC: Paul E. McKenney --- kernel/marker.c | 9 +++++++++ 1 file changed, 9 insertions(+) Index: linux-2.6-lttng/kernel/marker.c =================================================================== --- linux-2.6-lttng.orig/kernel/marker.c 2008-03-31 08:22:24.000000000 -0400 +++ linux-2.6-lttng/kernel/marker.c 2008-03-31 08:43:30.000000000 -0400 @@ -671,6 +671,9 @@ int marker_probe_register(const char *na entry->rcu_pending = 1; /* write rcu_pending before calling the RCU callback */ smp_wmb(); +#ifdef CONFIG_PREEMPT_RCU + synchronize_sched(); /* Until we have the call_rcu_sched() */ +#endif call_rcu(&entry->rcu, free_old_closure); end: mutex_unlock(&markers_mutex); @@ -714,6 +717,9 @@ int marker_probe_unregister(const char * entry->rcu_pending = 1; /* write rcu_pending before calling the RCU callback */ smp_wmb(); +#ifdef CONFIG_PREEMPT_RCU + synchronize_sched(); /* Until we have the call_rcu_sched() */ +#endif call_rcu(&entry->rcu, free_old_closure); remove_marker(name); /* Ignore busy error message */ ret = 0; @@ -792,6 +798,9 @@ int marker_probe_unregister_private_data entry->rcu_pending = 1; /* write rcu_pending before calling the RCU callback */ smp_wmb(); +#ifdef CONFIG_PREEMPT_RCU + synchronize_sched(); /* Until we have the call_rcu_sched() */ +#endif call_rcu(&entry->rcu, free_old_closure); remove_marker(entry->name); /* Ignore busy error message */ end: -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68