From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756197Ab3CYBQN (ORCPT ); Sun, 24 Mar 2013 21:16:13 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:34020 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756066Ab3CYBQE (ORCPT ); Sun, 24 Mar 2013 21:16:04 -0400 Message-Id: <20130325010530.023505840@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 25 Mar 2013 01:06:22 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, "Steven Rostedt (Red Hat)" , Paul McKenney Subject: [ 058/104] tracing: Fix free of probe entry by calling call_rcu_sched() Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In-Reply-To: <20130325010524.240972766@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:f137:78a:b654:affb X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Steven Rostedt (Red Hat)" commit 740466bc89ad8bd5afcc8de220f715f62b21e365 upstream. Because function tracing is very invasive, and can even trace calls to rcu_read_lock(), RCU access in function tracing is done with preempt_disable_notrace(). This requires a synchronize_sched() for updates and not a synchronize_rcu(). Function probes (traceon, traceoff, etc) must be freed after a synchronize_sched() after its entry has been removed from the hash. But call_rcu() is used. Fix this by using call_rcu_sched(). Also fix the usage to use hlist_del_rcu() instead of hlist_del(). Cc: Paul McKenney Signed-off-by: Steven Rostedt Signed-off-by: Ben Hutchings --- kernel/trace/ftrace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2725,8 +2725,8 @@ __unregister_ftrace_function_probe(char continue; } - hlist_del(&entry->node); - call_rcu(&entry->rcu, ftrace_free_entry_rcu); + hlist_del_rcu(&entry->node); + call_rcu_sched(&entry->rcu, ftrace_free_entry_rcu); } } __disable_ftrace_function_probe();