From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753492Ab1GIFyy (ORCPT ); Sat, 9 Jul 2011 01:54:54 -0400 Received: from out5.smtp.messagingengine.com ([66.111.4.29]:42934 "EHLO out5.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753189Ab1GIFyk (ORCPT ); Sat, 9 Jul 2011 01:54:40 -0400 X-Sasl-enc: nQFeN7c5JMx+fzTH3cQdMrM8511s53jPH/JFucCoIWXR 1310190879 X-Mailbox-Line: From gregkh@clark.kroah.org Fri Jul 8 15:51:20 2011 Message-Id: <20110708225120.282446425@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Fri, 08 Jul 2011 15:50:04 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Shaohua Li , Jens Axboe Subject: [15/35] cfq-iosched: fix a rcu warning In-Reply-To: <20110708225343.GA14402@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let us know. ------------------ From: Shaohua Li commit 3181faa85bda3dc3f5e630a1846526c9caaa38e3 upstream. I got a rcu warnning at boot. the ioc->ioc_data is rcu_deferenced, but doesn't hold rcu_read_lock. Signed-off-by: Shaohua Li Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/cfq-iosched.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1540,11 +1540,14 @@ static void __cfq_exit_single_io_context cic->dead_key = (unsigned long) cic->key; cic->key = NULL; + rcu_read_lock(); if (rcu_dereference(ioc->ioc_data) == cic) { + rcu_read_unlock(); spin_lock(&ioc->lock); rcu_assign_pointer(ioc->ioc_data, NULL); spin_unlock(&ioc->lock); - } + } else + rcu_read_unlock(); if (cic->cfqq[BLK_RW_ASYNC]) { cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);