Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S942232AbcJZMef (ORCPT ); Wed, 26 Oct 2016 08:34:35 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55965 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S942199AbcJZMeb (ORCPT ); Wed, 26 Oct 2016 08:34:31 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Bart Van Assche , Tejun Heo Subject: [PATCH 4.4 081/112] blkcg: Unlock blkcg_pol_mutex only once when cpd == NULL Date: Wed, 26 Oct 2016 14:23:04 +0200 Message-Id: <20161026122308.195422407@linuxfoundation.org> X-Mailer: git-send-email 2.10.1 In-Reply-To: <20161026122304.797016625@linuxfoundation.org> References: <20161026122304.797016625@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1192 Lines: 39 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bart Van Assche commit bbb427e342495df1cda10051d0566388697499c0 upstream. Unlocking a mutex twice is wrong. Hence modify blkcg_policy_register() such that blkcg_pol_mutex is unlocked once if cpd == NULL. This patch avoids that smatch reports the following error: block/blk-cgroup.c:1378: blkcg_policy_register() error: double unlock 'mutex:&blkcg_pol_mutex' Fixes: 06b285bd1125 ("blkcg: fix blkcg_policy_data allocation bug") Signed-off-by: Bart Van Assche Cc: Tejun Heo Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- block/blk-cgroup.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1331,10 +1331,8 @@ int blkcg_policy_register(struct blkcg_p struct blkcg_policy_data *cpd; cpd = pol->cpd_alloc_fn(GFP_KERNEL); - if (!cpd) { - mutex_unlock(&blkcg_pol_mutex); + if (!cpd) goto err_free_cpds; - } blkcg->cpd[pol->plid] = cpd; cpd->blkcg = blkcg;