From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965057AbdCJJfS (ORCPT ); Fri, 10 Mar 2017 04:35:18 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:42780 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935820AbdCJJfP (ORCPT ); Fri, 10 Mar 2017 04:35:15 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrew Price , Andreas Gruenbacher , Bob Peterson Subject: [PATCH 4.10 131/167] gfs2: Add missing rcu locking for glock lookup Date: Fri, 10 Mar 2017 10:09:34 +0100 Message-Id: <20170310084003.769685761@linuxfoundation.org> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170310083956.767605269@linuxfoundation.org> References: <20170310083956.767605269@linuxfoundation.org> User-Agent: quilt/0.65 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 4.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andrew Price commit f38e5fb95a1f8feda88531eedc98f69b24748712 upstream. We must hold the rcu read lock across looking up glocks and trying to bump their refcount to prevent the glocks from being freed in between. Signed-off-by: Andrew Price Signed-off-by: Andreas Gruenbacher Signed-off-by: Bob Peterson Signed-off-by: Greg Kroah-Hartman --- fs/gfs2/glock.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -658,9 +658,11 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, struct kmem_cache *cachep; int ret, tries = 0; + rcu_read_lock(); gl = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms); if (gl && !lockref_get_not_dead(&gl->gl_lockref)) gl = NULL; + rcu_read_unlock(); *glp = gl; if (gl) @@ -728,15 +730,18 @@ again: if (ret == -EEXIST) { ret = 0; + rcu_read_lock(); tmp = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms); if (tmp == NULL || !lockref_get_not_dead(&tmp->gl_lockref)) { if (++tries < 100) { + rcu_read_unlock(); cond_resched(); goto again; } tmp = NULL; ret = -ENOMEM; } + rcu_read_unlock(); } else { WARN_ON_ONCE(ret); }