linux-kernel - [PATCH 4.6 65/96] lockd: unregister notifier blocks if the service fails to come up completely

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Date:	Mon,  8 Aug 2016 21:11:28 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Scott Mayhew <smayhew@...hat.com>,
	"J. Bruce Fields" <bfields@...hat.com>
Subject: [PATCH 4.6 65/96] lockd: unregister notifier blocks if the service fails to come up completely

4.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Scott Mayhew <smayhew@...hat.com>

commit cb7d224f82e41d82518e7f9ea271d215d4d08e6e upstream.

If the lockd service fails to start up then we need to be sure that the
notifier blocks are not registered, otherwise a subsequent start of the
service could cause the same notifier to be registered twice, leading to
soft lockups.

Signed-off-by: Scott Mayhew <smayhew@...hat.com>
Fixes: 0751ddf77b6a "lockd: Register callbacks on the inetaddr_chain..."
Signed-off-by: J. Bruce Fields <bfields@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/lockd/svc.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -335,12 +335,17 @@ static struct notifier_block lockd_inet6
 };
 #endif
 
-static void lockd_svc_exit_thread(void)
+static void lockd_unregister_notifiers(void)
 {
 	unregister_inetaddr_notifier(&lockd_inetaddr_notifier);
 #if IS_ENABLED(CONFIG_IPV6)
 	unregister_inet6addr_notifier(&lockd_inet6addr_notifier);
 #endif
+}
+
+static void lockd_svc_exit_thread(void)
+{
+	lockd_unregister_notifiers();
 	svc_exit_thread(nlmsvc_rqst);
 }
 
@@ -462,7 +467,7 @@ int lockd_up(struct net *net)
 	 * Note: svc_serv structures have an initial use count of 1,
 	 * so we exit through here on both success and failure.
 	 */
-err_net:
+err_put:
 	svc_destroy(serv);
 err_create:
 	mutex_unlock(&nlmsvc_mutex);
@@ -470,7 +475,9 @@ err_create:
 
 err_start:
 	lockd_down_net(serv, net);
-	goto err_net;
+err_net:
+	lockd_unregister_notifiers();
+	goto err_put;
 }
 EXPORT_SYMBOL_GPL(lockd_up);