1 files changed, 17 insertions, 15 deletions

diff --git a/net/ipv4/udp_tunnel_nic.c b/net/ipv4/udp_tunnel_nic.c
index 3b32a0afa979..53a1a9c1f8bf 100644
--- a/net/ipv4/udp_tunnel_nic.c
+++ b/net/ipv4/udp_tunnel_nic.c
@@ -32,13 +32,12 @@ struct udp_tunnel_nic_table_entry {
  * @lock:	protects all fields
  * @need_sync:	at least one port start changed
  * @need_replay: space was freed, we need a replay of all ports
- * @work_pending: @work is currently scheduled
  * @n_tables:	number of tables under @entries
  * @missed:	bitmap of tables which overflown
  * @entries:	table of tables of ports currently offloaded
  */
 struct udp_tunnel_nic {
-	struct work_struct work;
+	struct delayed_work work;
 
 	struct net_device *dev;
 
@@ -46,7 +45,6 @@ struct udp_tunnel_nic {
 
 	u8 need_sync:1;
 	u8 need_replay:1;
-	u8 work_pending:1;
 
 	unsigned int n_tables;
 	unsigned long missed;
@@ -301,11 +299,10 @@ __udp_tunnel_nic_device_sync(struct net_device *dev, struct udp_tunnel_nic *utn)
 static void
 udp_tunnel_nic_device_sync(struct net_device *dev, struct udp_tunnel_nic *utn)
 {
-	if (!utn->need_sync || utn->work_pending)
+	if (!utn->need_sync)
 		return;
 
-	queue_work(udp_tunnel_nic_workqueue, &utn->work);
-	utn->work_pending = 1;
+	queue_delayed_work(udp_tunnel_nic_workqueue, &utn->work, 0);
 }
 
 static bool
@@ -731,12 +728,17 @@ udp_tunnel_nic_replay(struct net_device *dev, struct udp_tunnel_nic *utn)
 static void udp_tunnel_nic_device_sync_work(struct work_struct *work)
 {
 	struct udp_tunnel_nic *utn =
-		container_of(work, struct udp_tunnel_nic, work);
+		container_of(work, struct udp_tunnel_nic, work.work);
 
-	rtnl_lock();
+	/* We cannot block on RTNL here, otherwise we would deadlock with
+	 * udp_tunnel_nic_unregister() calling cancel_delayed_work_sync()
+	 * while holding RTNL. Requeue with 1 jiffy delay if RTNL is contended.
+	 */
+	if (!rtnl_trylock()) {
+		queue_delayed_work(udp_tunnel_nic_workqueue, &utn->work, 1);
+		return;
+	}
 	mutex_lock(&utn->lock);
-
-	utn->work_pending = 0;
 	__udp_tunnel_nic_device_sync(utn->dev, utn);
 
 	if (utn->need_replay)
@@ -757,7 +759,7 @@ udp_tunnel_nic_alloc(const struct udp_tunnel_nic_info *info,
 	if (!utn)
 		return NULL;
 	utn->n_tables = n_tables;
-	INIT_WORK(&utn->work, udp_tunnel_nic_device_sync_work);
+	INIT_DELAYED_WORK(&utn->work, udp_tunnel_nic_device_sync_work);
 	mutex_init(&utn->lock);
 
 	for (i = 0; i < n_tables; i++) {
@@ -901,11 +903,11 @@ udp_tunnel_nic_unregister(struct net_device *dev, struct udp_tunnel_nic *utn)
 	udp_tunnel_nic_flush(dev, utn);
 	udp_tunnel_nic_unlock(dev);
 
-	/* Wait for the work to be done using the state, netdev core will
-	 * retry unregister until we give up our reference on this device.
+	/* Make sure no work is running or queued before freeing @utn.
+	 * The work handler uses rtnl_trylock(), so it will not deadlock
+	 * against the RTNL we are holding here.
 	 */
-	if (utn->work_pending)
-		return;
+	cancel_delayed_work_sync(&utn->work);
 
 	udp_tunnel_nic_free(utn);
 release_dev: