Commit ede6c39c authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: make net->dev_unreg_count atomic 



Having to acquire rtnl from netdev_run_todo() for every dismantled
device is not desirable when/if rtnl is under stress.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ca2d5f1f

include/net/net_namespace.h

+1 −1
Original line number Diff line number Diff line
@@ -63,7 +63,7 @@ struct net { 
						 */

	spinlock_t		rules_mod_lock;



	unsigned int		dev_unreg_count;

	atomic_t		dev_unreg_count;



	unsigned int		dev_base_seq;	/* protected by rtnl_mutex */

	int			ifindex;

net/core/dev.c

+4 −7
Original line number Diff line number Diff line
@@ -9143,7 +9143,7 @@ DECLARE_WAIT_QUEUE_HEAD(netdev_unregistering_wq); 
static void net_set_todo(struct net_device *dev)

{

	list_add_tail(&dev->todo_list, &net_todo_list);

	dev_net(dev)->dev_unreg_count++;

	atomic_inc(&dev_net(dev)->dev_unreg_count);

}



static netdev_features_t netdev_sync_upper_features(struct net_device *lower,
@@ -9965,10 +9965,7 @@ void netdev_run_todo(void) 
		if (dev->needs_free_netdev)

			free_netdev(dev);



		/* Report a network device has been unregistered */

		rtnl_lock();

		dev_net(dev)->dev_unreg_count--;

		__rtnl_unlock();

		if (atomic_dec_and_test(&dev_net(dev)->dev_unreg_count))

			wake_up(&netdev_unregistering_wq);



		/* Free network device */
@@ -10898,7 +10895,7 @@ static void __net_exit rtnl_lock_unregistering(struct list_head *net_list) 
		unregistering = false;



		list_for_each_entry(net, net_list, exit_list) {

			if (net->dev_unreg_count > 0) {

			if (atomic_read(&net->dev_unreg_count) > 0) {

				unregistering = true;

				break;

			}

net/core/rtnetlink.c

+1 −1
Original line number Diff line number Diff line
@@ -459,7 +459,7 @@ static void rtnl_lock_unregistering_all(void) 
		 * setup_net() and cleanup_net() are not possible.

		 */

		for_each_net(net) {

			if (net->dev_unreg_count > 0) {

			if (atomic_read(&net->dev_unreg_count) > 0) {

				unregistering = true;

				break;

			}