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Commit 7c47cedf authored by Stephen Hemminger's avatar Stephen Hemminger
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vxlan: move IGMP join/leave to work queue 



Do join/leave from work queue to avoid lock inversion problems
between normal socket and RTNL. The code comes out cleaner
as well.

Uses Cong Wang's suggestion to turn refcnt into a real atomic
since now need to handle case where last use of socket is IGMP
worker.

Signed-off-by: default avatarStephen Hemminger <stephen@networkplumber.org>
parent 758c57d1

drivers/net/vxlan.c

+40 −63
Original line number Diff line number Diff line
@@ -85,7 +85,7 @@ struct vxlan_sock { 
	struct hlist_node hlist;

	struct rcu_head	  rcu;

	struct work_struct del_work;

	unsigned int	  refcnt;

	atomic_t	  refcnt;

	struct socket	  *sock;

	struct hlist_head vni_list[VNI_HASH_SIZE];

};
@@ -131,6 +131,7 @@ struct vxlan_dev { 
	__u8		  ttl;

	u32		  flags;	/* VXLAN_F_* below */



	struct work_struct igmp_work;

	unsigned long	  age_interval;

	struct timer_list age_timer;

	spinlock_t	  hash_lock;
@@ -648,76 +649,58 @@ static bool vxlan_snoop(struct net_device *dev, 




/* See if multicast group is already in use by other ID */

static bool vxlan_group_used(struct vxlan_net *vn,

			     const struct vxlan_dev *this)

static bool vxlan_group_used(struct vxlan_net *vn, __be32 remote_ip)

{

	struct vxlan_dev *vxlan;



	list_for_each_entry(vxlan, &vn->vxlan_list, next) {

		if (vxlan == this)

			continue;



		if (!netif_running(vxlan->dev))

			continue;



		if (vxlan->default_dst.remote_ip == this->default_dst.remote_ip)

		if (vxlan->default_dst.remote_ip == remote_ip)

			return true;

	}



	return false;

}



/* kernel equivalent to IP_ADD_MEMBERSHIP */

static int vxlan_join_group(struct net_device *dev)

static void vxlan_sock_hold(struct vxlan_sock *vs)

{

	struct vxlan_dev *vxlan = netdev_priv(dev);

	struct vxlan_net *vn = net_generic(dev_net(dev), vxlan_net_id);

	struct sock *sk = vxlan->vn_sock->sock->sk;

	struct ip_mreqn mreq = {

		.imr_multiaddr.s_addr	= vxlan->default_dst.remote_ip,

		.imr_ifindex		= vxlan->default_dst.remote_ifindex,

	};

	int err;



	/* Already a member of group */

	if (vxlan_group_used(vn, vxlan))

		return 0;

	atomic_inc(&vs->refcnt);

}



	/* Need to drop RTNL to call multicast join */

	rtnl_unlock();

	lock_sock(sk);

	err = ip_mc_join_group(sk, &mreq);

	release_sock(sk);

	rtnl_lock();

static void vxlan_sock_release(struct vxlan_sock *vs)

{

	if (!atomic_dec_and_test(&vs->refcnt))

		return;



	return err;

	hlist_del_rcu(&vs->hlist);

	queue_work(vxlan_wq, &vs->del_work);

}





/* kernel equivalent to IP_DROP_MEMBERSHIP */

static int vxlan_leave_group(struct net_device *dev)

/* Callback to update multicast group membership.

 * Scheduled when vxlan goes up/down.

 */

static void vxlan_igmp_work(struct work_struct *work)

{

	struct vxlan_dev *vxlan = netdev_priv(dev);

	struct vxlan_net *vn = net_generic(dev_net(dev), vxlan_net_id);

	int err = 0;

	struct sock *sk = vxlan->vn_sock->sock->sk;

	struct vxlan_dev *vxlan = container_of(work, struct vxlan_dev, igmp_work);

	struct vxlan_net *vn = net_generic(dev_net(vxlan->dev), vxlan_net_id);

	struct vxlan_sock *vs = vxlan->vn_sock;

	struct sock *sk = vs->sock->sk;

	struct ip_mreqn mreq = {

		.imr_multiaddr.s_addr	= vxlan->default_dst.remote_ip,

		.imr_ifindex		= vxlan->default_dst.remote_ifindex,

	};



	/* Only leave group when last vxlan is done. */

	if (vxlan_group_used(vn, vxlan))

		return 0;



	/* Need to drop RTNL to call multicast leave */

	rtnl_unlock();

	lock_sock(sk);

	err = ip_mc_leave_group(sk, &mreq);

	if (vxlan_group_used(vn, vxlan->default_dst.remote_ip))

		ip_mc_join_group(sk, &mreq);

	else

		ip_mc_leave_group(sk, &mreq);

	release_sock(sk);

	rtnl_lock();



	return err;

	vxlan_sock_release(vs);

	dev_put(vxlan->dev);

}



/* Callback from net/ipv4/udp.c to receive packets */
@@ -1249,12 +1232,11 @@ static int vxlan_init(struct net_device *dev) 
static int vxlan_open(struct net_device *dev)

{

	struct vxlan_dev *vxlan = netdev_priv(dev);

	int err;



	if (IN_MULTICAST(ntohl(vxlan->default_dst.remote_ip))) {

		err = vxlan_join_group(dev);

		if (err)

			return err;

		vxlan_sock_hold(vxlan->vn_sock);

		dev_hold(dev);

		queue_work(vxlan_wq, &vxlan->igmp_work);

	}



	if (vxlan->age_interval)
@@ -1285,8 +1267,11 @@ static int vxlan_stop(struct net_device *dev) 
{

	struct vxlan_dev *vxlan = netdev_priv(dev);



	if (IN_MULTICAST(ntohl(vxlan->default_dst.remote_ip)))

		vxlan_leave_group(dev);

	if (IN_MULTICAST(ntohl(vxlan->default_dst.remote_ip))) {

		vxlan_sock_hold(vxlan->vn_sock);

		dev_hold(dev);

		queue_work(vxlan_wq, &vxlan->igmp_work);

	}



	del_timer_sync(&vxlan->age_timer);
@@ -1355,6 +1340,7 @@ static void vxlan_setup(struct net_device *dev) 


	INIT_LIST_HEAD(&vxlan->next);

	spin_lock_init(&vxlan->hash_lock);

	INIT_WORK(&vxlan->igmp_work, vxlan_igmp_work);



	init_timer_deferrable(&vxlan->age_timer);

	vxlan->age_timer.function = vxlan_cleanup;
@@ -1498,8 +1484,8 @@ static struct vxlan_sock *vxlan_socket_create(struct net *net, __be16 port) 
	udp_sk(sk)->encap_type = 1;

	udp_sk(sk)->encap_rcv = vxlan_udp_encap_recv;

	udp_encap_enable();

	atomic_set(&vs->refcnt, 1);



	vs->refcnt = 1;

	return vs;

}
@@ -1589,7 +1575,7 @@ static int vxlan_newlink(struct net *net, struct net_device *dev, 


	vs = vxlan_find_port(net, vxlan->dst_port);

	if (vs)

		++vs->refcnt;

		atomic_inc(&vs->refcnt);

	else {

		/* Drop lock because socket create acquires RTNL lock */

		rtnl_unlock();
@@ -1606,12 +1592,7 @@ static int vxlan_newlink(struct net *net, struct net_device *dev, 


	err = register_netdevice(dev);

	if (err) {

		if (--vs->refcnt == 0) {

			rtnl_unlock();

			sk_release_kernel(vs->sock->sk);

			kfree(vs);

			rtnl_lock();

		}

		vxlan_sock_release(vs);

		return err;

	}
@@ -1629,11 +1610,7 @@ static void vxlan_dellink(struct net_device *dev, struct list_head *head) 
	hlist_del_rcu(&vxlan->hlist);

	list_del(&vxlan->next);

	unregister_netdevice_queue(dev, head);



	if (--vs->refcnt == 0) {

		hlist_del_rcu(&vs->hlist);

		queue_work(vxlan_wq, &vs->del_work);

	}

	vxlan_sock_release(vs);

}



static size_t vxlan_get_size(const struct net_device *dev)