From 7c47cedf43a8b3086c3dcf26cbc058747ee21bec Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Mon, 17 Jun 2013 14:16:10 -0700 Subject: [PATCH] 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: Stephen Hemminger --- drivers/net/vxlan.c | 103 +++++++++++++++++--------------------------- 1 file changed, 40 insertions(+), 63 deletions(-) diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index eb94bf5812cb..b061c98474ee 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -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) -- 2.20.1