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Date: Tue, 4 Jun 2013 21:24:07 -0700
From: Stephen Hemminger <stephen@...workplumber.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
Stephen Hemminger <stephen@...workplumber.org>
Subject: [PATCH net-next 03/10] 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.
Also fixes race where vxlan_stop could be called after
device was deleted on module removal. The call to rtnl_link_unregister
would call dellink while vxlan device was still up. Reordering
the calls fixes it.
Signed-off-by: Stephen Hemminger <stephen@...workplumber.org>
---
The last change probably needs a separate patch for -stable
---
drivers/net/vxlan.c | 105 ++++++++++++++++++++-------------------------------
1 file changed, 41 insertions(+), 64 deletions(-)
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 9085c81..f98f459 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;
@@ -644,76 +645,58 @@ static int 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);
+ schedule_work(&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 */
@@ -1261,12 +1244,11 @@ 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);
+ schedule_work(&vxlan->igmp_work);
}
if (vxlan->age_interval)
@@ -1297,8 +1279,11 @@ 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);
+ schedule_work(&vxlan->igmp_work);
+ }
del_timer_sync(&vxlan->age_timer);
@@ -1367,6 +1352,7 @@ 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;
@@ -1510,8 +1496,8 @@ 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;
}
@@ -1601,7 +1587,7 @@ 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();
@@ -1618,12 +1604,7 @@ 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;
}
@@ -1641,11 +1622,7 @@ 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);
- schedule_work(&vs->del_work);
- }
+ vxlan_sock_release(vs);
}
static size_t vxlan_get_size(const struct net_device *dev)
@@ -1784,8 +1761,8 @@ late_initcall(vxlan_init_module);
static void __exit vxlan_cleanup_module(void)
{
- rtnl_link_unregister(&vxlan_link_ops);
unregister_pernet_device(&vxlan_net_ops);
+ rtnl_link_unregister(&vxlan_link_ops);
rcu_barrier();
}
module_exit(vxlan_cleanup_module);
--
1.7.10.4
--
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