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Message-Id: <a66c29751c354fe08acd459479f2eacf66e9b284.1416486751.git.mleitner@redhat.com>
Date: Thu, 20 Nov 2014 10:33:32 -0200
From: Marcelo Ricardo Leitner <mleitner@...hat.com>
To: netdev@...r.kernel.org
Cc: stephen@...workplumber.org, pshelar@...ira.com
Subject: [PATCH] vxlan: move listen socket creation from workqueue to vxlan_open
With current code, after commits 1c51a9159dde ("vxlan: fix race caused
by dropping rtnl_unlock") and 9c2e24e16fbc ("vxlan: Restructure vxlan
socket apis.") (this last for removing log messages) any failure on
listening socket creation won't be reported, neither as a return value
or logged. This is very bad for user experience and also for
applications trying to manage vxlan interfaces.
A failure can be creating two vxlan interfaces using the same dst_port
but one using an AF_INET and the other an AF_INET6 peer/multicast. The
second vxlan created would silently fail and ip link set vxlanX up would
just return 'not connected' forever, until its recreated.
We cannot create the socket on vxlan_newlink() because, as Stephen
Hemminger had noted, we have to unlock/lock rtnl when creating the
socket (because igmp handling will acquire them in the other order) and
this may lead to a race that allows creating two vxlan interfaces with
the same name, commit 1c51a9159dde. But this doesn't apply to
vxlan_open() scenario. We can unlock/lock in there safely and, with
that, we can return a better error value to the user if that's the case.
This also allowed a simplification on reuse attempt/create/try reusing
again on vxlan_init() and old worker via vxlan_sock_add(). Now it just
tries reusing and try creating if not possible.
Note that the socket is not destroyed by vxlan_stop(). That's still left
to vxlan_uninit().
For example, with this patch:
# ip link add vxlan4 type vxlan id 41 group 229.0.0.3 dev eth0
# ip link add vxlan6 type vxlan id 42 group ff0e::110 dev eth0
# ip link set vxlan4 up
# ip link set vxlan6 up
RTNETLINK answers: Address already in use
# ip link set vxlan4 down
# ip link set vxlan6 up
RTNETLINK answers: Address already in use
# ip link del vxlan4
# ip link set vxlan6 up
#
Signed-off-by: Marcelo Ricardo Leitner <mleitner@...hat.com>
---
drivers/net/vxlan.c | 89 ++++++++++++++++-------------------------------------
1 file changed, 26 insertions(+), 63 deletions(-)
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index fa9dc45b75a6f9f7fb04e25c61fa3eb732d10af6..e648a89814238a9b00ac0de020367fe6860a4dc2 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -139,7 +139,6 @@ struct vxlan_dev {
__u8 ttl;
u32 flags; /* VXLAN_F_* in vxlan.h */
- struct work_struct sock_work;
struct work_struct igmp_join;
struct work_struct igmp_leave;
@@ -156,8 +155,6 @@ struct vxlan_dev {
static u32 vxlan_salt __read_mostly;
static struct workqueue_struct *vxlan_wq;
-static void vxlan_sock_work(struct work_struct *work);
-
#if IS_ENABLED(CONFIG_IPV6)
static inline
bool vxlan_addr_equal(const union vxlan_addr *a, const union vxlan_addr *b)
@@ -1980,38 +1977,24 @@ static void vxlan_cleanup(unsigned long arg)
static void vxlan_vs_add_dev(struct vxlan_sock *vs, struct vxlan_dev *vxlan)
{
+ struct vxlan_net *vn = net_generic(vxlan->net, vxlan_net_id);
+
__u32 vni = vxlan->default_dst.remote_vni;
vxlan->vn_sock = vs;
+
+ spin_lock(&vn->sock_lock);
hlist_add_head_rcu(&vxlan->hlist, vni_head(vs, vni));
+ spin_unlock(&vn->sock_lock);
}
/* Setup stats when device is created */
static int vxlan_init(struct net_device *dev)
{
- struct vxlan_dev *vxlan = netdev_priv(dev);
- struct vxlan_net *vn = net_generic(vxlan->net, vxlan_net_id);
- struct vxlan_sock *vs;
- bool ipv6 = vxlan->flags & VXLAN_F_IPV6;
-
dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
if (!dev->tstats)
return -ENOMEM;
- spin_lock(&vn->sock_lock);
- vs = vxlan_find_sock(vxlan->net, ipv6 ? AF_INET6 : AF_INET,
- vxlan->dst_port);
- if (vs) {
- /* If we have a socket with same port already, reuse it */
- atomic_inc(&vs->refcnt);
- vxlan_vs_add_dev(vs, vxlan);
- } else {
- /* otherwise make new socket outside of RTNL */
- dev_hold(dev);
- queue_work(vxlan_wq, &vxlan->sock_work);
- }
- spin_unlock(&vn->sock_lock);
-
return 0;
}
@@ -2042,11 +2025,17 @@ static void vxlan_uninit(struct net_device *dev)
static int vxlan_open(struct net_device *dev)
{
struct vxlan_dev *vxlan = netdev_priv(dev);
- struct vxlan_sock *vs = vxlan->vn_sock;
+ struct vxlan_sock *vs;
- /* socket hasn't been created */
- if (!vs)
- return -ENOTCONN;
+ /* ip_mc_join_group/leave will acquire these in inverse order */
+ rtnl_unlock();
+ vs = vxlan_sock_add(vxlan->net, vxlan->dst_port, vxlan_rcv, NULL,
+ false, vxlan->flags);
+ rtnl_lock();
+ if (IS_ERR(vs))
+ return PTR_ERR(vs);
+
+ vxlan_vs_add_dev(vs, vxlan);
if (vxlan_addr_multicast(&vxlan->default_dst.remote_ip)) {
vxlan_sock_hold(vs);
@@ -2210,7 +2199,6 @@ static void vxlan_setup(struct net_device *dev)
spin_lock_init(&vxlan->hash_lock);
INIT_WORK(&vxlan->igmp_join, vxlan_igmp_join);
INIT_WORK(&vxlan->igmp_leave, vxlan_igmp_leave);
- INIT_WORK(&vxlan->sock_work, vxlan_sock_work);
init_timer_deferrable(&vxlan->age_timer);
vxlan->age_timer.function = vxlan_cleanup;
@@ -2355,6 +2343,8 @@ static struct vxlan_sock *vxlan_socket_create(struct net *net, __be16 port,
sock = vxlan_create_sock(net, ipv6, port, flags);
if (IS_ERR(sock)) {
+ pr_info("Cannot bind port %d, err=%d\n", ntohs(port),
+ PTR_ERR(sock));
kfree(vs);
return ERR_CAST(sock);
}
@@ -2393,48 +2383,21 @@ struct vxlan_sock *vxlan_sock_add(struct net *net, __be16 port,
struct vxlan_sock *vs;
bool ipv6 = flags & VXLAN_F_IPV6;
- vs = vxlan_socket_create(net, port, rcv, data, flags);
- if (!IS_ERR(vs))
- return vs;
-
- if (no_share) /* Return error if sharing is not allowed. */
- return vs;
-
- spin_lock(&vn->sock_lock);
- vs = vxlan_find_sock(net, ipv6 ? AF_INET6 : AF_INET, port);
- if (vs) {
- if (vs->rcv == rcv)
+ if (!no_share) {
+ spin_lock(&vn->sock_lock);
+ vs = vxlan_find_sock(net, ipv6 ? AF_INET6 : AF_INET, port);
+ if (vs && vs->rcv == rcv) {
atomic_inc(&vs->refcnt);
- else
- vs = ERR_PTR(-EBUSY);
+ spin_unlock(&vn->sock_lock);
+ return vs;
+ }
+ spin_unlock(&vn->sock_lock);
}
- spin_unlock(&vn->sock_lock);
- if (!vs)
- vs = ERR_PTR(-EINVAL);
-
- return vs;
+ return vxlan_socket_create(net, port, rcv, data, flags);
}
EXPORT_SYMBOL_GPL(vxlan_sock_add);
-/* Scheduled at device creation to bind to a socket */
-static void vxlan_sock_work(struct work_struct *work)
-{
- struct vxlan_dev *vxlan = container_of(work, struct vxlan_dev, sock_work);
- struct net *net = vxlan->net;
- struct vxlan_net *vn = net_generic(net, vxlan_net_id);
- __be16 port = vxlan->dst_port;
- struct vxlan_sock *nvs;
-
- nvs = vxlan_sock_add(net, port, vxlan_rcv, NULL, false, vxlan->flags);
- spin_lock(&vn->sock_lock);
- if (!IS_ERR(nvs))
- vxlan_vs_add_dev(nvs, vxlan);
- spin_unlock(&vn->sock_lock);
-
- dev_put(vxlan->dev);
-}
-
static int vxlan_newlink(struct net *net, struct net_device *dev,
struct nlattr *tb[], struct nlattr *data[])
{
--
1.9.3
--
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