diff options
| author | Pravin B Shelar <pshelar@nicira.com> | 2013-09-24 10:25:40 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-09-30 14:22:59 -0400 |
| commit | 559835ea7292e2f09304d81eda16f4209433245e (patch) | |
| tree | 516a56d352969181deffa05466c7a0cfd0e15dc1 | |
| parent | 9a3bab6b05383f1e4c3716b3615500c51285959e (diff) | |
vxlan: Use RCU apis to access sk_user_data.
Use of RCU api makes vxlan code easier to understand. It also
fixes bug due to missing ACCESS_ONCE() on sk_user_data dereference.
In rare case without ACCESS_ONCE() compiler might omit vs on
sk_user_data dereference.
Compiler can use vs as alias for sk->sk_user_data, resulting in
multiple sk_user_data dereference in rcu read context which
could change.
CC: Jesse Gross <jesse@nicira.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/vxlan.c | 9 | ||||
| -rw-r--r-- | include/net/sock.h | 5 |
2 files changed, 8 insertions, 6 deletions
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index d1292fe746bc..2ef5b6219f3f 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -952,8 +952,7 @@ void vxlan_sock_release(struct vxlan_sock *vs) spin_lock(&vn->sock_lock); hlist_del_rcu(&vs->hlist); - smp_wmb(); - vs->sock->sk->sk_user_data = NULL; + rcu_assign_sk_user_data(vs->sock->sk, NULL); vxlan_notify_del_rx_port(sk); spin_unlock(&vn->sock_lock); @@ -1048,8 +1047,7 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb) port = inet_sk(sk)->inet_sport; - smp_read_barrier_depends(); - vs = (struct vxlan_sock *)sk->sk_user_data; + vs = rcu_dereference_sk_user_data(sk); if (!vs) goto drop; @@ -2302,8 +2300,7 @@ static struct vxlan_sock *vxlan_socket_create(struct net *net, __be16 port, atomic_set(&vs->refcnt, 1); vs->rcv = rcv; vs->data = data; - smp_wmb(); - vs->sock->sk->sk_user_data = vs; + rcu_assign_sk_user_data(vs->sock->sk, vs); spin_lock(&vn->sock_lock); hlist_add_head_rcu(&vs->hlist, vs_head(net, port)); diff --git a/include/net/sock.h b/include/net/sock.h index 6ba2e7b0e2b1..1d37a8086bed 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -409,6 +409,11 @@ struct sock { void (*sk_destruct)(struct sock *sk); }; +#define __sk_user_data(sk) ((*((void __rcu **)&(sk)->sk_user_data))) + +#define rcu_dereference_sk_user_data(sk) rcu_dereference(__sk_user_data((sk))) +#define rcu_assign_sk_user_data(sk, ptr) rcu_assign_pointer(__sk_user_data((sk)), ptr) + /* * SK_CAN_REUSE and SK_NO_REUSE on a socket mean that the socket is OK * or not whether his port will be reused by someone else. SK_FORCE_REUSE |