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authorPravin B Shelar <pshelar@nicira.com>2013-09-24 10:25:40 -0700
committerDavid S. Miller <davem@davemloft.net>2013-09-30 14:22:59 -0400
commit559835ea7292e2f09304d81eda16f4209433245e (patch)
tree516a56d352969181deffa05466c7a0cfd0e15dc1
parent9a3bab6b05383f1e4c3716b3615500c51285959e (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.c9
-rw-r--r--include/net/sock.h5
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