ipv6: avoid dev_hold()/dev_put() in rawv6_bind()

Using RCU helps not touching device refcount in rawv6_bind()

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 818ef21..926ce8e 100644 (file)
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -249,7 +249,7 @@ static int rawv6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 
        /* Raw sockets are IPv6 only */
        if (addr_type == IPV6_ADDR_MAPPED)
-               return(-EADDRNOTAVAIL);
+               return -EADDRNOTAVAIL;
 
        lock_sock(sk);
 
@@ -257,6 +257,7 @@ static int rawv6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
        if (sk->sk_state != TCP_CLOSE)
                goto out;
 
+       rcu_read_lock();
        /* Check if the address belongs to the host. */
        if (addr_type != IPV6_ADDR_ANY) {
                struct net_device *dev = NULL;
@@ -272,13 +273,13 @@ static int rawv6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 
                        /* Binding to link-local address requires an interface */
                        if (!sk->sk_bound_dev_if)
-                               goto out;
+                               goto out_unlock;
 
-                       dev = dev_get_by_index(sock_net(sk), sk->sk_bound_dev_if);
-                       if (!dev) {
-                               err = -ENODEV;
-                               goto out;
-                       }
+                       err = -ENODEV;
+                       dev = dev_get_by_index_rcu(sock_net(sk),
+                                                  sk->sk_bound_dev_if);
+                       if (!dev)
+                               goto out_unlock;
                }
 
                /* ipv4 addr of the socket is invalid.  Only the
@@ -289,13 +290,9 @@ static int rawv6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
                        err = -EADDRNOTAVAIL;
                        if (!ipv6_chk_addr(sock_net(sk), &addr->sin6_addr,
                                           dev, 0)) {
-                               if (dev)
-                                       dev_put(dev);
-                               goto out;
+                               goto out_unlock;
                        }
                }
-               if (dev)
-                       dev_put(dev);
        }
 
        inet->inet_rcv_saddr = inet->inet_saddr = v4addr;
@@ -303,6 +300,8 @@ static int rawv6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
        if (!(addr_type & IPV6_ADDR_MULTICAST))
                ipv6_addr_copy(&np->saddr, &addr->sin6_addr);
        err = 0;
+out_unlock:
+       rcu_read_unlock();
 out:
        release_sock(sk);
        return err;