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Diffstat (limited to 'net/ipv4/udp.c')
-rw-r--r--net/ipv4/udp.c22
1 files changed, 16 insertions, 6 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 16d246a51a02..62c19fdd102d 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1599,12 +1599,21 @@ static void flush_stack(struct sock **stack, unsigned int count,
kfree_skb(skb1);
}
-static void udp_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
+/* For TCP sockets, sk_rx_dst is protected by socket lock
+ * For UDP, we use sk_dst_lock to guard against concurrent changes.
+ */
+static void udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst)
{
- struct dst_entry *dst = skb_dst(skb);
+ struct dst_entry *old;
- dst_hold(dst);
- sk->sk_rx_dst = dst;
+ spin_lock(&sk->sk_dst_lock);
+ old = sk->sk_rx_dst;
+ if (likely(old != dst)) {
+ dst_hold(dst);
+ sk->sk_rx_dst = dst;
+ dst_release(old);
+ }
+ spin_unlock(&sk->sk_dst_lock);
}
/*
@@ -1737,10 +1746,11 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
sk = skb_steal_sock(skb);
if (sk) {
+ struct dst_entry *dst = skb_dst(skb);
int ret;
- if (unlikely(sk->sk_rx_dst == NULL))
- udp_sk_rx_dst_set(sk, skb);
+ if (unlikely(sk->sk_rx_dst != dst))
+ udp_sk_rx_dst_set(sk, dst);
ret = udp_queue_rcv_skb(sk, skb);
sock_put(sk);