tcp: refresh skb timestamp at retransmit time

In the very unlikely case __tcp_retransmit_skb() can not use the cloning
done in tcp_transmit_skb(), we need to refresh skb_mstamp before doing
the copy and transmit, otherwise TCP TS val will be an exact copy of
original transmit.

Fixes: 7faee5c0d514 ("tcp: remove TCP_SKB_CB(skb)->when")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 441ae9d..79a03b8 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2640,8 +2640,10 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
         */
        if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) ||
                     skb_headroom(skb) >= 0xFFFF)) {
-               struct sk_buff *nskb = __pskb_copy(skb, MAX_TCP_HEADER,
-                                                  GFP_ATOMIC);
+               struct sk_buff *nskb;
+
+               skb_mstamp_get(&skb->skb_mstamp);
+               nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC);
                err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) :
                             -ENOBUFS;
        } else {