tcp: fix retrans_out leaks

There's conflicting assumptions in shifting, the caller assumes
that dupsack results in S'ed skbs (or a part of it) for sure but
never gave a hint to tcp_sacktag_one when dsack is actually in
use. Thus DSACK retrans_out -= pcount was not taken and the
counter became out of sync. Remove obstacle from that information
flow to get DSACKs accounted in tcp_sacktag_one as expected.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Tested-by: Denys Fedoryshchenko <denys@visp.net.lb>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 4 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a6961d75c7ea..c28976a7e596 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1374,7 +1374,8 @@ static u8 tcp_sacktag_one(struct sk_buff *skb, struct sock *sk,
 
 static int tcp_shifted_skb(struct sock *sk, struct sk_buff *skb,
                            struct tcp_sacktag_state *state,
-                           unsigned int pcount, int shifted, int mss)
+                           unsigned int pcount, int shifted, int mss,
+                           int dup_sack)
 {
         struct tcp_sock *tp = tcp_sk(sk);
         struct sk_buff *prev = tcp_write_queue_prev(sk, skb);
@@ -1410,7 +1411,7 @@ static int tcp_shifted_skb(struct sock *sk, struct sk_buff *skb,
         }
 
         /* We discard results */
-        tcp_sacktag_one(skb, sk, state, 0, pcount);
+        tcp_sacktag_one(skb, sk, state, dup_sack, pcount);
 
         /* Difference in this won't matter, both ACKed by the same cumul. ACK */
         TCP_SKB_CB(prev)->sacked |= (TCP_SKB_CB(skb)->sacked & TCPCB_EVER_RETRANS);
@@ -1561,7 +1562,7 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
 
         if (!skb_shift(prev, skb, len))
                 goto fallback;
-        if (!tcp_shifted_skb(sk, skb, state, pcount, len, mss))
+        if (!tcp_shifted_skb(sk, skb, state, pcount, len, mss, dup_sack))
                 goto out;
 
         /* Hole filled allows collapsing with the next as well, this is very
@@ -1580,7 +1581,7 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
         len = skb->len;
         if (skb_shift(prev, skb, len)) {
                 pcount += tcp_skb_pcount(skb);
-                tcp_shifted_skb(sk, skb, state, tcp_skb_pcount(skb), len, mss);
+                tcp_shifted_skb(sk, skb, state, tcp_skb_pcount(skb), len, mss, 0);
         }
 
 out: