tcp: align tcp_xmit_size_goal() on tcp_tso_autosize()
With some mss values, it is possible tcp_xmit_size_goal() puts
one segment more in TSO packet than tcp_tso_autosize().
We send then one TSO packet followed by one single MSS.
It is not a serious bug, but we can do slightly better, especially
for drivers using netif_set_gso_max_size() to lower gso_max_size.
Using same formula avoids these corner cases and makes
tcp_xmit_size_goal() a bit faster.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 605ad7f184b6 ("tcp: refine TSO autosizing")
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 9d72a0f..995a225 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -835,17 +835,13 @@
int large_allowed)
{
struct tcp_sock *tp = tcp_sk(sk);
- u32 new_size_goal, size_goal, hlen;
+ u32 new_size_goal, size_goal;
if (!large_allowed || !sk_can_gso(sk))
return mss_now;
- /* Maybe we should/could use sk->sk_prot->max_header here ? */
- hlen = inet_csk(sk)->icsk_af_ops->net_header_len +
- inet_csk(sk)->icsk_ext_hdr_len +
- tp->tcp_header_len;
-
- new_size_goal = sk->sk_gso_max_size - 1 - hlen;
+ /* Note : tcp_tso_autosize() will eventually split this later */
+ new_size_goal = sk->sk_gso_max_size - 1 - MAX_TCP_HEADER;
new_size_goal = tcp_bound_to_half_wnd(tp, new_size_goal);
/* We try hard to avoid divides here */