tcp: Apply device TSO segment limit earlier
Cache the device gso_max_segs in sock::sk_gso_max_segs and use it to
limit the size of TSO skbs. This avoids the need to fall back to
software GSO for local TCP senders.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 4d4db16..1432cdb 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -291,7 +291,8 @@
left = tp->snd_cwnd - in_flight;
if (sk_can_gso(sk) &&
left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd &&
- left * tp->mss_cache < sk->sk_gso_max_size)
+ left * tp->mss_cache < sk->sk_gso_max_size &&
+ left < sk->sk_gso_max_segs)
return true;
return left <= tcp_max_tso_deferred_mss(tp);
}