tcp: more aggressive skipping

I knew already when rewriting the sacktag that this condition
was too conservative, change it now since it prevent lot of
useless work (especially in the sack shifter decision code
that is being added by a later patch). This shouldn't change
anything really, just save some processing regardless of the
shifter.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_input.c

@@ -1402,7 +1402,7 @@ static struct sk_buff *tcp_sacktag_skip(struct sk_buff *skb, struct sock *sk,
 		if (skb == tcp_send_head(sk))
 			break;
 
-		if (!before(TCP_SKB_CB(skb)->end_seq, skip_to_seq))
+		if (after(TCP_SKB_CB(skb)->end_seq, skip_to_seq))
 			break;
 
 		*fack_count += tcp_skb_pcount(skb);