tcp: replace ehash_size by ehash_mask

Storing the mask (size - 1) instead of the size allows fast path to be
a bit faster.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 7cda24b..9971870 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2000,7 +2000,7 @@
 	struct net *net = seq_file_net(seq);
 	void *rc = NULL;
 
-	for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) {
+	for (st->bucket = 0; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) {
 		struct sock *sk;
 		struct hlist_nulls_node *node;
 		struct inet_timewait_sock *tw;
@@ -2061,10 +2061,10 @@
 		st->state = TCP_SEQ_STATE_ESTABLISHED;
 
 		/* Look for next non empty bucket */
-		while (++st->bucket < tcp_hashinfo.ehash_size &&
+		while (++st->bucket <= tcp_hashinfo.ehash_mask &&
 				empty_bucket(st))
 			;
-		if (st->bucket >= tcp_hashinfo.ehash_size)
+		if (st->bucket > tcp_hashinfo.ehash_mask)
 			return NULL;
 
 		spin_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));