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/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 13f0781..2fe5711 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -430,7 +430,7 @@
 	int h;
 
 	local_bh_disable();
-	for (h = 0; h < (hashinfo->ehash_size); h++) {
+	for (h = 0; h <= hashinfo->ehash_mask; h++) {
 		struct inet_ehash_bucket *head =
 			inet_ehash_bucket(hashinfo, h);
 		spinlock_t *lock = inet_ehash_lockp(hashinfo, h);