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/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index d522dcf..5f11c4a 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -125,7 +125,7 @@
 	 */
 	struct inet_ehash_bucket	*ehash;
 	spinlock_t			*ehash_locks;
-	unsigned int			ehash_size;
+	unsigned int			ehash_mask;
 	unsigned int			ehash_locks_mask;
 
 	/* Ok, let's try this, I give up, we do need a local binding
@@ -158,7 +158,7 @@
 	struct inet_hashinfo *hashinfo,
 	unsigned int hash)
 {
-	return &hashinfo->ehash[hash & (hashinfo->ehash_size - 1)];
+	return &hashinfo->ehash[hash & hashinfo->ehash_mask];
 }
 
 static inline spinlock_t *inet_ehash_lockp(