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.c b/net/ipv4/tcp.c
index 64d0af6..cf13726 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2865,11 +2865,10 @@
 					(totalram_pages >= 128 * 1024) ?
 					13 : 15,
 					0,
-					&tcp_hashinfo.ehash_size,
 					NULL,
+					&tcp_hashinfo.ehash_mask,
 					thash_entries ? 0 : 512 * 1024);
-	tcp_hashinfo.ehash_size = 1 << tcp_hashinfo.ehash_size;
-	for (i = 0; i < tcp_hashinfo.ehash_size; i++) {
+	for (i = 0; i <= tcp_hashinfo.ehash_mask; i++) {
 		INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
 		INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].twchain, i);
 	}
@@ -2878,7 +2877,7 @@
 	tcp_hashinfo.bhash =
 		alloc_large_system_hash("TCP bind",
 					sizeof(struct inet_bind_hashbucket),
-					tcp_hashinfo.ehash_size,
+					tcp_hashinfo.ehash_mask + 1,
 					(totalram_pages >= 128 * 1024) ?
 					13 : 15,
 					0,
@@ -2933,8 +2932,8 @@
 	sysctl_tcp_rmem[2] = max(87380, max_share);
 
 	printk(KERN_INFO "TCP: Hash tables configured "
-	       "(established %d bind %d)\n",
-	       tcp_hashinfo.ehash_size, tcp_hashinfo.bhash_size);
+	       "(established %u bind %u)\n",
+	       tcp_hashinfo.ehash_mask + 1, tcp_hashinfo.bhash_size);
 
 	tcp_register_congestion_control(&tcp_reno);
 }