udp: split sk_hash into two u16 hashes

Union sk_hash with two u16 hashes for udp (no extra memory taken)

One 16 bits hash on (local port) value (the previous udp 'hash')

One 16 bits hash on (local address, local port) values, initialized
but not yet used. This second hash is using jenkin hash for better
distribution.

Because the 'port' is xored later, a partial hash is performed
on local address + net_hash_mix(net)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index 55de3bd719a5..827366b62680 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -109,6 +109,7 @@ struct net;
  *      @skc_refcnt: reference count
  *      @skc_tx_queue_mapping: tx queue number for this connection
  *      @skc_hash: hash value used with various protocol lookup tables
+ *      @skc_u16hashes: two u16 hash values used by UDP lookup tables
  *      @skc_family: network address family
  *      @skc_state: Connection state
  *      @skc_reuse: %SO_REUSEADDR setting
@@ -131,7 +132,10 @@ struct sock_common {
         atomic_t                skc_refcnt;
         int                     skc_tx_queue_mapping;
 
-        unsigned int            skc_hash;
+        union  {
+                unsigned int    skc_hash;
+                __u16           skc_u16hashes[2];
+        };
         unsigned short          skc_family;
         volatile unsigned char  skc_state;
         unsigned char           skc_reuse;