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>

2 files changed, 7 insertions, 1 deletions

diff --git a/include/linux/udp.h b/include/linux/udp.h
index 832361e3e59..5b4b5274e68 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -55,6 +55,8 @@ static inline int udp_hashfn(struct net *net, unsigned num, unsigned mask)
 struct udp_sock {
         /* inet_sock has to be the first member */
         struct inet_sock inet;
+#define udp_port_hash           inet.sk.__sk_common.skc_u16hashes[0]
+#define udp_portaddr_hash       inet.sk.__sk_common.skc_u16hashes[1]
         int              pending;       /* Any pending frames ? */
         unsigned int     corkflag;      /* Cork is required */
         __u16            encap_type;    /* Is this an Encapsulation socket? */
diff --git a/include/net/sock.h b/include/net/sock.h
index 55de3bd719a..827366b6268 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;