udp: introduce a udp_hashfn function

Currently the chain to store a UDP socket is calculated with
simple (x & (UDP_HTABLE_SIZE - 1)). But taking net into account
would make this calculation a bit more complex, so moving it into
a function would help.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/udp.h b/include/linux/udp.h
index 581ca2c14c52..9c94312b2de5 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -46,6 +46,11 @@ static inline struct udphdr *udp_hdr(const struct sk_buff *skb)
 
 #define UDP_HTABLE_SIZE         128
 
+static inline int udp_hashfn(const unsigned num)
+{
+        return num & (UDP_HTABLE_SIZE - 1);
+}
+
 struct udp_sock {
         /* inet_sock has to be the first member */
         struct inet_sock inet;