Re: [PATCH 1/2] ipv4: Add hash table of interface addresses.

This will be used to optimize __ip_dev_find() and friends.

Signed-off-by: David S. Miller <davem@davemloft.net>
---
 include/linux/inetdevice.h |    1 +
 net/ipv4/devinet.c         |   44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 0 deletions(-)

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index ae8fdc5..5f81466 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h

@@ -144,6 +144,7 @@ static inline void ipv4_devconf_setall(struct in_device *in_dev)
 #define IN_DEV_ARP_NOTIFY(in_dev)	IN_DEV_MAXCONF((in_dev), ARP_NOTIFY)
 
 struct in_ifaddr {
+	struct hlist_node	hash;
 	struct in_ifaddr	*ifa_next;
 	struct in_device	*ifa_dev;
 	struct rcu_head		rcu_head;

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 748cb5b..c1f2552 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c

@@ -92,6 +92,38 @@ static const struct nla_policy ifa_ipv4_policy[IFA_MAX+1] = {
 	[IFA_LABEL]     	= { .type = NLA_STRING, .len = IFNAMSIZ - 1 },
 };
 
+/* inet_addr_hash's shifting is dependent upon this IN4_ADDR_HSIZE
+ * value.  So if you change this define, make appropriate changes to
+ * inet_addr_hash as well.
+ */
+#define IN4_ADDR_HSIZE	256
+static struct hlist_head inet_addr_lst[IN4_ADDR_HSIZE];
+static DEFINE_SPINLOCK(inet_addr_hash_lock);
+
+static inline unsigned int inet_addr_hash(__be32 addr)
+{
+	u32 val = (__force u32) addr;
+
+	return ((val ^ (val >> 8) ^ (val >> 16) ^ (val >> 24)) &
+		(IN4_ADDR_HSIZE - 1));
+}