ipv4: Implement __ip_dev_find using new interface address hash.

Much quicker than going through the FIB tables.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 33 insertions, 0 deletions

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 2fe50765a672..ee144a4fca41 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -125,6 +125,39 @@ static void inet_hash_remove(struct in_ifaddr *ifa)
 	spin_unlock(&inet_addr_hash_lock);
 }
 
+/**
+ * __ip_dev_find - find the first device with a given source address.
+ * @net: the net namespace
+ * @addr: the source address
+ * @devref: if true, take a reference on the found device
+ *
+ * If a caller uses devref=false, it should be protected by RCU, or RTNL
+ */
+struct net_device *__ip_dev_find(struct net *net, __be32 addr, bool devref)
+{
+	unsigned int hash = inet_addr_hash(net, addr);
+	struct net_device *result = NULL;
+	struct in_ifaddr *ifa;
+	struct hlist_node *node;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(ifa, node, &inet_addr_lst[hash], hash) {
+		struct net_device *dev = ifa->ifa_dev->dev;
+
+		if (!net_eq(dev_net(dev), net))
+			continue;
+		if (ifa->ifa_address == addr) {
+			result = dev;
+			break;
+		}
+	}
+	if (result && devref)
+		dev_hold(result);
+	rcu_read_unlock();
+	return result;
+}
+EXPORT_SYMBOL(__ip_dev_find);
+
 static void rtmsg_ifa(int event, struct in_ifaddr *, struct nlmsghdr *, u32);
 
 static BLOCKING_NOTIFIER_HEAD(inetaddr_chain);