[PATCH for 3.18] ipv4: Map neigh lookup keys in __ipv4_neigh_lookup_noref()

[Wang Han <wanghan1995315@gmail.com>]

As discussed earlier,

From: Wang Han <wanghan1995315@gmail.com>
Date: Sat, 3 Feb 2018 03:28:35 +1400
Subject: [PATCH] ipv4: Map neigh lookup keys in __ipv4_neigh_lookup_noref()

Commit 6c16fa957e84 is an incorrect backport as we map the keys in
struct __ipv4_neigh_lookup(), but the correct place to add the
code is struct __ipv4_neigh_lookup_noref(), compared to upstream.

Fix it by moving the code, or fewer cases will be covered as
__ipv4_neigh_lookup_noref() will be called unconditionally from
__ipv4_neigh_lookup(), and it can be called from other places
such as ip_output.c.

Fixes: 6c16fa957e84 (ipv4: Make neigh lookup keys for loopback/point-to-point devices be INADDR_ANY)
Signed-off-by: Wang Han <wanghan1995315@gmail.com>
---
 include/net/arp.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/net/arp.h b/include/net/arp.h
index 174014585ade..5d8c7990582f 100644
--- a/include/net/arp.h
+++ b/include/net/arp.h
@@ -22,6 +22,9 @@ static inline struct neighbour *__ipv4_neigh_lookup_noref(struct net_device *dev
 	struct neighbour *n;
 	u32 hash_val;
 
+	if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
+		key = INADDR_ANY;
+
 	hash_val = arp_hashfn(key, dev, nht->hash_rnd[0]) >> (32 - nht->hash_shift);
 	for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]);
 	     n != NULL;
@@ -37,9 +40,6 @@ static inline struct neighbour *__ipv4_neigh_lookup(struct net_device *dev, u32
 {
 	struct neighbour *n;
 
-	if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
-		key = INADDR_ANY;
-
 	rcu_read_lock_bh();
 	n = __ipv4_neigh_lookup_noref(dev, key);
 	if (n && !atomic_inc_not_zero(&n->refcnt))
-- 
2.14.1