[PATCH v1 net-next 3/8] ipv4: Add wrappers for neigh_lookup() and neigh_create().

[Kuniyuki Iwashima <kuniyu@google.com>]

neigh_lookup() accepts struct neigh_table *tbl and struct
net_device *dev, and both of them must exist in the same
netns.

It is error-prone to require callers to fetch a netns and
get neigh_table, which might belong to a different netns
than dev_net(dev).

Let's add IPv4-specific wrappers for neigh_lookup() and
neigh_create() that always fetch netns from dev.

Note that we do not add wrappers for __neigh_lookup() and
__neigh_lookup_errno(), which we will remove later.

__neigh_lookup_errno() is a simple combo of neigh_lookup()
and neigh_create().  __neigh_lookup() is almost the same
but converts errno from neigh_create() to NULL.

So both names are confusing.

For IPv4, __neigh_lookup_errno() is only used in arp_req_set()
and is not worth a new wrapper.  Instead, it should be inlined.

arp_process() uses __neigh_lookup(create=0) but it should
simply be neigh_lookup(), and then __neigh_lookup(create=1)
is only used in arp_process(), so this should be inlined too.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
 include/net/arp.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/include/net/arp.h b/include/net/arp.h
index e932def63d62..329a5456987a 100644
--- a/include/net/arp.h
+++ b/include/net/arp.h
@@ -51,6 +51,22 @@ static inline struct neighbour *__ipv4_neigh_lookup(struct net_device *dev, u32
 	return n;
 }
 
+static inline struct neighbour *ipv4_neigh_lookup(struct net_device *dev,
+						  const void *pkey)
+{
+	struct neigh_table *tbl = arp_table(dev_net(dev));
+
+	return neigh_lookup(tbl, pkey, dev);
+}
+
+static inline struct neighbour *ipv4_neigh_create(struct net_device *dev,
+						  const void *pkey)
+{
+	struct neigh_table *tbl = arp_table(dev_net(dev));
+
+	return neigh_create(tbl, pkey, dev);
+}
+
 static inline void __ipv4_confirm_neigh(struct net_device *dev, u32 key)
 {
 	struct neighbour *n;
-- 
2.56.0.rc1.315.gc6ed9934b7-goog