v4.19.13 snapshot.
diff --git a/include/net/arp.h b/include/net/arp.h
new file mode 100644
index 0000000..977aabf
--- /dev/null
+++ b/include/net/arp.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* linux/net/inet/arp.h */
+#ifndef _ARP_H
+#define _ARP_H
+
+#include <linux/if_arp.h>
+#include <linux/hash.h>
+#include <net/neighbour.h>
+
+
+extern struct neigh_table arp_tbl;
+
+static inline u32 arp_hashfn(const void *pkey, const struct net_device *dev, u32 *hash_rnd)
+{
+ u32 key = *(const u32 *)pkey;
+ u32 val = key ^ hash32_ptr(dev);
+
+ return val * hash_rnd[0];
+}
+
+static inline struct neighbour *__ipv4_neigh_lookup_noref(struct net_device *dev, u32 key)
+{
+ if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
+ key = INADDR_ANY;
+
+ return ___neigh_lookup_noref(&arp_tbl, neigh_key_eq32, arp_hashfn, &key, dev);
+}
+
+static inline struct neighbour *__ipv4_neigh_lookup(struct net_device *dev, u32 key)
+{
+ struct neighbour *n;
+
+ rcu_read_lock_bh();
+ n = __ipv4_neigh_lookup_noref(dev, key);
+ if (n && !refcount_inc_not_zero(&n->refcnt))
+ n = NULL;
+ rcu_read_unlock_bh();
+
+ return n;
+}
+
+static inline void __ipv4_confirm_neigh(struct net_device *dev, u32 key)
+{
+ struct neighbour *n;
+
+ rcu_read_lock_bh();
+ n = __ipv4_neigh_lookup_noref(dev, key);
+ if (n) {
+ unsigned long now = jiffies;
+
+ /* avoid dirtying neighbour */
+ if (n->confirmed != now)
+ n->confirmed = now;
+ }
+ rcu_read_unlock_bh();
+}
+
+void arp_init(void);
+int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg);
+void arp_send(int type, int ptype, __be32 dest_ip,
+ struct net_device *dev, __be32 src_ip,
+ const unsigned char *dest_hw,
+ const unsigned char *src_hw, const unsigned char *th);
+int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir);
+void arp_ifdown(struct net_device *dev);
+
+struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
+ struct net_device *dev, __be32 src_ip,
+ const unsigned char *dest_hw,
+ const unsigned char *src_hw,
+ const unsigned char *target_hw);
+void arp_xmit(struct sk_buff *skb);
+
+#endif /* _ARP_H */