bonding: add helper function bond_get_targets_ip(targets, ip)

Add function bond_get_targets_ip(targets, ip) which searches through
targets array of ips (arp_targets) and returns the position of first
match. If ip == 0, returns the first free slot. On failure to find the
ip or free slot, return -1.

Use it to verify if the arp we've received is valid and in sysfs.

v1->v2:
Fix "[2/6] bonding: add helper function bond_get_targets_ip(targets, ip)",
per Nikolay's advice, to verify if source ip != 0.0.0.0, otherwise we might
update 'null' arp_ip_targets' last_rx. Also, address style.

Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index c990b42..486e532 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -464,6 +464,22 @@
 	return NULL;
 }
 
+/* Check if the ip is present in arp ip list, or first free slot if ip == 0
+ * Returns -1 if not found, index if found
+ */
+static inline int bond_get_targets_ip(__be32 *targets, __be32 ip)
+{
+	int i;
+
+	for (i = 0; i < BOND_MAX_ARP_TARGETS; i++)
+		if (targets[i] == ip)
+			return i;
+		else if (targets[i] == 0)
+			break;
+
+	return -1;
+}
+
 /* exported from bond_main.c */
 extern int bond_net_id;
 extern const struct bond_parm_tbl bond_lacp_tbl[];