vxlan: Split vxlan_fdb_update() in two

In order to make it easier to implement rollbacks after FDB update
vetoing, separate the FDB update code to two parts: one that deals with
updates of existing FDB entries, and one that creates new entries.
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vxlan.c

@@ -855,30 +855,21 @@ static void vxlan_fdb_destroy(struct vxlan_dev *vxlan, struct vxlan_fdb *f,
 	call_rcu(&f->rcu, vxlan_fdb_free);
 }
 
-/* Add new entry to forwarding table -- assumes lock held */
-static int vxlan_fdb_update(struct vxlan_dev *vxlan,
-			    const u8 *mac, union vxlan_addr *ip,
+static int vxlan_fdb_update_existing(struct vxlan_dev *vxlan,
+				     union vxlan_addr *ip,
 				     __u16 state, __u16 flags,
-			    __be16 port, __be32 src_vni, __be32 vni,
+				     __be16 port, __be32 vni,
 				     __u32 ifindex, __u16 ndm_flags,
+				     struct vxlan_fdb *f,
 				     bool swdev_notify)
 {
 	__u16 fdb_flags = (ndm_flags & ~NTF_USE);
 	struct vxlan_rdst *rd = NULL;
-	struct vxlan_fdb *f;
 	int notify = 0;
 	int rc;
 
-	f = __vxlan_find_mac(vxlan, mac, src_vni);
-	if (f) {
-		if (flags & NLM_F_EXCL) {
-			netdev_dbg(vxlan->dev,
-				   "lost race to create %pM\n", mac);
-			return -EEXIST;
-		}
-
-		/* Do not allow an externally learned entry to take over an
-		 * entry added by the user.
+	/* Do not allow an externally learned entry to take over an entry added
+	 * by the user.
 	 */
 	if (!(fdb_flags & NTF_EXT_LEARNED) ||
 	    !(f->flags & NTF_VXLAN_ADDED_BY_USER)) {
@@ -898,11 +889,13 @@ static int vxlan_fdb_update(struct vxlan_dev *vxlan,
 		/* Only change unicasts */
 		if (!(is_multicast_ether_addr(f->eth_addr) ||
 		      is_zero_ether_addr(f->eth_addr))) {
-				notify |= vxlan_fdb_replace(f, ip, port, vni,
+			rc = vxlan_fdb_replace(f, ip, port, vni,
 					       ifindex);
-			} else
+			notify |= rc;
+		} else {
 			return -EOPNOTSUPP;
 		}
+	}
 	if ((flags & NLM_F_APPEND) &&
 	    (is_multicast_ether_addr(f->eth_addr) ||
 	     is_zero_ether_addr(f->eth_addr))) {
@@ -915,9 +908,27 @@ static int vxlan_fdb_update(struct vxlan_dev *vxlan,
 
 	if (ndm_flags & NTF_USE)
 		f->used = jiffies;
-	} else {
-		if (!(flags & NLM_F_CREATE))
-			return -ENOENT;
+
+	if (notify) {
+		if (rd == NULL)
+			rd = first_remote_rtnl(f);
+
+		vxlan_fdb_notify(vxlan, f, rd, RTM_NEWNEIGH, swdev_notify);
+	}
+
+	return 0;
+}
+
+static int vxlan_fdb_update_create(struct vxlan_dev *vxlan,
+				   const u8 *mac, union vxlan_addr *ip,
+				   __u16 state, __u16 flags,
+				   __be16 port, __be32 src_vni, __be32 vni,
+				   __u32 ifindex, __u16 ndm_flags,
+				   bool swdev_notify)
+{
+	__u16 fdb_flags = (ndm_flags & ~NTF_USE);
+	struct vxlan_fdb *f;
+	int rc;
 
 	/* Disallow replace to add a multicast entry */
 	if ((flags & NLM_F_REPLACE) &&
@@ -929,16 +940,41 @@ static int vxlan_fdb_update(struct vxlan_dev *vxlan,
 			      vni, ifindex, fdb_flags, &f);
 	if (rc < 0)
 		return rc;
-		notify = 1;
-	}
 
-	if (notify) {
-		if (rd == NULL)
-			rd = first_remote_rtnl(f);
-		vxlan_fdb_notify(vxlan, f, rd, RTM_NEWNEIGH, swdev_notify);
+	vxlan_fdb_notify(vxlan, f, first_remote_rtnl(f), RTM_NEWNEIGH,
+			 swdev_notify);
+	return 0;
+}
+
+/* Add new entry to forwarding table -- assumes lock held */
+static int vxlan_fdb_update(struct vxlan_dev *vxlan,
+			    const u8 *mac, union vxlan_addr *ip,
+			    __u16 state, __u16 flags,
+			    __be16 port, __be32 src_vni, __be32 vni,
+			    __u32 ifindex, __u16 ndm_flags,
+			    bool swdev_notify)
+{
+	struct vxlan_fdb *f;
+
+	f = __vxlan_find_mac(vxlan, mac, src_vni);
+	if (f) {
+		if (flags & NLM_F_EXCL) {
+			netdev_dbg(vxlan->dev,
+				   "lost race to create %pM\n", mac);
+			return -EEXIST;
 		}
 
-	return 0;
+		return vxlan_fdb_update_existing(vxlan, ip, state, flags, port,
+						 vni, ifindex, ndm_flags, f,
+						 swdev_notify);
+	} else {
+		if (!(flags & NLM_F_CREATE))
+			return -ENOENT;
+
+		return vxlan_fdb_update_create(vxlan, mac, ip, state, flags,
+					       port, src_vni, vni, ifindex,
+					       ndm_flags, swdev_notify);
+	}
 }
 
 static void vxlan_dst_free(struct rcu_head *head)