vxlan: Create wrappers for FDB lookup

__vxlan_find_mac() is called from both the data path (e.g., during
learning) and the control path (e.g., when replacing an entry). The
function is missing lockdep annotations to make sure that the FDB hash
lock is held during FDB updates.

Rename __vxlan_find_mac() to vxlan_find_mac_rcu() to reflect the fact
that it should be called from an RCU read-side critical section and call
it from vxlan_find_mac() which checks that the FDB hash lock is held.
Change callers to invoke the appropriate function.

Reviewed-by: Petr Machata <[email protected]>
Signed-off-by: Ido Schimmel <[email protected]>
Link: https://patch.msgid.link/[email protected]
Reviewed-by: Nikolay Aleksandrov <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

Author: idosch

drivers/net/vxlan/vxlan_core.c

@@ -409,8 +409,8 @@ static inline struct hlist_head *vxlan_fdb_head(struct vxlan_dev *vxlan,
 }
 
 /* Look up Ethernet address in forwarding table */
-static struct vxlan_fdb *__vxlan_find_mac(struct vxlan_dev *vxlan,
-					  const u8 *mac, __be32 vni)
+static struct vxlan_fdb *vxlan_find_mac_rcu(struct vxlan_dev *vxlan,
+					    const u8 *mac, __be32 vni)
 {
 	struct hlist_head *head = vxlan_fdb_head(vxlan, mac, vni);
 	struct vxlan_fdb *f;
@@ -434,7 +434,7 @@ static struct vxlan_fdb *vxlan_find_mac_tx(struct vxlan_dev *vxlan,
 {
 	struct vxlan_fdb *f;
 
-	f = __vxlan_find_mac(vxlan, mac, vni);
+	f = vxlan_find_mac_rcu(vxlan, mac, vni);
 	if (f) {
 		unsigned long now = jiffies;
 
@@ -445,6 +445,20 @@ static struct vxlan_fdb *vxlan_find_mac_tx(struct vxlan_dev *vxlan,
 	return f;
 }
 
+static struct vxlan_fdb *vxlan_find_mac(struct vxlan_dev *vxlan,
+					const u8 *mac, __be32 vni)
+{
+	struct vxlan_fdb *f;
+
+	lockdep_assert_held_once(&vxlan->hash_lock);
+
+	rcu_read_lock();
+	f = vxlan_find_mac_rcu(vxlan, mac, vni);
+	rcu_read_unlock();
+
+	return f;
+}
+
 /* caller should hold vxlan->hash_lock */
 static struct vxlan_rdst *vxlan_fdb_find_rdst(struct vxlan_fdb *f,
 					      union vxlan_addr *ip, __be16 port,
@@ -480,7 +494,7 @@ int vxlan_fdb_find_uc(struct net_device *dev, const u8 *mac, __be32 vni,
 
 	rcu_read_lock();
 
-	f = __vxlan_find_mac(vxlan, eth_addr, vni);
+	f = vxlan_find_mac_rcu(vxlan, eth_addr, vni);
 	if (!f) {
 		rc = -ENOENT;
 		goto out;
@@ -1117,7 +1131,7 @@ int vxlan_fdb_update(struct vxlan_dev *vxlan,
 {
 	struct vxlan_fdb *f;
 
-	f = __vxlan_find_mac(vxlan, mac, src_vni);
+	f = vxlan_find_mac(vxlan, mac, src_vni);
 	if (f) {
 		if (flags & NLM_F_EXCL) {
 			netdev_dbg(vxlan->dev,
@@ -1286,7 +1300,7 @@ int __vxlan_fdb_delete(struct vxlan_dev *vxlan,
 	struct vxlan_fdb *f;
 	int err = -ENOENT;
 
-	f = __vxlan_find_mac(vxlan, addr, src_vni);
+	f = vxlan_find_mac(vxlan, addr, src_vni);
 	if (!f)
 		return err;
 
@@ -1409,7 +1423,7 @@ static int vxlan_fdb_get(struct sk_buff *skb,
 
 	rcu_read_lock();
 
-	f = __vxlan_find_mac(vxlan, addr, vni);
+	f = vxlan_find_mac_rcu(vxlan, addr, vni);
 	if (!f) {
 		NL_SET_ERR_MSG(extack, "Fdb entry not found");
 		err = -ENOENT;
@@ -1445,7 +1459,7 @@ static enum skb_drop_reason vxlan_snoop(struct net_device *dev,
 		ifindex = src_ifindex;
 #endif
 
-	f = __vxlan_find_mac(vxlan, src_mac, vni);
+	f = vxlan_find_mac_rcu(vxlan, src_mac, vni);
 	if (likely(f)) {
 		struct vxlan_rdst *rdst = first_remote_rcu(f);
 		unsigned long now = jiffies;
@@ -4727,7 +4741,7 @@ vxlan_fdb_offloaded_set(struct net_device *dev,
 
 	spin_lock_bh(&vxlan->hash_lock);
 
-	f = __vxlan_find_mac(vxlan, fdb_info->eth_addr, fdb_info->vni);
+	f = vxlan_find_mac(vxlan, fdb_info->eth_addr, fdb_info->vni);
 	if (!f)
 		goto out;
 
@@ -4779,7 +4793,7 @@ vxlan_fdb_external_learn_del(struct net_device *dev,
 
 	spin_lock_bh(&vxlan->hash_lock);
 
-	f = __vxlan_find_mac(vxlan, fdb_info->eth_addr, fdb_info->vni);
+	f = vxlan_find_mac(vxlan, fdb_info->eth_addr, fdb_info->vni);
 	if (!f)
 		err = -ENOENT;
 	else if (f->flags & NTF_EXT_LEARNED)