net: hsr: fix hsr build error when lockdep is not enabled

In hsr, lockdep_is_held() is needed for rcu_dereference_bh_check().
But if lockdep is not enabled, lockdep_is_held() causes a build error:

    ERROR: modpost: "lockdep_is_held" [net/hsr/hsr.ko] undefined!

Thus, this patch solved by adding lockdep_hsr_is_held(). This helper
function calls the lockdep_is_held() when lockdep is enabled, and returns 1
if not defined.

Fixes: e7f2742 ("net: hsr: fix suspicious RCU usage warning in hsr_node_get_first()")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Juhee Kang <claudiajkang@gmail.com>
Link: https://lore.kernel.org/r/20220220153250.5285-1-claudiajkang@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/hsr/hsr_framereg.c

@@ -20,18 +20,26 @@
 #include "hsr_framereg.h"
 #include "hsr_netlink.h"
 
+#ifdef CONFIG_LOCKDEP
+int lockdep_hsr_is_held(spinlock_t *lock)
+{
+	return lockdep_is_held(lock);
+}
+#endif
+
 u32 hsr_mac_hash(struct hsr_priv *hsr, const unsigned char *addr)
 {
 	u32 hash = jhash(addr, ETH_ALEN, hsr->hash_seed);
 
 	return reciprocal_scale(hash, hsr->hash_buckets);
 }
 
-struct hsr_node *hsr_node_get_first(struct hlist_head *head, int cond)
+struct hsr_node *hsr_node_get_first(struct hlist_head *head, spinlock_t *lock)
 {
 	struct hlist_node *first;
 
-	first = rcu_dereference_bh_check(hlist_first_rcu(head), cond);
+	first = rcu_dereference_bh_check(hlist_first_rcu(head),
+					 lockdep_hsr_is_held(lock));
 	if (first)
 		return hlist_entry(first, struct hsr_node, mac_list);
 
@@ -59,8 +67,7 @@ bool hsr_addr_is_self(struct hsr_priv *hsr, unsigned char *addr)
 {
 	struct hsr_node *node;
 
-	node = hsr_node_get_first(&hsr->self_node_db,
-				  lockdep_is_held(&hsr->list_lock));
+	node = hsr_node_get_first(&hsr->self_node_db, &hsr->list_lock);
 	if (!node) {
 		WARN_ONCE(1, "HSR: No self node\n");
 		return false;
@@ -107,8 +114,7 @@ int hsr_create_self_node(struct hsr_priv *hsr,
 	ether_addr_copy(node->macaddress_B, addr_b);
 
 	spin_lock_bh(&hsr->list_lock);
-	oldnode = hsr_node_get_first(self_node_db,
-				     lockdep_is_held(&hsr->list_lock));
+	oldnode = hsr_node_get_first(self_node_db, &hsr->list_lock);
 	if (oldnode) {
 		hlist_replace_rcu(&oldnode->mac_list, &node->mac_list);
 		spin_unlock_bh(&hsr->list_lock);
@@ -127,8 +133,7 @@ void hsr_del_self_node(struct hsr_priv *hsr)
 	struct hsr_node *node;
 
 	spin_lock_bh(&hsr->list_lock);
-	node = hsr_node_get_first(self_node_db,
-				  lockdep_is_held(&hsr->list_lock));
+	node = hsr_node_get_first(self_node_db, &hsr->list_lock);
 	if (node) {
 		hlist_del_rcu(&node->mac_list);
 		kfree_rcu(node, rcu_head);
@@ -194,7 +199,7 @@ static struct hsr_node *hsr_add_node(struct hsr_priv *hsr,
 
 	spin_lock_bh(&hsr->list_lock);
 	hlist_for_each_entry_rcu(node, node_db, mac_list,
-				 lockdep_is_held(&hsr->list_lock)) {
+				 lockdep_hsr_is_held(&hsr->list_lock)) {
 		if (ether_addr_equal(node->macaddress_A, addr))
 			goto out;
 		if (ether_addr_equal(node->macaddress_B, addr))
@@ -601,7 +606,7 @@ void *hsr_get_next_node(struct hsr_priv *hsr, void *_pos,
 
 	if (!_pos) {
 		node = hsr_node_get_first(&hsr->node_db[hash],
-					  lockdep_is_held(&hsr->list_lock));
+					  &hsr->list_lock);
 		if (node)
 			ether_addr_copy(addr, node->macaddress_A);
 		return node;

net/hsr/hsr_framereg.h

@@ -28,8 +28,14 @@ struct hsr_frame_info {
 	bool is_from_san;
 };
 
+#ifdef CONFIG_LOCKDEP
+int lockdep_hsr_is_held(spinlock_t *lock);
+#else
+#define lockdep_hsr_is_held(lock)	1
+#endif
+
 u32 hsr_mac_hash(struct hsr_priv *hsr, const unsigned char *addr);
-struct hsr_node *hsr_node_get_first(struct hlist_head *head, int cond);
+struct hsr_node *hsr_node_get_first(struct hlist_head *head, spinlock_t *lock);
 void hsr_del_self_node(struct hsr_priv *hsr);
 void hsr_del_nodes(struct hlist_head *node_db);
 struct hsr_node *hsr_get_node(struct hsr_port *port, struct hlist_head *node_db,