net: vlan: Replace BUG() with WARN_ON_ONCE() in vlan_dev_* stubs

When CONFIG_VLAN_8021Q=n, a set of stub helpers are used, three of these
helpers use BUG() unconditionally.

This code should not be reached, as callers of these functions should
always check for is_vlan_dev() first, but the usage of BUG() is not
recommended, replace it with WARN_ON() instead.

Reviewed-by: Alex Lazar <[email protected]>
Reviewed-by: Dragos Tatulea <[email protected]>
Signed-off-by: Gal Pressman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: gal-pressman

include/linux/if_vlan.h

@@ -259,19 +259,19 @@ vlan_for_each(struct net_device *dev,
 
 static inline struct net_device *vlan_dev_real_dev(const struct net_device *dev)
 {
-	BUG();
+	WARN_ON_ONCE(1);
 	return NULL;
 }
 
 static inline u16 vlan_dev_vlan_id(const struct net_device *dev)
 {
-	BUG();
+	WARN_ON_ONCE(1);
 	return 0;
 }
 
 static inline __be16 vlan_dev_vlan_proto(const struct net_device *dev)
 {
-	BUG();
+	WARN_ON_ONCE(1);
 	return 0;
 }