[PATCH 5.4 20/43] net: Fix bridge enslavement failure

[Greg Kroah-Hartman]

From: Ido Schimmel <idosch@xxxxxxxxxx>

[ Upstream commit e1b9efe6baebe79019a2183176686a0e709388ae ]

When a netdev is enslaved to a bridge, its parent identifier is queried.
This is done so that packets that were already forwarded in hardware
will not be forwarded again by the bridge device between netdevs
belonging to the same hardware instance.

The operation fails when the netdev is an upper of netdevs with
different parent identifiers.

Instead of failing the enslavement, have dev_get_port_parent_id() return
'-EOPNOTSUPP' which will signal the bridge to skip the query operation.
Other callers of the function are not affected by this change.

Fixes: 7e1146e8c10c ("net: devlink: introduce devlink_compat_switch_id_get() helper")
Signed-off-by: Ido Schimmel <idosch@xxxxxxxxxx>
Reported-by: Vasundhara Volam <vasundhara-v.volam@xxxxxxxxxxxx>
Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx>
Reviewed-by: Nikolay Aleksandrov <nikolay@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/core/dev.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8241,7 +8241,7 @@ int dev_get_port_parent_id(struct net_de
 		if (!first.id_len)
 			first = *ppid;
 		else if (memcmp(&first, ppid, sizeof(*ppid)))
-			return -ENODATA;
+			return -EOPNOTSUPP;
 	}
 
 	return err;