[PATCH net v4 2/2] net/mlx5: Bridge, don't fail unlink of untracked/unsupported peer ports

[Bernardo Soares <bsoares.it@gmail.com>]

mlx5_esw_bridge_vport_unlink() returns -EINVAL when the port isn't
tracked by this instance's br_offloads. This is reachable on a sibling
instance that registered its notifier after the port was already
enslaved: it never saw the NETDEV_CHANGEUPPER link event, so
peer_link() never created a peer port for it, but it does see the
later unlink event and fails. Return 0 instead, and give
mlx5_esw_bridge_vport_peer_unlink() the same merged_eswitch capability
guard peer_link() already has, since without it peer_link() likewise
never creates a port to unlink.

This also matters beyond the -EINVAL itself:
mlx5_esw_bridge_switchdev_port_event() runs on the per-netns
netdev_chain, and notifier_from_errno(-EINVAL) sets NOTIFY_STOP_MASK,
which call_netdevice_notifiers_info() checks to stop calling further
listeners on that chain - so the old -EINVAL silently dropped the
event for any listener registered later on the same chain, even
though none of it was visible to user space since
__netdev_upper_dev_unlink() discards the return value.

Fixes: c358ea1741bc ("net/mlx5: Bridge, allow merged eswitch connectivity")
Signed-off-by: Bernardo Soares <bsoares.it@gmail.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/esw/bridge.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/esw/bridge.c b/drivers/net/ethernet/mellanox/mlx5/core/esw/bridge.c
index ac90ccda1272..b4cf3c5ac0dd 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/esw/bridge.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/esw/bridge.c
@@ -1649,10 +1649,8 @@ int mlx5_esw_bridge_vport_unlink(struct net_device *br_netdev, u16 vport_num,
 	int err;
 
 	port = mlx5_esw_bridge_port_lookup(vport_num, esw_owner_vhca_id, br_offloads);
-	if (!port) {
-		NL_SET_ERR_MSG_MOD(extack, "Port is not attached to any bridge");
-		return -EINVAL;
-	}
+	if (!port)
+		return 0;
 	if (port->bridge->ifindex != br_netdev->ifindex) {
 		NL_SET_ERR_MSG_MOD(extack, "Port is attached to another bridge");
 		return -EINVAL;
@@ -1682,6 +1680,9 @@ int mlx5_esw_bridge_vport_peer_unlink(struct net_device *br_netdev, u16 vport_nu
 				      struct mlx5_esw_bridge_offloads *br_offloads,
 				      struct netlink_ext_ack *extack)
 {
+	if (!MLX5_CAP_ESW(br_offloads->esw->dev, merged_eswitch))
+		return 0;
+
 	return mlx5_esw_bridge_vport_unlink(br_netdev, vport_num, esw_owner_vhca_id, br_offloads,
 					    extack);
 }
-- 
2.43.0