diff mbox

[net,mlxsw,v2] mlxsw: spectrum_switchdev: Fix port_vlan refcounting

Message ID c8cb7c89c468882cc7f9ce0d98e17e147630ed52.1528388122.git.petrm@mellanox.com (mailing list archive)
State Accepted
Delegated to: Ido Schimmel
Headers show

Commit Message

Petr Machata June 7, 2018, 4:17 p.m. UTC 
Switchdev notifications for addition of SWITCHDEV_OBJ_ID_PORT_VLAN are
distributed not only on clean addition, but also when flags on an
existing VLAN are changed. mlxsw_sp_bridge_port_vlan_add() calls
mlxsw_sp_port_vlan_get() to get at the port_vlan in question, which
implicitly references the object. This then leads to discrepancies in
reference counting when the VLAN is removed. spectrum.c warns about the
problem when the module is removed:

[13578.493090] WARNING: CPU: 0 PID: 2454 at drivers/net/ethernet/mellanox/mlxsw/spectrum.c:2973 mlxsw_sp_port_remove+0xfd/0x110 [mlxsw_spectrum]
[...]
[13578.627106] Call Trace:
[13578.629617]  mlxsw_sp_fini+0x2a/0xe0 [mlxsw_spectrum]
[13578.634748]  mlxsw_core_bus_device_unregister+0x3e/0x130 [mlxsw_core]
[13578.641290]  mlxsw_pci_remove+0x13/0x40 [mlxsw_pci]
[13578.646238]  pci_device_remove+0x31/0xb0
[13578.650244]  device_release_driver_internal+0x14f/0x220
[13578.655562]  driver_detach+0x32/0x70
[13578.659183]  bus_remove_driver+0x47/0xa0
[13578.663134]  pci_unregister_driver+0x1e/0x80
[13578.667486]  mlxsw_sp_module_exit+0xc/0x3fa [mlxsw_spectrum]
[13578.673207]  __x64_sys_delete_module+0x13b/0x1e0
[13578.677888]  ? exit_to_usermode_loop+0x78/0x80
[13578.682374]  do_syscall_64+0x39/0xe0
[13578.685976]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fix by putting the port_vlan when mlxsw_sp_port_vlan_bridge_join()
determines it's a flag-only change.

Fixes: c57529e1d5d8 ("mlxsw: spectrum: Replace vPorts with Port-VLAN")
Signed-off-by: Petr Machata <petrm@mellanox.com>
---

Notes:
    Changes from v1 to v2:
    
    - Instead of replacing the problematic get() with find_by_pvid() and
      create(), put() the port_vlan in mlxsw_sp_port_vlan_bridge_join().
    
      Besides being simpler, this approach is also correct. The error path
      was broken in v1, as reference would only be acquired sometimes, but
      after an error it would always be dropped.

 drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c
index e97652c..eea5666 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c
@@ -1018,8 +1018,10 @@  mlxsw_sp_port_vlan_bridge_join(struct mlxsw_sp_port_vlan *mlxsw_sp_port_vlan,
 	int err;
 
 	/* No need to continue if only VLAN flags were changed */
-	if (mlxsw_sp_port_vlan->bridge_port)
+	if (mlxsw_sp_port_vlan->bridge_port) {
+		mlxsw_sp_port_vlan_put(mlxsw_sp_port_vlan);
 		return 0;
+	}
 
 	err = mlxsw_sp_port_vlan_fid_join(mlxsw_sp_port_vlan, bridge_port);
 	if (err)