netdev - [PATCH net 4/4] mlxsw: spectrum_switchdev: Fix port

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Message-Id: <20180615132338.14241-5-idosch@mellanox.com>
Date:   Fri, 15 Jun 2018 16:23:38 +0300
From:   Ido Schimmel <idosch@...lanox.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, jiri@...lanox.com, petrm@...lanox.com,
        dsahern@...il.com, mlxsw@...lanox.com,
        Ido Schimmel <idosch@...lanox.com>
Subject: [PATCH net 4/4] mlxsw: spectrum_switchdev: Fix port_vlan refcounting

From: Petr Machata <petrm@...lanox.com>

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: b3529af6bb0d ("spectrum: Reference count VLAN entries")
Signed-off-by: Petr Machata <petrm@...lanox.com>
Acked-by: Jiri Pirko <jiri@...lanox.com>
Signed-off-by: Ido Schimmel <idosch@...lanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c
index e97652c40d13..eea5666a86b2 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)
-- 
2.14.4