mlxsw: destroy workqueue when trap_register in mlxsw_emad_init

stable inclusion
from linux-4.19.135
commit 20d385250f884e6a9fcfb492ff7f2fff50aade30

--------------------------------

[ Upstream commit 5dbaeb87 ]

When mlxsw_core_trap_register fails in mlxsw_emad_init,
destroy_workqueue() shouled be called to destroy mlxsw_core->emad_wq.

Fixes: d965465b ("mlxsw: core: Fix possible deadlock")
Signed-off-by: NLiu Jian <liujian56@huawei.com>
Reviewed-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NLi Aichun <liaichun@huawei.com>
Reviewed-by: Nguodeqing <geffrey.guo@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/net/ethernet/mellanox/mlxsw/core.c

@@ -587,7 +587,7 @@ static int mlxsw_emad_init(struct mlxsw_core *mlxsw_core)
 	err = mlxsw_core_trap_register(mlxsw_core, &mlxsw_emad_rx_listener,
 				       mlxsw_core);
 	if (err)
-		return err;
+		goto err_trap_register;
 
 	err = mlxsw_core->driver->basic_trap_groups_set(mlxsw_core);
 	if (err)
@@ -599,6 +599,7 @@ static int mlxsw_emad_init(struct mlxsw_core *mlxsw_core)
 err_emad_trap_set:
 	mlxsw_core_trap_unregister(mlxsw_core, &mlxsw_emad_rx_listener,
 				   mlxsw_core);
+err_trap_register:
 	destroy_workqueue(mlxsw_core->emad_wq);
 	return err;
 }