net/mlx5: Unregister notifier on eswitch init failure

It otherwise remains registered and a subsequent attempt at eswitch
enabling might trigger warnings of the sort:

[  682.589148] ------------[ cut here ]------------
[  682.590204] notifier callback eswitch_vport_event [mlx5_core] already registered
[  682.590256] WARNING: CPU: 13 PID: 2660 at kernel/notifier.c:31 notifier_chain_register+0x3e/0x90
[...snipped]
[  682.610052] Call Trace:
[  682.610369]  <TASK>
[  682.610663]  ? __warn+0x7c/0x110
[  682.611050]  ? notifier_chain_register+0x3e/0x90
[  682.611556]  ? report_bug+0x148/0x170
[  682.611977]  ? handle_bug+0x36/0x70
[  682.612384]  ? exc_invalid_op+0x13/0x60
[  682.612817]  ? asm_exc_invalid_op+0x16/0x20
[  682.613284]  ? notifier_chain_register+0x3e/0x90
[  682.613789]  atomic_notifier_chain_register+0x25/0x40
[  682.614322]  mlx5_eswitch_enable_locked+0x1d4/0x3b0 [mlx5_core]
[  682.614965]  mlx5_eswitch_enable+0xc9/0x100 [mlx5_core]
[  682.615551]  mlx5_device_enable_sriov+0x25/0x340 [mlx5_core]
[  682.616170]  mlx5_core_sriov_configure+0x50/0x170 [mlx5_core]
[  682.616789]  sriov_numvfs_store+0xb0/0x1b0
[  682.617248]  kernfs_fop_write_iter+0x117/0x1a0
[  682.617734]  vfs_write+0x231/0x3f0
[  682.618138]  ksys_write+0x63/0xe0
[  682.618536]  do_syscall_64+0x4c/0x100
[  682.618958]  entry_SYSCALL_64_after_hwframe+0x4b/0x53

Fixes: 7624e58 ("net/mlx5: E-switch, register event handler before arming the event")
Signed-off-by: Cosmin Ratiu <[email protected]>
Signed-off-by: Tariq Toukan <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

Author: Cosmin Ratiu

drivers/net/ethernet/mellanox/mlx5/core/eswitch.c

@@ -1489,7 +1489,7 @@ int mlx5_eswitch_enable_locked(struct mlx5_eswitch *esw, int num_vfs)
 	}
 
 	if (err)
-		goto abort;
+		goto err_esw_enable;
 
 	esw->fdb_table.flags |= MLX5_ESW_FDB_CREATED;
 
@@ -1503,7 +1503,8 @@ int mlx5_eswitch_enable_locked(struct mlx5_eswitch *esw, int num_vfs)
 
 	return 0;
 
-abort:
+err_esw_enable:
+	mlx5_eq_notifier_unregister(esw->dev, &esw->nb);
 	mlx5_esw_acls_ns_cleanup(esw);
 	return err;
 }