net/mlx5e: Correctly handle changing the number of queues when the interface is down

This commit addresses two issues related to changing the number of
queues when the channels are closed:

1. Missing call to mlx5e_num_channels_changed to update
real_num_tx_queues when the number of TCs is changed.

2. When mlx5e_num_channels_changed returns an error, the channel
parameters must be reverted.

Two Fixes: tags correspond to the first commits where these two issues
were introduced.

Fixes: 3909a12e ("net/mlx5e: Fix configuration of XPS cpumasks and netdev queues in corner cases")
Fixes: fa374877 ("net/mlx5e: Handle errors from netif_set_real_num_{tx,rx}_queues")
Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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

@@ -447,12 +447,18 @@ int mlx5e_ethtool_set_channels(struct mlx5e_priv *priv,
 		goto out;
 	}
 
-	new_channels.params = priv->channels.params;
+	new_channels.params = *cur_params;
 	new_channels.params.num_channels = count;
 
 	if (!test_bit(MLX5E_STATE_OPENED, &priv->state)) {
+		struct mlx5e_params old_params;
+
+		old_params = *cur_params;
 		*cur_params = new_channels.params;
 		err = mlx5e_num_channels_changed(priv);
+		if (err)
+			*cur_params = old_params;
+
 		goto out;
 	}
 

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

@@ -3614,7 +3614,14 @@ static int mlx5e_setup_tc_mqprio(struct mlx5e_priv *priv,
 	new_channels.params.num_tc = tc ? tc : 1;
 
 	if (!test_bit(MLX5E_STATE_OPENED, &priv->state)) {
+		struct mlx5e_params old_params;
+
+		old_params = priv->channels.params;
 		priv->channels.params = new_channels.params;
+		err = mlx5e_num_channels_changed(priv);
+		if (err)
+			priv->channels.params = old_params;
+
 		goto out;
 	}