net/mlx5e: Add error flow for ethtool -X command

Prior to this patch, ethtool -X fail but the user receives a success
status. Try to roll-back when failing and return success status
accordingly.
Signed-off-by: Aya Levin <ayal@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en/rss.c

@@ -391,7 +391,7 @@ int mlx5e_rss_obtain_tirn(struct mlx5e_rss *rss,
 	return 0;
 }
 
-static void mlx5e_rss_apply(struct mlx5e_rss *rss, u32 *rqns, unsigned int num_rqns)
+static int mlx5e_rss_apply(struct mlx5e_rss *rss, u32 *rqns, unsigned int num_rqns)
 {
 	int err;
 
@@ -399,6 +399,7 @@ static void mlx5e_rss_apply(struct mlx5e_rss *rss, u32 *rqns, unsigned int num_r
 	if (err)
 		mlx5e_rss_warn(rss->mdev, "Failed to redirect RQT %#x to channels: err = %d\n",
 			       mlx5e_rqt_get_rqtn(&rss->rqt), err);
+	return err;
 }
 
 void mlx5e_rss_enable(struct mlx5e_rss *rss, u32 *rqns, unsigned int num_rqns)
@@ -490,6 +491,14 @@ int mlx5e_rss_set_rxfh(struct mlx5e_rss *rss, const u32 *indir,
 {
 	bool changed_indir = false;
 	bool changed_hash = false;
+	struct mlx5e_rss *old_rss;
+	int err = 0;
+
+	old_rss = mlx5e_rss_alloc();
+	if (!old_rss)
+		return -ENOMEM;
+
+	*old_rss = *rss;
 
 	if (hfunc && *hfunc != rss->hash.hfunc) {
 		switch (*hfunc) {
@@ -497,7 +506,8 @@ int mlx5e_rss_set_rxfh(struct mlx5e_rss *rss, const u32 *indir,
 		case ETH_RSS_HASH_TOP:
 			break;
 		default:
-			return -EINVAL;
+			err = -EINVAL;
+			goto out;
 		}
 		changed_hash = true;
 		changed_indir = true;
@@ -520,13 +530,20 @@ int mlx5e_rss_set_rxfh(struct mlx5e_rss *rss, const u32 *indir,
 			rss->indir.table[i] = indir[i];
 	}
 
-	if (changed_indir && rss->enabled)
-		mlx5e_rss_apply(rss, rqns, num_rqns);
+	if (changed_indir && rss->enabled) {
+		err = mlx5e_rss_apply(rss, rqns, num_rqns);
+		if (err) {
+			*rss = *old_rss;
+			goto out;
+		}
+	}
 
 	if (changed_hash)
 		mlx5e_rss_update_tirs(rss);
 
-	return 0;
+out:
+	mlx5e_rss_free(old_rss);
+	return err;
 }
 
 struct mlx5e_rss_params_hash mlx5e_rss_get_hash(struct mlx5e_rss *rss)