net/mlx5e: Update rx ring hw mtu upon each rx-fcs flag change

rq->hw_mtu is used in function en_rx.c/mlx5e_skb_from_cqe_mpwrq_linear()
to catch oversized packets. If FCS is concatenated to the end of the
packet then the check should be updated accordingly.

Rx rings initialization (mlx5e_init_rxq_rq()) invoked for every new set
of channels, as part of mlx5e_safe_switch_params(), unknowingly if it
runs with default configuration or not. Current rq->hw_mtu
initialization assumes default configuration and ignores
params->scatter_fcs_en flag state.
Fix this, by accounting for params->scatter_fcs_en flag state during
rq->hw_mtu initialization.

In addition, updating rq->hw_mtu value during ingress traffic might
lead to packets drop and oversize_pkts_sw_drop counter increase with no
good reason. Hence we remove this optimization and switch the set of
channels with a new one, to make sure we don't get false positives on
the oversize_pkts_sw_drop counter.

Fixes: 102722fc ("net/mlx5e: Add support for RXFCS feature flag")
Signed-off-by: Adham Faris <afaris@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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

@@ -591,7 +591,8 @@ static int mlx5e_init_rxq_rq(struct mlx5e_channel *c, struct mlx5e_params *param
 	rq->ix           = c->ix;
 	rq->channel      = c;
 	rq->mdev         = mdev;
-	rq->hw_mtu       = MLX5E_SW2HW_MTU(params, params->sw_mtu);
+	rq->hw_mtu =
+		MLX5E_SW2HW_MTU(params, params->sw_mtu) - ETH_FCS_LEN * !params->scatter_fcs_en;
 	rq->xdpsq        = &c->rq_xdpsq;
 	rq->stats        = &c->priv->channel_stats[c->ix]->rq;
 	rq->ptp_cyc2time = mlx5_rq_ts_translator(mdev);
@@ -1014,35 +1015,6 @@ int mlx5e_flush_rq(struct mlx5e_rq *rq, int curr_state)
 	return mlx5e_rq_to_ready(rq, curr_state);
 }
 
-static int mlx5e_modify_rq_scatter_fcs(struct mlx5e_rq *rq, bool enable)
-{
-	struct mlx5_core_dev *mdev = rq->mdev;
-
-	void *in;
-	void *rqc;
-	int inlen;
-	int err;
-
-	inlen = MLX5_ST_SZ_BYTES(modify_rq_in);
-	in = kvzalloc(inlen, GFP_KERNEL);
-	if (!in)
-		return -ENOMEM;
-
-	rqc = MLX5_ADDR_OF(modify_rq_in, in, ctx);
-
-	MLX5_SET(modify_rq_in, in, rq_state, MLX5_RQC_STATE_RDY);
-	MLX5_SET64(modify_rq_in, in, modify_bitmask,
-		   MLX5_MODIFY_RQ_IN_MODIFY_BITMASK_SCATTER_FCS);
-	MLX5_SET(rqc, rqc, scatter_fcs, enable);
-	MLX5_SET(rqc, rqc, state, MLX5_RQC_STATE_RDY);
-
-	err = mlx5_core_modify_rq(mdev, rq->rqn, in);
-
-	kvfree(in);
-
-	return err;
-}
-
 static int mlx5e_modify_rq_vsd(struct mlx5e_rq *rq, bool vsd)
 {
 	struct mlx5_core_dev *mdev = rq->mdev;
@@ -3314,20 +3286,6 @@ static void mlx5e_cleanup_nic_tx(struct mlx5e_priv *priv)
 	mlx5e_destroy_tises(priv);
 }
 
-static int mlx5e_modify_channels_scatter_fcs(struct mlx5e_channels *chs, bool enable)
-{
-	int err = 0;
-	int i;
-
-	for (i = 0; i < chs->num; i++) {
-		err = mlx5e_modify_rq_scatter_fcs(&chs->c[i]->rq, enable);
-		if (err)
-			return err;
-	}
-
-	return 0;
-}
-
 static int mlx5e_modify_channels_vsd(struct mlx5e_channels *chs, bool vsd)
 {
 	int err;
@@ -3903,41 +3861,27 @@ static int mlx5e_set_rx_port_ts(struct mlx5_core_dev *mdev, bool enable)
 	return mlx5_set_ports_check(mdev, in, sizeof(in));
 }
 
+static int mlx5e_set_rx_port_ts_wrap(struct mlx5e_priv *priv, void *ctx)
+{
+	struct mlx5_core_dev *mdev = priv->mdev;
+	bool enable = *(bool *)ctx;
+
+	return mlx5e_set_rx_port_ts(mdev, enable);
+}
+
 static int set_feature_rx_fcs(struct net_device *netdev, bool enable)
 {
 	struct mlx5e_priv *priv = netdev_priv(netdev);
 	struct mlx5e_channels *chs = &priv->channels;
-	struct mlx5_core_dev *mdev = priv->mdev;
+	struct mlx5e_params new_params;
 	int err;
 
 	mutex_lock(&priv->state_lock);
 
-	if (enable) {
-		err = mlx5e_set_rx_port_ts(mdev, false);
-		if (err)
-			goto out;
-
-		chs->params.scatter_fcs_en = true;
-		err = mlx5e_modify_channels_scatter_fcs(chs, true);
-		if (err) {
-			chs->params.scatter_fcs_en = false;
-			mlx5e_set_rx_port_ts(mdev, true);
-		}
-	} else {
-		chs->params.scatter_fcs_en = false;
-		err = mlx5e_modify_channels_scatter_fcs(chs, false);
-		if (err) {
-			chs->params.scatter_fcs_en = true;
-			goto out;
-		}
-		err = mlx5e_set_rx_port_ts(mdev, true);
-		if (err) {
-			mlx5_core_warn(mdev, "Failed to set RX port timestamp %d\n", err);
-			err = 0;
-		}
-	}
-
-out:
+	new_params = chs->params;
+	new_params.scatter_fcs_en = enable;
+	err = mlx5e_safe_switch_params(priv, &new_params, mlx5e_set_rx_port_ts_wrap,
+				       &new_params.scatter_fcs_en, true);
 	mutex_unlock(&priv->state_lock);
 	return err;
 }