Re: [PATCH net-next v6 4/6] net/mlx5: Refactor tc miss handling to a single function

[Leon Romanovsky <leon@kernel.org>]

On Sun, Jan 29, 2023 at 12:16:11PM +0200, Paul Blakey wrote:
> Move tc miss handling code to en_tc.c, and remove
> duplicate code.
> 
> Signed-off-by: Paul Blakey <paulb@nvidia.com>
> Reviewed-by: Roi Dayan <roid@nvidia.com>
> ---
>  .../ethernet/mellanox/mlx5/core/en/rep/tc.c   | 225 ++----------------
>  .../net/ethernet/mellanox/mlx5/core/en_rx.c   |   4 +-
>  .../net/ethernet/mellanox/mlx5/core/en_tc.c   | 221 +++++++++++++++--
>  .../net/ethernet/mellanox/mlx5/core/en_tc.h   |  11 +-
>  4 files changed, 232 insertions(+), 229 deletions(-)

<...>

>  void mlx5e_rep_tc_receive(struct mlx5_cqe64 *cqe, struct mlx5e_rq *rq,
>  			  struct sk_buff *skb)
>  {
> -	u32 reg_c1 = be32_to_cpu(cqe->ft_metadata);
> +	u32 reg_c1 = be32_to_cpu(cqe->ft_metadata), reg_c0, zone_restore_id, tunnel_id;
>  	struct mlx5e_tc_update_priv tc_priv = {};
> -	struct mlx5_mapped_obj mapped_obj;
> +	struct mlx5_rep_uplink_priv *uplink_priv;
> +	struct mlx5e_rep_priv *uplink_rpriv;
> +	struct mlx5_tc_ct_priv *ct_priv;
> +	struct mapping_ctx *mapping_ctx;
>  	struct mlx5_eswitch *esw;
> -	bool forward_tx = false;
>  	struct mlx5e_priv *priv;
> -	u32 reg_c0;
> -	int err;
>  
>  	reg_c0 = (be32_to_cpu(cqe->sop_drop_qpn) & MLX5E_TC_FLOW_ID_MASK);
>  	if (!reg_c0 || reg_c0 == MLX5_FS_DEFAULT_FLOW_TAG)
>  		goto forward;
>  
> -	/* If reg_c0 is not equal to the default flow tag then skb->mark
> +	/* If mapped_obj_id is not equal to the default flow tag then skb->mark
>  	 * is not supported and must be reset back to 0.
>  	 */
>  	skb->mark = 0;
>  
>  	priv = netdev_priv(skb->dev);
>  	esw = priv->mdev->priv.eswitch;
> -	err = mapping_find(esw->offloads.reg_c0_obj_pool, reg_c0, &mapped_obj);
> -	if (err) {
> -		netdev_dbg(priv->netdev,
> -			   "Couldn't find mapped object for reg_c0: %d, err: %d\n",
> -			   reg_c0, err);
> -		goto free_skb;
> -	}
> +	mapping_ctx = esw->offloads.reg_c0_obj_pool;
> +	zone_restore_id = reg_c1 & ESW_ZONE_ID_MASK;
> +	tunnel_id = (reg_c1 >> ESW_TUN_OFFSET) & TUNNEL_ID_MASK;
>  
> -	if (mapped_obj.type == MLX5_MAPPED_OBJ_CHAIN) {
> -		if (!mlx5e_restore_skb_chain(skb, mapped_obj.chain, reg_c1, &tc_priv) &&
> -		    !mlx5_ipsec_is_rx_flow(cqe))
> -			goto free_skb;
> -	} else if (mapped_obj.type == MLX5_MAPPED_OBJ_SAMPLE) {
> -		mlx5e_restore_skb_sample(priv, skb, &mapped_obj, &tc_priv);
> -		goto free_skb;
> -	} else if (mapped_obj.type == MLX5_MAPPED_OBJ_INT_PORT_METADATA) {
> -		if (!mlx5e_restore_skb_int_port(priv, skb, &mapped_obj, &tc_priv,
> -						&forward_tx, reg_c1))
> -			goto free_skb;
> -	} else {
> -		netdev_dbg(priv->netdev, "Invalid mapped object type: %d\n", mapped_obj.type);
> +	uplink_rpriv = mlx5_eswitch_get_uplink_priv(esw, REP_ETH);
> +	uplink_priv = &uplink_rpriv->uplink_priv;
> +	ct_priv = uplink_priv->ct_priv;
> +
> +	if (!mlx5_ipsec_is_rx_flow(cqe) &&
> +	    !mlx5e_tc_update_skb(cqe, skb, mapping_ctx, reg_c0, ct_priv, zone_restore_id, tunnel_id,
> +				 &tc_priv))
>  		goto free_skb;
> -	}
>  
>  forward:
> -	if (forward_tx)
> +	if (tc_priv.skb_done)
> +		goto free_skb;
> +
> +	if (tc_priv.forward_tx)
>  		dev_queue_xmit(skb);
>  	else
>  		napi_gro_receive(rq->cq.napi, skb);
>  
> -	mlx5_rep_tc_post_napi_receive(&tc_priv);
> +	if (tc_priv.fwd_dev)
> +		dev_put(tc_priv.fwd_dev);
>  
>  	return;
>  
>  free_skb:
> +	WARN_ON(tc_priv.fwd_dev);

Kernel splat which can be triggered from the network by sending traffic
to the target is not good idea.

It is safer to remove this WARN_ON().

Thanks