netdev - Re: [PATCH net-next v3 4/4] net/mlx5e: Return -EOPNOTSUPP when attempting to offload an unsupported action

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Message-ID: <37c79899-ebb7-4caf-d76a-f2a9bcd49af2@mellanox.com>
Date:   Wed, 27 Feb 2019 14:01:35 +0000
From:   Roi Dayan <roid@...lanox.com>
To:     "xiangxia.m.yue@...il.com" <xiangxia.m.yue@...il.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        "gerlitz.or@...il.com" <gerlitz.or@...il.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next v3 4/4] net/mlx5e: Return -EOPNOTSUPP when
 attempting to offload an unsupported action



On 26/02/2019 14:27, xiangxia.m.yue@...il.com wrote:
> From: Tonghao Zhang <xiangxia.m.yue@...il.com>
> 
> * Now the encapsulation is not supported for mlx5 VFs. When we try to
> offload that action, the -EINVAL is returned, but not -EOPNOTSUPP.
> This patch changes the returned value and ignore to confuse user.
> The command is shown as below [1].
> 
> * When max modify header action is zero, we return -EOPNOTSUPP
> directly. In this way, we can ignore wrong message info (e.g.
> "mlx5: parsed 0 pedit actions, can't do more"). This happens when
> offloading pedit actions on mlx(cx4) VFs. The command is shown as below [2].
> 
> For example: (p2p1_0 is VF net device)
> [1]
> $ tc filter add dev p2p1_0 protocol ip  parent ffff: prio 1 flower skip_sw \
>     src_mac e4:11:22:33:44:01    \
>     action tunnel_key set        \
>     src_ip 1.1.1.100        \
>     dst_ip 1.1.1.200        \
>     dst_port 4789 id 100        \
>     action mirred egress redirect dev vxlan0
> 
> [2]
> $ tc filter add dev p2p1_0 parent ffff: protocol ip prio 1 \
>     flower skip_sw dst_mac 00:10:56:fb:64:e8 \
>     dst_ip 1.1.1.100 src_ip 1.1.1.200 \
>     action pedit ex munge eth src set 00:10:56:b4:5d:20
> 
> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@...il.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 19 ++++++++++++++++---
>  1 file changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> index 56ac50d..3a02b22 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> @@ -2035,7 +2035,7 @@ static int parse_tc_pedit_action(struct mlx5e_priv *priv,
>  				 struct netlink_ext_ack *extack)
>  {
>  	u8 cmd = (act->id == FLOW_ACTION_MANGLE) ? 0 : 1;
> -	int err = -EOPNOTSUPP;
> +	int max_actions, err = -EOPNOTSUPP;
>  	u32 mask, val, offset;
>  	u8 htype;
>  
> @@ -2047,6 +2047,17 @@ static int parse_tc_pedit_action(struct mlx5e_priv *priv,
>  		goto out_err;
>  	}
>  
> +        if (namespace == MLX5_FLOW_NAMESPACE_FDB) /* FDB offloading */
> +                max_actions = MLX5_CAP_ESW_FLOWTABLE_FDB(priv->mdev, max_modify_header_actions);
> +        else /* namespace is MLX5_FLOW_NAMESPACE_KERNEL - NIC offloading */
> +                max_actions = MLX5_CAP_FLOWTABLE_NIC_RX(priv->mdev, max_modify_header_actions);
> +

we have the exact same block with comments in alloc_mod_hdr_actions() which
is called later after we parse the action and now parsing the pedit fields.
your check for max_actions was there in prev v. why move it?
if like this I suggest we create a small static function to get max actions
for a namespace and call it from both places to get max actions.

> +	if (!max_actions) {
> +		NL_SET_ERR_MSG_MOD(extack,
> +				   "don't support pedit actions, can't offload");

please rephrase the msg to be consistent
i.e. The pedit offload action is not supported

> +		goto out_err;
> +	}
> +
>  	mask = act->mangle.mask;
>  	val = act->mangle.val;
>  	offset = act->mangle.offset;
> @@ -2294,7 +2305,8 @@ static int parse_tc_nic_actions(struct mlx5e_priv *priv,
>  			}
>  			break;
>  		default:
> -			return -EINVAL;
> +			NL_SET_ERR_MSG_MOD(extack, "The offload action is not supported");
> +			return -EOPNOTSUPP;
>  		}
>  	}
>  
> @@ -2616,7 +2628,8 @@ static int parse_tc_fdb_actions(struct mlx5e_priv *priv,
>  			break;
>  			}
>  		default:
> -			return -EINVAL;
> +			NL_SET_ERR_MSG_MOD(extack, "The offload action is not supported");
> +			return -EOPNOTSUPP;
>  		}
>  	}
>  
>