netdev - Re: [net-next 09/10] net/mlx5e: Move TX code into functions to be used by MPWQE

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Date:   Fri, 4 Sep 2020 17:06:37 +0200
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Saeed Mahameed <saeedm@...dia.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Network Development <netdev@...r.kernel.org>,
        Maxim Mikityanskiy <maximmi@...lanox.com>
Subject: Re: [net-next 09/10] net/mlx5e: Move TX code into functions to be
 used by MPWQE

On Thu, Sep 3, 2020 at 11:01 PM Saeed Mahameed <saeedm@...dia.com> wrote:
>
> From: Maxim Mikityanskiy <maximmi@...lanox.com>
>
> mlx5e_txwqe_complete performs some actions that can be taken to separate
> functions:
>
> 1. Update the flags needed for hardware timestamping.
>
> 2. Stop the TX queue if it's full.
>
> Take these actions into separate functions to be reused by the MPWQE
> code in the following commit and to maintain clear responsibilities of
> functions.
>
> Signed-off-by: Maxim Mikityanskiy <maximmi@...lanox.com>
> Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
> ---
>  .../net/ethernet/mellanox/mlx5/core/en_tx.c   | 23 ++++++++++++++-----
>  1 file changed, 17 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
> index 9ced350150b3..3b68c8333875 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
> @@ -311,6 +311,20 @@ static inline void mlx5e_sq_calc_wqe_attr(struct sk_buff *skb,
>         };
>  }
>
> +static inline void mlx5e_tx_skb_update_hwts_flags(struct sk_buff *skb)
> +{
> +       if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP))
> +               skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
> +}

Subjective, but this helper adds a level of indirection and introduces
code churn without simplying anything, imho.

> +static inline void mlx5e_tx_check_stop(struct mlx5e_txqsq *sq)
> +{
> +       if (unlikely(!mlx5e_wqc_has_room_for(&sq->wq, sq->cc, sq->pc, sq->stop_room))) {
> +               netif_tx_stop_queue(sq->txq);
> +               sq->stats->stopped++;
> +       }
> +}
> +
>  static inline void
>  mlx5e_txwqe_complete(struct mlx5e_txqsq *sq, struct sk_buff *skb,
>                      const struct mlx5e_tx_attr *attr,
> @@ -332,14 +346,11 @@ mlx5e_txwqe_complete(struct mlx5e_txqsq *sq, struct sk_buff *skb,
>         cseg->opmod_idx_opcode = cpu_to_be32((sq->pc << 8) | attr->opcode);
>         cseg->qpn_ds           = cpu_to_be32((sq->sqn << 8) | wqe_attr->ds_cnt);
>
> -       if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP))
> -               skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
> +       mlx5e_tx_skb_update_hwts_flags(skb);
>
>         sq->pc += wi->num_wqebbs;
> -       if (unlikely(!mlx5e_wqc_has_room_for(wq, sq->cc, sq->pc, sq->stop_room))) {
> -               netif_tx_stop_queue(sq->txq);
> -               sq->stats->stopped++;
> -       }
> +
> +       mlx5e_tx_check_stop(sq);
>
>         send_doorbell = __netdev_tx_sent_queue(sq->txq, attr->num_bytes, xmit_more);
>         if (send_doorbell)
> --
> 2.26.2
>