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

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Date:   Tue, 8 Sep 2020 11:59:42 +0300
From:   Maxim Mikityanskiy <maximmi@...dia.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        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 2020-09-04 18:06, Willem de Bruijn wrote:
> 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.

It's added for the sake of being reused in non-MPWQE and MPWQE flows.

>> +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
>>