netdev - Re: [PATCH net] net/mlx4_en: fix spurious timestamping callbacks

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Message-ID: <CAJ3xEMg3HwbZG6qh5=ydaUesQX_goRSD6H_LowsEuW46TVDnbA@mail.gmail.com>
Date:	Sat, 23 Apr 2016 23:23:07 +0300
From:	Or Gerlitz <gerlitz.or@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>,
	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>,
	Eugenia Emantayev <eugenia@...lanox.com>,
	Eran Ben Elisha <eranbe@...lanox.com>
Subject: Re: [PATCH net] net/mlx4_en: fix spurious timestamping callbacks

On Sat, Apr 23, 2016 at 9:35 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> When multiple skb are TX-completed in a row, we might incorrectly keep
> a timestamp of a prior skb and cause extra work.
>
> Fixes: ec693d47010e8 ("net/mlx4_en: Add HW timestamping (TS) support")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Willem de Bruijn <willemb@...gle.com>

Eric, was that supposed to be Reported-by: or Signed-off-by: ...

FWIW, Dave, I wanted to use the opportunity and comment that this week
many of us gonna be on Passover vacation, so response rate should be
lower than usual


>  drivers/net/ethernet/mellanox/mlx4/en_tx.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
> index c0d7b7296236..a386f047c1af 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
> @@ -405,7 +405,6 @@ static bool mlx4_en_process_tx_cq(struct net_device *dev,
>         u32 packets = 0;
>         u32 bytes = 0;
>         int factor = priv->cqe_factor;
> -       u64 timestamp = 0;
>         int done = 0;
>         int budget = priv->tx_work_limit;
>         u32 last_nr_txbb;
> @@ -445,9 +444,12 @@ static bool mlx4_en_process_tx_cq(struct net_device *dev,
>                 new_index = be16_to_cpu(cqe->wqe_index) & size_mask;
>
>                 do {
> +                       u64 timestamp = 0;
> +
>                         txbbs_skipped += last_nr_txbb;
>                         ring_index = (ring_index + last_nr_txbb) & size_mask;
> -                       if (ring->tx_info[ring_index].ts_requested)
> +
> +                       if (unlikely(ring->tx_info[ring_index].ts_requested))
>                                 timestamp = mlx4_en_get_cqe_ts(cqe);
>
>                         /* free next descriptor */
>
>