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References: <20231102172503.3413318-1-alexey.pakhunov@spacex.com> <20231102172503.3413318-2-alexey.pakhunov@spacex.com>
In-Reply-To: <20231102172503.3413318-2-alexey.pakhunov@spacex.com>
From:   Michael Chan <michael.chan@broadcom.com>
Date:   Thu, 2 Nov 2023 13:04:13 -0700
Message-ID: <CACKFLik-Ey1eptrCkhSEp0Oi66kBKnVWa+yDk7-_uzxqSTHb6A@mail.gmail.com>
Subject: Re: [PATCH v2 1/2] tg3: Increment tx_dropped in tg3_tso_bug()
To:     alexey.pakhunov@spacex.com
Cc:     mchan@broadcom.com, vincent.wong2@spacex.com,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        siva.kallam@broadcom.com, prashant@broadcom.com
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On Thu, Nov 2, 2023 at 10:25=E2=80=AFAM <alexey.pakhunov@spacex.com> wrote:
>
> From: Alex Pakhunov <alexey.pakhunov@spacex.com>
>
> tg3_tso_bug() drops a packet if it cannot be segmented for any reason.
> The number of discarded frames should be incremeneted accordingly.
>
> Signed-off-by: Alex Pakhunov <alexey.pakhunov@spacex.com>
> Signed-off-by: Vincent Wong <vincent.wong2@spacex.com>
> ---
>  drivers/net/ethernet/broadcom/tg3.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/b=
roadcom/tg3.c
> index 14b311196b8f..99638e6c9e16 100644
> --- a/drivers/net/ethernet/broadcom/tg3.c
> +++ b/drivers/net/ethernet/broadcom/tg3.c
> @@ -7874,8 +7874,10 @@ static int tg3_tso_bug(struct tg3 *tp, struct tg3_=
napi *tnapi,
>
>         segs =3D skb_gso_segment(skb, tp->dev->features &
>                                     ~(NETIF_F_TSO | NETIF_F_TSO6));
> -       if (IS_ERR(segs) || !segs)
> +       if (IS_ERR(segs) || !segs) {
> +               tp->tx_dropped++;

This is prone to race conditions if we have more than one TX queue.
The original driver code only supported one TX queue and the counters
were never modified properly to support multiple queues.  We should
convert them to per queue counters by moving tx_dropped and rx_dropped
to the tg3_napi struct.

>                 goto tg3_tso_bug_end;
> +       }
>
>         skb_list_walk_safe(segs, seg, next) {
>                 skb_mark_not_on_list(seg);
> --
> 2.39.3
>

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