netdev - Re: [PATCH v2 net-next 00/14] mlx4: order-0 allocations and page recycling

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Date:   Mon, 13 Feb 2017 11:33:16 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     Tariq Toukan <ttoukan.linux@...il.com>
Cc:     Tariq Toukan <tariqt@...lanox.com>,
        "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>, Martin KaFai Lau <kafai@...com>,
        Willem de Bruijn <willemb@...gle.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Brenden Blanco <bblanco@...mgrid.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH v2 net-next 00/14] mlx4: order-0 allocations and page recycling

On Mon, Feb 13, 2017 at 12:50 AM, Tariq Toukan <ttoukan.linux@...il.com> wrote:
>

>
> MTU is changed from 1500 to 500, with VLAN configured.

Thanks, I now see what is happening.

mlx4_en_free_rx_buf() needs to clean whole rx_info buffer, not the
part between ring->cons & ring->prod,
otherwise we still could see garbage later.

I will include in v3 the appropriate fix.

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index 31e3f92b45f47f10055552f0cfe2f21c22a2b4d0..0810039fcd739e9e355965fe6e87b5907d2913e8
100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -230,12 +230,12 @@ static void mlx4_en_free_rx_buf(struct mlx4_en_priv *priv,
               ring->cons, ring->prod);

        /* Unmap and free Rx buffers */
-       while (!mlx4_en_is_ring_empty(ring)) {
-               index = ring->cons & ring->size_mask;
+       for (index = 0; index < ring->size; index++) {
                en_dbg(DRV, priv, "Processing descriptor:%d\n", index);
                mlx4_en_free_rx_desc(priv, ring, index);
-               ++ring->cons;
        }
+       ring->cons = 0;
+       ring->prod = 0;
 }