lkml.org 
[lkml]   [2018]   [Jan]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] net/mlx4_en: ensure rx_desc updating reaches HW before prod db updating
On Fri, Jan 12, 2018 at 11:42:22AM +0800, Jianchao Wang wrote:
> Customer reported memory corruption issue on previous mlx4_en driver
> version where the order-3 pages and multiple page reference counting
> were still used.
>
> Finally, find out one of the root causes is that the HW may see stale
> rx_descs due to prod db updating reaches HW before rx_desc. Especially
> when cross order-3 pages boundary and update a new one, HW may write
> on the pages which may has been freed and allocated again by others.
>
> To fix it, add a wmb between rx_desc and prod db updating to ensure
> the order. Even thougth order-0 and page recycling has been introduced,
> the disorder between rx_desc and prod db still could lead to corruption
> on different inbound packages.
>
> Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
> drivers/net/ethernet/mellanox/mlx4/en_rx.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> index 85e28ef..eefa82c 100644
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> @@ -555,7 +555,7 @@ static void mlx4_en_refill_rx_buffers(struct mlx4_en_priv *priv,
> break;
> ring->prod++;
> } while (likely(--missing));
> -
> + wmb(); /* ensure rx_desc updating reaches HW before prod db updating */
> mlx4_en_update_rx_prod_db(ring);
> }
>

Does this need to be dma_wmb(), and should it be in
mlx4_en_update_rx_prod_db ?

Jason

\
 
 \ /
  Last update: 2018-01-14 23:25    [W:0.079 / U:0.052 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site