netdev - Re: [RFC net-next PATCH 2/5] mlx5: fix bug reading rss_hash

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Date:   Fri, 19 May 2017 17:47:01 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Jesper Dangaard Brouer <brouer@...hat.com>,
        Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>
CC:     John Fastabend <john.r.fastabend@...el.com>,
        netdev@...r.kernel.org, saeedm@...lanox.com
Subject: Re: [RFC net-next PATCH 2/5] mlx5: fix bug reading rss_hash_type
 from CQE

On 05/18/2017 05:41 PM, Jesper Dangaard Brouer wrote:
> Masks for extracting part of the Completion Queue Entry (CQE)
> field rss_hash_type was swapped, namely CQE_RSS_HTYPE_IP and
> CQE_RSS_HTYPE_L4.
>
> The bug resulted in setting skb->l4_hash, even-though the
> rss_hash_type indicated that hash was NOT computed over the
> L4 (UDP or TCP) part of the packet.
>
> Added comments from the datasheet, to make it more clear what
> these masks are selecting.
>
> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
> ---

Stand-alone fix for -net tree?

>   include/linux/mlx5/device.h |   10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/mlx5/device.h b/include/linux/mlx5/device.h
> index dd9a263ed368..a940ec6a046c 100644
> --- a/include/linux/mlx5/device.h
> +++ b/include/linux/mlx5/device.h
> @@ -787,8 +787,14 @@ enum {
>   };
>
>   enum {
> -	CQE_RSS_HTYPE_IP	= 0x3 << 6,
> -	CQE_RSS_HTYPE_L4	= 0x3 << 2,
> +	CQE_RSS_HTYPE_IP	= 0x3 << 2,
> +	/* cqe->rss_hash_type[3:2] - IP destination selected for hash
> +	 * (00 = none,  01 = IPv4, 10 = IPv6, 11 = Reserved)
> +	 */
> +	CQE_RSS_HTYPE_L4	= 0x3 << 6,
> +	/* cqe->rss_hash_type[7:6] - L4 destination selected for hash
> +	 * (00 = none, 01 = TCP. 10 = UDP, 11 = IPSEC.SPI
> +	 */
>   };
>
>   enum {
>