netdev - Re: [PATCH] doc: fix wrongly referencing dev->skb

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Date:   Mon, 10 Oct 2016 16:49:43 +0300
From:   Ido Schimmel <idosch@...sch.org>
To:     Ryota Ozaki <ozaki.ryota@...il.com>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH] doc: fix wrongly referencing dev->skb_mark

Hi,

On Mon, Oct 10, 2016 at 08:15:39PM +0900, Ryota Ozaki wrote:
> Section "Flooding L2 domain" says, to avoid duplicated flooding, if
> skb->offload_fwd_mark is matched with dev->skb_mark, the kernel will
> drop the packet. However, the relevant code in __dev_queue_xmit
> compares skb->offload_fwd_mark with dev->offload_fwd_mark, not
> dev->skb_mark. I guess the text is wrong.
> 
> Signed-off-by: Ryota Ozaki <ozaki.ryota@...il.com>
> ---
>  Documentation/networking/switchdev.txt | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/networking/switchdev.txt b/Documentation/networking/switchdev.txt
> index 31c3911..d4124a0 100644
> --- a/Documentation/networking/switchdev.txt
> +++ b/Documentation/networking/switchdev.txt
> @@ -286,8 +286,8 @@ otherwise there will be duplicate packets on the wire.
>  To avoid duplicate packets, the device/driver should mark a packet as already
>  forwarded using skb->offload_fwd_mark.  The same mark is set on the device
>  ports in the domain using dev->offload_fwd_mark.  If the skb->offload_fwd_mark
> -is non-zero and matches the forwarding egress port's dev->skb_mark, the kernel
> -will drop the skb right before transmit on the egress port, with the
> +is non-zero and matches the forwarding egress port's dev->offload_fwd_mark,
> +the kernel will drop the skb right before transmit on the egress port, with the

I think your tree isn't up to date. The flooding mechanism (and this
document) were modified in commit 6bc506b4fb06 ("bridge: switchdev: Add
forward mark support for stacked devices")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6bc506b4fb065eac3d89ca1ce37082e174493d9e

Also, in the future, please specify to which tree (net, net-next) your
patch should go. See:
https://www.kernel.org/doc/Documentation/networking/netdev-FAQ.txt
(under "How do I indicate which tree (net vs. net-next) my patch
should be in?").

Thanks!

>  understanding that the device already forwarded the packet on same egress port.
>  The driver can use switchdev_port_fwd_mark_set() to set a globally unique mark
>  for port's dev->offload_fwd_mark, based on the port's parent ID (switch ID) and
> -- 
> 2.7.4
>