netdev - Re: [PATCH net] bridge: switchdev: Clear forward mark when transmitting packet

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Date:   Fri, 01 Sep 2017 10:12:00 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     idosch@...lanox.com
Cc:     netdev@...r.kernel.org, stephen@...workplumber.org,
        nikolay@...ulusnetworks.com, jiri@...lanox.com,
        yotamg@...lanox.com, mlxsw@...lanox.com,
        bridge@...ts.linux-foundation.org
Subject: Re: [PATCH net] bridge: switchdev: Clear forward mark when
 transmitting packet

From: Ido Schimmel <idosch@...lanox.com>
Date: Fri,  1 Sep 2017 12:22:25 +0300

> Commit 6bc506b4fb06 ("bridge: switchdev: Add forward mark support for
> stacked devices") added the 'offload_fwd_mark' bit to the skb in order
> to allow drivers to indicate to the bridge driver that they already
> forwarded the packet in L2.
> 
> In case the bit is set, before transmitting the packet from each port,
> the port's mark is compared with the mark stored in the skb's control
> block. If both marks are equal, we know the packet arrived from a switch
> device that already forwarded the packet and it's not re-transmitted.
> 
> However, if the packet is transmitted from the bridge device itself
> (e.g., br0), we should clear the 'offload_fwd_mark' bit as the mark
> stored in the skb's control block isn't valid.
> 
> This scenario can happen in rare cases where a packet was trapped during
> L3 forwarding and forwarded by the kernel to a bridge device.
> 
> Fixes: 6bc506b4fb06 ("bridge: switchdev: Add forward mark support for stacked devices")
> Signed-off-by: Ido Schimmel <idosch@...lanox.com>
> Reported-by: Yotam Gigi <yotamg@...lanox.com>
> Tested-by: Yotam Gigi <yotamg@...lanox.com>
> Reviewed-by: Jiri Pirko <jiri@...lanox.com>

Applied and queued up for -stable, thanks.