From: Ido Schimmel <idosch@nvidia.com>
To: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Cc: netdev@vger.kernel.org, "David S . Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@kernel.org>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>, David Ahern <dsahern@kernel.org>,
William Tu <u9012063@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 2/2] erspan: skip the platform specific sub-header of ERSPAN type III
Date: Tue, 20 Oct 2026 20:16:23 +0300 [thread overview]
Message-ID: <20261020171623.GB3236673@shredder> (raw)
In-Reply-To: <20261018090236.2487997-3-yanhaishuang@cmss.chinamobile.com>
On Sun, Oct 18, 2026 at 05:02:36PM +0800, Haishuang Yan wrote:
> The ERSPAN type III header has an O flag, which tells whether an
> optional platform specific sub-header of 8 octets follows it. The
> ERSPAN payload starts after that sub-header when the flag is set [1].
>
> Linux never sets the flag on transmit, but it ignores it on receive
> too. When a peer sends the sub-header, its 8 bytes are passed up as the
> start of the mirrored Ethernet frame, so the frame is corrupted.
>
> Pull the sub-header as well when the O flag is set. The collect_md
> metadata still only carries the fixed part of the type III header.
>
> [1] https://datatracker.ietf.org/doc/html/draft-foschiano-erspan-03
>
> Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
The cover letter says this was tested with hand-built packets. Do you
have a device that actually sends the sub-header? If not, then I don't
see a reason to add more dead code to this driver which nobody seems to
care about given the lack of reviews.
next prev parent reply other threads:[~2026-10-20 17:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-18 9:02 [PATCH net-next 0/2] erspan: fix two header parsing issues on receive Haishuang Yan
2026-10-18 9:02 ` [PATCH net-next 1/2] erspan: drop packets with an unknown ERSPAN version Haishuang Yan
2026-10-20 17:15 ` Ido Schimmel
2026-10-21 6:00 ` Haishuang Yan
2026-10-18 9:02 ` [PATCH net-next 2/2] erspan: skip the platform specific sub-header of ERSPAN type III Haishuang Yan
2026-10-20 17:16 ` Ido Schimmel [this message]
2026-10-21 6:01 ` Haishuang Yan
2026-10-18 9:09 ` [PATCH net-next 0/2] erspan: fix two header parsing issues on receive netdev-bot+sinfo
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