From: Jakub Kicinski <kuba@kernel.org>
To: Stanislav Fomichev <sdf.kernel@gmail.com>
Cc: Lorenzo Bianconi <lorenzo@kernel.org>,
Donald Hunter <donald.hunter@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Jesper Dangaard Brouer <hawk@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Stanislav Fomichev <sdf@fomichev.me>,
Andrew Lunn <andrew+netdev@lunn.ch>,
Tony Nguyen <anthony.l.nguyen@intel.com>,
Przemek Kitszel <przemyslaw.kitszel@intel.com>,
Alexander Lobakin <aleksander.lobakin@intel.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
KP Singh <kpsingh@kernel.org>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>, Shuah Khan <shuah@kernel.org>,
Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
Jonathan Corbet <corbet@lwn.net>,
Shuah Khan <skhan@linuxfoundation.org>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Emil Tsalapatis <emil@etsalapatis.com>,
Vladimir Vdovin <deliran@verdict.gg>,
Jakub Sitnicki <jakub@cloudflare.com>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
intel-wired-lan@lists.osuosl.org,
linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org
Subject: Re: [PATCH bpf-next v5 8/8] selftests: net: add test for XDP_PASS skb checksum invalidation
Date: Wed, 22 Jul 2026 11:35:25 -0700 [thread overview]
Message-ID: <20260722113525.34092660@kernel.org> (raw)
In-Reply-To: <amEEEohxmC8hkBvY@devvm7509.cco0.facebook.com>
On Wed, 22 Jul 2026 11:00:07 -0700 Stanislav Fomichev wrote:
> > > This is about current drivers that only report UNNECESSARY with xdp: the xdp
> > > prog has to maintain in-packet checksum if it changes the payload. I think
> > > it's a fair assumption?
> >
> > What about decap? If we decap the header that device validated
> > as UNNECESSARY there's no possibility of maintaining the checksum
> > (by which IIUC you mean correcting it in along the payload changes).
> >
> > I think we'd need some API to "decrement the csum level" ?
> > Or some heuristic in the drivers to decrement if the head moved
> > by at least len(IP+UDP) into the packet ?
>
> True :-/ I guess one more case to document?
What would we be documenting? That it's a known bug and we have no idea
how to address it? Or am I missing something?
Again:
.. the ask was to sketch out the plan of explicitly
updating/invalidating the checksum even if we don't
implement it today
WARNING: multiple messages have this Message-ID (diff)
From: Jakub Kicinski <kuba@kernel.org>
To: Stanislav Fomichev <sdf.kernel@gmail.com>
Cc: Lorenzo Bianconi <lorenzo@kernel.org>,
Donald Hunter <donald.hunter@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Jesper Dangaard Brouer <hawk@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Stanislav Fomichev <sdf@fomichev.me>,
Andrew Lunn <andrew+netdev@lunn.ch>,
Tony Nguyen <anthony.l.nguyen@intel.com>,
Przemek Kitszel <przemyslaw.kitszel@intel.com>,
Alexander Lobakin <aleksander.lobakin@intel.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
KP Singh <kpsingh@kernel.org>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>, Shuah Khan <shuah@kernel.org>,
Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
Jonathan Corbet <corbet@lwn.net>,
Shuah Khan <skhan@linuxfoundation.org>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Emil Tsalapatis <emil@etsalapatis.com>,
Vladimir Vdovin <deliran@verdict.gg>,
Jakub Sitnicki <jakub@cloudflare.com>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
intel-wired-lan@lists.osuosl.org,
linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org
Subject: Re: [Intel-wired-lan] [PATCH bpf-next v5 8/8] selftests: net: add test for XDP_PASS skb checksum invalidation
Date: Wed, 22 Jul 2026 11:35:25 -0700 [thread overview]
Message-ID: <20260722113525.34092660@kernel.org> (raw)
In-Reply-To: <amEEEohxmC8hkBvY@devvm7509.cco0.facebook.com>
On Wed, 22 Jul 2026 11:00:07 -0700 Stanislav Fomichev wrote:
> > > This is about current drivers that only report UNNECESSARY with xdp: the xdp
> > > prog has to maintain in-packet checksum if it changes the payload. I think
> > > it's a fair assumption?
> >
> > What about decap? If we decap the header that device validated
> > as UNNECESSARY there's no possibility of maintaining the checksum
> > (by which IIUC you mean correcting it in along the payload changes).
> >
> > I think we'd need some API to "decrement the csum level" ?
> > Or some heuristic in the drivers to decrement if the head moved
> > by at least len(IP+UDP) into the packet ?
>
> True :-/ I guess one more case to document?
What would we be documenting? That it's a known bug and we have no idea
how to address it? Or am I missing something?
Again:
.. the ask was to sketch out the plan of explicitly
updating/invalidating the checksum even if we don't
implement it today
next prev parent reply other threads:[~2026-07-22 18:35 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-15 21:39 [PATCH bpf-next v5 0/8] Add the the capability to load HW RX checksum in eBPF programs Lorenzo Bianconi
2026-07-15 21:39 ` [Intel-wired-lan] " Lorenzo Bianconi
2026-07-15 21:39 ` [PATCH bpf-next v5 1/8] netlink: specs: add XDP RX checksum capability to XDP metadata specs Lorenzo Bianconi
2026-07-15 21:39 ` [Intel-wired-lan] " Lorenzo Bianconi
2026-07-15 22:24 ` bot+bpf-ci
2026-07-15 22:24 ` [Intel-wired-lan] " bot+bpf-ci
2026-07-21 15:21 ` Jakub Kicinski
2026-07-21 15:21 ` [Intel-wired-lan] " Jakub Kicinski
2026-07-15 21:39 ` [PATCH bpf-next v5 2/8] net: veth: add xmo_rx_checksum callback to veth driver Lorenzo Bianconi
2026-07-15 21:39 ` [Intel-wired-lan] " Lorenzo Bianconi
2026-07-15 22:08 ` sashiko-bot
2026-07-15 21:39 ` [PATCH bpf-next v5 3/8] net: ice: add xmo_rx_checksum callback Lorenzo Bianconi
2026-07-15 21:39 ` [Intel-wired-lan] " Lorenzo Bianconi
2026-07-15 21:48 ` sashiko-bot
2026-07-15 21:39 ` [PATCH bpf-next v5 4/8] selftests/bpf: add selftest support for bpf_xdp_metadata_rx_checksum Lorenzo Bianconi
2026-07-15 21:39 ` [Intel-wired-lan] " Lorenzo Bianconi
2026-07-15 21:39 ` [PATCH bpf-next v5 5/8] selftests/bpf: add bpf_xdp_metadata_rx_checksum support to xdp_hw_metadat prog Lorenzo Bianconi
2026-07-15 21:39 ` [Intel-wired-lan] " Lorenzo Bianconi
2026-07-15 21:39 ` [PATCH bpf-next v5 6/8] net: add bpf_skb_rx_checksum kfunc to read skb checksum metadata Lorenzo Bianconi
2026-07-15 21:39 ` [Intel-wired-lan] " Lorenzo Bianconi
2026-07-15 21:39 ` [PATCH bpf-next v5 7/8] selftests/bpf: Add test for bpf_skb_rx_checksum kfunc Lorenzo Bianconi
2026-07-15 21:39 ` [Intel-wired-lan] " Lorenzo Bianconi
2026-07-15 22:08 ` sashiko-bot
2026-07-15 21:39 ` [PATCH bpf-next v5 8/8] selftests: net: add test for XDP_PASS skb checksum invalidation Lorenzo Bianconi
2026-07-15 21:39 ` [Intel-wired-lan] " Lorenzo Bianconi
2026-07-15 21:58 ` sashiko-bot
2026-07-16 12:30 ` [Intel-wired-lan] " Stanislav Fomichev
2026-07-16 12:30 ` Stanislav Fomichev
2026-07-16 16:06 ` Lorenzo Bianconi
2026-07-16 16:06 ` [Intel-wired-lan] " Lorenzo Bianconi
2026-07-20 19:32 ` Stanislav Fomichev
2026-07-20 19:32 ` Stanislav Fomichev
2026-07-20 22:08 ` Lorenzo Bianconi
2026-07-20 22:08 ` [Intel-wired-lan] " Lorenzo Bianconi
2026-07-21 15:27 ` Jakub Kicinski
2026-07-21 15:27 ` [Intel-wired-lan] " Jakub Kicinski
2026-07-21 23:03 ` Stanislav Fomichev
2026-07-21 23:03 ` [Intel-wired-lan] " Stanislav Fomichev
2026-07-22 1:32 ` Jakub Kicinski
2026-07-22 1:32 ` Jakub Kicinski
2026-07-22 18:00 ` Stanislav Fomichev
2026-07-22 18:00 ` [Intel-wired-lan] " Stanislav Fomichev
2026-07-22 18:35 ` Jakub Kicinski [this message]
2026-07-22 18:35 ` Jakub Kicinski
2026-07-22 20:40 ` Stanislav Fomichev
2026-07-22 20:40 ` [Intel-wired-lan] " Stanislav Fomichev
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