From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Nick Hudson <nhudson@akamai.com>,
bpf@vger.kernel.org, netdev@vger.kernel.org,
Willem de Bruijn <willemb@google.com>,
Martin KaFai Lau <martin.lau@linux.dev>
Cc: Nick Hudson <nhudson@akamai.com>,
Max Tottenham <mtottenh@akamai.com>,
Anna Glasgall <aglasgal@akamai.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 5/6] bpf: clear decap state on skb_adjust_room shrink path
Date: Mon, 04 May 2026 13:15:12 -0400 [thread overview]
Message-ID: <willemdebruijn.kernel.3b7e1901d86e3@gmail.com> (raw)
In-Reply-To: <20260504101759.3319427-6-nhudson@akamai.com>
Nick Hudson wrote:
> On shrink in bpf_skb_adjust_room(), apply decapsulation state updates
> according to BPF_F_ADJ_ROOM_DECAP_* flags.
>
> For GSO skbs, clear only the tunnel gso_type bits that correspond to the
> requested decap layer:
> - DECAP_L4_UDP: SKB_GSO_UDP_TUNNEL{,_CSUM}
> - DECAP_L4_GRE: SKB_GSO_GRE{,_CSUM}
> - DECAP_IPXIP4: SKB_GSO_IPXIP4
> - DECAP_IPXIP6: SKB_GSO_IPXIP6
>
> Then clear skb->encapsulation only if no tunnel GSO bits remain, keeping
> encapsulation set for cases such as ESP-in-UDP where tunnel state remains.
>
> For non-GSO skbs, there are no tunnel GSO bits to consult, so clear
> skb->encapsulation directly when DECAP_L4_* or DECAP_IPXIP_* flags are set.
>
> This keeps decap state handling consistent between GSO and non-GSO packets.
>
> Co-developed-by: Max Tottenham <mtottenh@akamai.com>
> Signed-off-by: Max Tottenham <mtottenh@akamai.com>
> Co-developed-by: Anna Glasgall <aglasgal@akamai.com>
> Signed-off-by: Anna Glasgall <aglasgal@akamai.com>
> Signed-off-by: Nick Hudson <nhudson@akamai.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
next prev parent reply other threads:[~2026-05-04 17:15 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-04 10:17 [PATCH bpf-next v6 0/6] bpf: decap flags and GSO state updates Nick Hudson
2026-05-04 10:17 ` [PATCH v6 1/6] bpf: name the enum for BPF_FUNC_skb_adjust_room flags Nick Hudson
2026-05-04 11:03 ` bot+bpf-ci
2026-05-04 10:17 ` [PATCH v6 2/6] bpf: refactor masks for ADJ_ROOM flags and encap validation Nick Hudson
2026-05-04 11:03 ` bot+bpf-ci
2026-05-04 17:14 ` Willem de Bruijn
2026-05-04 10:17 ` [PATCH v6 3/6] bpf: add BPF_F_ADJ_ROOM_DECAP_* flags for tunnel decapsulation Nick Hudson
2026-05-04 11:03 ` bot+bpf-ci
2026-05-04 10:17 ` [PATCH v6 4/6] bpf: allow new DECAP flags and add guard rails Nick Hudson
2026-05-04 10:17 ` [PATCH v6 5/6] bpf: clear decap state on skb_adjust_room shrink path Nick Hudson
2026-05-04 17:15 ` Willem de Bruijn [this message]
2026-05-04 10:17 ` [PATCH v6 6/6] selftests/bpf: tc_tunnel - validate decap GSO and encapsulation state Nick Hudson
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