From: Jakub Kicinski <kuba@kernel.org>
To: Amery Hung <ameryhung@gmail.com>
Cc: Nimrod Oren <noren@nvidia.com>,
bpf@vger.kernel.org, netdev@vger.kernel.org,
alexei.starovoitov@gmail.com, andrii@kernel.org,
daniel@iogearbox.net, martin.lau@kernel.org,
mohsin.bashr@gmail.com, saeedm@nvidia.com, tariqt@nvidia.com,
mbloch@nvidia.com, maciej.fijalkowski@intel.com,
kernel-team@meta.com, Dragos Tatulea <dtatulea@nvidia.com>,
Gal Pressman <gal@nvidia.com>
Subject: Re: [RFC bpf-next v1 2/7] bpf: Allow bpf_xdp_shrink_data to shrink a frag from head and tail
Date: Thu, 4 Sep 2025 18:52:41 -0700 [thread overview]
Message-ID: <20250904185241.607552f7@kernel.org> (raw)
In-Reply-To: <CAMB2axOZW_t1y8_wQN=e-vx1LHWLA-CKnYDjVo_g6FcY9NQ5uA@mail.gmail.com>
On Thu, 4 Sep 2025 15:19:28 -0700 Amery Hung wrote:
> On Thu, Aug 28, 2025 at 6:44 AM Nimrod Oren <noren@nvidia.com> wrote:
> > On 25/08/2025 22:39, Amery Hung wrote:
> > > Move skb_frag_t adjustment into bpf_xdp_shrink_data() and extend its
> > > functionality to be able to shrink an xdp fragment from both head and
> > > tail. In a later patch, bpf_xdp_pull_data() will reuse it to shrink an
> > > xdp fragment from head.
> > I had assumed that XDP multi-buffer frags must always be the same size,
> > except for the last one. If that’s the case, shrinking from the head
> > seems to break this rule.
>
> I am not aware of the assumption in the code. Is this documented somewhere?
There's no such rule. Perhaps conflating frags with segments after TSO.
next prev parent reply other threads:[~2025-09-05 1:52 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-25 19:39 [RFC bpf-next v1 0/7] Add kfunc bpf_xdp_pull_data Amery Hung
2025-08-25 19:39 ` [RFC bpf-next v1 1/7] net/mlx5e: Fix generating skb from nonlinear xdp_buff Amery Hung
2025-08-27 13:45 ` Dragos Tatulea
2025-08-28 3:44 ` Amery Hung
2025-08-28 16:23 ` Dragos Tatulea
2025-09-04 17:26 ` Amery Hung
2025-08-28 13:41 ` Nimrod Oren
2025-08-25 19:39 ` [RFC bpf-next v1 2/7] bpf: Allow bpf_xdp_shrink_data to shrink a frag from head and tail Amery Hung
2025-08-28 13:43 ` Nimrod Oren
2025-09-04 22:19 ` Amery Hung
2025-09-05 1:52 ` Jakub Kicinski [this message]
2025-08-25 19:39 ` [RFC bpf-next v1 3/7] bpf: Support pulling non-linear xdp data Amery Hung
2025-08-25 21:29 ` Stanislav Fomichev
2025-08-25 22:23 ` Amery Hung
2025-08-25 22:29 ` Jakub Kicinski
2025-08-25 22:36 ` Amery Hung
2025-08-25 22:46 ` Stanislav Fomichev
2025-08-25 22:58 ` Jakub Kicinski
2025-08-26 0:12 ` Stanislav Fomichev
2025-08-26 0:30 ` Jakub Kicinski
2025-08-25 22:39 ` Jakub Kicinski
2025-08-26 5:12 ` Amery Hung
2025-08-26 13:20 ` Jakub Kicinski
2025-08-26 13:44 ` Amery Hung
2025-08-25 19:39 ` [RFC bpf-next v1 4/7] bpf: Clear packet pointers after changing packet data in kfuncs Amery Hung
2025-08-25 19:39 ` [RFC bpf-next v1 5/7] bpf: Support specifying linear xdp packet data size in test_run Amery Hung
2025-08-25 19:39 ` [RFC bpf-next v1 6/7] selftests/bpf: Test bpf_xdp_pull_data Amery Hung
2025-08-25 19:39 ` [RFC bpf-next v1 7/7] selftests: drv-net: Pull data before parsing headers Amery Hung
2025-08-25 22:41 ` [RFC bpf-next v1 0/7] Add kfunc bpf_xdp_pull_data Jakub Kicinski
2025-08-26 19:38 ` Gal Pressman
2025-08-28 13:39 ` Nimrod Oren
2025-08-29 7:26 ` Amery Hung
2025-08-30 0:09 ` Jakub Kicinski
2025-09-09 9:28 ` Nimrod Oren
2025-08-29 18:21 ` Martin KaFai Lau
2025-09-04 17:28 ` Amery Hung
2025-09-05 17:20 ` Martin KaFai Lau
2025-09-04 22:16 ` Amery Hung
2025-09-09 13:21 ` Nimrod Oren
2025-09-09 15:53 ` Amery Hung
2025-09-09 19:20 ` Amery Hung
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