From: Stanislav Fomichev <stfomichev@gmail.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Amery Hung <ameryhung@gmail.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
Subject: Re: [RFC bpf-next v1 3/7] bpf: Support pulling non-linear xdp data
Date: Mon, 25 Aug 2025 17:12:13 -0700 [thread overview]
Message-ID: <aKz73WdkzhOmLhjJ@mini-arch> (raw)
In-Reply-To: <20250825155813.763d2a59@kernel.org>
On 08/25, Jakub Kicinski wrote:
> On Mon, 25 Aug 2025 15:46:02 -0700 Stanislav Fomichev wrote:
> > > > skb_frag_address can return NULL for unreadable frags.
> > >
> > > Is it safe to assume that drivers will ensure frags to be readable? It
> > > seems at least mlx5 does.
> > >
> > > I did a quick check and found other xdp kfuncs using
> > > skb_frag_address() without checking the return.
> >
> > The unreadable frags will always be unredabale to the host. This is TCP
> > device memory, the memory on the accelerators that is not mapped onto
> > the CPU. Any attempts to read that memory should gracefully error out.
> >
> > Can you also pls fix that other one? (not as part of the series should
> > be ok)
>
> But we don't support mixing XDP with unreadable mem today.
> Is the concern just for future proofing?
Good point. I though we did add that proofing during the initial rx
patch series, but I don't see any. Ignore me!
next prev parent reply other threads:[~2025-08-26 0:12 UTC|newest]
Thread overview: 31+ 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
2025-08-28 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
2025-08-25 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 [this message]
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
2025-08-29 18:21 ` Martin KaFai Lau
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=aKz73WdkzhOmLhjJ@mini-arch \
--to=stfomichev@gmail.com \
--cc=alexei.starovoitov@gmail.com \
--cc=ameryhung@gmail.com \
--cc=andrii@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=kernel-team@meta.com \
--cc=kuba@kernel.org \
--cc=maciej.fijalkowski@intel.com \
--cc=martin.lau@kernel.org \
--cc=mbloch@nvidia.com \
--cc=mohsin.bashr@gmail.com \
--cc=netdev@vger.kernel.org \
--cc=saeedm@nvidia.com \
--cc=tariqt@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).