From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Stanislav Fomichev <sdf@google.com>
Cc: Andrii Nakryiko <andriin@fb.com>, bpf <bpf@vger.kernel.org>,
Networking <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
David Ahern <dsahern@gmail.com>, Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v4 bpf-next 3/9] bpf, xdp: extract common XDP program attachment logic
Date: Tue, 11 Aug 2020 19:19:23 -0700 [thread overview]
Message-ID: <CAEf4BzbXLg2EogSt1+oqmKY54E1gcVo3FLpY78p9jUrBQST_yA@mail.gmail.com> (raw)
In-Reply-To: <20200811181403.GH184844@google.com>
On Tue, Aug 11, 2020 at 11:14 AM <sdf@google.com> wrote:
>
> On 07/21, Andrii Nakryiko wrote:
> > Further refactor XDP attachment code. dev_change_xdp_fd() is split into
> > two
> > parts: getting bpf_progs from FDs and attachment logic, working with
> > bpf_progs. This makes attachment logic a bit more straightforward and
> > prepares code for bpf_xdp_link inclusion, which will share the common
> > logic.
> It looks like this patch breaks xdp tests for me:
> * test_xdping.sh
> * test_xdp_vlan.sh
>
> Can you please verify on your side?
>
> Looking at tools/testing/selftests/bpf/xdping.c I see it has:
> static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
>
> And it attaches program two times in the same net namespace,
> so I don't see how it could've worked before the change :-/
> (unless, of coarse, the previous code was buggy).
Ok, so according to the old logic, XDP_FLAGS_UPDATE_IF_NOEXIST flag is
only checked if new program fd is not -1. So if we are installing a
new program and specify XDP_FLAGS_UPDATE_IF_NOEXIST, we'll be allowed
to do this only if there is no BPF program already attached. But we
are uninstalling program, then XDP_FLAGS_UPDATE_IF_NOEXIST is ignored
and we are allowed to uninstall any BPF program.
I can easily fix this by moving the XDP_FLAGS_UPDATE_IF_NOEXIST check
inside `if (new_prog) {}` section. I'm not sure which semantics was
actually originally intended. Maybe XDP folks can chime in here?
next prev parent reply other threads:[~2020-08-12 2:19 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-22 6:45 [PATCH v4 bpf-next 0/9] BPF XDP link Andrii Nakryiko
2020-07-22 6:45 ` [PATCH v4 bpf-next 1/9] bpf: make bpf_link API available indepently of CONFIG_BPF_SYSCALL Andrii Nakryiko
2020-07-22 6:45 ` [PATCH v4 bpf-next 2/9] bpf, xdp: maintain info on attached XDP BPF programs in net_device Andrii Nakryiko
2020-07-22 15:26 ` Maciej Fijalkowski
2020-07-22 19:35 ` Andrii Nakryiko
2020-07-22 19:56 ` Maciej Fijalkowski
2020-07-22 6:45 ` [PATCH v4 bpf-next 3/9] bpf, xdp: extract common XDP program attachment logic Andrii Nakryiko
2020-07-22 19:13 ` Maciej Fijalkowski
2020-07-22 19:29 ` Andrii Nakryiko
2020-07-27 12:07 ` Shay Agroskin
2020-07-27 18:51 ` Andrii Nakryiko
2020-08-11 18:14 ` sdf
2020-08-12 2:19 ` Andrii Nakryiko [this message]
2020-07-22 6:45 ` [PATCH v4 bpf-next 4/9] bpf, xdp: add bpf_link-based XDP attachment API Andrii Nakryiko
2020-07-22 6:45 ` [PATCH v4 bpf-next 5/9] bpf, xdp: implement LINK_UPDATE for BPF XDP link Andrii Nakryiko
2020-07-22 6:45 ` [PATCH v4 bpf-next 6/9] bpf: implement BPF XDP link-specific introspection APIs Andrii Nakryiko
2020-07-22 6:46 ` [PATCH v4 bpf-next 7/9] libbpf: add support for BPF XDP link Andrii Nakryiko
2020-07-22 6:46 ` [PATCH v4 bpf-next 8/9] selftests/bpf: add BPF XDP link selftests Andrii Nakryiko
2020-07-22 6:46 ` [PATCH v4 bpf-next 9/9] bpf, xdp: remove XDP_QUERY_PROG and XDP_QUERY_PROG_HW XDP commands Andrii Nakryiko
2020-07-26 3:46 ` [PATCH v4 bpf-next 0/9] BPF XDP link Alexei Starovoitov
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=CAEf4BzbXLg2EogSt1+oqmKY54E1gcVo3FLpY78p9jUrBQST_yA@mail.gmail.com \
--to=andrii.nakryiko@gmail.com \
--cc=andriin@fb.com \
--cc=ast@fb.com \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=dsahern@gmail.com \
--cc=kernel-team@fb.com \
--cc=netdev@vger.kernel.org \
--cc=sdf@google.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.