Re: [PATCH bpf-next v4 3/3] selftests/bpf: xdp: test dev_xdp_install() rejects device-bound program

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Multi-line comment opening `/*` is not on its own line, violating BPF subsystem coding style.
--

--- Patch [3]: [PATCH bpf-next v4 3/3] selftests/bpf: xdp: test dev_xdp_install() rejects device-bound program ---
commit b147dadba98d80bfb5e1c977447162a9b3e3bc29
Author: Jiayuan Chen <jiayuan.chen@linux.dev>

selftests/bpf: xdp: test dev_xdp_install() rejects device-bound program

This commit adds a test to ensure that device-bound XDP programs cannot be
swapped into a generic XDP link via BPF_LINK_UPDATE, bypassing the original
checks in dev_xdp_attach().

> diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_dev_bound_only.c b/tools/testing/selftests/bpf/prog_tests/xdp_dev_bound_only.c
> index 7dd18c6d06c60..4a13f8ec43009 100644
> --- a/tools/testing/selftests/bpf/prog_tests/xdp_dev_bound_only.c
> +++ b/tools/testing/selftests/bpf/prog_tests/xdp_dev_bound_only.c

[ ... ]

> @@ -59,3 +61,50 @@ void test_xdp_dev_bound_only_offdev(void)
>  	 */
>  	SYS_NOFAIL("ip netns del " LOCAL_NETNS);
>  }
> +
> +/* A device-bound program must not run on the XDP software path.
> + * dev_xdp_attach() rejected such programs, but bpf_xdp_link_update() reaches
> + * dev_xdp_install() directly and bypasses it, so the check has to live in
> + * dev_xdp_install(). Create a generic (SKB) XDP link with a normal program,
> + * then try to swap in a device-bound program via BPF_LINK_UPDATE.
> + */

[Severity: Low]
This isn't a bug, but does this multi-line comment follow the preferred BPF
subsystem comment style? 

The BPF subsystem guidelines prefer the opening /* to be on its own line for
multi-line comments, with the comment text starting on the next line.

> +void test_xdp_dev_bound_only_link_update(void)
> +{
> +	LIBBPF_OPTS(bpf_link_create_opts, lopts, .flags = XDP_FLAGS_SKB_MODE);

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260810050621.82035-1-jiayuan.chen@linux.dev?part=3