From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: "Sun Jian" <sun.jian.kdev@gmail.com>, <bpf@vger.kernel.org>
Cc: <ast@kernel.org>, <daniel@iogearbox.net>,
<john.fastabend@gmail.com>, <andrii@kernel.org>,
<eddyz87@gmail.com>, <memxor@gmail.com>, <martin.lau@linux.dev>,
<song@kernel.org>, <yonghong.song@linux.dev>, <jolsa@kernel.org>,
<emil@etsalapatis.com>, <shuah@kernel.org>,
<laoar.shao@gmail.com>, <linux-kernel@vger.kernel.org>,
<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH bpf 1/2] bpf: Preserve link info metadata on ENOSPC
Date: Wed, 24 Jun 2026 13:59:02 -0700 [thread overview]
Message-ID: <DJHKXOX035PB.5RNR3ZGIELZS@gmail.com> (raw)
In-Reply-To: <20260624111837.889209-1-sun.jian.kdev@gmail.com>
On Wed Jun 24, 2026 at 4:18 AM PDT, Sun Jian wrote:
> BPF_OBJ_GET_INFO_BY_FD for bpf_link copies struct bpf_link_info back to
> userspace only when ->fill_link_info() succeeds. Some link info providers,
> however, can return -ENOSPC after computing valid metadata when a nested
> userspace output buffer is too small.
>
> For example, perf event tracepoint link info can determine the required
> tp_name length before copying the name fails with -ENOSPC. The current
> top-level error handling returns immediately in that case, so userspace
> observes -ENOSPC but loses the metadata needed to retry with a sufficiently
> large buffer.
>
> Allow bpf_link_get_info_by_fd() to copy the top-level bpf_link_info back
> on -ENOSPC, while still returning -ENOSPC to userspace. Also let perf
> event kprobe, uprobe, and tracepoint link info fill their metadata before
> returning -ENOSPC from nested name buffer copying.
>
> Fixes: f2e10bff16a0 ("bpf: Add support for BPF_OBJ_GET_INFO_BY_FD for bpf_link")
> Fixes: 1b715e1b0ec5 ("bpf: Support ->fill_link_info for perf_event")
> Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com>
This one is in "wont-fix" category.
Please stop taking AI reports and convert them to pointless patches.
Fix only what humans can hit.
pw-bot: cr
next prev parent reply other threads:[~2026-06-24 20:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-24 11:18 [PATCH bpf 1/2] bpf: Preserve link info metadata on ENOSPC Sun Jian
2026-06-24 11:18 ` [PATCH bpf 2/2] selftests/bpf: Cover " Sun Jian
2026-06-24 12:08 ` bot+bpf-ci
2026-06-24 20:59 ` Alexei Starovoitov [this message]
2026-06-25 7:14 ` [PATCH bpf 1/2] bpf: Preserve " Jiri Olsa
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