From: Jiri Olsa <olsajiri@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: andrii@kernel.org, yhs@fb.com, linux-kernel@vger.kernel.org,
daniel@iogearbox.net, sean@mess.org
Subject: Re: perf_event_detach_bpf_prog() broken?
Date: Tue, 22 Oct 2024 16:03:40 +0200 [thread overview]
Message-ID: <ZxewvPQX7bq40PK3@krava> (raw)
In-Reply-To: <20241022111638.GC16066@noisy.programming.kicks-ass.net>
On Tue, Oct 22, 2024 at 01:16:38PM +0200, Peter Zijlstra wrote:
> Hi guys,
>
> Per commit 170a7e3ea070 ("bpf: bpf_prog_array_copy() should return
> -ENOENT if exclude_prog not found") perf_event_detach_bpf_prog() can now
> return without doing bpf_prog_put() and leaving event->prog set.
>
> This is very 'unexpected' behaviour.
>
> I'm not sure what's sane from the BPF side of things here, but leaving
> event->prog set is really rather unexpected.
>
> Help?
IIUC the ENOENT should never happen in perf event context, so not
sure why we have that check.. also does not seem to be used from
lirc code, Sean?
perf_event_detach_bpf_prog is called when the event is being freed
so I think we should always put and clear the event->prog
jirka
next prev parent reply other threads:[~2024-10-22 14:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-22 11:16 perf_event_detach_bpf_prog() broken? Peter Zijlstra
2024-10-22 14:03 ` Jiri Olsa [this message]
2024-10-22 14:12 ` Sean Young
2024-10-22 21:08 ` Jiri Olsa
2024-10-22 17:33 ` Andrii Nakryiko
2024-10-23 8:19 ` Jiri Olsa
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