Re: [PATCH] perf/bpf: Don't call bpf_overflow_handler() for tracing events

[Jiri Olsa]

On Mon, Jul 15, 2024 at 09:48:58AM -0700, Kyle Huey wrote:
> On Mon, Jul 15, 2024 at 9:30 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> >
> > On Mon, Jul 15, 2024 at 08:19:44AM -0700, Kyle Huey wrote:
> >
> > > I think this would probably work but stealing the bit seems far more
> > > complicated than just gating on perf_event_is_tracing().
> >
> > perf_event_is_tracing() is something like 3 branches. It is not a simple
> > conditional. Combined with that re-load and the wrong return value, this
> > all wants a cleanup.
> >
> > Using that LSB works, it's just that the code aint pretty.
> 
> Maybe we could gate on !event->tp_event instead. Somebody who is more
> familiar with this code than me should probably confirm that tp_event
> being non-null and perf_event_is_tracing() being true are equivalent
> though.
> 

it looks like that's the case, AFAICS tracepoint/kprobe/uprobe events
are the only ones having the tp_event pointer set, Masami?

fwiw I tried to run bpf selftests with that and it's fine

jirka