Messages in this thread |  | | From | Namhyung Kim <> | | Date | Thu, 18 Jan 2024 21:14:27 -0800 | | Subject | Re: [PATCH v4 3/4] perf/bpf: Allow a bpf program to suppress all sample side effects |
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Hello,
On Thu, Jan 18, 2024 at 4:14 PM Kyle Huey <me@kylehuey.com> wrote: > > Returning zero from a bpf program attached to a perf event already > suppresses any data output. Return early from __perf_event_overflow() in > this case so it will also suppress event_limit accounting, SIGTRAP > generation, and F_ASYNC signalling. > > Signed-off-by: Kyle Huey <khuey@kylehuey.com> > Acked-by: Song Liu <song@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Thanks, Namhyung
> --- > kernel/events/core.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 24a718e7eb98..a329bec42c4d 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -9574,6 +9574,11 @@ static int __perf_event_overflow(struct perf_event *event, > > ret = __perf_event_account_interrupt(event, throttle); > > +#ifdef CONFIG_BPF_SYSCALL > + if (event->prog && !bpf_overflow_handler(event, data, regs)) > + return ret; > +#endif > + > /* > * XXX event_limit might not quite work as expected on inherited > * events > @@ -9623,10 +9628,7 @@ static int __perf_event_overflow(struct perf_event *event, > irq_work_queue(&event->pending_irq); > } > > -#ifdef CONFIG_BPF_SYSCALL > - if (!(event->prog && !bpf_overflow_handler(event, data, regs))) > -#endif > - READ_ONCE(event->overflow_handler)(event, data, regs); > + READ_ONCE(event->overflow_handler)(event, data, regs); > > if (*perf_event_fasync(event) && event->pending_kill) { > event->pending_wakeup = 1; > -- > 2.34.1 >
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