diff mbox series

[v2,2/3] perf/bpf: Allow a bpf program to suppress all sample side effects.

Message ID 20231207163458.5554-3-khuey@kylehuey.com
State New
Headers
Series Combine perf and bpf for fast eval of hw breakpoint conditions |

Commit Message

Kyle Huey Dec. 7, 2023, 4:34 p.m. UTC 
  Returning zero from a bpf program attached to a perf event already
suppresses any data output. By clearing pending_kill, returning zero from a
bpf program will effectively pretend the sample never happened for all
userspace purposes.

Signed-off-by: Kyle Huey <khuey@kylehuey.com>
---
 kernel/events/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Andrii Nakryiko Dec. 7, 2023, 7:12 p.m. UTC | #1 
On Thu, Dec 7, 2023 at 8:35 AM Kyle Huey <me@kylehuey.com> wrote:
>
> Returning zero from a bpf program attached to a perf event already
> suppresses any data output. By clearing pending_kill, returning zero from a
> bpf program will effectively pretend the sample never happened for all
> userspace purposes.
>
> Signed-off-by: Kyle Huey <khuey@kylehuey.com>
> ---
>  kernel/events/core.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>

LGTM

Acked-by: Andrii Nakryiko <andrii@kernel.org>

> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 19fddfc27a4a..6cda05a4969d 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -10421,8 +10421,10 @@ static void bpf_overflow_handler(struct perf_event *event,
>         rcu_read_unlock();
>  out:
>         __this_cpu_dec(bpf_prog_active);
> -       if (!ret)
> +       if (!ret) {
> +               event->pending_kill = 0;
>                 return;
> +       }
>
>         event->orig_overflow_handler(event, data, regs);
>  }
> --
> 2.34.1
>
diff mbox series

Patch

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 19fddfc27a4a..6cda05a4969d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10421,8 +10421,10 @@  static void bpf_overflow_handler(struct perf_event *event,
 	rcu_read_unlock();
 out:
 	__this_cpu_dec(bpf_prog_active);
-	if (!ret)
+	if (!ret) {
+		event->pending_kill = 0;
 		return;
+	}
 
 	event->orig_overflow_handler(event, data, regs);
 }