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[v6,6/7] perf/bpf: Allow a bpf program to suppress all sample side effects

Message ID 20240412015019.7060-7-khuey@kylehuey.com (mailing list archive)
State New, archived
Delegated to: BPF
Headers show
Series Combine perf and bpf for fast eval of hw breakpoint conditions | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch
bpf/vmtest-bpf-next-PR success PR summary
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Commit Message

Kyle Huey April 12, 2024, 1:50 a.m. UTC 
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: Jiri Olsa <jolsa@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
---
 kernel/events/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/kernel/events/core.c b/kernel/events/core.c
index fd601d509cea..cd88d1e89eb8 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9658,6 +9658,9 @@  static int __perf_event_overflow(struct perf_event *event,
 
 	ret = __perf_event_account_interrupt(event, throttle);
 
+	if (event->prog && !bpf_overflow_handler(event, data, regs))
+		return ret;
+
 	/*
 	 * XXX event_limit might not quite work as expected on inherited
 	 * events
@@ -9707,8 +9710,7 @@  static int __perf_event_overflow(struct perf_event *event,
 		irq_work_queue(&event->pending_irq);
 	}
 
-	if (!(event->prog && !bpf_overflow_handler(event, data, regs)))
-		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;