[PATCH v4 3/5] perf/core: Account dropped samples from BPF

[Namhyung Kim]

Like in the software events, the BPF overflow handler can drop samples
by returning 0.  Let's count the dropped samples here too.

Acked-by: Kyle Huey <me@xxxxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
Cc: Song Liu <song@xxxxxxxxxx>
Cc: bpf@xxxxxxxxxxxxxxx
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 kernel/events/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 5d24597180dec167..b41c17a0bc19f7c2 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9831,8 +9831,10 @@ static int __perf_event_overflow(struct perf_event *event,
 	ret = __perf_event_account_interrupt(event, throttle);
 
 	if (event->prog && event->prog->type == BPF_PROG_TYPE_PERF_EVENT &&
-	    !bpf_overflow_handler(event, data, regs))
+	    !bpf_overflow_handler(event, data, regs)) {
+		atomic64_inc(&event->dropped_samples);
 		return ret;
+	}
 
 	/*
 	 * XXX event_limit might not quite work as expected on inherited
-- 
2.47.0.105.g07ac214952-goog