linux-kernel - [PATCH] perf/arm-dmc620: Fix lockdep assert in ->event

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Date: Tue, 14 May 2024 11:00:50 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Will Deacon <will@...nel.org>,
	Mark Rutland <mark.rutland@....com>
Cc: Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-arm-kernel@...ts.infradead.org,
	Greg Thelen <gthelen@...gle.com>,
	Robin Murphy <robin.murphy@....com>,
	Tuan Phan <tuanphan@...amperecomputing.com>
Subject: [PATCH] perf/arm-dmc620: Fix lockdep assert in ->event_init()

for_each_sibling_event() checks leader's ctx but it doesn't have the ctx
yet if it's the leader.  Like in perf_event_validate_size(), we should
skip checking siblings in that case.

Fixes: f3c0eba287049 ("perf: Add a few assertions")
Reported-by: Greg Thelen <gthelen@...gle.com>
Cc: Robin Murphy <robin.murphy@....com>
Cc: Tuan Phan <tuanphan@...amperecomputing.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 drivers/perf/arm_dmc620_pmu.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/perf/arm_dmc620_pmu.c b/drivers/perf/arm_dmc620_pmu.c
index 8a81be2dd5ec..88c17c1d6d49 100644
--- a/drivers/perf/arm_dmc620_pmu.c
+++ b/drivers/perf/arm_dmc620_pmu.c
@@ -542,12 +542,16 @@ static int dmc620_pmu_event_init(struct perf_event *event)
 	if (event->cpu < 0)
 		return -EINVAL;
 
+	hwc->idx = -1;
+
+	if (event->group_leader == event)
+		return 0;
+
 	/*
 	 * We can't atomically disable all HW counters so only one event allowed,
 	 * although software events are acceptable.
 	 */
-	if (event->group_leader != event &&
-			!is_software_event(event->group_leader))
+	if (!is_software_event(event->group_leader))
 		return -EINVAL;
 
 	for_each_sibling_event(sibling, event->group_leader) {
@@ -556,7 +560,6 @@ static int dmc620_pmu_event_init(struct perf_event *event)
 			return -EINVAL;
 	}
 
-	hwc->idx = -1;
 	return 0;
 }
 
-- 
2.45.0.rc1.225.g2a3ae87e7f-goog