perf/arm-smmuv3: Fix lockdep assert in ->event_init()

[ Upstream commit 02a55f2743012a8089f09f6867220c3d57f16564 ]

Same as
https://lore.kernel.org/all/20240514180050.182454-1-namhyung@kernel.org/,
we should skip `for_each_sibling_event()` for group leader since it
doesn't have the ctx yet.

Fixes: f3c0eba28704 ("perf: Add a few assertions")
Reported-by: Greg Thelen <gthelen@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Tuan Phan <tuanphan@os.amperecomputing.com>
Signed-off-by: Chun-Tse Shao <ctshao@google.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20241108050806.3730811-1-ctshao@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
index d5fa92ba8373976982a35cd5d706551d885e657e..dabdb9f7bb82c41a8be67ff3f7ed9bf6fd8c30a2 100644 (file)
--- a/drivers/perf/arm_smmuv3_pmu.c
+++ b/drivers/perf/arm_smmuv3_pmu.c
@@ -431,6 +431,17 @@ static int smmu_pmu_event_init(struct perf_event *event)
                        return -EINVAL;
        }
 
+       /*
+        * Ensure all events are on the same cpu so all events are in the
+        * same cpu context, to avoid races on pmu_enable etc.
+        */
+       event->cpu = smmu_pmu->on_cpu;
+
+       hwc->idx = -1;
+
+       if (event->group_leader == event)
+               return 0;
+
        for_each_sibling_event(sibling, event->group_leader) {
                if (is_software_event(sibling))
                        continue;
@@ -442,14 +453,6 @@ static int smmu_pmu_event_init(struct perf_event *event)
                        return -EINVAL;
        }
 
-       hwc->idx = -1;
-
-       /*
-        * Ensure all events are on the same cpu so all events are in the
-        * same cpu context, to avoid races on pmu_enable etc.
-        */
-       event->cpu = smmu_pmu->on_cpu;
-
        return 0;
 }