Some PMUs have well defined parents such as PCI devices.
As the device_initialize() and device_add() are all within
pmu_dev_alloc() which is called from perf_pmu_register()
there is no opportunity to set the parent from within a driver.

Add a struct device *parent field to struct pmu and use that
to set the parent.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 include/linux/perf_event.h | 1 +
 kernel/events/core.c       | 1 +
 2 files changed, 2 insertions(+)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index d5628a7b5eaa..b99db1eda72c 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -303,6 +303,7 @@ struct pmu {
 
 	struct module			*module;
 	struct device			*dev;
+	struct device			*parent;
 	const struct attribute_group	**attr_groups;
 	const struct attribute_group	**attr_update;
 	const char			*name;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index db016e418931..285cf6ca6e81 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11379,6 +11379,7 @@ static int pmu_dev_alloc(struct pmu *pmu)
 
 	dev_set_drvdata(pmu->dev, pmu);
 	pmu->dev->bus = &pmu_bus;
+	pmu->dev->parent = pmu->parent;
 	pmu->dev->release = pmu_dev_release;
 
 	ret = dev_set_name(pmu->dev, "%s", pmu->name);
-- 
2.39.2