drm/i915: Provide the perf pmu.module

Rather than manually implement our own module reference counting for perf
pmu events, finally realise that there is a module parameter to struct
pmu for this very purpose.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200716094643.31410-1-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
(cherry picked from commit 27e897beec)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_pmu.c

@@ -445,8 +445,6 @@ static void i915_pmu_event_destroy(struct perf_event *event)
 		container_of(event->pmu, typeof(*i915), pmu.base);
 
 	drm_WARN_ON(&i915->drm, event->parent);
-
-	module_put(THIS_MODULE);
 }
 
 static int
@@ -538,10 +536,8 @@ static int i915_pmu_event_init(struct perf_event *event)
 	if (ret)
 		return ret;
 
-	if (!event->parent) {
-		__module_get(THIS_MODULE);
+	if (!event->parent)
 		event->destroy = i915_pmu_event_destroy;
-	}
 
 	return 0;
 }
@@ -1130,6 +1126,7 @@ void i915_pmu_register(struct drm_i915_private *i915)
 	if (!pmu->base.attr_groups)
 		goto err_attr;
 
+	pmu->base.module	= THIS_MODULE;
 	pmu->base.task_ctx_nr	= perf_invalid_context;
 	pmu->base.event_init	= i915_pmu_event_init;
 	pmu->base.add		= i915_pmu_event_add;