drm/i915/pmu: Stop setting event_init to NULL

Setting event_init to NULL is mostly done to detect when the driver is
partially working: i915 probed, but pmu is not registered. However,
checking for event_init is odd as it was supposed to always be set and
kernel/events/ would just crash if it found it set to NULL.

Since there's already a "closed" boolean, use that instead and extend
it's meaning to unregistered/unregistering.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241104213512.2314930-3-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

Author: Lucas De Marchi

drivers/gpu/drm/i915/i915_pmu.c

@@ -302,7 +302,7 @@ void i915_pmu_gt_parked(struct intel_gt *gt)
 {
 	struct i915_pmu *pmu = &gt->i915->pmu;
 
-	if (!pmu->base.event_init)
+	if (pmu->closed)
 		return;
 
 	spin_lock_irq(&pmu->lock);
@@ -324,7 +324,7 @@ void i915_pmu_gt_unparked(struct intel_gt *gt)
 {
 	struct i915_pmu *pmu = &gt->i915->pmu;
 
-	if (!pmu->base.event_init)
+	if (pmu->closed)
 		return;
 
 	spin_lock_irq(&pmu->lock);
@@ -1177,8 +1177,6 @@ static int i915_pmu_cpu_online(unsigned int cpu, struct hlist_node *node)
 {
 	struct i915_pmu *pmu = hlist_entry_safe(node, typeof(*pmu), cpuhp.node);
 
-	GEM_BUG_ON(!pmu->base.event_init);
-
 	/* Select the first online CPU as a designated reader. */
 	if (cpumask_empty(&i915_pmu_cpumask))
 		cpumask_set_cpu(cpu, &i915_pmu_cpumask);
@@ -1191,8 +1189,6 @@ static int i915_pmu_cpu_offline(unsigned int cpu, struct hlist_node *node)
 	struct i915_pmu *pmu = hlist_entry_safe(node, typeof(*pmu), cpuhp.node);
 	unsigned int target = i915_pmu_target_cpu;
 
-	GEM_BUG_ON(!pmu->base.event_init);
-
 	/*
 	 * Unregistering an instance generates a CPU offline event which we must
 	 * ignore to avoid incorrectly modifying the shared i915_pmu_cpumask.
@@ -1265,9 +1261,10 @@ void i915_pmu_register(struct drm_i915_private *i915)
 		&i915_pmu_cpumask_attr_group,
 		NULL
 	};
-
 	int ret = -ENOMEM;
 
+	pmu->closed = true;
+
 	spin_lock_init(&pmu->lock);
 	hrtimer_init(&pmu->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	pmu->timer.function = i915_sample;
@@ -1316,14 +1313,15 @@ void i915_pmu_register(struct drm_i915_private *i915)
 	if (ret)
 		goto err_unreg;
 
+	pmu->closed = false;
+
 	return;
 
 err_unreg:
 	perf_pmu_unregister(&pmu->base);
 err_groups:
 	kfree(pmu->base.attr_groups);
 err_attr:
-	pmu->base.event_init = NULL;
 	free_event_attributes(pmu);
 err_name:
 	if (IS_DGFX(i915))
@@ -1336,9 +1334,6 @@ void i915_pmu_unregister(struct drm_i915_private *i915)
 {
 	struct i915_pmu *pmu = &i915->pmu;
 
-	if (!pmu->base.event_init)
-		return;
-
 	/*
 	 * "Disconnect" the PMU callbacks - since all are atomic synchronize_rcu
 	 * ensures all currently executing ones will have exited before we
@@ -1352,7 +1347,6 @@ void i915_pmu_unregister(struct drm_i915_private *i915)
 	i915_pmu_unregister_cpuhp_state(pmu);
 
 	perf_pmu_unregister(&pmu->base);
-	pmu->base.event_init = NULL;
 	kfree(pmu->base.attr_groups);
 	if (IS_DGFX(i915))
 		kfree(pmu->name);