[Intel-gfx] [PATCH] drm/i915/pmu: Avoid using globals for per-device state

["Michał Winiarski" <michal.winiarski@intel.com>]

Attempting to bind / unbind module from devices where we have both
integrated and discreete GPU handed by i915 may lead to interesting
results where we're keeping per-device state in per-module globals.

Fixes: 05488673a4d4 ("drm/i915/pmu: Support multiple GPUs")
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/i915_pmu.c | 56 ++++++++++++++++++---------------
 drivers/gpu/drm/i915/i915_pmu.h |  8 +++++
 2 files changed, 39 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index a3b61fb96226..1b4fdcb9045d 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -822,11 +822,6 @@ static ssize_t i915_pmu_event_show(struct device *dev,
 	return sprintf(buf, "config=0x%lx\n", eattr->val);
 }
 
-static struct attribute_group i915_pmu_events_attr_group = {
-	.name = "events",
-	/* Patch in attrs at runtime. */
-};
-
 static ssize_t
 i915_pmu_get_attr_cpumask(struct device *dev,
 			  struct device_attribute *attr,
@@ -846,13 +841,6 @@ static const struct attribute_group i915_pmu_cpumask_attr_group = {
 	.attrs = i915_cpumask_attrs,
 };
 
-static const struct attribute_group *i915_pmu_attr_groups[] = {
-	&i915_pmu_format_attr_group,
-	&i915_pmu_events_attr_group,
-	&i915_pmu_cpumask_attr_group,
-	NULL
-};
-
 #define __event(__config, __name, __unit) \
 { \
 	.config = (__config), \
@@ -1026,16 +1014,16 @@ err:;
 
 static void free_event_attributes(struct i915_pmu *pmu)
 {
-	struct attribute **attr_iter = i915_pmu_events_attr_group.attrs;
+	struct attribute **attr_iter = pmu->events_attr_group.attrs;
 
 	for (; *attr_iter; attr_iter++)
 		kfree((*attr_iter)->name);
 
-	kfree(i915_pmu_events_attr_group.attrs);
+	kfree(pmu->events_attr_group.attrs);
 	kfree(pmu->i915_attr);
 	kfree(pmu->pmu_attr);
 
-	i915_pmu_events_attr_group.attrs = NULL;
+	pmu->events_attr_group.attrs = NULL;
 	pmu->i915_attr = NULL;
 	pmu->pmu_attr = NULL;
 }
@@ -1072,8 +1060,6 @@ static int i915_pmu_cpu_offline(unsigned int cpu, struct hlist_node *node)
 	return 0;
 }
 
-static enum cpuhp_state cpuhp_slot = CPUHP_INVALID;
-
 static int i915_pmu_register_cpuhp_state(struct i915_pmu *pmu)
 {
 	enum cpuhp_state slot;
@@ -1093,15 +1079,16 @@ static int i915_pmu_register_cpuhp_state(struct i915_pmu *pmu)
 		return ret;
 	}
 
-	cpuhp_slot = slot;
+	pmu->cpuhp_slot = slot;
 	return 0;
 }
 
 static void i915_pmu_unregister_cpuhp_state(struct i915_pmu *pmu)
 {
-	WARN_ON(cpuhp_slot == CPUHP_INVALID);
-	WARN_ON(cpuhp_state_remove_instance(cpuhp_slot, &pmu->node));
-	cpuhp_remove_multi_state(cpuhp_slot);
+	WARN_ON(pmu->cpuhp_slot == CPUHP_INVALID);
+	WARN_ON(cpuhp_state_remove_instance(pmu->cpuhp_slot, &pmu->node));
+	cpuhp_remove_multi_state(pmu->cpuhp_slot);
+	pmu->cpuhp_slot = CPUHP_INVALID;
 }
 
 static bool is_igp(struct drm_i915_private *i915)
@@ -1118,6 +1105,13 @@ static bool is_igp(struct drm_i915_private *i915)
 void i915_pmu_register(struct drm_i915_private *i915)
 {
 	struct i915_pmu *pmu = &i915->pmu;
+	const struct attribute_group *attr_groups[] = {
+		&i915_pmu_format_attr_group,
+		&pmu->events_attr_group,
+		&i915_pmu_cpumask_attr_group,
+		NULL
+	};
+
 	int ret = -ENOMEM;
 
 	if (INTEL_GEN(i915) <= 2) {
@@ -1128,6 +1122,7 @@ void i915_pmu_register(struct drm_i915_private *i915)
 	spin_lock_init(&pmu->lock);
 	hrtimer_init(&pmu->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	pmu->timer.function = i915_sample;
+	pmu->cpuhp_slot = CPUHP_INVALID;
 
 	if (!is_igp(i915)) {
 		pmu->name = kasprintf(GFP_KERNEL,
@@ -1143,11 +1138,19 @@ void i915_pmu_register(struct drm_i915_private *i915)
 	if (!pmu->name)
 		goto err;
 
-	i915_pmu_events_attr_group.attrs = create_event_attributes(pmu);
-	if (!i915_pmu_events_attr_group.attrs)
+	pmu->events_attr_group.name = "events";
+	pmu->events_attr_group.attrs = create_event_attributes(pmu);
+	if (!pmu->events_attr_group.attrs)
 		goto err_name;
 
-	pmu->base.attr_groups	= i915_pmu_attr_groups;
+	pmu->base.attr_groups = kcalloc(ARRAY_SIZE(attr_groups),
+					sizeof(*attr_groups),
+					GFP_KERNEL);
+	if (!pmu->base.attr_groups)
+		goto err_attr;
+	memcpy(attr_groups, pmu->base.attr_groups,
+	       ARRAY_SIZE(attr_groups) * sizeof(*attr_groups));
+
 	pmu->base.task_ctx_nr	= perf_invalid_context;
 	pmu->base.event_init	= i915_pmu_event_init;
 	pmu->base.add		= i915_pmu_event_add;
@@ -1159,7 +1162,7 @@ void i915_pmu_register(struct drm_i915_private *i915)
 
 	ret = perf_pmu_register(&pmu->base, pmu->name, -1);
 	if (ret)
-		goto err_attr;
+		goto err_groups;
 
 	ret = i915_pmu_register_cpuhp_state(pmu);
 	if (ret)
@@ -1169,6 +1172,8 @@ void i915_pmu_register(struct drm_i915_private *i915)
 
 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);
@@ -1194,6 +1199,7 @@ void i915_pmu_unregister(struct drm_i915_private *i915)
 
 	perf_pmu_unregister(&pmu->base);
 	pmu->base.event_init = NULL;
+	kfree(pmu->base.attr_groups);
 	if (!is_igp(i915))
 		kfree(pmu->name);
 	free_event_attributes(pmu);
diff --git a/drivers/gpu/drm/i915/i915_pmu.h b/drivers/gpu/drm/i915/i915_pmu.h
index 6c1647c5daf2..dc1361e8e27a 100644
--- a/drivers/gpu/drm/i915/i915_pmu.h
+++ b/drivers/gpu/drm/i915/i915_pmu.h
@@ -42,6 +42,10 @@ struct i915_pmu {
 	 * @node: List node for CPU hotplug handling.
 	 */
 	struct hlist_node node;
+	/**
+	 * @cpuhp_slot: State for CPU hotplug handling.
+	 */
+	enum cpuhp_state cpuhp_slot;
 	/**
 	 * @base: PMU base.
 	 */
@@ -104,6 +108,10 @@ struct i915_pmu {
 	 * @sleep_last: Last time GT parked for RC6 estimation.
 	 */
 	ktime_t sleep_last;
+	/**
+	 * @events_attr_group: Device events attribute group.
+	 */
+	struct attribute_group events_attr_group;
 	/**
 	 * @i915_attr: Memory block holding device attributes.
 	 */
-- 
2.21.1

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