linux-kernel - [PATCH 5/7] drm/i915/pmu: Let resource survive unbind

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Message-ID: <20240722210648.80892-6-lucas.demarchi@intel.com>
Date: Mon, 22 Jul 2024 14:06:46 -0700
From: Lucas De Marchi <lucas.demarchi@...el.com>
To: intel-gfx@...ts.freedesktop.org,
	linux-perf-users@...r.kernel.org
Cc: Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
	dri-devel@...ts.freedesktop.org,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	linux-kernel@...r.kernel.org,
	Lucas De Marchi <lucas.demarchi@...el.com>
Subject: [PATCH 5/7] drm/i915/pmu: Let resource survive unbind

There's no need to free the resources during unbind. Since perf events
may still access them due to open events, it's safer to free them when
dropping the last i915 reference.

Signed-off-by: Lucas De Marchi <lucas.demarchi@...el.com>
---
 drivers/gpu/drm/i915/i915_pmu.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index b5d14dd318e4..8708f905f4f4 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -5,6 +5,7 @@
  */
 
 #include <linux/pm_runtime.h>
+#include <drm/drm_managed.h>
 
 #include "gt/intel_engine.h"
 #include "gt/intel_engine_pm.h"
@@ -1152,6 +1153,17 @@ static void free_event_attributes(struct i915_pmu *pmu)
 	pmu->pmu_attr = NULL;
 }
 
+static void free_pmu(struct drm_device *dev, void *res)
+{
+	struct i915_pmu *pmu = res;
+	struct drm_i915_private *i915 = pmu_to_i915(pmu);
+
+	free_event_attributes(pmu);
+	kfree(pmu->base.attr_groups);
+	if (IS_DGFX(i915))
+		kfree(pmu->name);
+}
+
 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);
@@ -1302,6 +1314,9 @@ void i915_pmu_register(struct drm_i915_private *i915)
 	if (ret)
 		goto err_unreg;
 
+	if (drmm_add_action_or_reset(&i915->drm, free_pmu, pmu))
+		goto err_unreg;
+
 	return;
 
 err_unreg:
@@ -1336,11 +1351,7 @@ void i915_pmu_unregister(struct drm_i915_private *i915)
 	hrtimer_cancel(&pmu->timer);
 
 	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);
-	free_event_attributes(pmu);
 }
-- 
2.43.0