Re: [PATCH 5/7] drm/i915/pmu: Let resource survive unbind

[Tvrtko Ursulin]

On 22/07/2024 22:06, Lucas De Marchi wrote:

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.demar...@intel.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;

Is i915_pmu_unregister_cpuhp_state missing on this error path?

Regards,

Tvrtko

+
        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);
  }