[PATCH 2/8] drm/i915/pmu: Let resource survive unbind

[Matt Roper]

On Fri, Oct 11, 2024 at 03:54:24PM -0700, 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. It will also allow to ask perf to
> release its own resources when dropping the last reference in a follow
> up change.
> 
> Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>

Reviewed-by: Matt Roper <matthew.d.roper at 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 67b6cbdeff1da..4d05d98f51b8e 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"
> @@ -1148,6 +1149,17 @@ 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);
> @@ -1296,6 +1308,9 @@ void i915_pmu_register(struct drm_i915_private *i915)
>  	if (ret)
>  		goto err_unreg;
>  
> +	if (drmm_add_action(&i915->drm, free_pmu, pmu))
> +		goto err_unreg;
> +
>  	return;
>  
>  err_unreg:
> @@ -1330,11 +1345,7 @@ 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);
>  }
> -- 
> 2.47.0
> 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation