Re: [PATCH] drm/i915/pmu: Keep a reference to module while active

[Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>]

On 30/04/2020 19:33, Chris Wilson wrote:
> While a perf event is open, keep a reference to the module so we don't
> remove the driver internals mid-sampling.
>
> Testcase: igt/perf_pmu/module-unload
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
>   drivers/gpu/drm/i915/i915_pmu.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> index 83c6a8ccd2cb..e991a707bdb7 100644
> --- a/drivers/gpu/drm/i915/i915_pmu.c
> +++ b/drivers/gpu/drm/i915/i915_pmu.c
> @@ -442,6 +442,7 @@ static u64 count_interrupts(struct drm_i915_private *i915)
>   static void i915_pmu_event_destroy(struct perf_event *event)
>   {
>   	WARN_ON(event->parent);
> +	module_put(THIS_MODULE);
>   }
>   
>   static int
> @@ -533,8 +534,10 @@ static int i915_pmu_event_init(struct perf_event *event)
>   	if (ret)
>   		return ret;
>   
> -	if (!event->parent)
> +	if (!event->parent) {
> +		__module_get(THIS_MODULE);
>   		event->destroy = i915_pmu_event_destroy;
> +	}
>   
>   	return 0;
>   }

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>

Regards,

Tvrtko
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