Re: [Intel-gfx] [PATCH] drm/i915/pmu: Check is pmu is closed before stopping event

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 19 Oct 2023, Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com> wrote:
> When the driver unbinds, pmu is unregistered and i915->uabi_engines is
> set to RB_ROOT. Due to this, when i915 PMU tries to stop the engine
> events, it issues a warn_on because engine lookup fails.
>
> All perf hooks are taking care of this using a pmu->closed flag that is
> set when PMU unregisters. The stop event seems to have been left out.
>
> Check for pmu->closed in pmu_event_stop as well.
>
> Based on discussion here -
> https://patchwork.freedesktop.org/patch/492079/?series=105790&rev=2
>
> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_pmu.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> index 108b675088ba..f861863eb7c1 100644
> --- a/drivers/gpu/drm/i915/i915_pmu.c
> +++ b/drivers/gpu/drm/i915/i915_pmu.c
> @@ -831,9 +831,18 @@ static void i915_pmu_event_start(struct perf_event *event, int flags)
>  
>  static void i915_pmu_event_stop(struct perf_event *event, int flags)
>  {
> +	struct drm_i915_private *i915 =
> +		container_of(event->pmu, typeof(*i915), pmu.base);
> +	struct i915_pmu *pmu = &i915->pmu;

This inspired me to write [1]. Please review.

BR,
Jani.

[1] https://patchwork.freedesktop.org/series/125464/


> +
> +	if (pmu->closed)
> +		goto out;
> +
>  	if (flags & PERF_EF_UPDATE)
>  		i915_pmu_event_read(event);
>  	i915_pmu_disable(event);
> +
> +out:
>  	event->hw.state = PERF_HES_STOPPED;
>  }

-- 
Jani Nikula, Intel