[Intel-gfx] [PATCH] drm/i915/pmu: Fix wakeref leak in PMU busyness during reset

[Dixit, Ashutosh]

On Mon, 06 Dec 2021 16:45:42 -0800, Umesh Nerlige Ramappa wrote:
>
> GuC PMU busyness gets gt wakeref if awake, but fails to release the
> wakeref if a reset is in progress. Release the wakeref if it was
> acquried successfully.
>
> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index 1f9d4fde421f..a243304a2db1 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -1181,6 +1181,7 @@ static ktime_t guc_engine_busyness(struct intel_engine_cs *engine, ktime_t *now)
>	struct intel_gt *gt = engine->gt;
>	struct intel_guc *guc = &gt->uc.guc;
>	u64 total, gt_stamp_saved;
> +	intel_wakeref_t wakeref;

Should be bool.

>	unsigned long flags;
>	u32 reset_count;
>	bool in_reset;
> @@ -1206,18 +1207,21 @@ static ktime_t guc_engine_busyness(struct intel_engine_cs *engine, ktime_t *now)
>	 * start_gt_clk is derived from GuC state. To get a consistent
>	 * view of activity, we query the GuC state only if gt is awake.
>	 */
> -	if (intel_gt_pm_get_if_awake(gt) && !in_reset) {

Also how about just switch them around:

	if (!in_reset && intel_gt_pm_get_if_awake(gt))

Then you don't need any other changes I think.

> +	wakeref = intel_gt_pm_get_if_awake(gt);
> +	if (wakeref && !in_reset) {
>		stats_saved = *stats;
>		gt_stamp_saved = guc->timestamp.gt_stamp;
>		guc_update_engine_gt_clks(engine);
>		guc_update_pm_timestamp(guc, engine, now);
> -		intel_gt_pm_put_async(gt);
>		if (i915_reset_count(gpu_error) != reset_count) {
>			*stats = stats_saved;
>			guc->timestamp.gt_stamp = gt_stamp_saved;
>		}
>	}
>
> +	if (wakeref)
> +		intel_gt_pm_put_async(gt);
> +
>	total = intel_gt_clock_interval_to_ns(gt, stats->total_gt_clks);
>	if (stats->running) {
>		u64 clk = guc->timestamp.gt_stamp - stats->start_gt_clk;
> --
> 2.20.1
>