Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
> Assume that intel_wakereg_get() may take the mutex, and perform other
> sleeping actions in the course of its callbacks and so use might_sleep()
> to ensure that all callers abide. Anything that cannot sleep has to use
> e.g. intel_wakeref_get_if_active() to guarantee its avoidance of the
> non-atomic paths.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gt/intel_gt_pm.h | 5 +++++
> drivers/gpu/drm/i915/gt/intel_lrc.c | 2 +-
> .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 2 +-
> drivers/gpu/drm/i915/intel_wakeref.h | 17 +++++++++++++++--
> 4 files changed, 22 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.h b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
> index 990efc27a4e4..4a9e48c12bd4 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
> @@ -22,6 +22,11 @@ static inline void intel_gt_pm_get(struct intel_gt *gt)
> intel_wakeref_get(>->wakeref);
> }
>
> +static inline void __intel_gt_pm_get(struct intel_gt *gt)
> +{
> + __intel_wakeref_get(>->wakeref);
> +}
> +
> static inline bool intel_gt_pm_get_if_awake(struct intel_gt *gt)
> {
> return intel_wakeref_get_if_active(>->wakeref);
> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
> index b65bc06855b0..516306ebc839 100644
> --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> @@ -1121,7 +1121,7 @@ __execlists_schedule_in(struct i915_request *rq)
> BUILD_BUG_ON(NUM_CONTEXT_TAG > GEN12_MAX_CONTEXT_HW_ID);
> }
>
> - intel_gt_pm_get(engine->gt);
> + __intel_gt_pm_get(engine->gt);
> execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_IN);
> intel_engine_context_in(engine);
>
> 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 dcccbd640809..6f94af7ad1de 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -529,7 +529,7 @@ static struct i915_request *schedule_in(struct i915_request *rq, int idx)
> * required if we generalise the inflight tracking.
> */
>
> - intel_gt_pm_get(rq->engine->gt);
> + __intel_gt_pm_get(rq->engine->gt);
> return i915_request_get(rq);
> }
>
> diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
> index da6e8fd506e6..3897bfea72d9 100644
> --- a/drivers/gpu/drm/i915/intel_wakeref.h
> +++ b/drivers/gpu/drm/i915/intel_wakeref.h
> @@ -59,9 +59,7 @@ void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags);
>
> /**
> * intel_wakeref_get: Acquire the wakeref
> - * @i915: the drm_i915_private device
> * @wf: the wakeref
> - * @fn: callback for acquired the wakeref, called only on first acquire.
> *
> * Acquire a hold on the wakeref. The first user to do so, will acquire
> * the runtime pm wakeref and then call the @fn underneath the wakeref
> @@ -76,12 +74,27 @@ void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags);
> static inline int
> intel_wakeref_get(struct intel_wakeref *wf)
> {
> + might_sleep();
> if (unlikely(!atomic_inc_not_zero(&wf->count)))
> return __intel_wakeref_get_first(wf);
>
> return 0;
> }
>
> +/**
> + * __intel_wakeref_get: Acquire the wakeref, again
> + * @wf: the wakeref
> + *
> + * Increment the wakeref counter, but only valid if it is already held by
> + * the caller.
> + */
> +static inline void
> +__intel_wakeref_get(struct intel_wakeref *wf)
> +{
> + INTEL_WAKEREF_BUG_ON(!atomic_read(&wf->count));
> + atomic_inc(&wf->count);
> +}
> +
> /**
> * intel_wakeref_get_if_in_use: Acquire the wakeref
> * @wf: the wakeref
> --
> 2.24.0
>
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> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
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