[Intel-gfx] [PATCH v3 04/63] drm/i915: Pin timeline map after first timeline pin, v3.

[Thomas Hellström (Intel)]

On 10/15/20 1:25 PM, Maarten Lankhorst wrote:
> We're starting to require the reservation lock for pinning,
> so wait until we have that.
>
> Update the selftests to handle this correctly, and ensure pin is
> called in live_hwsp_rollover_user() and mock_hwsp_freelist().
>
> Changes since v1:
> - Fix NULL + XX arithmatic, use casts. (kbuild)
> Changes since v2:
> - Clear entire cacheline when pinning.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Reported-by: kernel test robot <lkp at intel.com>
...
> @@ -150,6 +161,12 @@ int intel_timeline_pin(struct intel_timeline *tl, struct i915_gem_ww_ctx *ww)
>   	if (atomic_add_unless(&tl->pin_count, 1, 0))
>   		return 0;
>   
> +	if (!tl->hwsp_map) {
> +		err = intel_timeline_pin_map(tl);
> +		if (err)
> +			return err;
> +	}
> +

On subsequent errors or if somebody beats us to the 0->1 transition, we 
need to unpin_map to avoid leaking pins.

>   	err = i915_ggtt_pin(tl->hwsp_ggtt, ww, 0, PIN_HIGH);
>   	if (err)
>   		return err;

> diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.h b/drivers/gpu/drm/i915/gt/intel_timeline.h
> index 9882cd911d8e..1cfdc4679b62 100644
> --- a/drivers/gpu/drm/i915/gt/intel_timeline.h
> +++ b/drivers/gpu/drm/i915/gt/intel_timeline.h
> @@ -106,4 +106,6 @@ int intel_timeline_read_hwsp(struct i915_request *from,
>   void intel_gt_init_timelines(struct intel_gt *gt);
>   void intel_gt_fini_timelines(struct intel_gt *gt);
>   
> +I915_SELFTEST_DECLARE(int intel_timeline_pin_map(struct intel_timeline *tl));
> +
>   #endif
> diff --git a/drivers/gpu/drm/i915/gt/mock_engine.c b/drivers/gpu/drm/i915/gt/mock_engine.c
> index 2f830017c51d..effbac877eec 100644
> --- a/drivers/gpu/drm/i915/gt/mock_engine.c
> +++ b/drivers/gpu/drm/i915/gt/mock_engine.c
> @@ -32,9 +32,20 @@
>   #include "mock_engine.h"
>   #include "selftests/mock_request.h"
>   
> -static void mock_timeline_pin(struct intel_timeline *tl)
> +static int mock_timeline_pin(struct intel_timeline *tl)
>   {
> +	int err;
> +
> +	if (WARN_ON(!i915_gem_object_trylock(tl->hwsp_ggtt->obj)))
> +		return -EBUSY;

I think we should either annotate this properly as an isolated lock, or 
allow a silent -EBUSY.

/Thomas