[Intel-gfx] [PATCH 2/2] drm/i915: Wait on vma activity before taking the mutex

[Tvrtko Ursulin]

On 23/01/2020 22:44, Chris Wilson wrote:
> Optimistically wait for the prior vma activity before taking the mutex
> to minimise the mutex hold time while unbinding. We will then verify the
> vma is idle with a second wait under the mutex to ensure it is safe to
> unbind.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>   drivers/gpu/drm/i915/i915_vma.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index 4999882fbceb..84e03da0d5f9 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -1279,16 +1279,21 @@ int i915_vma_unbind(struct i915_vma *vma)
>   		/* XXX not always required: nop_clear_range */
>   		wakeref = intel_runtime_pm_get(&vm->i915->runtime_pm);
>   
> +	/* Optimistic wait before taking the mutex */
> +	err = i915_vma_sync(vma);
> +	if (err)
> +		goto out_rpm;
> +
>   	err = mutex_lock_interruptible(&vm->mutex);
>   	if (err)
> -		return err;
> +		goto out_rpm;
>   
>   	err = __i915_vma_unbind(vma);
>   	mutex_unlock(&vm->mutex);
>   
> +out_rpm:
>   	if (wakeref)
>   		intel_runtime_pm_put(&vm->i915->runtime_pm, wakeref);
> -
>   	return err;
>   }
>   
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko