[Intel-gfx] [PATCH 2/2] drm/i915: Make GPU pages movable

[Goel, Akash]

On 11/4/2016 7:07 PM, Chris Wilson wrote:
> Best if we send these as a new series to unconfuse CI.
>
Okay will send as a new series.

> On Fri, Nov 04, 2016 at 06:18:26PM +0530, akash.goel at intel.com wrote:
>> +static int do_migrate_page(struct drm_i915_gem_object *obj)
>> +{
>> +	struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
>> +	int ret = 0;
>> +
>> +	if (!can_migrate_page(obj))
>> +		return -EBUSY;
>> +
>> +	/* HW access would be required for a GGTT bound object, for which
>> +	 * device has to be kept awake. But a deadlock scenario can arise if
>> +	 * the attempt is made to resume the device, when either a suspend
>> +	 * or a resume operation is already happening concurrently from some
>> +	 * other path and that only also triggers compaction. So only unbind
>> +	 * if the device is currently awake.
>> +	 */
>> +	if (!intel_runtime_pm_get_if_in_use(dev_priv))
>> +		return -EBUSY;
>> +
>> +	i915_gem_object_get(obj);
>> +	if (!unsafe_drop_pages(obj))
>> +		ret = -EBUSY;
>> +	i915_gem_object_put(obj);
>
> Since the object release changes, we can now do this without the
> i915_gem_object_get / i915_gem_object_put (as we are guarded by the BKL
> struct_mutex).
Fine will remove object_get/put as with struct_mutex protection object 
can't disappear across unsafe_drop_pages().

Best regards
Akash


> -Chris
>