Commit ff865885 authored by John Harrison's avatar John Harrison Committed by Daniel Vetter
Browse files

drm/i915: Ensure requests stick around during waits 



Added reference counting of the request structure around __wait_seqno() calls.
This is a precursor to updating the wait code itself to take the request rather
than a seqno. At that point, it would be a Bad Idea for a request object to be
retired and freed while the wait code is still using it.

v3:

Note that even though the mutex lock is held during a call to i915_wait_seqno(),
it is still necessary to explicitly bump the reference count. It appears that
the shrinker can asynchronously retire items even though the mutex is locked.

For: VIZ-4377
Signed-off-by: default avatarJohn Harrison <John.C.Harrison@Intel.com>
Reviewed-by: default avatarThomas Daniel <Thomas.Daniel@intel.com>
[danvet: Remove wrongly squashed hunk which breaks the build.]
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 54fb2411

drivers/gpu/drm/i915/i915_gem.c

+18 −3
Original line number Diff line number Diff line
@@ -1417,10 +1417,12 @@ i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj, 
		return ret;



	reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);

	i915_gem_request_reference(req);

	mutex_unlock(&dev->struct_mutex);

	ret = __i915_wait_seqno(ring, seqno, reset_counter, true, NULL,

				file_priv);

	mutex_lock(&dev->struct_mutex);

	i915_gem_request_unreference(req);

	if (ret)

		return ret;
@@ -2920,6 +2922,7 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file) 
	struct drm_i915_private *dev_priv = dev->dev_private;

	struct drm_i915_gem_wait *args = data;

	struct drm_i915_gem_object *obj;

	struct drm_i915_gem_request *req;

	struct intel_engine_cs *ring = NULL;

	unsigned reset_counter;

	u32 seqno = 0;
@@ -2946,7 +2949,8 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file) 
	if (!obj->active || !obj->last_read_req)

		goto out;



	seqno = i915_gem_request_get_seqno(obj->last_read_req);

	req = obj->last_read_req;

	seqno = i915_gem_request_get_seqno(req);

	WARN_ON(seqno == 0);

	ring = obj->ring;
@@ -2960,10 +2964,15 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file) 


	drm_gem_object_unreference(&obj->base);

	reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);

	i915_gem_request_reference(req);

	mutex_unlock(&dev->struct_mutex);



	return __i915_wait_seqno(ring, seqno, reset_counter, true,

				 &args->timeout_ns, file->driver_priv);

	ret = __i915_wait_seqno(ring, seqno, reset_counter, true, &args->timeout_ns,

			   file->driver_priv);

	mutex_lock(&dev->struct_mutex);

	i915_gem_request_unreference(req);

	mutex_unlock(&dev->struct_mutex);

	return ret;



out:

	drm_gem_object_unreference(&obj->base);
@@ -4118,6 +4127,8 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file) 
		target = request;

	}

	reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);

	if (target)

		i915_gem_request_reference(target);

	spin_unlock(&file_priv->mm.lock);



	if (target == NULL)
@@ -4129,6 +4140,10 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file) 
	if (ret == 0)

		queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, 0);



	mutex_lock(&dev->struct_mutex);

	i915_gem_request_unreference(target);

	mutex_unlock(&dev->struct_mutex);



	return ret;

}

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