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Commit ff7c60c5 authored by Daniel Vetter's avatar Daniel Vetter Committed by Dave Airlie
Browse files

drm/ttm: fix fence locking in ttm_buffer_object_transfer, 2nd try 



This fixes up

commit e8e89622
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue Dec 18 22:25:11 2012 +0100

    drm/ttm: fix fence locking in ttm_buffer_object_transfer

which leaves behind a might_sleep in atomic context, since the
fence_lock spinlock is held over a kmalloc(GFP_KERNEL) call. The fix
is to revert the above commit and only take the lock where we need it,
around the call to ->sync_obj_ref.

v2: Fixup things noticed by Maarten Lankhorst:
- Brown paper bag locking bug.
- No need for kzalloc if we clear the entire thing on the next line.
- check for bo->sync_obj (totally unlikely race, but still someone
  else could have snuck in) and clear fbo->sync_obj if it's cleared
  already.

Reported-by: default avatarDave Airlie <airlied@gmail.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent 6bacaa9d

drivers/gpu/drm/ttm/ttm_bo_util.c

+8 −5
Original line number Diff line number Diff line
@@ -429,7 +429,7 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo, 
	struct ttm_bo_device *bdev = bo->bdev;

	struct ttm_bo_driver *driver = bdev->driver;



	fbo = kzalloc(sizeof(*fbo), GFP_KERNEL);

	fbo = kmalloc(sizeof(*fbo), GFP_KERNEL);

	if (!fbo)

		return -ENOMEM;
@@ -448,7 +448,12 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo, 
	fbo->vm_node = NULL;

	atomic_set(&fbo->cpu_writers, 0);



	spin_lock(&bdev->fence_lock);

	if (bo->sync_obj)

		fbo->sync_obj = driver->sync_obj_ref(bo->sync_obj);

	else

		fbo->sync_obj = NULL;

	spin_unlock(&bdev->fence_lock);

	kref_init(&fbo->list_kref);

	kref_init(&fbo->kref);

	fbo->destroy = &ttm_transfered_destroy;
@@ -661,13 +666,11 @@ int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo, 
		 */



		set_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags);



		/* ttm_buffer_object_transfer accesses bo->sync_obj */

		ret = ttm_buffer_object_transfer(bo, &ghost_obj);

		spin_unlock(&bdev->fence_lock);

		if (tmp_obj)

			driver->sync_obj_unref(&tmp_obj);



		ret = ttm_buffer_object_transfer(bo, &ghost_obj);

		if (ret)

			return ret;