drm/syncobj: call might_sleep before waiting for fence submission

If either the DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT or
DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE flags are passed to
drm_syncobj_array_wait_timeout, the function might sleep if the fence at
one of the given timeline points has not yet been submitted. Therefore,
we should call might_sleep in that case to catch potential bugs.

Signed-off-by: Erik Kurzinger <ekurzinger@nvidia.com>
Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Simon Ser <contact@emersion.fr>
Link: https://patchwork.freedesktop.org/patch/msgid/20240119163208.3723457-3-ekurzinger@nvidia.com

Author: Erik Kurzinger

drivers/gpu/drm/drm_syncobj.c

@@ -1044,8 +1044,10 @@ static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
 	uint32_t signaled_count, i;
 
 	if (flags & (DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT |
-		     DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE))
+		     DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE)) {
+		might_sleep();
 		lockdep_assert_none_held_once();
+	}
 
 	points = kmalloc_array(count, sizeof(*points), GFP_KERNEL);
 	if (points == NULL)