We can already have object properties, which technically can be fb's. Switch the property validation logic over to a get/put style interface so it can take a ref to refcnt'd objects, and then drop that ref after the driver has a chance to take it's own ref.
Signed-off-by: Rob Clark <robdclark at gmail.com> --- Alternative approach to: http://lists.freedesktop.org/archives/dri-devel/2014-November/072925.html This allows us to take a ref to the property as part of the validate step, and drop the ref after it has been pushed down to driver. drivers/gpu/drm/drm_crtc.c | 57 ++++++++++++++++++++++++++++++++++------------ 1 file changed, 42 insertions(+), 15 deletions(-) diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index 82158c6..c48c8c3 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -4162,12 +4162,22 @@ int drm_mode_connector_update_edid_property(struct drm_connector *connector, } EXPORT_SYMBOL(drm_mode_connector_update_edid_property); -static bool drm_property_change_is_valid(struct drm_property *property, - uint64_t value) +/* Some properties could refer to dynamic refcnt'd objects, or things that + * need special locking to handle lifetime issues (ie. to ensure the prop + * value doesn't become invalid part way through the property update due to + * race). The value returned by reference via 'obj' should be passed back + * to drm_property_change_valid_put() after the property is set (and the + * object to which the property is attached has a chance to take it's own + * reference). + */ +static bool drm_property_change_valid_get(struct drm_property *property, + uint64_t value, void **ref) { if (property->flags & DRM_MODE_PROP_IMMUTABLE) return false; + *ref = NULL; + if (drm_property_type_is(property, DRM_MODE_PROP_RANGE)) { if (value < property->values[0] || value > property->values[1]) return false; @@ -4188,19 +4198,23 @@ static bool drm_property_change_is_valid(struct drm_property *property, /* Only the driver knows */ return true; } else if (drm_property_type_is(property, DRM_MODE_PROP_OBJECT)) { - struct drm_mode_object *obj; /* a zero value for an object property translates to null: */ if (value == 0) return true; - /* - * NOTE: use _object_find() directly to bypass restriction on - * looking up refcnt'd objects (ie. fb's). For a refcnt'd - * object this could race against object finalization, so it - * simply tells us that the object *was* valid. Which is good - * enough. - */ - obj = _object_find(property->dev, value, property->values[0]); - return obj != NULL; + + /* handle refcnt'd objects specially: */ + if (property->values[0] == DRM_MODE_OBJECT_FB) { + struct drm_framebuffer *fb; + fb = drm_framebuffer_lookup(property->dev, value); + if (fb) { + *ref = fb; + return true; + } else { + return false; + } + } else { + return _object_find(property->dev, value, property->values[0]) != NULL; + } } else { int i; for (i = 0; i < property->num_values; i++) @@ -4210,6 +4224,17 @@ static bool drm_property_change_is_valid(struct drm_property *property, } } +static void drm_property_change_valid_put(struct drm_property *property, void *ref) +{ + if (!ref) + return; + + if (drm_property_type_is(property, DRM_MODE_PROP_OBJECT)) { + if (property->values[0] == DRM_MODE_OBJECT_FB) + drm_framebuffer_unreference(ref); + } +} + /** * drm_mode_connector_property_set_ioctl - set the current value of a connector property * @dev: DRM device @@ -4404,8 +4429,8 @@ int drm_mode_obj_set_property_ioctl(struct drm_device *dev, void *data, struct drm_mode_object *arg_obj; struct drm_mode_object *prop_obj; struct drm_property *property; - int ret = -EINVAL; - int i; + int i, ret = -EINVAL; + void *ref; if (!drm_core_check_feature(dev, DRIVER_MODESET)) return -EINVAL; @@ -4435,7 +4460,7 @@ int drm_mode_obj_set_property_ioctl(struct drm_device *dev, void *data, } property = obj_to_property(prop_obj); - if (!drm_property_change_is_valid(property, arg->value)) + if (!drm_property_change_valid_get(property, arg->value, &ref)) goto out; switch (arg_obj->type) { @@ -4452,6 +4477,8 @@ int drm_mode_obj_set_property_ioctl(struct drm_device *dev, void *data, break; } + drm_property_change_valid_put(property, ref); + out: drm_modeset_unlock_all(dev); return ret; -- 1.9.3
