The dev->registered variable was initially added in such a way that it is only set after all functions that could have failed have been called and haven't returned an error. However, since then, the function drm_modeset_register_all() is being checked for its return value, which opens a possibility of failing the register after setting the registered variable anyway. drm_dev_register() cleans up after itself in case of failure, mimicking the functions called in drm_dev_unregister(), with the exception of drm_client_sysrq_unregister() and drm_panic_unregister() (_register() counterparts of which are not checked for their return values), and the dev->registered flag.
This creates a situation in which after calling drm_dev_register() nothing is registered (as the function entered an error path and cleaned up), but the device is reported as being registered according to the dev->registered variable. This, for example, confuses the WARN_ON() in drm_mode_object_register(), which is raised if a non-dynamic mode object is attempted to be unregistered in between the drm_dev_register() and drm_dev_unregister() calls. If drm_dev_register() fails - meaning the device *isn't* registered - currently it still reports dev->registered = true, which triggers the WARN_ON(), even though the usage is correct in that instance. Set dev->registered back to false in the error path to prevent this. Signed-off-by: Krzysztof Niemiec <[email protected]> --- drivers/gpu/drm/drm_drv.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index 985c283cf59f..92403d79bb64 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -1116,6 +1116,7 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags) if (dev->driver->unload) dev->driver->unload(dev); err_minors: + dev->registered = false; remove_compat_control_link(dev); drm_minor_unregister(dev, DRM_MINOR_ACCEL); drm_minor_unregister(dev, DRM_MINOR_PRIMARY); -- 2.45.2
