On 2026-05-22 at 17:40:39 GMT, Krzysztof Niemiec wrote: > 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
(typo, s/drm_mode_object_register/drm_mode_object_unregister) > 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 >
