On Thu, Apr 12, 2018 at 03:42:32PM +0100, Ayan Kumar Halder wrote: > In a situation when the reference count of the drm connector is greater than > 1, > the unbind function should not invoke drm_connector_cleanup as this will lead > to an inconsistent state where the drm_crtc_state->connector_mask still has > a bitmask referring to the stale connector. Later, when drm driver invokes > drm_atomic_helper_shutdown() which invokes ---> > drm_atomic_helper_disable_all() > ---> drm_atomic_commit() --> drm_atomic_check_only() --> > drm_atomic_helper_check() --> drm_atomic_helper_check_modeset(). This returns > an error due to enabled/connectors mismatch. > > In such a scenario, one should just return from _unbind() and let the drm > driver > subsequently invoke drm_atomic_helper_shutdown. This will reset the > drm_crtc_state->connector_mask and will shutdown the crtcs. It will also > decrement > the reference count of the connectors to 1. Subsequently, > drm_mode_config_cleanup > will get invoked which will do the following :-
If the device is still in-use after unbind() has been called, that is _very_ bad news, and probably means that the "host" driver is not calling component_unbind() at the right point. Any resources claimed in the bind() callback using devm functions will be freed, which will include (eg) the drm_encoder structure and in fact the drm_connector. So what you have here is a use-after-free bug, and your change does nothing for that. Please fix the "host" driver instead. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up According to speedtest.net: 8.21Mbps down 510kbps up _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
