On Fri, Nov 29, 2024 at 05:58:56PM +0200, Jani Nikula wrote: > On Fri, 29 Nov 2024, Maxime Ripard <mripard@xxxxxxxxxx> wrote: > > On Fri, Nov 29, 2024 at 04:26:01PM +0200, Imre Deak wrote: > >> Adding more people from DRM core domain. Any comment, objection to this > >> change? > >> > >> On Tue, Nov 26, 2024 at 06:18:56PM +0200, Imre Deak wrote: > >> > Atm when the connector is added to the drm_mode_config::connector_list, > >> > the connector may not be fully initialized yet. This is not a problem > >> > for user space, which will see the connector only after it's registered > >> > later, it could be a problem for in-kernel users looking up connectors > >> > via the above list. > > > > It could be, or it actually is a problem? If so, in what situation? > > It's an actual problem. > > While in most cases connectors are created at probe, for DP MST they're > created at runtime via the ->add_connector hook. We want to call > drm_connector_init() on them soon in that hook, so we can pass the > connector around and expect it to have connector->dev etc. initialized > while we continue its initialization. > > But there's a race. As soon as we call drm_connector_init(), the > connector gets added to dev->mode_config.connector_list, and any drm > code may discover it. For example connector polling. And we might not be > done with the initialization yet. Ack. This should be in the commit log then. > >> > To resolve the above issue, add a way to separately initialize the DRM > >> > core specific parts of the connector and add it to the above list. This > >> > will move adding the connector to the list after the properties on the > >> > connector have been added, this is ok since these steps don't have a > >> > dependency. > >> > > >> > v2: (Jani) > >> > - Let initing DDC as well via drm_connector_init_core(). > >> > - Rename __drm_connector_init to drm_connector_init_core_and_add(). > >> > > >> > Cc: Jani Nikula <jani.nikula@xxxxxxxxx> > >> > Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> (v1) > >> > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> > > > > If we do have an actual problem to solve, we'll need kunit tests too. > > That's not an unreasonable request, per se, but what exactly should they > test? That the new init core didn't add stuff to the list, and the new > add connector did? Everything we test with drm_connector_init* already, plus the fact that we now might have callers that call add without init, so we need to test that too. Maxime
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