[PATCH 1/9] drm/connector: Make the drm_sysfs connector->kdev device hold a reference to the connector

[Hans de Goede]

p.s.

On 4/30/21 1:38 PM, Daniel Vetter wrote:

Offtopic:

> I'm also not sure why we have to use the kdev stuff here. For other
> random objects we need to look up we're building that functionality on
> that object. It means you need to keep another list_head around for
> that lookup, but that's really not a big cost. E.g. drm_bridge/panel
> work like that.

So I took a peek at the bridge/panel code and that actually seems to
have an issue with removal vs lookup. It is not even just a race,
it seems a lookup does not take a reference and there is nothing
stopping a user from doing an unbind or rmmod causing the panel
to be removed while other code which got a pointer to the panel
through of_drm_find_panel() will not be prepared to deal with
that pointer all of a sudden no longer being valid.

Now this would be a case of the user shooting his-self in the
foot (where as connectors can actually dynamically disappear
under normal circumstances), but ideally we really should do
better here.

Is there a TODO list somewhere for issues like this ?  Or shall
I submit a patch adding a FIXME comment, or is this considered
not worth the trouble of fixing it?

Regards,

Hans