Re: [RFC PATCH] printk: console: Allow each console to have its own loglevel

Greg Kroah-Hartman
2022-05-19T15:26:49Z

On Thu, May 19, 2022 at 04:08:04PM +0100, Chris Down wrote:
> Greg Kroah-Hartman writes:
> > > struct console {
> > > char name[16];
> > > void (*write)(struct console *, const char *, unsigned);
> > > @@ -179,9 +173,11 @@ struct console {
> > > void *data;
> > > struct console *next;
> > > int level;
> > > - struct device classdev;
> > > + struct device *classdev;
> >
> > Ick, no, keep the real structure here. It can properly handle the
> > reference counting for the object. Just correctly clean up in the
> > release function, not anywhere else.
>
> Sorry, I'm getting more and more confused about what you're asking me to do,
> and less and less clear on the rationale.
>
> Can you please clarify what "correctly cleaning up" would mean for a
> non-pointer `struct device'?
>
> Is your concern that...
>
> register_console(c)
> device_initialize(c->d)
> device_add(c->d)
> unregister_console(c)
> device_unregister(c->d) console_classdev_release(c->d)
> register_console(c)
> device_initialize(c->d) <-- classdev was not previously zeroed out
> in console_classdev_release() and bad things may happen

Note, you can not "recycle" a structure in the driver model. So when
the console is unregistered, it should be freed. When it is registered,
it should be created. Perhaps that is the confusion here?

thakns,

greg k-h