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

From: Chris Down
Date: Wed May 18 2022 - 16:27:27 EST


Greg Kroah-Hartman writes:
If you're talking about properly freeing the memory, I suppose it should
happen by doing something like the following in unregister_console():

if (!console_drivers)
/* free the class object under console lock */

...right? Let me know if I'm misunderstanding you.

You can't do that as the driver core should now be managing the
lifespace of that object. You can't "know" when the object's memory is
to be freed EXCEPT in the release function.

So free it there please.

Or do not tie the lifepan of the console class device object to the
console object, and keep it separate. I don't remember exactly how you
tied them together here, sorry.

[...]

> Do you ever free the class?

Currently no. What do you think about the above proposal to do it once the
console driver list is exhausted?

If the code can never be unloaded, no, don't worry about it.

So just so I understand, there's no problem here if we're not going to free the class object, correct? These two stanzas in your reply refer to the same thing, right?

For context: the class comes up with printk, and printk can never be unloaded, so the class is never freed.

The devices that attach to this class are stored in `struct console', which has its lifecycle managed externally from this code.

I feel like I'm missing something here, but the two quoted parts of your reply seem to contradict each other (the first one talks about the right place to free the class, whereas the second says it's not necessary to free the class), so I'm a bit confused.