linux-kernel - Re: [PATCH v4] printk: Userspace format enumeration support

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Message-ID: <YC5ggyeC0uqtOD6R@chrisdown.name>
Date:   Thu, 18 Feb 2021 12:41:39 +0000
From:   Chris Down <chris@...isdown.name>
To:     Petr Mladek <pmladek@...e.com>
Cc:     linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        John Ogness <john.ogness@...utronix.de>,
        Johannes Weiner <hannes@...xchg.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kees Cook <keescook@...omium.org>, kernel-team@...com
Subject: Re: [PATCH v4] printk: Userspace format enumeration support

Petr Mladek writes:
>> - Move to another file, kernel/printk/debug_formats.c or similar
>
>Just to be sure. The filename should be ideally based on the configure
>option and API names, e.g. formats_index.c or so.
>
>The printk_ prefix is not strictly necessary. The file is in printk/
>directory. IMHO, we should have used ringbuffer.c but ...

Sure thing.

>> - Use `struct module *mod` instead of calling it module
>> - Add documentation for printk_fmt_sec (or whatever it will be called)
>> - Rename things to pf_, pi_, or something
>> - See if it's safe to pass a printk_fmt_sec to seq_file instead of a module
>
>Also it might be needed to store the pointer to struct module.

You mean, have a `struct module` entry for this? I somewhat suspect that 
module.c maintainers are not likely to be happy about injecting non-generic 
code into there if it's possible to be avoided, but maybe I'm misunderstanding? 

>Both things together might allow to remove the global hash table and likely
>even the mutex.
>
>> - Handle cont + level
>> - Don't expose level/KERN_SOH directly
>
>I can't remember anything else. I am curious how v5 would look like.

You can join the club on that one... ;-)

Let me know if I understood you correctly on the `struct module` point, and 
after that I'll start work on v5. Thanks!