linux-kernel - Re: [PATCH printk v3 19/40] printk: console_device: use srcu console list iterator

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Message-ID: <Y2vOQLRdDRhbyaTe@alley>
Date:   Wed, 9 Nov 2022 16:58:56 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     John Ogness <john.ogness@...utronix.de>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH printk v3 19/40] printk: console_device: use srcu console
 list iterator

On Mon 2022-11-07 15:22:17, John Ogness wrote:
> Use srcu console list iteration for console list traversal.

I wonder if it would make sense to describe why this is acceptable.
But I am not sure how to explain this a reasonable way. I am afraid
that it might cause more confusion.

I would write something like:

<proposal>
It is acceptable because the consoles might come and go at any time.
Strict synchronizing with console registration code would not bring
any advantage over RCU.
</proposal>

> Document why the console_lock is still necessary. Note that this
> is a preparatory change for when console_lock no longer provides
> synchronization for the console list.
> 
> Signed-off-by: John Ogness <john.ogness@...utronix.de>

As I said, I do not have strong opinion if the extra explanation
would help. So, with or without it:

Reviewed-by: Petr Mladek <pmladek@...e.com>

Best Regards,
Petr