linux-kernel - Re: [PATCH] printk: CON_PRINTBUFFER console registration is a bit racy

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Date:   Thu, 27 Sep 2018 06:02:04 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] printk: CON_PRINTBUFFER console registration is a bit
 racy

On Wed, 26 Sep 2018 13:37:15 +0200
Petr Mladek <pmladek@...e.com> wrote:

> If you really want this change, please add a comment, for example:
> 
> /*
>  * Set exclusive_console still with disabled interrupts to
>  * reduce race window with eventual console_flush_on_panic()
>  * that ignores console_lock.
>  */
> 
> I am not against the change. It makes some sense and it does
> not break anything. It is just not obvious and might either
> get easily lost again or it might cause confusion. I mean that
> it might cause false feeling that exclusive_console is
> synchronized by logbuf_lock.
> 
> printk code already is complex enough without this subtle
> tricks.

I'm fine with the change and agree that a comment should be added.

-- Steve