linux-kernel - Re: [PATCH printk v3 15/15] printk: remove @console

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Message-ID: <20220421124604.GC11747@pathway.suse.cz>
Date:   Thu, 21 Apr 2022 14:46:04 +0200
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 15/15] printk: remove @console_locked

On Wed 2022-04-20 01:52:37, John Ogness wrote:
> The static global variable @console_locked is used to help debug
> VT code to make sure that certain code paths are running with
> the console_lock held. However, this information is also available
> with the static global variable @console_kthreads_blocked (for
> locking via console_lock()), and the static global variable
> @console_kthreads_active (for locking via console_trylock()).
> 
> Remove @console_locked and update is_console_locked() to use the
> alternative variables.
> 
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2705,13 +2696,11 @@ void console_lock_single_hold(struct console *con)
>  	might_sleep();
>  	down_console_sem();
>  	mutex_lock(&con->lock);
> -	console_locked = 1;

is_console_locked() is not able to detect that a given console
is locked by console_lock_single_hold().

>  	console_may_schedule = 1;
>  }
>  

Best Regards,
Petr