linux-kernel - Re: [PATCHv2 4/4] printk: make sure we always print console disabled message

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Message-ID: <20190515144702.uja2mk2vfip6maws@pathway.suse.cz>
Date:   Wed, 15 May 2019 16:47:02 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [PATCHv2 4/4] printk: make sure we always print console disabled
 message

On Fri 2019-04-26 14:44:45, Sergey Senozhatsky wrote:
> 
> Forgot to mention that the series is still in RFC phase.
> 
> 
> On (04/26/19 14:33), Sergey Senozhatsky wrote:
> [..]
> > +++ b/kernel/printk/printk.c
> > @@ -2613,6 +2613,12 @@ static int __unregister_console(struct console *console)
> >  	pr_info("%sconsole [%s%d] disabled\n",
> >  		(console->flags & CON_BOOT) ? "boot" : "",
> >  		console->name, console->index);
> > +	/*
> > +	 * Print 'console disabled' on all the consoles, including the
> > +	 * one we are about to unregister.
> > +	 */
> > +	console_unlock();
> > +	console_lock();
> >  
> >  	res = _braille_unregister_console(console);
> >  	if (res)
> 
> Need to think more if this is race free...

I am afraid that it is racy against for_each_console() when
removing the boot consoles.

I think that it is _not_ worth a code complication. It worked
this way for ages and people do not seem to complain.

Best Regards,
Petr