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Date:   Tue, 27 Sep 2022 17:19:23 +0200
From:   Petr Mladek <pmladek@suse.com>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        John Ogness <john.ogness@linutronix.de>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Linus Torvalds <torvalds@linuxfoundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Helge Deller <deller@gmx.de>,
        Jason Wessel <jason.wessel@windriver.com>,
        Daniel Thompson <daniel.thompson@linaro.org>
Subject: Re: [patch RFC 06/29] printk: Protect [un]register_console() with a
 mutex
Message-ID: <YzMUe5soxMrsFM8V@alley>
References: <20220910221947.171557773@linutronix.de>
 <20220910222300.712668210@linutronix.de>
 <YzLIy4emYX6JpzuN@alley>
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On Tue 2022-09-27 11:56:30, Petr Mladek wrote:
> On Sun 2022-09-11 00:27:41, Thomas Gleixner wrote:
> > Unprotected list walks are a brilliant idea. Especially in the context of
> > hotpluggable consoles.
> 
> Yeah, it is crazy. And it is there probably since the beginning.
> 
> > @@ -3107,13 +3143,14 @@ void register_console(struct console *ne
> >  	bool realcon_enabled = false;
> >  	int err;
> >  
> > -	for_each_console(con) {
> > +	console_list_lock();
> 
> Hmm, the new mutex is really nasty. It has very strange semantic.
> It makes the locking even more complicated.

Please, continue the discussion in the reply to the v1 patchset,
see https://lore.kernel.org/r/YzMT27FVllY3u05k@alley

I send it to this RFC by mistake.

I am sorry for the mess.

Best Regards,
Petr