linux-kernel - Re: [PATCH] printk: handle blank console arguments passed in.

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Message-ID: <20201008105603.GB554@jagdpanzerIV.localdomain>
Date:   Thu, 8 Oct 2020 19:56:03 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Shreyas Joshi <shreyas.joshi@...mp.com>, rostedt@...dmis.org,
        shreyasjoshi15@...il.com, linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] printk: handle blank console arguments passed in.

On (20/10/08 11:01), Petr Mladek wrote:
> 
> Interesting idea. Well, it looks like yet another mess:
> 
>   + it would show the consoles in /proc/consoles
>     even thought they will be basically unusable

Which is fine, no? We already can have disables consoles in
/proc/consoles.


$ cat /proc/consoles 
tty0                 -WU ( C p  )    4:1

So tty0 is not 'E'-enabled. I see no problems with that.

These are the flags that /proc/consoles handle

	con_flags[] = {
		{ CON_ENABLED,		'E' },
		{ CON_CONSDEV,		'C' },
		{ CON_BOOT,		'B' },
		{ CON_PRINTBUFFER,	'p' },
		{ CON_BRL,		'b' },
		{ CON_ANYTIME,		'a' },
	};

Why do you think that having disabled consoles in /proc/consoles
is a mess?

> IMHO, we should try to understand why it actually crashes first.
> It might help to solve the problem some cleaner way.

Well, I guess, we have files (either regular files or devices) sitting
in fd-s 0,1,2. God knows what mount/fsck/modprobe can fprintf(), for
instance, to stdout/stderr and what they can corrupt.

	-ss