linux-kernel - Re: [PATCH printk v3 06/40] um: kmsg_dump: only dump when no output console available

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Message-ID: <Y2pOYBkNPY3wd6vn@alley>
Date:   Tue, 8 Nov 2022 13:41:04 +0100
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, Richard Weinberger <richard@....at>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        Johannes Berg <johannes@...solutions.net>,
        linux-um@...ts.infradead.org
Subject: Re: [PATCH printk v3 06/40] um: kmsg_dump: only dump when no output
 console available

On Mon 2022-11-07 15:22:04, John Ogness wrote:
> The initial intention of the UML kmsg_dumper is to dump the kernel
> buffers to stdout if there is no console available to perform the
> regular crash output.
> 
> However, if ttynull was registered as a console, no crash output was
> seen. Commit e23fe90dec28 ("um: kmsg_dumper: always dump when not tty
> console") tried to fix this by performing the kmsg_dump unless the
> stdio console was behind /dev/console or enabled. But this allowed
> kmsg dumping to occur even if other non-stdio consoles will output
> the crash output. Also, a console being the driver behind
> /dev/console has nothing to do with a crash scenario.
> 
> Restore the initial intention by dumping the kernel buffers to stdout
> only if a non-ttynull console is registered and enabled. Also add
> detailed comments so that it is clear why these rules are applied.
> 
> Signed-off-by: John Ogness <john.ogness@...utronix.de>

The change makes sense to me:

Reviewed-by: Petr Mladek <pmladek@...e.com>

Best Regards,
Petr