linux-kernel - Re: [PATCH] printk: fix return value of printk.devkmsg _

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Message-ID: <20220301153636.GA24138@pathway.suse.cz>
Date:   Tue, 1 Mar 2022 16:36:36 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     linux-kernel@...r.kernel.org,
        Igor Zhbanov <i.zhbanov@...russia.ru>,
        Borislav Petkov <bp@...e.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        John Ogness <john.ogness@...utronix.de>
Subject: Re: [PATCH] printk: fix return value of printk.devkmsg __setup
 handler

On Mon 2022-02-28 14:05:56, Randy Dunlap wrote:
> If an invalid option value is used with "printk.devkmsg=<value>",
> it is silently ignored.
> If a valid option value is used, it is honored but the wrong return
> value (0) is used, indicating that the command line option had an
> error and was not handled. This string is not added to init's
> environment strings due to init/main.c::unknown_bootoption()
> checking for a '.' in the boot option string and then considering
> that string to be an "Unused module parameter".
> 
> Print a warning message if a bad option string is used.
> Always return 1 from the __setup handler to indicate that the command
> line option has been handled.
> 
> Fixes: 750afe7babd1 ("printk: add kernel parameter to control writes to /dev/kmsg")
> Signed-off-by: Randy Dunlap <rdunlap@...radead.org>
> Reported-by: Igor Zhbanov <i.zhbanov@...russia.ru>
> Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@...russia.ru

Good catch! I am learning something new every day :-)

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

Best Regards,
Petr