linux-kernel - Re: printk: what is going on with additional newlines?

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Date:   Mon, 18 Sep 2017 11:55:07 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Joe Perches <joe@...ches.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Pavel Machek <pavel@....cz>, Jan Kara <jack@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jiri Slaby <jslaby@...e.com>, Andreas Mohr <andi@...as.de>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: printk: what is going on with additional newlines?

On (09/17/17 19:45), Joe Perches wrote:
[..]
> > take a look at ACPI acpi_os_vprintf(). for instance.
> 
> I've looked.

I don't get your point.

#define ACPI_MSG_ERROR          KERN_ERR "ACPI Error: "
#define ACPI_MSG_EXCEPTION      KERN_ERR "ACPI Exception: "
#define ACPI_MSG_WARNING        KERN_WARNING "ACPI Warning: "
#define ACPI_MSG_INFO           KERN_INFO "ACPI: "

so when we do

	acpi_os_printf(ACPI_MSG_WARNING "%s: ", pathname);

we end up with

	printk("%s",  KERN_WARNING "ACPI Warning: %%pathname%%");

note how acpi_os_vprintf() calls printk_get_level() _on_ the
buffer is passes to

	printk("%s", buffer)

because KERN_WARNING is part of the buffer, not the fmt.

there are also other examples that do similar things.


> Try git grep KERN_SOH.

what for?

	-ss