linux-kernel - Re: [PATCH -v4 2/2] printk: Add kernel parameter to control writes to /dev/kmsg

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Message-ID: <20160718052032.GA7911@dhcp-128-65.nay.redhat.com>
Date:	Mon, 18 Jul 2016 13:20:32 +0800
From:	Dave Young <dyoung@...hat.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>, Franck Bui <fbui@...e.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
Subject: Re: [PATCH -v4 2/2] printk: Add kernel parameter to control writes
 to /dev/kmsg

On 07/18/16 at 06:44am, Borislav Petkov wrote:
> On Mon, Jul 18, 2016 at 10:18:09AM +0800, Dave Young wrote:
> > I would say avoiding ratelimit during boot make no much sense. Userspace can not
> > write to /dev/kmsg when system_state == SYSTEM_BOOTING because init process
> > has not run yet.
> 
> You're right - kernel_init() sets SYSTEM_RUNNING before running the init
> process. I probably should kill all that logic in the second patch.
> 
> > I means to set printk.devkmsg=off by default, userspace can set it to
> > on by sysctl.
> 
> That can't happen: DEVKMSG_LOG_MASK_LOCK.

Sorry, seems I do not get your point, suppose using the bis defined in your
patch, shouldn't below work?

#define DEVKMSG_LOG_MASK_DEFAULT	2

Thanks
Dave