linux-kernel - Re: [PATCH] Use existing helper to convert "on/off" to boolean

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Date:	Fri, 29 Apr 2016 17:07:42 +0800
From:	Minfei Huang <mnghuan@...il.com>
To:	Michal Hocko <mhocko@...nel.org>
Cc:	akpm@...ux-foundation.org, labbott@...oraproject.org,
	rjw@...ysocki.net, mgorman@...hsingularity.net, vbabka@...e.cz,
	rientjes@...gle.com, kirill.shutemov@...ux.intel.com,
	iamjoonsoo.kim@....com, izumi.taku@...fujitsu.com,
	alexander.h.duyck@...hat.com, hannes@...xchg.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Use existing helper to convert "on/off" to boolean

On 04/29/16 at 10:04P, Michal Hocko wrote:
> On Fri 29-04-16 13:47:04, Minfei Huang wrote:
> > It's more convenient to use existing function helper to convert string
> > "on/off" to boolean.
> 
> But kstrtobool in linux-next only does "This routine returns 0 iff the
> first character is one of 'Yy1Nn0'" so it doesn't know about on/off.
> Or am I missing anything?

Hi, Michal.

Thanks for your reply.

Following is the kstrtobool comment from linus tree, which has explained
that this function can parse "on"/"off" string. Also Kees Cook has
posted such patch to fix this issue as well. So I think it's safe to fix
it.

"
  This routine returns 0 if the first character is one of 'Yy1Nn0', or
  [oO][NnFf] for "on" and "off". Otherwise it will return -EINVAL.  Value
  pointed to by res is updated upon finding a match.
"

  commit 4cc7ecb7f2a60e8deb783b8fbf7c1ae467acb920
  Author: Kees Cook <keescook@...omium.org>
  Date:   Thu Mar 17 14:23:00 2016 -0700
  
      param: convert some "on"/"off" users to strtobool
  
      This changes several users of manual "on"/"off" parsing to use
      strtobool.
  
      Some side-effects:
      - these uses will now parse y/n/1/0 meaningfully too
      - the early_param uses will now bubble up parse errors

Thanks
Minfei