linux-kernel - Re: [PATCH 1/2] lib: add __sysfs_match_string_with

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Date:   Mon, 6 May 2019 17:46:20 +0300
From:   "andriy.shevchenko@...ux.intel.com" 
        <andriy.shevchenko@...ux.intel.com>
To:     Alexandru Ardelean <ardeleanalex@...il.com>
Cc:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Jonathan Cameron <jonathan.cameron@...wei.com>,
        "Ardelean, Alexandru" <alexandru.Ardelean@...log.com>,
        "namhyung@...nel.org" <namhyung@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "mingo@...nel.org" <mingo@...nel.org>
Subject: Re: [PATCH 1/2] lib: add __sysfs_match_string_with_gaps() helper

On Mon, May 06, 2019 at 04:45:43PM +0300, Alexandru Ardelean wrote:
> On Fri, Apr 26, 2019 at 5:27 PM andriy.shevchenko@...ux.intel.com
> <andriy.shevchenko@...ux.intel.com> wrote:
> >
> > On Fri, Apr 26, 2019 at 12:29:11PM +0300, Alexandru Ardelean wrote:
> >
> > > Hmm, I actually did not give much thought to that -1.
> > > I'll check into this and see about a V3.
> > > It may make more sense to just fix the original
> > > `__sysfs_match_string()`, but I'll need to go through the users of
> > > this function and see.
> >
> > I was thinking about existing users of such (with "gaps") cases.
> > Not all of them have NULL there and would like to avoid some members.
> > Though, I think that we may ignore NULL items if -1 is supplied.
> >
> > Think as well about ARRAY_SIZE() as given to that.
> >
> 
> I am a bit vague on what you are proposing.
> Is it:
> 
> a) Leave __sysfs_match_string() as-is and introduce a new
> `__sysfs_match_string_with_gaps()` helper/variant ?
> b) Fix __sysfs_match_string() to break/exit on the first NULL, only if
> -1 is provided ?
> 
> Either is fine, but I wanted to clarify.

The current logic something like "-1 to go till first NULL" and ARRAY_SIZE() in
*some* cases is basically the synonym to above.

What I meant is to check if there is *any* case where ARRAY_SIZE() behaves in
the same way as -1. Those cases should be fixed accordingly.

Otherwise, the b) is what would be preferred according to the discussion.

> > And consider to fix match_string() accordingly.

-- 
With Best Regards,
Andy Shevchenko