linux-kernel - Re: [PATCH 1/2] lib/string_helpers: Introduce strsplit

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Date:   Fri, 8 Jul 2022 17:25:20 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Péter Ujfalusi <peter.ujfalusi@...ux.intel.com>
Cc:     Cezary Rojewski <cezary.rojewski@...el.com>,
        Andy Shevchenko <andy@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        ALSA Development Mailing List <alsa-devel@...a-project.org>,
        Takashi Iwai <tiwai@...e.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        amadeuszx.slawinski@...ux.intel.com,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Kai Vehmanen <kai.vehmanen@...ux.intel.com>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>
Subject: Re: [PATCH 1/2] lib/string_helpers: Introduce strsplit_u32()

On Fri, Jul 8, 2022 at 2:34 PM Péter Ujfalusi
<peter.ujfalusi@...ux.intel.com> wrote:
> On 08/07/2022 15:30, Andy Shevchenko wrote:
> > On Fri, Jul 08, 2022 at 02:13:14PM +0200, Cezary Rojewski wrote:

...

> > It seems you are missing the (1). The code has checks for the case where you
> > can do get number upfront, it would just require two passes, but it's nothing
> > in comparison of heave realloc().
> >
> >   unsigned int *tokens;
> >   char *p;
> >   int num;
> >
> >   p = get_options(str, 0, &num);
> >   if (num == 0)
> >       // No numbers in the string!
> >
> >   tokens = kcalloc(num + 1, sizeof(*tokens), GFP_KERNEL);
> >   if (!tokens)
> >       return -ENOMEM;
> >
> >   p = get_oprions(str, num, &tokens);
> >   if (*p)
> >       // String was parsed only partially!
> >       // assuming it's not a fatal error
> >
> >   return tokens;

> This diff is tested and works:

Thanks, Peter!

But at least you can memove() to avoid second allocation.
ideally to refactor that the result of get_options is consumed as is
(it may be casted to struct tokens { int n; u32 v[]; })

...

> Could be made nicer with some brain work put to it, we need strict u32 within the IPC message for the array...

True, it needs to be thought through. But I guess you got the idea of
how to use existing library routines.

-- 
With Best Regards,
Andy Shevchenko