linux-kernel - Re: [PATCH v1 3/8] iio: core: Switch to krealloc

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Message-ID: <f565b705ba6656ae1c8b34740aa176ccfe260f60.camel@gmail.com>
Date:   Fri, 21 Jul 2023 12:53:53 +0200
From:   Nuno Sá <noname.nuno@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>
Subject: Re: [PATCH v1 3/8] iio: core: Switch to krealloc_array()

On Fri, 2023-07-21 at 13:14 +0300, Andy Shevchenko wrote:
> On Fri, Jul 21, 2023 at 09:59:37AM +0200, Nuno Sá wrote:
> > On Thu, 2023-07-20 at 23:53 +0300, Andy Shevchenko wrote:
> 
> ...
> 
> > > +       struct attribute **attrs, **attr, *clk = NULL;
> > >         struct iio_dev_attr *p;
> > > -       struct attribute **attr, *clk = NULL;
> > >  
> > >         /* First count elements in any existing group */
> > > -       if (indio_dev->info->attrs) {
> > > -               attr = indio_dev->info->attrs->attrs;
> > > -               while (*attr++ != NULL)
> > > +       attrs = indio_dev->info->attrs ? indio_dev->info->attrs->attrs :
> > > NULL;
> > > +       if (attrs) {
> > > +               for (attr = attrs; *attr; attr++)
> > >                         attrcount_orig++;
> 
> > not really related with the change... maybe just mention it in the commit?
> 
> Hmm... It's related to make krealloc_array() to work as expected.
> 

Hmm, I think it's arguable :). while() -> for() it's not really needed unless
I'm missing something. You could even initialize 'attrs' to NULL at declaration
and keep the above diff minimum.

That said, I actually prefer this style (even though some people don't like much
the ternary operator).

> > >         }
> 
> ...
> 
> > >         iio_dev_opaque->chan_attr_group.attrs =
> > > -               kcalloc(attrcount + 1,
> > > -                       sizeof(iio_dev_opaque->chan_attr_group.attrs[0]),
> > > -                       GFP_KERNEL);
> > > +               krealloc_array(attrs, attrcount + 1, sizeof(*attrs),
> > > GFP_KERNEL);
> > >         if (iio_dev_opaque->chan_attr_group.attrs == NULL) {
> > 
> > since you're here and you also already did some style cleanups above, maybe
> > change it to 'if (!iio_dev_opaque->chan_attr_group.attrs)'?
> 
> I don't think it's related (but you can tell that this check related to
> the allocator, and since we touch it, we may touch this), if Jonathan
> wants this, I definitely do.

Fair enough...


- Nuno Sá