linux-kernel - Re: [PATCH 2/5] iio: adc: xilinx: use devm_krealloc() instead of kfree() + kcalloc()

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Message-ID: <CAMRc=Mf33JMNMT1vcrHx33QK7wj_gPY-CPaPUsqtON8X8S-JtQ@mail.gmail.com>
Date:   Tue, 27 Oct 2020 11:04:44 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Michal Simek <michal.simek@...inx.com>,
        linux-iio <linux-iio@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH 2/5] iio: adc: xilinx: use devm_krealloc() instead of
 kfree() + kcalloc()

On Tue, Oct 27, 2020 at 10:33 AM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
>
> On Mon, Oct 26, 2020 at 4:03 PM Bartosz Golaszewski <brgl@...ev.pl> wrote:
> >
> > From: Bartosz Golaszewski <bgolaszewski@...libre.com>
> >
> > We now have devm_krealloc() in the kernel Use it indstead of calling
> > kfree() and kcalloc() separately.
>
> Which is completely lawful when size > previous_size (I mean, the
> additional patch you sent previously seems not related to this).
>

Sure but devm_krealloc() is cleaner and adds the benefit of resource management.

> > -       kfree(xadc->data);
> > -       xadc->data = kcalloc(n, sizeof(*xadc->data), GFP_KERNEL);
> > +       xadc->data = devm_krealloc(indio_dev->dev.parent, xadc->data,
> > +                                  n * sizeof(*xadc->data),
>
> I think you need to use something from overflow.h instead of explicit
> multiplication here.
>

Or maybe add devm_krealloc_array() which would perform the checks
behind the scenes?

> > +                                  GFP_KERNEL | __GFP_ZERO);
>
> --
> With Best Regards,
> Andy Shevchenko

Bartosz