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From: Bartosz Golaszewski <brgl@bgdev.pl>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Jonathan Cameron <jic23@kernel.org>,
	Hartmut Knaack <knaack.h@gmx.de>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
	Michal Simek <michal.simek@xilinx.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Guenter Roeck <linux@roeck-us.net>,
	linux-iio <linux-iio@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>
Subject: Re: [PATCH v8 1/3] devres: provide devm_krealloc()
Date: Fri, 21 Aug 2020 10:59:19 +0200	[thread overview]
Message-ID: <CAMRc=Me=D1cOsaRqK-BwHT7f-_=3=eciduA=G95FfE2e_XUWfg@mail.gmail.com> (raw)
In-Reply-To: <20200821081555.GG1891694@smile.fi.intel.com>

On Fri, Aug 21, 2020 at 10:35 AM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Thu, Aug 20, 2020 at 08:51:08PM +0200, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> >
> > Implement the managed variant of krealloc(). This function works with
> > all memory allocated by devm_kmalloc() (or devres functions using it
> > implicitly like devm_kmemdup(), devm_kstrdup() etc.).
> >
> > Managed realloc'ed chunks can be manually released with devm_kfree().
> >
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>
> ...
>
> > +static struct devres *to_devres(void *data)
> > +{
> > +     return data - ALIGN(sizeof(struct devres), ARCH_KMALLOC_MINALIGN);
> > +}
> > +
> > +static size_t devres_data_size(size_t total_size)
> > +{
> > +     return total_size - ALIGN(sizeof(struct devres), ARCH_KMALLOC_MINALIGN);
> > +}
>
> I'm fine with above, but here is a side note, perhaps
>
>         offsetof(struct devres, data)
>
> will be more practical (no duplication of alignment and hence slightly better
> maintenance)? (Note, I didn't check if it provides the correct result)
>

Hi Andy,

The data pointer in struct devres is defined as:

    u8 __aligned(ARCH_KMALLOC_MINALIGN) data[];

And this value (assigned the value of ARCH_DMA_MINALIGN) varies from
one arch to another. I wasn't really sure if offsetof() would work for
every case so I went with something very explicit.

> Another side note: do we have existing users of these helpers?
>

Which ones? Because I assume you're not referring to the ones I'm
adding in this patch. :)

Bart

  parent reply	other threads:[~2020-08-21  8:59 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-20 18:51 [PATCH v8 0/3] devres: provide and use devm_krealloc() Bartosz Golaszewski
2020-08-20 18:51 ` [PATCH v8 1/3] devres: provide devm_krealloc() Bartosz Golaszewski
2020-08-21  8:15   ` Andy Shevchenko
2020-08-21  8:18     ` Andy Shevchenko
2020-08-21  8:59     ` Bartosz Golaszewski [this message]
2020-08-21 10:51       ` Andy Shevchenko
2020-08-21 11:04         ` Andy Shevchenko
2020-08-21 16:00           ` Bartosz Golaszewski
2020-08-20 18:51 ` [PATCH v8 2/3] hwmon: pmbus: use more devres helpers Bartosz Golaszewski
2020-08-20 18:51 ` [PATCH v8 3/3] iio: adc: xilinx-xadc: use devm_krealloc() Bartosz Golaszewski

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