On Fri, Aug 21, 2020 at 10:35 AM Andy Shevchenko
[off-list ref] wrote:

On Thu, Aug 20, 2020 at 08:51:08PM +0200, Bartosz Golaszewski wrote:

quoted

From: Bartosz Golaszewski <redacted>

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 <redacted>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

...

quoted

+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

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