Subject: Re: [PATCH] powerpc/8xx: tqm8xx: fix incorrect placement of __initdata tag

From: Bartlomiej Zolnierkiewicz <[email-masked]>
Date: Mon, 30 Sep 2013 17:05:51 +0200

On Monday, September 30, 2013 03:20:29 PM David Laight wrote:
> > __initdata tag should be placed between the variable name and equal
> > sign for the variable to be placed in the intended .init.data section.
> ...
> > -static struct __initdata cpm_pin tqm8xx_pins[] = {
> > +static struct cpm_pin tqm8xx_pins[] __initdata = {
> 
> As far as gcc is concerned it can go almost anywhere before the '=',
> even before the 'static'.
> Splitting 'struct cpm_pin' does seem an odd choice.

It is not only an odd choice, it just doesn't work as it should in
the practice (as tested with gcc-4.6.3 from Ubuntu 12.04).

> The Linux coding standards might suggest a location.
> I'd have thought that either before or after the 'static' would be best
> (ie as a storage class qualifier).

The majority of the kernel code uses __initdata before equal sign
and the __initdata documentation in <linux/init.h> recommends such
usage:

"
 * For initialized data:
 * You should insert __initdata or __initconst between the variable name
 * and equal sign followed by value, e.g.:
 *
 * static int init_variable __initdata = 0;
 * static const char linux_logo[] __initconst = { 0x32, 0x36, ... };
"

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics