Re: [RFC][PATCH] Btrfs-progs: Fix compiler warnings on PPC64.

[Wade Cline <clinew@linux.vnet.ibm.com>]

On 09/14/2012 06:59 AM, David Sterba wrote:
> On Wed, Sep 12, 2012 at 04:21:56PM -0700, clinew@linux.vnet.ibm.com wrote:
>> Defining __KERNEL__ before the file<asm/types.h>, or any file that
>> includes this file, will let PPC64 know to use unsigned long long
>> for u64 instead. This patch adds the defines and fixes the print
>> warnings on PPC64.
> Defining __KERNEL__ in random places does not seem clean, I understand
> it in kerncompat.h which should transparently fix any compatibility
> issues, and the files like cmd-receive.c should include this instead of
> the explicit defines.
>
>
> david
>

I agree that defining __KERNEL__ does not seem clean, but the problem is 
that
the various include files sort of "race" to include the type definition. 
For example,
in cmds-scrub.c:

#include <sys/ioctl.h>
#include <sys/wait.h>
#define __KERNEL__
#include <sys/stat.h>

will generate compiler warnings while:

#include <sys/ioctl.h>
#define __KERNEL__
#include <sys/wait.h>
#include <sys/stat.h>

will not. By the time kerncompat.h is included, u64 is almost always 
defined to
the non-compatible value. So either kerncompat.h needs to be defined as 
the -first-
included header file, or __KERNEL__ needs to be defined.

...it would also be possible to do something like:

#define __KERNEL__
#include <sys/wait.h>
#undef __KERNEL__

but that seems a bit too hacky.

I'm open to any other ideas, though.

Thank you,
Wade