Re: [PATCH] af_key: suppress a warning for 64k pages.

[David Miller <davem@davemloft.net>]

From: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Wed, 31 Oct 2007 15:34:22 +1100

> On Tue, 30 Oct 2007 21:08:46 -0700 (PDT) David Miller <davem@davemloft.net> wrote:
> > I think we should retain the check, but modify it so that GCC knows we
> > understand that it's OK if it is always false.  Perhaps a simple (u32)
> > cast on the left branch of the comparison is sufficient?
> 
> Unfortunately, that does not suppress the warning (gcc is getting too
> smart :-().

It seems if you break the comparison out into a function which
takes a u32, that's enough to get rid of the warning.

I can't figure out a way to make this prettier, can you?

#define PAGE_SIZE	(64 * 1024)

typedef unsigned int u32;
typedef unsigned short u16;

int compare(u32 val)
{
	if (val >= PAGE_SIZE)
		return -1;
	return 0;
}

int foo(u16 val)
{
#if 1
	return compare(val);
#else
	if (val >= PAGE_SIZE)
		return -1;
	return 0;
#endif
}