[PATCH -V2] powerpc: thp: Fix crash on mremap

[Benjamin Herrenschmidt]

On Thu, 2014-01-02 at 16:22 +0530, Aneesh Kumar K.V wrote:
> > Just use config option directly:
> >
> >       if (new_ptl != old_ptl ||
> >               IS_ENABLED(CONFIG_ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW))
> 
> 
> I didn't like that. I found the earlier one easier for reading.
> If you and others strongly feel about this, I can redo the patch.
> Please let me know

Yes, use IS_ENABLED, no need to have two indirections of #define's

Another option is to have

	if (pmd_move_must_withdraw(new,old)) {
	}

With in a generic header:

#ifndef pmd_move_must_withdraw
static inline bool pmd_move_must_withdraw(spinlock_t *new_ptl, ...)
{
	return new_ptl != old_ptl;
}
#endif

And in powerpc:

static inline bool pmd_move_must_withdraw(spinlock_t *new_ptl, ...)
{
	return true;
}
#define pmd_move_must_withdraw pmd_move_must_withdraw

Cheers,
Ben.