Re: [RFC PATCH v2 3/3] mm: make generic pXd_addr_end() macros inline functions

[Christophe Leroy <christophe.leroy@xxxxxxxxxx>]

Le 08/09/2020 à 17:48, Alexander Gordeev a écrit :
> On Tue, Sep 08, 2020 at 07:19:38AM +0200, Christophe Leroy wrote:
>
> [...]
>
> > > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> > > index 67ebc22cf83d..d9e7d16c2263 100644
> > > --- a/include/linux/pgtable.h
> > > +++ b/include/linux/pgtable.h
> > > @@ -656,31 +656,35 @@ static inline int arch_unmap_one(struct mm_struct *mm,
> > >    */
> > >   #ifndef pgd_addr_end
> > > -#define pgd_addr_end(pgd, addr, end)					\
> > > -({	unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK;	\
> > > -	(__boundary - 1 < (end) - 1)? __boundary: (end);		\
> > > -})
> > > +#define pgd_addr_end pgd_addr_end
> >
> > I think that #define is pointless, usually there is no such #define
> > for the default case.
>
> Default pgd_addr_end() gets overriden on s390 (arch/s390/include/asm/pgtable.h):
>
> #define pgd_addr_end pgd_addr_end
> static inline unsigned long pgd_addr_end(pgd_t pgd, unsigned long addr, unsigned long end)
> {
> 	return rste_addr_end_folded(pgd_val(pgd), addr, end);
> }

Yes, there in s390 the #define is needed to hit the #ifndef pgd_addr_end 
that's in include/linux/pgtable.h

But in include/linux/pgtable.h, there is no need of an #define 
pgd_addr_end pgd_addr_end I think

> > > +static inline unsigned long pgd_addr_end(pgd_t pgd, unsigned long addr, unsigned long end)
> > > +{	unsigned long __boundary = (addr + PGDIR_SIZE) & PGDIR_MASK;
> > > +	return (__boundary - 1 < end - 1) ? __boundary : end;
> > > +}


Christophe