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SubjectRe: [PATCH] arm/mm: fix compiler warning in pmdp_invalidate() (in -next)
On Fri, 30 Jan 2015 16:40:15 +0000 Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:

> On Fri, Jan 30, 2015 at 04:37:32PM +0000, Andre Przywara wrote:
> > Commit ff61d185f4e7 ("mm: convert p[te|md]_mknonnuma and remaining
> > page table manipulations") removed a check in
> > mm/pgtable-generic.c:pmdp_invalidate(), which leaves the
> > pmd_mknotpresent macro the only user of the entry variable.
> > For ARM/LPAE we use a constant 0 without referencing the argument to
> > mark this condition, so the entry variable is no longer used here:
> >
> > mm/pgtable-generic.c: In function 'pmdp_invalidate':
> > mm/pgtable-generic.c:195:8: warning: unused variable 'entry' [-Wunused-variable]
> > pmd_t entry = *pmdp;
> > ^
> >
> > Replace the ARM macro implementation with a static inline function to
> > get rid of this warning.
> >
> > Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> > ---
> > Hi Andrew,
> >
> > Mel mentioned that I should send that simple fix below to you to
> > merge it with his original mmotm patch:
> > mm-convert-p_mknonnuma-and-remaining-page-table-manipulations.patch
> > The commit message above contains the mmotm-reference to this patch,
> > which will break when it hits mainline.
> >
> > Can you consider this? Given that's only a warning fix I am also
> > happy with resending it after -rc1, if you reckon that this arch/arm
> > change should not go via mmotm.
>
> This isn't correct though.
>
> > /* represent a notpresent pmd by zero, this is used by pmdp_invalidate */
> > -#define pmd_mknotpresent(pmd) (__pmd(0))
> > +static inline pmd_t pmd_mknotpresent(pmd_t pmd)
> > +{
> > + return 0;
> > +}
>
> typedef struct { pmdval_t pmd; } pmd_t;
>
> typedef u32 pmdval_t;
>
> "0" is not compatible with pmd_t when STRICT_MM_TYPECHECKS is enabled.

This?

--- a/arch/arm/include/asm/pgtable-3level.h~mm-convert-p_mknonnuma-and-remaining-page-table-manipulations-fix-fix
+++ a/arch/arm/include/asm/pgtable-3level.h
@@ -259,7 +259,7 @@ PMD_BIT_FUNC(mkyoung, |= PMD_SECT_AF);
/* represent a notpresent pmd by zero, this is used by pmdp_invalidate */
static inline pmd_t pmd_mknotpresent(pmd_t pmd)
{
- return 0;
+ return __pmd(0);
}

static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)


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