[PATCH] mm: Constify arguments in default pxdp_get()

[Anshuman Khandual]

Generic MM default pxdp_get() helpers fetch the values contained in pgtable
entries via READ_ONCE() without modifying them. Just make their arguments
explicitly 'const' for some additional protection.

Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Lorenzo Stoakes <ljs@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
This patch applies on v7.2-rc3 and builds on many platforms. Some earlier
discussion could be found here. Platorm implementations for these helpers
could convert into these "const" format later if required.

https://lore.kernel.org/all/yjqldpl7il6uqfoqrszaopchqthhlffssprmlqjkljvpkbpwkt@zetb5hyvllsl/

 include/linux/pgtable.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 2981e386da7b3..f09a91ff5833b 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -490,35 +490,35 @@ static inline int pudp_set_access_flags(struct vm_area_struct *vma,
 #endif
 
 #ifndef ptep_get
-static inline pte_t ptep_get(pte_t *ptep)
+static inline pte_t ptep_get(const pte_t *ptep)
 {
 	return READ_ONCE(*ptep);
 }
 #endif
 
 #ifndef pmdp_get
-static inline pmd_t pmdp_get(pmd_t *pmdp)
+static inline pmd_t pmdp_get(const pmd_t *pmdp)
 {
 	return READ_ONCE(*pmdp);
 }
 #endif
 
 #ifndef pudp_get
-static inline pud_t pudp_get(pud_t *pudp)
+static inline pud_t pudp_get(const pud_t *pudp)
 {
 	return READ_ONCE(*pudp);
 }
 #endif
 
 #ifndef p4dp_get
-static inline p4d_t p4dp_get(p4d_t *p4dp)
+static inline p4d_t p4dp_get(const p4d_t *p4dp)
 {
 	return READ_ONCE(*p4dp);
 }
 #endif
 
 #ifndef pgdp_get
-static inline pgd_t pgdp_get(pgd_t *pgdp)
+static inline pgd_t pgdp_get(const pgd_t *pgdp)
 {
 	return READ_ONCE(*pgdp);
 }
-- 
2.43.0