[PATCH v3 01/13] mm/pgtable: add rcu_read_lock() and rcu_read_unlock()s

[Hugh Dickins]

Before putting them to use (several commits later), add rcu_read_lock()
to pte_offset_map(), and rcu_read_unlock() to pte_unmap().  Make this a
separate commit, since it risks exposing imbalances: prior commits have
fixed all the known imbalances, but we may find some have been missed.

Signed-off-by: Hugh Dickins <hu...@google.com>
---
 include/linux/pgtable.h | 4 ++--
 mm/pgtable-generic.c    | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 5063b482e34f..5134edcec668 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -99,7 +99,7 @@ static inline pte_t *pte_offset_kernel(pmd_t *pmd, unsigned 
long address)
        ((pte_t *)kmap_local_page(pmd_page(*(pmd))) + pte_index((address)))
 #define pte_unmap(pte) do {    \
        kunmap_local((pte));    \
-       /* rcu_read_unlock() to be added later */       \
+       rcu_read_unlock();      \
 } while (0)
 #else
 static inline pte_t *__pte_map(pmd_t *pmd, unsigned long address)
@@ -108,7 +108,7 @@ static inline pte_t *__pte_map(pmd_t *pmd, unsigned long 
address)
 }
 static inline void pte_unmap(pte_t *pte)
 {
-       /* rcu_read_unlock() to be added later */
+       rcu_read_unlock();
 }
 #endif
 
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 4d454953046f..400e5a045848 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -236,7 +236,7 @@ pte_t *__pte_offset_map(pmd_t *pmd, unsigned long addr, 
pmd_t *pmdvalp)
 {
        pmd_t pmdval;
 
-       /* rcu_read_lock() to be added later */
+       rcu_read_lock();
        pmdval = pmdp_get_lockless(pmd);
        if (pmdvalp)
                *pmdvalp = pmdval;
@@ -250,7 +250,7 @@ pte_t *__pte_offset_map(pmd_t *pmd, unsigned long addr, 
pmd_t *pmdvalp)
        }
        return __pte_map(&pmdval, addr);
 nomap:
-       /* rcu_read_unlock() to be added later */
+       rcu_read_unlock();
        return NULL;
 }
 
-- 
2.35.3