diff options
Diffstat (limited to 'include/linux/mm.h')
| -rw-r--r-- | include/linux/mm.h | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 81443d557a2..8aa4006b963 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -297,12 +297,26 @@ static inline int put_page_testzero(struct page *page) /* * Try to grab a ref unless the page has a refcount of zero, return false if * that is the case. + * This can be called when MMU is off so it must not access + * any of the virtual mappings. */ static inline int get_page_unless_zero(struct page *page) { return atomic_inc_not_zero(&page->_count); } +/* + * Try to drop a ref unless the page has a refcount of one, return false if + * that is the case. + * This is to make sure that the refcount won't become zero after this drop. + * This can be called when MMU is off so it must not access + * any of the virtual mappings. + */ +static inline int put_page_unless_one(struct page *page) +{ + return atomic_add_unless(&page->_count, -1, 1); +} + extern int page_is_ram(unsigned long pfn); /* Support for virtually mapped pages */ |