On Tue 04-02-20 15:41:09, John Hubbard wrote:
An upcoming patch requires subtracting a large chunk of refcounts from a page, and checking what the resulting refcount is. This is a little different than the usual "check for zero refcount" that many of the page ref functions already do. However, it is similar to a few other routines that (like this one) are generally useful for things such as 1-based refcounting.
Add page_ref_sub_return(), that subtracts a chunk of refcounts atomically, and returns an atomic snapshot of the result.
Signed-off-by: John Hubbard jhubbard@nvidia.com
Looks good to me. You can add:
Reviewed-by: Jan Kara jack@suse.cz
Honza
include/linux/page_ref.h | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/include/linux/page_ref.h b/include/linux/page_ref.h index 14d14beb1f7f..a0e171265b79 100644 --- a/include/linux/page_ref.h +++ b/include/linux/page_ref.h @@ -102,6 +102,15 @@ static inline void page_ref_sub(struct page *page, int nr) __page_ref_mod(page, -nr); } +static inline int page_ref_sub_return(struct page *page, int nr) +{
- int ret = atomic_sub_return(nr, &page->_refcount);
- if (page_ref_tracepoint_active(__tracepoint_page_ref_mod))
__page_ref_mod_and_return(page, -nr, ret);- return ret;
+}
static inline void page_ref_inc(struct page *page) { atomic_inc(&page->_refcount); -- 2.25.0