try_get_page() is very similar to try_get_compound_head(), and in fact
try_get_page() has fallen a little behind in terms of maintenance:
try_get_compound_head() handles speculative page references more
thoroughly.
Change try_get_page() so that it is implemented in terms of
try_get_compound_head(), but without changing try_get_page()'s API
contract.
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---
include/linux/mm.h | 11 ++++++-----
mm/gup.c | 2 +-
2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ce8fc0fd6d6e..92d3b37357d5 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1207,14 +1207,15 @@ bool __must_check try_grab_page(struct page *page, unsigned int flags);
__maybe_unused struct page *try_grab_compound_head(struct page *page, int refs,
unsigned int flags);
+struct page *try_get_compound_head(struct page *page, int refs);
+/*
+ * This has the same functionality as try_get_compound_head(), just with a
+ * slightly different API.
+ */
static inline __must_check bool try_get_page(struct page *page)
{
- page = compound_head(page);
- if (WARN_ON_ONCE(page_ref_count(page) <= 0))
- return false;
- page_ref_inc(page);
- return true;
+ return try_get_compound_head(page, 1) != NULL;
}
/**
diff --git a/mm/gup.c b/mm/gup.c
index 4be6f060fa0b..ba75906ba7f7 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -66,7 +66,7 @@ static void put_page_refs(struct page *page, int refs)
* Return the compound head page with ref appropriately incremented,
* or NULL if that failed.
*/
-static inline struct page *try_get_compound_head(struct page *page, int refs)
+struct page *try_get_compound_head(struct page *page, int refs)
{
struct page *head = compound_head(page);
--
2.32.0
