From: John Hubbard <jhubb...@nvidia.com>
This combines the common elements of these routines:
page_cache_get_speculative()
page_cache_add_speculative()
This was anticipated by the original author, as shown by the comment
in commit ce0ad7f095258 ("powerpc/mm: Lockless get_user_pages_fast()
for 64-bit (v3)"):
"Same as above, but add instead of inc (could just be merged)"
An upcoming patch for get_user_pages() tracking will use these routines,
so let's remove the duplication now.
There is no intention to introduce any behavioral change, but there is a
small risk of that, due to slightly differing ways of expressing the
TINY_RCU and related configurations.
Cc: Nick Piggin <npig...@suse.de>
Cc: Dave Kleikamp <sha...@linux.vnet.ibm.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Signed-off-by: John Hubbard <jhubb...@nvidia.com>
---
include/linux/pagemap.h | 33 +++++++++++----------------------
1 file changed, 11 insertions(+), 22 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e2d7039af6a3..5c8a9b59cbdc 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -164,8 +164,10 @@ void release_pages(struct page **pages, int nr);
* will find the page or it will not. Likewise, the old find_get_page could run
* either before the insertion or afterwards, depending on timing.
*/
-static inline int page_cache_get_speculative(struct page *page)
+static inline int __page_cache_add_speculative(struct page *page, int count)
{
+ VM_BUG_ON(in_interrupt());
+
#ifdef CONFIG_TINY_RCU
# ifdef CONFIG_PREEMPT_COUNT
VM_BUG_ON(!in_atomic() && !irqs_disabled());
@@ -180,10 +182,10 @@ static inline int page_cache_get_speculative(struct page
*page)
* SMP requires.
*/
VM_BUG_ON_PAGE(page_count(page) == 0, page);
- page_ref_inc(page);
+ page_ref_add(page, count);
#else
- if (unlikely(!get_page_unless_zero(page))) {
+ if (unlikely(!page_ref_add_unless(page, count, 0))) {
/*
* Either the page has been freed, or will be freed.
* In either case, retry here and the caller should
@@ -197,27 +199,14 @@ static inline int page_cache_get_speculative(struct page
*page)
return 1;
}
-/*
- * Same as above, but add instead of inc (could just be merged)
- */
-static inline int page_cache_add_speculative(struct page *page, int count)
+static inline int page_cache_get_speculative(struct page *page)
{
- VM_BUG_ON(in_interrupt());
-
-#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
-# ifdef CONFIG_PREEMPT_COUNT
- VM_BUG_ON(!in_atomic() && !irqs_disabled());
-# endif
- VM_BUG_ON_PAGE(page_count(page) == 0, page);
- page_ref_add(page, count);
-
-#else
- if (unlikely(!page_ref_add_unless(page, count, 0)))
- return 0;
-#endif
- VM_BUG_ON_PAGE(PageCompound(page) && page != compound_head(page), page);
+ return __page_cache_add_speculative(page, 1);
+}
- return 1;
+static inline int page_cache_add_speculative(struct page *page, int count)
+{
+ return __page_cache_add_speculative(page, count);
}
#ifdef CONFIG_NUMA
--
2.20.1
