Linux-libre 4.8.2-gnupck-4.8.2-gnu

1 files changed, 20 insertions, 14 deletions

diff --git a/include/linux/frontswap.h b/include/linux/frontswap.h
index e65ef9595..c46d2aa16 100644
--- a/include/linux/frontswap.h
+++ b/include/linux/frontswap.h
@@ -4,6 +4,7 @@
 #include <linux/swap.h>
 #include <linux/mm.h>
 #include <linux/bitops.h>
+#include <linux/jump_label.h>
 
 struct frontswap_ops {
 	void (*init)(unsigned); /* this swap type was just swapon'ed */
@@ -14,7 +15,6 @@ struct frontswap_ops {
 	struct frontswap_ops *next; /* private pointer to next ops */
 };
 
-extern bool frontswap_enabled;
 extern void frontswap_register_ops(struct frontswap_ops *ops);
 extern void frontswap_shrink(unsigned long);
 extern unsigned long frontswap_curr_pages(void);
@@ -30,7 +30,12 @@ extern void __frontswap_invalidate_page(unsigned, pgoff_t);
 extern void __frontswap_invalidate_area(unsigned);
 
 #ifdef CONFIG_FRONTSWAP
-#define frontswap_enabled (1)
+extern struct static_key_false frontswap_enabled_key;
+
+static inline bool frontswap_enabled(void)
+{
+	return static_branch_unlikely(&frontswap_enabled_key);
+}
 
 static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
 {
@@ -50,7 +55,10 @@ static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
 #else
 /* all inline routines become no-ops and all externs are ignored */
 
-#define frontswap_enabled (0)
+static inline bool frontswap_enabled(void)
+{
+	return false;
+}
 
 static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
 {
@@ -70,37 +78,35 @@ static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
 
 static inline int frontswap_store(struct page *page)
 {
-	int ret = -1;
+	if (frontswap_enabled())
+		return __frontswap_store(page);
 
-	if (frontswap_enabled)
-		ret = __frontswap_store(page);
-	return ret;
+	return -1;
 }
 
 static inline int frontswap_load(struct page *page)
 {
-	int ret = -1;
+	if (frontswap_enabled())
+		return __frontswap_load(page);
 
-	if (frontswap_enabled)
-		ret = __frontswap_load(page);
-	return ret;
+	return -1;
 }
 
 static inline void frontswap_invalidate_page(unsigned type, pgoff_t offset)
 {
-	if (frontswap_enabled)
+	if (frontswap_enabled())
 		__frontswap_invalidate_page(type, offset);
 }
 
 static inline void frontswap_invalidate_area(unsigned type)
 {
-	if (frontswap_enabled)
+	if (frontswap_enabled())
 		__frontswap_invalidate_area(type);
 }
 
 static inline void frontswap_init(unsigned type, unsigned long *map)
 {
-	if (frontswap_enabled)
+	if (frontswap_enabled())
 		__frontswap_init(type, map);
 }