include/linux/jump_label.h: expose the reference count

This patch exposes the jump_label reference count in preparation for the
next patch. cpusets cares about both the jump_label being enabled and how
many users of the cpusets there currently are.

Signed-off-by: Peter Zijlstra <[e-mail]>
Signed-off-by: Mel Gorman <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Cc: Jan Kara <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Hugh Dickins <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: Theodore Ts'o <[e-mail]>
Cc: "Paul E. McKenney" <[e-mail]>
Cc: Oleg Nesterov <[e-mail]>
Cc: Rik van Riel <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/jump_label.h

···
 
 # include <asm/jump_label.h>
 # define HAVE_JUMP_LABEL
+#else
+struct static_key {
+	atomic_t enabled;
+};
 #endif	/* CC_HAVE_ASM_GOTO && CONFIG_JUMP_LABEL */
 
 enum jump_label_type {
···
 struct module;
 
 #include <linux/atomic.h>
+
+static inline int static_key_count(struct static_key *key)
+{
+	return atomic_read(&key->enabled);
+}
+
 #ifdef HAVE_JUMP_LABEL
 
 #define JUMP_LABEL_TYPE_FALSE_BRANCH	0UL
···
 
 #else  /* !HAVE_JUMP_LABEL */
 
-struct static_key {
-	atomic_t enabled;
-};
-
 static __always_inline void jump_label_init(void)
 {
 	static_key_initialized = true;
···
 
 static __always_inline bool static_key_false(struct static_key *key)
 {
-	if (unlikely(atomic_read(&key->enabled) > 0))
+	if (unlikely(static_key_count(key) > 0))
 		return true;
 	return false;
 }
 
 static __always_inline bool static_key_true(struct static_key *key)
 {
-	if (likely(atomic_read(&key->enabled) > 0))
+	if (likely(static_key_count(key) > 0))
 		return true;
 	return false;
 }
···
 
 static inline bool static_key_enabled(struct static_key *key)
 {
-	return (atomic_read(&key->enabled) > 0);
+	return static_key_count(key) > 0;
 }
 
 #endif	/* _LINUX_JUMP_LABEL_H */