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 <peterz@infradead.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/jump_label.h

@@ -69,6 +69,10 @@ struct static_key {
 
 # 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 {
@@ -79,6 +83,12 @@ 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
@@ -134,10 +144,6 @@ extern void jump_label_apply_nops(struct module *mod);
 
 #else  /* !HAVE_JUMP_LABEL */
 
-struct static_key {
-	atomic_t enabled;
-};
-
 static __always_inline void jump_label_init(void)
 {
 	static_key_initialized = true;
@@ -145,14 +151,14 @@ static __always_inline void jump_label_init(void)
 
 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;
 }
@@ -194,7 +200,7 @@ static inline int jump_label_apply_nops(struct module *mod)
 
 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 */