rcu/sync: Kill rcu_sync_type/gp_type

Now that the RCU flavors have been consolidated, rcu_sync_type makes no
sense because none of internal update functions aside from .held() depend
on gp_type.  This commit therefore removes this field and consolidates
the relevant code.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
[ paulmck: Added RCU and RCU-bh checks to rcu_sync_is_idle(). ]
[ paulmck: And applied subsequent feedback from Oleg Nesterov. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h
index 6fc53a1..87971e8 100644
--- a/include/linux/rcu_sync.h
+++ b/include/linux/rcu_sync.h
@@ -13,8 +13,6 @@
 #include <linux/wait.h>
 #include <linux/rcupdate.h>
 
-enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC };
-
 /* Structure to mediate between updaters and fastpath-using readers.  */
 struct rcu_sync {
 	int			gp_state;
@@ -23,52 +21,38 @@ struct rcu_sync {
 
 	int			cb_state;
 	struct rcu_head		cb_head;
-
-	enum rcu_sync_type	gp_type;
 };
 
-extern void rcu_sync_lockdep_assert(struct rcu_sync *);
-
 /**
  * rcu_sync_is_idle() - Are readers permitted to use their fastpaths?
  * @rsp: Pointer to rcu_sync structure to use for synchronization
  *
- * Returns true if readers are permitted to use their fastpaths.
- * Must be invoked within an RCU read-side critical section whose
- * flavor matches that of the rcu_sync struture.
+ * Returns true if readers are permitted to use their fastpaths.  Must be
+ * invoked within some flavor of RCU read-side critical section.
  */
 static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
 {
-#ifdef CONFIG_PROVE_RCU
-	rcu_sync_lockdep_assert(rsp);
-#endif
+	RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
+			 !rcu_read_lock_bh_held() &&
+			 !rcu_read_lock_sched_held(),
+			 "suspicious rcu_sync_is_idle() usage");
 	return !rsp->gp_state; /* GP_IDLE */
 }
 
-extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type);
+extern void rcu_sync_init(struct rcu_sync *);
 extern void rcu_sync_enter_start(struct rcu_sync *);
 extern void rcu_sync_enter(struct rcu_sync *);
 extern void rcu_sync_exit(struct rcu_sync *);
 extern void rcu_sync_dtor(struct rcu_sync *);
 
-#define __RCU_SYNC_INITIALIZER(name, type) {				\
+#define __RCU_SYNC_INITIALIZER(name) {					\
 		.gp_state = 0,						\
 		.gp_count = 0,						\
 		.gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait),	\
 		.cb_state = 0,						\
-		.gp_type = type,					\
 	}
 
-#define	__DEFINE_RCU_SYNC(name, type)	\
-	struct rcu_sync_struct name = __RCU_SYNC_INITIALIZER(name, type)
-
-#define DEFINE_RCU_SYNC(name)		\
-	__DEFINE_RCU_SYNC(name, RCU_SYNC)
-
-#define DEFINE_RCU_SCHED_SYNC(name)	\
-	__DEFINE_RCU_SYNC(name, RCU_SCHED_SYNC)
-
-#define DEFINE_RCU_BH_SYNC(name)	\
-	__DEFINE_RCU_SYNC(name, RCU_BH_SYNC)
+#define	DEFINE_RCU_SYNC(name)	\
+	struct rcu_sync name = __RCU_SYNC_INITIALIZER(name)
 
 #endif /* _LINUX_RCU_SYNC_H_ */