Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU updates from Ingo Molnar:
 "This cycle's RCU changes were:

   - A few more RCU flavor consolidation cleanups.

   - Updates to RCU's list-traversal macros improving lockdep usability.

   - Forward-progress improvements for no-CBs CPUs: Avoid ignoring
     incoming callbacks during grace-period waits.

   - Forward-progress improvements for no-CBs CPUs: Use ->cblist
     structure to take advantage of others' grace periods.

   - Also added a small commit that avoids needlessly inflicting
     scheduler-clock ticks on callback-offloaded CPUs.

   - Forward-progress improvements for no-CBs CPUs: Reduce contention on
     ->nocb_lock guarding ->cblist.

   - Forward-progress improvements for no-CBs CPUs: Add ->nocb_bypass
     list to further reduce contention on ->nocb_lock guarding ->cblist.

   - Miscellaneous fixes.

   - Torture-test updates.

   - minor LKMM updates"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (86 commits)
  MAINTAINERS: Update from paulmck@linux.ibm.com to paulmck@kernel.org
  rcu: Don't include <linux/ktime.h> in rcutiny.h
  rcu: Allow rcu_do_batch() to dynamically adjust batch sizes
  rcu/nocb: Don't wake no-CBs GP kthread if timer posted under overload
  rcu/nocb: Reduce __call_rcu_nocb_wake() leaf rcu_node ->lock contention
  rcu/nocb: Reduce nocb_cb_wait() leaf rcu_node ->lock contention
  rcu/nocb: Advance CBs after merge in rcutree_migrate_callbacks()
  rcu/nocb: Avoid synchronous wakeup in __call_rcu_nocb_wake()
  rcu/nocb: Print no-CBs diagnostics when rcutorture writer unduly delayed
  rcu/nocb: EXP Check use and usefulness of ->nocb_lock_contended
  rcu/nocb: Add bypass callback queueing
  rcu/nocb: Atomic ->len field in rcu_segcblist structure
  rcu/nocb: Unconditionally advance and wake for excessive CBs
  rcu/nocb: Reduce ->nocb_lock contention with separate ->nocb_gp_lock
  rcu/nocb: Reduce contention at no-CBs invocation-done time
  rcu/nocb: Reduce contention at no-CBs registry-time CB advancement
  rcu/nocb: Round down for number of no-CBs grace-period kthreads
  rcu/nocb: Avoid ->nocb_lock capture by corresponding CPU
  rcu/nocb: Avoid needless wakeups of no-CBs grace-period kthread
  rcu/nocb: Make __call_rcu_nocb_wake() safe for many callbacks
  ...

6 files changed, 50 insertions, 14 deletions

diff --git a/include/linux/rcu_segcblist.h b/include/linux/rcu_segcblist.h
index 87404cb015f1..646759042333 100644
--- a/include/linux/rcu_segcblist.h
+++ b/include/linux/rcu_segcblist.h
@@ -14,6 +14,9 @@
 #ifndef __INCLUDE_LINUX_RCU_SEGCBLIST_H
 #define __INCLUDE_LINUX_RCU_SEGCBLIST_H
 
+#include <linux/types.h>
+#include <linux/atomic.h>
+
 /* Simple unsegmented callback lists. */
 struct rcu_cblist {
 	struct rcu_head *head;
@@ -65,8 +68,14 @@ struct rcu_segcblist {
 	struct rcu_head *head;
 	struct rcu_head **tails[RCU_CBLIST_NSEGS];
 	unsigned long gp_seq[RCU_CBLIST_NSEGS];
+#ifdef CONFIG_RCU_NOCB_CPU
+	atomic_long_t len;
+#else
 	long len;
+#endif
 	long len_lazy;
+	u8 enabled;
+	u8 offloaded;
 };
 
 #define RCU_SEGCBLIST_INITIALIZER(n) \
diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h
index 9b83865d24f9..0027d4c8087c 100644
--- a/include/linux/rcu_sync.h
+++ b/include/linux/rcu_sync.h
@@ -31,9 +31,7 @@ struct rcu_sync {
  */
 static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
 {
-	RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
-			 !rcu_read_lock_bh_held() &&
-			 !rcu_read_lock_sched_held(),
+	RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
 			 "suspicious rcu_sync_is_idle() usage");
 	return !READ_ONCE(rsp->gp_state); /* GP_IDLE */
 }
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index e91ec9ddcd30..4158b7212936 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -41,6 +41,24 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head *list)
 #define list_next_rcu(list)	(*((struct list_head __rcu **)(&(list)->next)))
 
 /*
+ * Check during list traversal that we are within an RCU reader
+ */
+
+#define check_arg_count_one(dummy)
+
+#ifdef CONFIG_PROVE_RCU_LIST
+#define __list_check_rcu(dummy, cond, extra...)				\
+	({								\
+	check_arg_count_one(extra);					\
+	RCU_LOCKDEP_WARN(!cond && !rcu_read_lock_any_held(),		\
+			 "RCU-list traversed in non-reader section!");	\
+	 })
+#else
+#define __list_check_rcu(dummy, cond, extra...)				\
+	({ check_arg_count_one(extra); })
+#endif
+
+/*
  * Insert a new entry between two known consecutive entries.
  *
  * This is only for internal list manipulation where we know
@@ -343,14 +361,16 @@ static inline void list_splice_tail_init_rcu(struct list_head *list,
  * @pos:	the type * to use as a loop cursor.
  * @head:	the head for your list.
  * @member:	the name of the list_head within the struct.
+ * @cond:	optional lockdep expression if called from non-RCU protection.
  *
  * This list-traversal primitive may safely run concurrently with
  * the _rcu list-mutation primitives such as list_add_rcu()
  * as long as the traversal is guarded by rcu_read_lock().
  */
-#define list_for_each_entry_rcu(pos, head, member) \
-	for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \
-		&pos->member != (head); \
+#define list_for_each_entry_rcu(pos, head, member, cond...)		\
+	for (__list_check_rcu(dummy, ## cond, 0),			\
+	     pos = list_entry_rcu((head)->next, typeof(*pos), member);	\
+		&pos->member != (head);					\
 		pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
 
 /**
@@ -616,13 +636,15 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
  * @pos:	the type * to use as a loop cursor.
  * @head:	the head for your list.
  * @member:	the name of the hlist_node within the struct.
+ * @cond:	optional lockdep expression if called from non-RCU protection.
  *
  * This list-traversal primitive may safely run concurrently with
  * the _rcu list-mutation primitives such as hlist_add_head_rcu()
  * as long as the traversal is guarded by rcu_read_lock().
  */
-#define hlist_for_each_entry_rcu(pos, head, member)			\
-	for (pos = hlist_entry_safe (rcu_dereference_raw(hlist_first_rcu(head)),\
+#define hlist_for_each_entry_rcu(pos, head, member, cond...)		\
+	for (__list_check_rcu(dummy, ## cond, 0),			\
+	     pos = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),\
 			typeof(*(pos)), member);			\
 		pos;							\
 		pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(\
@@ -642,10 +664,10 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
  * not do any RCU debugging or tracing.
  */
 #define hlist_for_each_entry_rcu_notrace(pos, head, member)			\
-	for (pos = hlist_entry_safe (rcu_dereference_raw_notrace(hlist_first_rcu(head)),\
+	for (pos = hlist_entry_safe(rcu_dereference_raw_check(hlist_first_rcu(head)),\
 			typeof(*(pos)), member);			\
 		pos;							\
-		pos = hlist_entry_safe(rcu_dereference_raw_notrace(hlist_next_rcu(\
+		pos = hlist_entry_safe(rcu_dereference_raw_check(hlist_next_rcu(\
 			&(pos)->member)), typeof(*(pos)), member))
 
 /**
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 8f7167478c1d..80d6056f5855 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -221,6 +221,7 @@ int debug_lockdep_rcu_enabled(void);
 int rcu_read_lock_held(void);
 int rcu_read_lock_bh_held(void);
 int rcu_read_lock_sched_held(void);
+int rcu_read_lock_any_held(void);
 
 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
@@ -241,6 +242,12 @@ static inline int rcu_read_lock_sched_held(void)
 {
 	return !preemptible();
 }
+
+static inline int rcu_read_lock_any_held(void)
+{
+	return !preemptible();
+}
+
 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
 #ifdef CONFIG_PROVE_RCU
@@ -476,7 +483,7 @@ do {									      \
  * The no-tracing version of rcu_dereference_raw() must not call
  * rcu_read_lock_held().
  */
-#define rcu_dereference_raw_notrace(p) __rcu_dereference_check((p), 1, __rcu)
+#define rcu_dereference_raw_check(p) __rcu_dereference_check((p), 1, __rcu)
 
 /**
  * rcu_dereference_protected() - fetch RCU pointer when updates prevented
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 8e727f57d814..9bf1dfe7781f 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -12,7 +12,7 @@
 #ifndef __LINUX_TINY_H
 #define __LINUX_TINY_H
 
-#include <linux/ktime.h>
+#include <asm/param.h> /* for HZ */
 
 /* Never flag non-existent other CPUs! */
 static inline bool rcu_eqs_special_set(int cpu) { return false; }
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 02a3f78f7cd8..694bd040cf51 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -100,7 +100,6 @@ TRACE_EVENT_RCU(rcu_grace_period,
  * "Startedroot": Requested a nocb grace period based on root-node data.
  * "NoGPkthread": The RCU grace-period kthread has not yet started.
  * "StartWait": Start waiting for the requested grace period.
- * "ResumeWait": Resume waiting after signal.
  * "EndWait": Complete wait.
  * "Cleanup": Clean up rcu_node structure after previous GP.
  * "CleanupMore": Clean up, and another GP is needed.
@@ -267,7 +266,8 @@ TRACE_EVENT_RCU(rcu_exp_funnel_lock,
  *	"WakeNotPoll": Don't wake rcuo kthread because it is polling.
  *	"DeferredWake": Carried out the "IsDeferred" wakeup.
  *	"Poll": Start of new polling cycle for rcu_nocb_poll.
- *	"Sleep": Sleep waiting for CBs for !rcu_nocb_poll.
+ *	"Sleep": Sleep waiting for GP for !rcu_nocb_poll.
+ *	"CBSleep": Sleep waiting for CBs for !rcu_nocb_poll.
  *	"WokeEmpty": rcuo kthread woke to find empty list.
  *	"WokeNonEmpty": rcuo kthread woke to find non-empty list.
  *	"WaitQueue": Enqueue partially done, timed wait for it to complete.