Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 4786c22..4158b72 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -41,6 +41,24 @@
 #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
@@ -182,7 +200,7 @@
  * @list:	the RCU-protected list to splice
  * @prev:	points to the last element of the existing list
  * @next:	points to the first element of the existing list
- * @sync:	function to sync: synchronize_rcu(), synchronize_sched(), ...
+ * @sync:	synchronize_rcu, synchronize_rcu_expedited, ...
  *
  * The list pointed to by @prev and @next can be RCU-read traversed
  * concurrently with this function.
@@ -240,7 +258,7 @@
  *                        designed for stacks.
  * @list:	the RCU-protected list to splice
  * @head:	the place in the existing list to splice the first list into
- * @sync:	function to sync: synchronize_rcu(), synchronize_sched(), ...
+ * @sync:	synchronize_rcu, synchronize_rcu_expedited, ...
  */
 static inline void list_splice_init_rcu(struct list_head *list,
 					struct list_head *head,
@@ -255,7 +273,7 @@
  *                             list, designed for queues.
  * @list:	the RCU-protected list to splice
  * @head:	the place in the existing list to splice the first list into
- * @sync:	function to sync: synchronize_rcu(), synchronize_sched(), ...
+ * @sync:	synchronize_rcu, synchronize_rcu_expedited, ...
  */
 static inline void list_splice_tail_init_rcu(struct list_head *list,
 					     struct list_head *head,
@@ -343,14 +361,16 @@
  * @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))
 
 /**
@@ -359,13 +379,12 @@
  * @type:       the type of the struct this is embedded in.
  * @member:     the name of the list_head within the struct.
  *
- * This primitive may safely run concurrently with the _rcu list-mutation
- * primitives such as list_add_rcu(), but requires some implicit RCU
- * read-side guarding.  One example is running within a special
- * exception-time environment where preemption is disabled and where
- * lockdep cannot be invoked (in which case updaters must use RCU-sched,
- * as in synchronize_sched(), call_rcu_sched(), and friends).  Another
- * example is when items are added to the list, but never deleted.
+ * This primitive may safely run concurrently with the _rcu
+ * list-mutation primitives such as list_add_rcu(), but requires some
+ * implicit RCU read-side guarding.  One example is running within a special
+ * exception-time environment where preemption is disabled and where lockdep
+ * cannot be invoked.  Another example is when items are added to the list,
+ * but never deleted.
  */
 #define list_entry_lockless(ptr, type, member) \
 	container_of((typeof(ptr))READ_ONCE(ptr), type, member)
@@ -376,13 +395,12 @@
  * @head:	the head for your list.
  * @member:	the name of the list_struct within the struct.
  *
- * This primitive may safely run concurrently with the _rcu list-mutation
- * primitives such as list_add_rcu(), but requires some implicit RCU
- * read-side guarding.  One example is running within a special
- * exception-time environment where preemption is disabled and where
- * lockdep cannot be invoked (in which case updaters must use RCU-sched,
- * as in synchronize_sched(), call_rcu_sched(), and friends).  Another
- * example is when items are added to the list, but never deleted.
+ * This primitive may safely run concurrently with the _rcu
+ * list-mutation primitives such as list_add_rcu(), but requires some
+ * implicit RCU read-side guarding.  One example is running within a special
+ * exception-time environment where preemption is disabled and where lockdep
+ * cannot be invoked.  Another example is when items are added to the list,
+ * but never deleted.
  */
 #define list_for_each_entry_lockless(pos, head, member) \
 	for (pos = list_entry_lockless((head)->next, typeof(*pos), member); \
@@ -618,13 +636,15 @@
  * @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(\
@@ -644,10 +664,10 @@
  * 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))
 
 /**