1 files changed, 57 insertions, 4 deletions

diff --git a/include/linux/list.h b/include/linux/list.h
index 00ea8e5fb88b..77fb62f79928 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -34,6 +34,14 @@
 	struct list_head name = LIST_HEAD_INIT(name)
 
 /**
+ * LIST_HEAD_GUARDED - define a &struct list_head annotated with __guarded_by()
+ * @name: name of the list_head
+ * @lock: lock protecting the list
+ */
+#define LIST_HEAD_GUARDED(name, lock) \
+	__guarded_by(&(lock)) LIST_HEAD(name)
+
+/**
  * INIT_LIST_HEAD - Initialize a list_head structure
  * @list: list_head structure to be initialized.
  *
@@ -150,10 +158,13 @@ static inline bool __list_del_entry_valid(struct list_head *entry)
  *
  * This is only for internal list manipulation where we know
  * the prev/next entries already!
+ *
+ * Must be inlined to ensure it can be safely called
+ * with initdata arguments.
  */
-static inline void __list_add(struct list_head *new,
-			      struct list_head *prev,
-			      struct list_head *next)
+static __always_inline void __list_add(struct list_head *new,
+				       struct list_head *prev,
+				       struct list_head *next)
 {
 	if (!__list_add_valid(new, prev, next))
 		return;
@@ -171,8 +182,12 @@ static inline void __list_add(struct list_head *new,
  *
  * Insert a new entry after the specified head.
  * This is good for implementing stacks.
+ *
+ * Must be inlined to ensure it can be safely called
+ * with initdata arguments.
  */
-static inline void list_add(struct list_head *new, struct list_head *head)
+static __always_inline void list_add(struct list_head *new,
+				     struct list_head *head)
 {
 	__list_add(new, head, head->next);
 }
@@ -191,6 +206,29 @@ static inline void list_add_tail(struct list_head *new, struct list_head *head)
 	__list_add(new, head->prev, head);
 }
 
+/**
+ * list_add_tail_release - add a new entry with release barrier
+ * @new: new entry to be added
+ * @head: list head to add it before
+ *
+ * Insert a new entry before the specified head, using a release barrier to set
+ * the ->next pointer that points to it.  This is useful for implementing
+ * queues, in particular one that the elements will be walked through forwards
+ * locklessly.
+ */
+static inline void list_add_tail_release(struct list_head *new,
+					 struct list_head *head)
+{
+	struct list_head *prev = head->prev;
+
+	if (__list_add_valid(new, prev, head)) {
+		new->next = head;
+		new->prev = prev;
+		head->prev = new;
+		smp_store_release(&prev->next, new);
+	}
+}
+
 /*
  * Delete a list entry by making the prev/next entries
  * point to each other.
@@ -413,6 +451,7 @@ static inline void list_del_init_careful(struct list_head *entry)
  * if another CPU could re-list_add() it.
  */
 static inline int list_empty_careful(const struct list_head *head)
+	__context_unsafe(/* intentional lockless access to @head */)
 {
 	struct list_head *next = smp_load_acquire(&head->next);
 	return list_is_head(next, head) && (next == READ_ONCE(head->prev));
@@ -645,6 +684,20 @@ static inline void list_splice_tail_init(struct list_head *list,
 })
 
 /**
+ * list_first_entry_or_null_acquire - get the first element from a list with barrier
+ * @ptr:	the list head to take the element from.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_head within the struct.
+ *
+ * Note that if the list is empty, it returns NULL.
+ */
+#define list_first_entry_or_null_acquire(ptr, type, member) ({ \
+	struct list_head *head__ = (ptr); \
+	struct list_head *pos__ = smp_load_acquire(&head__->next); \
+	pos__ != head__ ? list_entry(pos__, type, member) : NULL; \
+})
+
+/**
  * list_last_entry_or_null - get the last element from a list
  * @ptr:	the list head to take the element from.
  * @type:	the type of the struct this is embedded in.