[patch V3 11/22] hlist: Add hlist_is_singular_node() helper

[Thomas Gleixner]

Required to figure out whether the entry is the only one in the hlist.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Chris Mason <clm@xxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: rt@xxxxxxxxxxxxx
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxx>

---
 include/linux/list.h |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -679,6 +679,16 @@ static inline bool hlist_fake(struct hli
 }
 
 /*
+ * Check whether the node is the only node of the head without
+ * accessing head.
+ */
+static inline bool hlist_is_singular_node(struct hlist_node *n,
+					  struct hlist_head *h)
+{
+	return !n->next && n->pprev == &h->first;
+}
+
+/*
  * Move a list from one list head to another. Fixup the pprev
  * reference of the first entry if it exists.
  */