X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=urcu%2Frculfstack.h;h=a9e624ce792ee2b59ecb648084df5cda73a60e46;hb=ad918eeb98d1ac8b12015050ee60b488e850ac0d;hp=f43c9d8c1e679c344bdb289b445fdd99ed0c466d;hpb=453629a9317adef5b96c3d55e4dcd98db680997a;p=urcu.git

diff --git a/urcu/rculfstack.h b/urcu/rculfstack.h
index f43c9d8..a9e624c 100644
--- a/urcu/rculfstack.h
+++ b/urcu/rculfstack.h
@@ -1,3 +1,6 @@
+#ifndef _URCU_RCULFSTACK_H
+#define _URCU_RCULFSTACK_H
+
 /*
  * rculfstack.h
  *
@@ -43,10 +46,11 @@ void rcu_lfs_init(struct rcu_lfs_stack *s)
 
 void rcu_lfs_push(struct rcu_lfs_stack *s, struct rcu_lfs_node *node)
 {
-	rcu_read_lock();
 	for (;;) {
-		struct rcu_lfs_node *head = rcu_dereference(s->head);
+		struct rcu_lfs_node *head;
 
+		rcu_read_lock();
+		head = rcu_dereference(s->head);
 		node->next = head;
 		/*
 		 * uatomic_cmpxchg() implicit memory barrier orders earlier
@@ -57,18 +61,25 @@ void rcu_lfs_push(struct rcu_lfs_stack *s, struct rcu_lfs_node *node)
 			return;
 		} else {
 			/* Failure to prepend. Retry. */
+			rcu_read_unlock();
 			continue;
 		}
 	}
 }
 
+/*
+ * The caller must wait for a grace period to pass before freeing the returned
+ * node.
+ * Returns NULL if stack is empty.
+ */
 struct rcu_lfs_node *
 rcu_lfs_pop(struct rcu_lfs_stack *s)
 {
-	rcu_read_lock();
 	for (;;) {
-		struct rcu_lfs_node *head = rcu_dereference(s->head);
+		struct rcu_lfs_node *head;
 
+		rcu_read_lock();
+		head = rcu_dereference(s->head);
 		if (head) {
 			struct rcu_lfs_node *next = rcu_dereference(head->next);
 
@@ -77,6 +88,7 @@ rcu_lfs_pop(struct rcu_lfs_stack *s)
 				return head;
 			} else {
 				/* Concurrent modification. Retry. */
+				rcu_read_unlock();
 				continue;
 			}
 		} else {
@@ -86,3 +98,5 @@ rcu_lfs_pop(struct rcu_lfs_stack *s)
 		}
 	}
 }
+
+#endif /* _URCU_RCULFSTACK_H */