X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu%2Frculfstack.h;h=8cf7d13b35cc09ffc79f6646dd9c0d2c75b3e9b5;hp=f43c9d8c1e679c344bdb289b445fdd99ed0c466d;hb=3d02c34dba0edc4a3554a3862a2ae96d77b3b4e8;hpb=453629a9317adef5b96c3d55e4dcd98db680997a

diff --git a/urcu/rculfstack.h b/urcu/rculfstack.h
index f43c9d8..8cf7d13 100644
--- a/urcu/rculfstack.h
+++ b/urcu/rculfstack.h
@@ -1,3 +1,6 @@
+#ifndef _URCU_RCULFSTACK_H
+#define _URCU_RCULFSTACK_H
+
 /*
  * rculfstack.h
  *
@@ -20,6 +23,10 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #if (!defined(_GNU_SOURCE) && !defined(_LGPL_SOURCE))
 #error "Dynamic loader LGPL wrappers not implemented yet"
 #endif
@@ -43,10 +50,11 @@ 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 +65,25 @@ 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 or modifying the rcu_lfs_node structure.
+ * 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 +92,7 @@ rcu_lfs_pop(struct rcu_lfs_stack *s)
 				return head;
 			} else {
 				/* Concurrent modification. Retry. */
+				rcu_read_unlock();
 				continue;
 			}
 		} else {
@@ -86,3 +102,9 @@ rcu_lfs_pop(struct rcu_lfs_stack *s)
 		}
 	}
 }
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _URCU_RCULFSTACK_H */