lfstack: simplification

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/urcu/rculfstack-static.h b/urcu/rculfstack-static.h
index 8eae35d1bc0d2c9fc12955d6c5185f3bcb1ecfbb..49e5ef4adf905530d82577544d35ae6e1602f895 100644 (file)
--- a/urcu/rculfstack-static.h
+++ b/urcu/rculfstack-static.h
@@ -44,24 +44,19 @@ void _rcu_lfs_init(struct rcu_lfs_stack *s)
 
 void _rcu_lfs_push(struct rcu_lfs_stack *s, struct rcu_lfs_node *node)
 {
+       struct rcu_lfs_node *head = NULL;
+
        for (;;) {
-               struct rcu_lfs_node *head;
+               struct rcu_lfs_node *old_head = head;
 
-               rcu_read_lock();
-               head = rcu_dereference(s->head);
                node->next = head;
                /*
                 * uatomic_cmpxchg() implicit memory barrier orders earlier
                 * stores to node before publication.
                 */
-               if (uatomic_cmpxchg(&s->head, head, node) == head) {
-                       rcu_read_unlock();
-                       return;
-               } else {
-                       /* Failure to prepend. Retry. */
-                       rcu_read_unlock();
-                       continue;
-               }
+               head = uatomic_cmpxchg(&s->head, old_head, node);
+               if (old_head == head)
+                       break;
        }
 }
 
@@ -73,28 +68,22 @@ void _rcu_lfs_push(struct rcu_lfs_stack *s, struct rcu_lfs_node *node)
 struct rcu_lfs_node *
 _rcu_lfs_pop(struct rcu_lfs_stack *s)
 {
+       struct rcu_lfs_node *head = NULL;
+
        for (;;) {
-               struct rcu_lfs_node *head;
+               struct rcu_lfs_node *old_head = head;
+               struct rcu_lfs_node *next;
 
-               rcu_read_lock();
-               head = rcu_dereference(s->head);
-               if (head) {
-                       struct rcu_lfs_node *next = rcu_dereference(head->next);
+               if (head)
+                       next = head->next;
+               else
+                       next = NULL;
 
-                       if (uatomic_cmpxchg(&s->head, head, next) == head) {
-                               rcu_read_unlock();
-                               return head;
-                       } else {
-                               /* Concurrent modification. Retry. */
-                               rcu_read_unlock();
-                               continue;
-                       }
-               } else {
-                       /* Empty stack */
-                       rcu_read_unlock();
-                       return NULL;
-               }
+               head = uatomic_cmpxchg(&s->head, old_head, next);
+               if (old_head == head)
+                       break;
        }
+       return head;
 }
 
 #ifdef __cplusplus