Make lf stack push return if the stack was empty

[urcu.git] / urcu / rculfstack.h

diff --git a/urcu/rculfstack.h b/urcu/rculfstack.h
index 8cf7d13b35cc09ffc79f6646dd9c0d2c75b3e9b5..cf00daf26cc65cf09d300dafb91dd73467cf6f42 100644 (file)
--- a/urcu/rculfstack.h
+++ b/urcu/rculfstack.h
@@ -27,81 +27,60 @@
 extern "C" {
 #endif
 
-#if (!defined(_GNU_SOURCE) && !defined(_LGPL_SOURCE))
-#error "Dynamic loader LGPL wrappers not implemented yet"
-#endif
-
-struct rcu_lfs_node {
-       struct rcu_lfs_node *next;
+struct cds_lfs_node_rcu {
+       struct cds_lfs_node_rcu *next;
 };
 
-struct rcu_lfs_stack {
-       struct rcu_lfs_node *head;
+struct cds_lfs_stack_rcu {
+       struct cds_lfs_node_rcu *head;
 };
 
-void rcu_lfs_node_init(struct rcu_lfs_node *node)
-{
-}
+#ifdef _LGPL_SOURCE
 
-void rcu_lfs_init(struct rcu_lfs_stack *s)
-{
-       s->head = NULL;
-}
+#include <urcu/static/rculfstack.h>
 
-void rcu_lfs_push(struct rcu_lfs_stack *s, struct rcu_lfs_node *node)
-{
-       for (;;) {
-               struct rcu_lfs_node *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;
-               }
-       }
-}
+#define cds_lfs_node_init_rcu_qsbr     _cds_lfs_node_init_rcu
+#define cds_lfs_init_rcu_qsbr          _cds_lfs_init_rcu
+#define cds_lfs_push_rcu_qsbr          _cds_lfs_push_rcu
+#define cds_lfs_pop_rcu_qsbr           _cds_lfs_pop_rcu
+
+#define cds_lfs_node_init_rcu_bp       _cds_lfs_node_init_rcu
+#define cds_lfs_init_rcu_bp            _cds_lfs_init_rcu
+#define cds_lfs_push_rcu_bp            _cds_lfs_push_rcu
+#define cds_lfs_pop_rcu_bp             _cds_lfs_pop_rcu
+
+#define cds_lfs_node_init_rcu_memb     _cds_lfs_node_init_rcu
+#define cds_lfs_init_rcu_memb          _cds_lfs_init_rcu
+#define cds_lfs_push_rcu_memb          _cds_lfs_push_rcu
+#define cds_lfs_pop_rcu_memb           _cds_lfs_pop_rcu
+
+#define cds_lfs_node_init_rcu_mb       _cds_lfs_node_init_rcu
+#define cds_lfs_init_rcu_mb            _cds_lfs_init_rcu
+#define cds_lfs_push_rcu_mb            _cds_lfs_push_rcu
+#define cds_lfs_pop_rcu_mb             _cds_lfs_pop_rcu
+
+#define cds_lfs_node_init_rcu_sig      _cds_lfs_node_init_rcu
+#define cds_lfs_init_rcu_sig           _cds_lfs_init_rcu
+#define cds_lfs_push_rcu_sig           _cds_lfs_push_rcu
+#define cds_lfs_pop_rcu_sig            _cds_lfs_pop_rcu
+
+#else /* !_LGPL_SOURCE */
+
+extern void cds_lfs_node_init_rcu(struct cds_lfs_node_rcu *node);
+extern void cds_lfs_init_rcu(struct cds_lfs_stack_rcu *s);
+extern int cds_lfs_push_rcu(struct cds_lfs_stack_rcu *s,
+                       struct cds_lfs_node_rcu *node);
 
 /*
+ * Acts as a RCU reader.
+ *
  * The caller must wait for a grace period to pass before freeing the returned
- * node or modifying the rcu_lfs_node structure.
+ * node or modifying the cds_lfs_node_rcu structure.
  * Returns NULL if stack is empty.
  */
-struct rcu_lfs_node *
-rcu_lfs_pop(struct rcu_lfs_stack *s)
-{
-       for (;;) {
-               struct rcu_lfs_node *head;
-
-               rcu_read_lock();
-               head = rcu_dereference(s->head);
-               if (head) {
-                       struct rcu_lfs_node *next = rcu_dereference(head->next);
-
-                       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;
-               }
-       }
-}
+extern struct cds_lfs_node_rcu *cds_lfs_pop_rcu(struct cds_lfs_stack_rcu *s);
+
+#endif /* !_LGPL_SOURCE */
 
 #ifdef __cplusplus
 }