Fix: add missing destroy functions to queues/stack APIs

[urcu.git] / urcu / static / lfstack.h

diff --git a/urcu/static/lfstack.h b/urcu/static/lfstack.h
index 63af91adf301918b0331eb3cf55c0c52c5f9711f..05d0bb478b8b169a03864272810d1b5c76bfa4f8 100644 (file)
--- a/urcu/static/lfstack.h
+++ b/urcu/static/lfstack.h
@@ -66,7 +66,8 @@ void _cds_lfs_node_init(struct cds_lfs_node *node)
 }
 
 /*
- * cds_lfs_init: initialize lock-free stack.
+ * cds_lfs_init: initialize lock-free stack (with lock). Pair with
+ * cds_lfs_destroy().
  */
 static inline
 void _cds_lfs_init(struct cds_lfs_stack *s)
@@ -79,7 +80,19 @@ void _cds_lfs_init(struct cds_lfs_stack *s)
 }
 
 /*
- * ___cds_lfs_init: initialize lock-free stack.
+ * cds_lfs_destroy: destroy lock-free stack (with lock). Pair with
+ * cds_lfs_init().
+ */
+static inline
+void _cds_lfs_destroy(struct cds_lfs_stack *s)
+{
+        int ret = pthread_mutex_destroy(&s->lock);
+       assert(!ret);
+}
+
+/*
+ * ___cds_lfs_init: initialize lock-free stack (without lock).
+ * Don't pair with any destroy function.
  */
 static inline
 void ___cds_lfs_init(struct __cds_lfs_stack *s)
@@ -158,7 +171,7 @@ bool _cds_lfs_push(cds_lfs_stack_ptr_t u_s,
                if (old_head == head)
                        break;
        }
-       return ___cds_lfs_empty_head(head);
+       return !___cds_lfs_empty_head(head);
 }
 
 /*
@@ -169,9 +182,13 @@ bool _cds_lfs_push(cds_lfs_stack_ptr_t u_s,
  * __cds_lfs_pop needs to be synchronized using one of the following
  * techniques:
  *
- * 1) Calling __cds_lfs_pop under rcu read lock critical section. The
- *    caller must wait for a grace period to pass before freeing the
- *    returned node or modifying the cds_lfs_node structure.
+ * 1) Calling __cds_lfs_pop under rcu read lock critical section.
+ *    Both __cds_lfs_pop and __cds_lfs_pop_all callers must wait for a
+ *    grace period to pass before freeing the returned node or pushing
+ *    the node back into the stack. It is valid to overwrite the content
+ *    of cds_lfs_node immediately after __cds_lfs_pop and
+ *    __cds_lfs_pop_all. No RCU read-side critical section is needed
+ *    around __cds_lfs_pop_all.
  * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop
  *    and __cds_lfs_pop_all callers.
  * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
@@ -213,10 +230,12 @@ struct cds_lfs_node *___cds_lfs_pop(cds_lfs_stack_ptr_t u_s)
  * matching the technique used to synchronize __cds_lfs_pop:
  *
  * 1) If __cds_lfs_pop is called under rcu read lock critical section,
- *    both __cds_lfs_pop and cds_lfs_pop_all callers must wait for a
- *    grace period to pass before freeing the returned node or modifying
- *    the cds_lfs_node structure. However, no RCU read-side critical
- *    section is needed around __cds_lfs_pop_all.
+ *    both __cds_lfs_pop and __cds_lfs_pop_all callers must wait for a
+ *    grace period to pass before freeing the returned node or pushing
+ *    the node back into the stack. It is valid to overwrite the content
+ *    of cds_lfs_node immediately after __cds_lfs_pop and
+ *    __cds_lfs_pop_all. No RCU read-side critical section is needed
+ *    around __cds_lfs_pop_all.
  * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop and
  *    __cds_lfs_pop_all callers.
  * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and