Fix: auto-resize hash table destroy deadlock

[urcu.git] / include / urcu / rculfhash.h

diff --git a/include/urcu/rculfhash.h b/include/urcu/rculfhash.h
index 292fc0d9fc9c0fadcdd370864fe6ca249140a298..fbd33cc3ff346c704ae264d724563977a5ff473f 100644 (file)
--- a/include/urcu/rculfhash.h
+++ b/include/urcu/rculfhash.h
@@ -27,6 +27,7 @@
  * _after_ including your URCU flavor.
  */
 
+#include <urcu/config.h>
 #include <stdint.h>
 #include <pthread.h>
 #include <urcu/compiler.h>
@@ -35,6 +36,8 @@
 extern "C" {
 #endif
 
+struct cds_lfht;
+
 /*
  * cds_lfht_node: Contains the next pointers and reverse-hash
  * value required for lookup and traversal of the hash table.
@@ -65,6 +68,18 @@ struct cds_lfht_node {
 /* cds_lfht_iter: Used to track state while traversing a hash chain. */
 struct cds_lfht_iter {
        struct cds_lfht_node *node, *next;
+       /*
+        * For debugging purposes, build both API users and rculfhash
+        * library with CDS_LFHT_ITER_DEBUG defined. This enables extra
+        * consistency checks for calls to a cds_lfht_next() or
+        * cds_lfht_next_duplicate() after the iterator has been
+        * re-purposed to iterate on a different hash table. This is a
+        * common programming mistake when performing hash table lookup
+        * nested in a hash table traversal.
+        */
+#ifdef CONFIG_CDS_LFHT_ITER_DEBUG
+       struct cds_lfht *lfht;
+#endif
 };
 
 static inline
@@ -73,7 +88,6 @@ struct cds_lfht_node *cds_lfht_iter_get_node(struct cds_lfht_iter *iter)
        return iter->node;
 }
 
-struct cds_lfht;
 struct rcu_flavor_struct;
 
 /*
@@ -91,10 +105,20 @@ typedef int (*cds_lfht_match_fct)(struct cds_lfht_node *node, const void *key);
  * (detection of memory corruption).
  */
 static inline
-void cds_lfht_node_init(struct cds_lfht_node *node)
+void cds_lfht_node_init(struct cds_lfht_node *node __attribute__((unused)))
 {
 }
 
+/*
+ * cds_lfht_node_init_deleted - initialize a hash table node to "removed" state
+ * @node: the node to initialize.
+ *
+ * Initialize the node such that cds_lfht_is_node_deleted() can be used
+ * on the node before it is added to a hash table.
+ */
+extern
+void cds_lfht_node_init_deleted(struct cds_lfht_node *node);
+
 /*
  * Hash table creation flags.
  */
@@ -223,16 +247,16 @@ struct cds_lfht *cds_lfht_new(unsigned long init_size,
  *
  * Return 0 on success, negative error value on error.
 
+ * Threads calling this API need to be registered RCU read-side threads.
+ *
  * Prior to liburcu 0.10:
- * - Threads calling this API need to be registered RCU read-side
- *   threads.
  * - cds_lfht_destroy should *not* be called from a RCU read-side
  *   critical section. It should *not* be called from a call_rcu thread
  *   context neither.
  *
  * Starting from liburcu 0.10, rculfhash implements its own worker
- * thread to handle resize operations, which removes RCU requirements on
- * cds_lfht_destroy.
+ * thread to handle resize operations, which removes the above RCU
+ * read-side critical section requirement on cds_lfht_destroy.
  */
 extern
 int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
@@ -485,7 +509,7 @@ int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node);
  * This function does not issue any memory barrier.
  */
 extern
-int cds_lfht_is_node_deleted(struct cds_lfht_node *node);
+int cds_lfht_is_node_deleted(const struct cds_lfht_node *node);
 
 /*
  * cds_lfht_resize - Force a hash table resize