X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu%2Fref.h;h=e546da567120e086e5773950ac135d510900b4fc;hp=74be50d6bbe4e46d28603ba4cb8de3db2ed7794a;hb=4d0d7cbccec1c35f544f6fee24b762e398a2f0b9;hpb=cd21955a846566b3cd7ca77d58cd3d006f3c533a

diff --git a/urcu/ref.h b/urcu/ref.h
index 74be50d..e546da5 100644
--- a/urcu/ref.h
+++ b/urcu/ref.h
@@ -16,6 +16,8 @@
 
 #include <assert.h>
 #include <stdbool.h>
+#include <limits.h>
+#include <stdlib.h>
 #include <urcu/uatomic.h>
 
 struct urcu_ref {
@@ -32,9 +34,29 @@ static inline void urcu_ref_init(struct urcu_ref *ref)
 	urcu_ref_set(ref, 1);
 }
 
+static inline bool  __attribute__((warn_unused_result))
+		urcu_ref_get_safe(struct urcu_ref *ref)
+{
+	long old, _new, res;
+
+	old = uatomic_read(&ref->refcount);
+	for (;;) {
+		if (old == LONG_MAX) {
+			return false;	/* Failure. */
+		}
+		_new = old + 1;
+		res = uatomic_cmpxchg(&ref->refcount, old, _new);
+		if (res == old) {
+			return true;	/* Success. */
+		}
+		old = res;
+	}
+}
+
 static inline void urcu_ref_get(struct urcu_ref *ref)
 {
-	uatomic_add(&ref->refcount, 1);
+	if (!urcu_ref_get_safe(ref))
+		abort();
 }
 
 static inline void urcu_ref_put(struct urcu_ref *ref,
@@ -53,7 +75,8 @@ static inline void urcu_ref_put(struct urcu_ref *ref,
  * zero. Returns true if the reference is taken, false otherwise. This
  * needs to be used in conjunction with another synchronization
  * technique (e.g.  RCU or mutex) to ensure existence of the reference
- * count.
+ * count. False is also returned in case incrementing the refcount would
+ * result in an overflow.
  */
 static inline bool urcu_ref_get_unless_zero(struct urcu_ref *ref)
 {
@@ -61,7 +84,7 @@ static inline bool urcu_ref_get_unless_zero(struct urcu_ref *ref)
 
 	old = uatomic_read(&ref->refcount);
 	for (;;) {
-		if (old == 0)
+		if (old == 0 || old == LONG_MAX)
 			return false;	/* Failure. */
 		_new = old + 1;
 		res = uatomic_cmpxchg(&ref->refcount, old, _new);