Add rcu_assign_pointer

[urcu.git] / urcu.h

diff --git a/urcu.h b/urcu.h
index 01a4c6857d7e6fd31668dec57615be03e94ccc91..27695d495aeeb6388b121a099183949cbbdbac06 100644 (file)
--- a/urcu.h
+++ b/urcu.h
@@ -169,7 +169,29 @@ static inline void rcu_read_unlock(void)
        debug_yield_read();
 }
 
+/**
+ * rcu_assign_pointer - assign (publicize) a pointer to a newly
+ * initialized structure that will be dereferenced by RCU read-side
+ * critical sections.  Returns the value assigned.
+ *
+ * Inserts memory barriers on architectures that require them
+ * (pretty much all of them other than x86), and also prevents
+ * the compiler from reordering the code that initializes the
+ * structure after the pointer assignment.  More importantly, this
+ * call documents which pointers will be dereferenced by RCU read-side
+ * code.
+ */
+
+#define rcu_assign_pointer(p, v) \
+       ({ \
+               if (!__builtin_constant_p(v) || \
+                   ((v) != NULL)) \
+                       wmb(); \
+               (p) = (v); \
+       })
+
 extern void *urcu_publish_content(void **ptr, void *new);
+extern void synchronize_rcu(void);
 
 /*
  * Reader thread registration.