nat n_nurseries = 0; /* == RtsFlags.ParFlags.nNodes, convenience */
step *nurseries = NULL; /* array of nurseries, >1 only if THREADED_RTS */
+#ifdef THREADED_RTS
/*
* Storage manager mutex: protects all the above state from
* simultaneous access by two STG threads.
*/
-#ifdef THREADED_RTS
Mutex sm_mutex;
+/*
+ * This mutex is used by atomicModifyMutVar# only
+ */
+Mutex atomic_modify_mutvar_mutex;
#endif
+
/*
* Forward references
*/