Index: libcfa/src/concurrency/io/setup.cfa
===================================================================
--- libcfa/src/concurrency/io/setup.cfa	(revision 22226e4c0c12d34b6c6883c00f1607a84fce93f5)
+++ libcfa/src/concurrency/io/setup.cfa	(revision a76202de1f5d3940e9f0142dbd9a4e3bb3683a1c)
@@ -214,4 +214,5 @@
 
 		// completion queue
+		cq.lock      = 0;
 		cq.head      = (volatile __u32 *)(((intptr_t)cq.ring_ptr) + params.cq_off.head);
 		cq.tail      = (volatile __u32 *)(((intptr_t)cq.ring_ptr) + params.cq_off.tail);
Index: libcfa/src/concurrency/io/types.hfa
===================================================================
--- libcfa/src/concurrency/io/types.hfa	(revision 22226e4c0c12d34b6c6883c00f1607a84fce93f5)
+++ libcfa/src/concurrency/io/types.hfa	(revision a76202de1f5d3940e9f0142dbd9a4e3bb3683a1c)
@@ -78,4 +78,6 @@
 
 	struct __cmp_ring_t {
+		volatile bool lock;
+
 		// Head and tail of the ring
 		volatile __u32 * head;