Index: src/libcfa/concurrency/kernel
===================================================================
--- src/libcfa/concurrency/kernel	(revision fa21ac9d92ef632e6c4267d08a93662032644c8d)
+++ src/libcfa/concurrency/kernel	(revision fda816874a6a323b57c9ce0409b20c6c3ddea4cf)
@@ -28,4 +28,5 @@
 //-----------------------------------------------------------------------------
 // Locks
+bool try_lock( spinlock * );
 void lock( spinlock * );
 void unlock( spinlock * );
@@ -85,4 +86,11 @@
 
 	struct FinishAction finish;
+
+	struct alarm_node_t * preemption_alarm;
+	unsigned int preemption;
+
+	unsigned short disable_preempt_count;
+
+	bool pending_preemption;
 };