Index: kernel/generic/include/synch/mutex.h
===================================================================
--- kernel/generic/include/synch/mutex.h	(revision 82cbf8c6161e2ff15d39a43b59096447a98acc21)
+++ kernel/generic/include/synch/mutex.h	(revision eca820c68a88b21d4b9fef3a00447516bc3f7684)
@@ -43,10 +43,15 @@
 typedef enum {
 	MUTEX_PASSIVE,
+	MUTEX_RECURSIVE,
 	MUTEX_ACTIVE
 } mutex_type_t;
+
+struct thread;
 
 typedef struct {
 	mutex_type_t type;
 	semaphore_t sem;
+	struct thread *owner;
+	unsigned nesting;
 } mutex_t;