Index: kernel/generic/include/synch/mutex.h
===================================================================
--- kernel/generic/include/synch/mutex.h	(revision 83dab11c929c1a48613d4dc70ed8ca9113463484)
+++ kernel/generic/include/synch/mutex.h	(revision c1f68b0b464a5358c1ef12ca16a6a4fb18b3ad5a)
@@ -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;