diff --git a/kern/include/synch.h b/kern/include/synch.h
index c80c62d..ac5f730 100644
--- a/kern/include/synch.h
+++ b/kern/include/synch.h
@@ -127,6 +127,8 @@ struct cv {
         char *cv_name;
         // add what you need here
         // (don't forget to mark things volatile as needed)
+        struct wchan *wchan;
+        struct spinlock slk;
 };
 
 struct cv *cv_create(const char *name);
diff --git a/kern/thread/synch.c b/kern/thread/synch.c
index bc64eac..d5d4e3d 100644
--- a/kern/thread/synch.c
+++ b/kern/thread/synch.c
@@ -227,7 +227,7 @@ lock_release(struct lock *lock)
 #elif OPT_WCHANLOCK
         spinlock_acquire(&lock->slk);
         lock->owner = NULL;
-	wchan_wakeall(lock->wchan, &lock->slk);
+	wchan_wakeone(lock->wchan, &lock->slk);
         spinlock_release(&lock->slk);
 #else
         lock->owner = NULL;
@@ -272,8 +272,15 @@ cv_create(const char *name)
                 return NULL;
         }
 
-        // add stuff here as needed
-
+#if OPT_WCHANLOCK
+        cv->wchan = wchan_create(name);
+        if (cv->wchan == NULL) {
+                kfree(cv->cv_name);
+                kfree(cv);
+                return NULL;
+        }
+        spinlock_init(&cv->slk);
+#endif
         return cv;
 }
 
@@ -282,8 +289,10 @@ cv_destroy(struct cv *cv)
 {
         KASSERT(cv != NULL);
 
-        // add stuff here as needed
-
+#if OPT_WCHANLOCK
+        spinlock_cleanup(&cv->slk);
+        wchan_destroy(cv->wchan);
+#endif
         kfree(cv->cv_name);
         kfree(cv);
 }
@@ -291,23 +300,50 @@ cv_destroy(struct cv *cv)
 void
 cv_wait(struct cv *cv, struct lock *lock)
 {
-        // Write this
+#if OPT_WCHANLOCK
+        KASSERT(cv != NULL);
+        KASSERT(lock_do_i_hold(lock));
+
+        spinlock_acquire(&cv->slk);
+
+        lock_release(lock);
+        wchan_sleep(cv->wchan,&cv->slk);
+        spinlock_release(&cv->slk);
+        lock_acquire(lock);
+#else
         (void)cv;    // suppress warning until code gets written
         (void)lock;  // suppress warning until code gets written
+#endif
 }
 
 void
 cv_signal(struct cv *cv, struct lock *lock)
 {
-        // Write this
+#if OPT_WCHANLOCK
+        KASSERT(cv != NULL);
+        KASSERT(lock_do_i_hold(lock));
+
+        spinlock_acquire(&cv->slk);
+        wchan_wakeone(cv->wchan, &cv->slk);
+        spinlock_release(&cv->slk);
+#else
 	(void)cv;    // suppress warning until code gets written
 	(void)lock;  // suppress warning until code gets written
+#endif
 }
 
 void
 cv_broadcast(struct cv *cv, struct lock *lock)
 {
-	// Write this
+#if OPT_WCHANLOCK
+        KASSERT(cv != NULL);
+	KASSERT(lock_do_i_hold(lock));
+
+        spinlock_acquire(&cv->slk);
+        wchan_wakeall(cv->wchan, &cv->slk);
+        spinlock_release(&cv->slk);
+#else
 	(void)cv;    // suppress warning until code gets written
 	(void)lock;  // suppress warning until code gets written
+#endif
 }