1 files changed, 51 insertions, 0 deletions

diff --git a/pintos-progos/tests/threads/priority-donate-lower.c b/pintos-progos/tests/threads/priority-donate-lower.c
new file mode 100644
index 0000000..4965d75
--- /dev/null
+++ b/pintos-progos/tests/threads/priority-donate-lower.c
@@ -0,0 +1,51 @@
+/* The main thread acquires a lock.  Then it creates a
+   higher-priority thread that blocks acquiring the lock, causing
+   it to donate their priorities to the main thread.  The main
+   thread attempts to lower its priority, which should not take
+   effect until the donation is released. */
+
+#include <stdio.h>
+#include "tests/threads/tests.h"
+#include "threads/init.h"
+#include "threads/synch.h"
+#include "threads/thread.h"
+
+static thread_func acquire_thread_func;
+
+void
+test_priority_donate_lower (void) 
+{
+  struct lock lock;
+
+  /* This test does not work with the MLFQS. */
+  ASSERT (!thread_mlfqs);
+
+  /* Make sure our priority is the default. */
+  ASSERT (thread_get_priority () == PRI_DEFAULT);
+
+  lock_init (&lock);
+  lock_acquire (&lock);
+  thread_create ("acquire", PRI_DEFAULT + 10, acquire_thread_func, &lock);
+  msg ("Main thread should have priority %d.  Actual priority: %d.",
+       PRI_DEFAULT + 10, thread_get_priority ());
+
+  msg ("Lowering base priority...");
+  thread_set_priority (PRI_DEFAULT - 10);
+  msg ("Main thread should have priority %d.  Actual priority: %d.",
+       PRI_DEFAULT + 10, thread_get_priority ());
+  lock_release (&lock);
+  msg ("acquire must already have finished.");
+  msg ("Main thread should have priority %d.  Actual priority: %d.",
+       PRI_DEFAULT - 10, thread_get_priority ());
+}
+
+static void
+acquire_thread_func (void *lock_) 
+{
+  struct lock *lock = lock_;
+
+  lock_acquire (lock);
+  msg ("acquire: got the lock");
+  lock_release (lock);
+  msg ("acquire: done");
+}