Update implementation of thread set priority to account for donations, w/ T

src/threads/thread.c

@@ -370,21 +370,35 @@ priority_more (const struct list_elem *a_, const struct list_elem *b_,
   return a->priority > b->priority;
 }
 
-/* Sets the current thread's priority to NEW_PRIORITY. */
+/* Sets the current thread's base priority to new_base_priority.
+   Updates the current thread's effective priority if necessary. */
 void
-thread_set_priority (int new_priority) 
+thread_set_priority (int new_base_priority)
 {
-  ASSERT (new_priority >= PRI_MIN);
-  ASSERT (new_priority <= PRI_MAX);
+  ASSERT (new_base_priority >= PRI_MIN);
+  ASSERT (new_base_priority <= PRI_MAX);
 
+  struct thread *t = thread_current ();
+
+  int old_base_priority = t->base_priority;
   int old_priority = thread_get_priority ();
-  if (new_priority == old_priority)
+  if (new_base_priority == old_base_priority)
     return;
 
-  thread_current ()->priority = new_priority;
 
-  if (new_priority < old_priority && !list_empty (&ready_list))
-    thread_yield ();
+  t->base_priority = new_base_priority;
+  t->priority = new_base_priority;
+
+  if (!list_empty (&t->donors_list) && new_base_priority < old_priority) {
+    int max_donated_priority =
+      list_entry (list_max (&t->donors_list, priority_more, NULL),
+                  struct thread, donor_elem)->priority;
+
+    if(new_base_priority < max_donated_priority)
+      t->priority = new_base_priority;
+  }
+
+  thread_yield ();
 }
 
 /* Returns the current thread's priority. */