If the specified thread is not runnable, not run it.

2 files changed, 7 insertions, 3 deletions

diff --git a/viengoos/scheduler.c b/viengoos/scheduler.c
index 210bdc7..1a50618 100644
--- a/viengoos/scheduler.c
+++ b/viengoos/scheduler.c
@@ -116,19 +116,23 @@ schedule (struct thread *thread)
 	}
     }
 
-  if (likely (! thread && current_thread))
+  if (likely (current_thread)
+      && (likely (! thread) || thread == current_thread))
     /* We don't have to switch and the current thread hasn't exceed
        its allowance.  Keep it on the CPU.  */
     return;
 
   if (thread)
-    /* The caller specified a thread to run.  Use it.  */
+    /* The caller specified a different thread to run.  Use it.  */
     {
       assert (thread->state == THREAD_RUNNABLE
 	      || thread->state == THREAD_SUSPENDED);
 
       if (thread->state == THREAD_RUNNABLE)
 	thread_remove_from_run_queue (thread);
+      else
+	/* The specified thread is not runnable.  */
+	thread = NULL;
     }
 
   if (! thread)
diff --git a/viengoos/scheduler.h b/viengoos/scheduler.h
index 308927a..7bd1e0e 100644
--- a/viengoos/scheduler.h
+++ b/viengoos/scheduler.h
@@ -27,7 +27,7 @@ extern struct thread *current_thread;
 
 /* Schedule thread THREAD to run next.  If thread is NULL, selects a
    new thread.  */
-extern void thread_schedule (struct thread *thread);
+extern void schedule (struct thread *thread);
 
 extern void thread_make_runnable (struct thread *thread);