Update process_wait skeleton to loop infinitely for testing purposes

src/userprog/process.c

@@ -17,6 +17,7 @@
 #include "threads/palloc.h"
 #include "threads/thread.h"
 #include "threads/vaddr.h"
+#include "threads/synch.h"
 
 static thread_func start_process NO_RETURN;
 static bool load (const char *cmdline, void (**eip) (void), void **esp);
@@ -88,7 +89,12 @@ start_process (void *file_name_)
 int
 process_wait (tid_t child_tid UNUSED) 
 {
-  return -1;
+  /* TODO: Implement correct process waiting behaviour.
+    Currently an infinite loop for testing purposes. */
+  while (1)
+    {
+      barrier ();
+    }
 }
 
 /* Free the current process's resources. */