X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fuserprog%2Fprocess.c;h=5b50aa53a199e64001302574428091436809aaf8;hb=35d96421c3bdd3911dc679918ae3d81ab7479797;hp=08e78c683e0024af747573e9fb78e48d63aee4e2;hpb=421148a51f97254bd53d8a3d5965f8ea92c36684;p=pintos-anon

diff --git a/src/userprog/process.c b/src/userprog/process.c
index 08e78c6..5b50aa5 100644
--- a/src/userprog/process.c
+++ b/src/userprog/process.c
@@ -82,17 +82,24 @@ execute_thread (void *filename_)
   NOT_REACHED ();
 }
 
-/* Destroys the user address space in T and frees all of its
-   resources. */
+/* Free the current process's resources. */
 void
-process_destroy (struct thread *t)
+process_exit (void)
 {
-  ASSERT (t != thread_current ());
-
-  if (t->pagedir != NULL) 
+  struct thread *cur = thread_current ();
+  uint32_t *pd;
+
+  /* Destroy the current process's page directory and switch back
+     to the kernel-only page directory.  We have to set
+     cur->pagedir to NULL before switching page directories, or a
+     timer interrupt might switch back to the process page
+     directory. */
+  pd = cur->pagedir;
+  if (pd != NULL) 
     {
-      pagedir_destroy (t->pagedir);
-      t->pagedir = NULL; 
+      cur->pagedir = NULL;
+      pagedir_activate (NULL);
+      pagedir_destroy (pd);
     }
 }
 
@@ -103,10 +110,11 @@ process_activate (void)
 {
   struct thread *t = thread_current ();
 
-  /* Activate T's page tables. */
+  /* Activate thread's page tables. */
   pagedir_activate (t->pagedir);
 
-  /* Set T's kernel stack for use in processing interrupts. */
+  /* Set thread's kernel stack for use in processing
+     interrupts. */
   tss_set_esp0 ((uint8_t *) t + PGSIZE);
 }