X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Flib%2Fkernel%2Flist.c;h=ba4fae68bfe51919dc30a43007f634c2fa8d0474;hb=0ec49949304b13ff22287d7d9e3dcb05090c61a4;hp=1227d6b6b5679f5c2708af027e0a69241684d613;hpb=62e4f39fca59b2ff84fc0ae8e74240cb9941b3ec;p=pintos-anon

diff --git a/src/lib/kernel/list.c b/src/lib/kernel/list.c
index 1227d6b..ba4fae6 100644
--- a/src/lib/kernel/list.c
+++ b/src/lib/kernel/list.c
@@ -216,15 +216,15 @@ list_push_back (struct list *list, list_elem *elem)
   list_insert (list_end (list), elem);
 }
 
-/* Removes ELEM from its list.  Undefined behavior if ELEM is not
-   in a list. */
+/* Removes ELEM from its list and returns the element that
+   followed it.  Undefined behavior if ELEM is not in a list.  */
 list_elem *
 list_remove (list_elem *elem)
 {
   ASSERT (is_interior (elem));
   elem->prev->next = elem->next;
   elem->next->prev = elem->prev;
-  return elem;
+  return elem->next;
 }
 
 /* Removes the front element from LIST and returns it.
@@ -232,8 +232,9 @@ list_remove (list_elem *elem)
 list_elem *
 list_pop_front (struct list *list)
 {
-  ASSERT (list != NULL);
-  return list_remove (list_front (list));
+  list_elem *front = list_front (list);
+  list_remove (front);
+  return front;
 }
 
 /* Removes the back element from LIST and returns it.
@@ -241,8 +242,9 @@ list_pop_front (struct list *list)
 list_elem *
 list_pop_back (struct list *list)
 {
-  ASSERT (list != NULL);
-  return list_remove (list_back (list));
+  list_elem *back = list_back (list);
+  list_remove (back);
+  return back;
 }
 
 /* Returns the front element in LIST.