1 files changed, 22 insertions, 12 deletions

diff --git a/src/buffer.c b/src/buffer.c
index 75cb470af8d..f8c57a74b4e 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -1,6 +1,6 @@
 /* Buffer manipulation primitives for GNU Emacs.
 
-Copyright (C) 1985-1989, 1993-1995, 1997-2017 Free Software Foundation,
+Copyright (C) 1985-1989, 1993-1995, 1997-2018 Free Software Foundation,
 Inc.
 
 This file is part of GNU Emacs.
@@ -1320,7 +1320,12 @@ menu bar menus and the frame title.  */)
 DEFUN ("set-buffer-modified-p", Fset_buffer_modified_p, Sset_buffer_modified_p,
        1, 1, 0,
        doc: /* Mark current buffer as modified or unmodified according to FLAG.
-A non-nil FLAG means mark the buffer modified.  */)
+A non-nil FLAG means mark the buffer modified.
+In addition, this function unconditionally forces redisplay of the
+mode lines of the windows that display the current buffer, and also
+locks or unlocks the file visited by the buffer, depending on whether
+the function's argument is non-nil, but only if both `buffer-file-name'
+and `buffer-file-truename' are non-nil.  */)
   (Lisp_Object flag)
 {
   Frestore_buffer_modified_p (flag);
@@ -1341,12 +1346,14 @@ A non-nil FLAG means mark the buffer modified.  */)
 
 DEFUN ("restore-buffer-modified-p", Frestore_buffer_modified_p,
        Srestore_buffer_modified_p, 1, 1, 0,
-       doc: /* Like `set-buffer-modified-p', with a difference concerning redisplay.
+       doc: /* Like `set-buffer-modified-p', but doesn't redisplay buffer's mode line.
+This function also locks and unlocks the file visited by the buffer,
+if both `buffer-file-truename' and `buffer-file-name' are non-nil.
+
 It is not ensured that mode lines will be updated to show the modified
 state of the current buffer.  Use with care.  */)
   (Lisp_Object flag)
 {
-  Lisp_Object fn;
 
   /* If buffer becoming modified, lock the file.
      If buffer becoming unmodified, unlock the file.  */
@@ -1355,15 +1362,18 @@ state of the current buffer.  Use with care.  */)
     ? current_buffer->base_buffer
     : current_buffer;
 
-  fn = BVAR (b, file_truename);
-  /* Test buffer-file-name so that binding it to nil is effective.  */
-  if (!NILP (fn) && ! NILP (BVAR (b, filename)))
+  if (!inhibit_modification_hooks)
     {
-      bool already = SAVE_MODIFF < MODIFF;
-      if (!already && !NILP (flag))
-        lock_file (fn);
-      else if (already && NILP (flag))
-        unlock_file (fn);
+      Lisp_Object fn = BVAR (b, file_truename);
+      /* Test buffer-file-name so that binding it to nil is effective.  */
+      if (!NILP (fn) && ! NILP (BVAR (b, filename)))
+        {
+          bool already = SAVE_MODIFF < MODIFF;
+          if (!already && !NILP (flag))
+            lock_file (fn);
+          else if (already && NILP (flag))
+            unlock_file (fn);
+        }
     }
 
   /* Here we have a problem.  SAVE_MODIFF is used here to encode