tty: vt, compute vc offsets in advance

Only improves readability, no functional changes.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/vt/vt.c

@@ -4283,6 +4283,9 @@ void vc_scrolldelta_helper(struct vc_data *c, int lines,
 		unsigned int rolled_over, void *base, unsigned int size)
 {
 	unsigned long ubase = (unsigned long)base;
+	ptrdiff_t scr_end = (void *)c->vc_scr_end - base;
+	ptrdiff_t vorigin = (void *)c->vc_visible_origin - base;
+	ptrdiff_t origin = (void *)c->vc_origin - base;
 	int margin = c->vc_size_row * 4;
 	int ul, we, p, st;
 
@@ -4293,17 +4296,16 @@ void vc_scrolldelta_helper(struct vc_data *c, int lines,
 	}
 
 	/* Do we have already enough to allow jumping from 0 to the end? */
-	if (rolled_over > (c->vc_scr_end - ubase) + margin) {
-		ul = c->vc_scr_end - ubase;
+	if (rolled_over > scr_end + margin) {
+		ul = scr_end;
 		we = rolled_over + c->vc_size_row;
 	} else {
 		ul = 0;
 		we = size;
 	}
 
-	p = (c->vc_visible_origin - ubase - ul + we) % we +
-		lines * c->vc_size_row;
-	st = (c->vc_origin - ubase - ul + we) % we;
+	p = (vorigin - ul + we) % we + lines * c->vc_size_row;
+	st = (origin - ul + we) % we;
 
 	/* Only a little piece would be left? Show all incl. the piece! */
 	if (st < 2 * margin)