| Message ID | n58o097s-s20p-4222-nqo5-2qp26843rs35@onlyvoer.pbz |
|---|---|
| State | New |
| Headers | show |
| Series | vt: remove redundant condition from redraw_screen() | expand |
On Fri, 23 May 2025, Nicolas Pitre wrote: > Given !con_is_visible(vc) is the equivalent of *vc->vc_display_fg != vc > we have: > > struct vc_data *old_vc = vc_cons[fg_console].d; > if (old_vc == vc) > return; > *vc->vc_display_fg = vc; > if (*vc->vc_display_fg != old_vc) /* !con_is_visible(old_vc) */ > ... Please disregard this patch. Obviously the last if substitution should rather be: if (*old_vcvc->vc_display_fg != old_vc) and there is no guarantee that vc->vc_display_fg and old_vc->vc_display_fg have the same value. Nicolas
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index ed39d9cb4432..af5186d2c219 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -946,10 +946,8 @@ void redraw_screen(struct vc_data *vc, int is_switch) *vc->vc_display_fg = vc; fg_console = vc->vc_num; hide_cursor(old_vc); - if (!con_is_visible(old_vc)) { - save_screen(old_vc); - set_origin(old_vc); - } + save_screen(old_vc); + set_origin(old_vc); if (tty0dev) sysfs_notify(&tty0dev->kobj, NULL, "active"); } else {
Given !con_is_visible(vc) is the equivalent of *vc->vc_display_fg != vc we have: struct vc_data *old_vc = vc_cons[fg_console].d; if (old_vc == vc) return; *vc->vc_display_fg = vc; if (*vc->vc_display_fg != old_vc) /* !con_is_visible(old_vc) */ ... Therefore the last if condition is always true. Signed-off-by: Nicolas Pitre <npitre@baylibre.com>