tty: vt: cache row count in con_scroll()

It's used on few places, so make the code easier to follow by caching
the subtraction result.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230112080136.4929-11-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index e3f62ff..71f1824 100644 (file)
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -561,10 +561,11 @@ static void con_scroll(struct vc_data *vc, unsigned int top,
                       unsigned int bottom, enum con_scroll dir,
                       unsigned int nr)
 {
+       unsigned int rows = bottom - top;
        u16 *clear, *dst, *src;
 
        if (top + nr >= bottom)
-               nr = bottom - top - 1;
+               nr = rows - 1;
        if (bottom > vc->vc_rows || top >= bottom || nr < 1)
                return;
 
@@ -577,10 +578,10 @@ static void con_scroll(struct vc_data *vc, unsigned int top,
        dst = (u16 *)(vc->vc_origin + vc->vc_size_row * (top + nr));
 
        if (dir == SM_UP) {
-               clear = src + (bottom - top - nr) * vc->vc_cols;
+               clear = src + (rows - nr) * vc->vc_cols;
                swap(src, dst);
        }
-       scr_memmovew(dst, src, (bottom - top - nr) * vc->vc_size_row);
+       scr_memmovew(dst, src, (rows - nr) * vc->vc_size_row);
        scr_memsetw(clear, vc->vc_video_erase_char, vc->vc_size_row * nr);
 }