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vt: perform safe console erase in the right order 

Commit 4b4ecd9cb8 ("vt: Perform safe console erase only once") removed
what appeared to be an extra call to scr_memsetw(). This missed the fact
that set_origin() must be called before clearing the screen otherwise
old screen content gets restored on the screen when using vgacon. Let's
fix that by moving all the scrollback handling to flush_scrollback()
where it logically belongs, and invoking it before the actual screen
clearing in csi_J(), making the code simpler in the end.

Reported-by: Matthew Whitehead <tedheadster@gmail.com>
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Matthew Whitehead <tedheadster@gmail.com>
Fixes: 4b4ecd9cb8 ("vt: Perform safe console erase only once")
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nicolas Pitre 2019-02-11 19:36:41 -05:00 committed by Greg Kroah-Hartman
parent c392ed4642
commit a6dbe44275
1 changed files with 7 additions and 8 deletions
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15
drivers/tty/vt/vt.c
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@ -935,8 +935,11 @@ static void flush_scrollback(struct vc_data *vc)
{
WARN_CONSOLE_UNLOCKED();
set_origin(vc);
if (vc->vc_sw->con_flush_scrollback)
vc->vc_sw->con_flush_scrollback(vc);
else
vc->vc_sw->con_switch(vc);
}
/*
@ -1505,8 +1508,10 @@ static void csi_J(struct vc_data *vc, int vpar)
count = ((vc->vc_pos - vc->vc_origin) >> 1) + 1;
start = (unsigned short *)vc->vc_origin;
break;
case 3: /* include scrollback */
flush_scrollback(vc);
/* fallthrough */
case 2: /* erase whole display */
case 3: /* (and scrollback buffer later) */
vc_uniscr_clear_lines(vc, 0, vc->vc_rows);
count = vc->vc_cols * vc->vc_rows;
start = (unsigned short *)vc->vc_origin;
@ -1515,13 +1520,7 @@ static void csi_J(struct vc_data *vc, int vpar)
return;
}
scr_memsetw(start, vc->vc_video_erase_char, 2 * count);
if (vpar == 3) {
set_origin(vc);
flush_scrollback(vc);
if (con_is_visible(vc))
update_screen(vc);
} else if (con_should_update(vc))
do_update_region(vc, (unsigned long) start, count);
update_region(vc, (unsigned long) start, count);
vc->vc_need_wrap = 0;
}