4.19-stable review patch. If anyone has any objections, please let me know.
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From: Nicolas Pitre nicolas.pitre@linaro.org
commit a6dbe442755999960ca54a9b8ecfd9606be0ea75 upstream.
Commit 4b4ecd9cb853 ("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: 4b4ecd9cb853 ("vt: Perform safe console erase only once") Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/tty/vt/vt.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)
--- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -935,8 +935,11 @@ static void flush_scrollback(struct vc_d { 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); }
/* @@ -1506,8 +1509,10 @@ static void csi_J(struct vc_data *vc, in 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; @@ -1516,13 +1521,7 @@ static void csi_J(struct vc_data *vc, in 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; }