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Commit b05581b8 authored by Nicolas Pitre's avatar Nicolas Pitre Committed by Greg Kroah-Hartman
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vt: perform safe console erase in the right order 



commit a6dbe442755999960ca54a9b8ecfd9606be0ea75 upstream.

Commit 4b4ecd9c ("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: default avatarMatthew Whitehead <tedheadster@gmail.com>
Signed-off-by: default avatarNicolas Pitre <nico@linaro.org>
Tested-by: default avatarMatthew Whitehead <tedheadster@gmail.com>
Fixes: 4b4ecd9c ("vt: Perform safe console erase only once")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2ca85aac

drivers/tty/vt/vt.c

+7 −8
Original line number Diff line number Diff line
@@ -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);

}



/*
@@ -1506,8 +1509,10 @@ 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;
@@ -1516,13 +1521,7 @@ 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;

}