vt: perform safe console erase in the right order (a6dbe442) · Commits · 戴 / test

Commit ("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: ("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

+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);
		}

		/*
		@@ -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;
		}

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