vt: Perform safe console erase only once (4b4ecd9c) · Commits · 戴 / test

Commit ("tty: Clean console safely") added code to clear both the scrollback buffer and the screen with "\e[3J", then execution falls through into the code to simply clear the screen. This means scr_memsetw() and the console driver update callback are called twice on the whole screen buffer. Let's reorganize the code so the same work is not performed twice needlessly. Signed-off-by:

Nicolas Pitre <nico@linaro.org> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/vt/vt.c

+7 −9

Original line number	Diff line number	Diff line
		@@ -1178,15 +1178,8 @@ 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: /* erase scroll-back buffer (and whole display) */
		scr_memsetw(vc->vc_screenbuf, vc->vc_video_erase_char,
		vc->vc_screenbuf_size);
		flush_scrollback(vc);
		set_origin(vc);
		if (con_is_visible(vc))
		update_screen(vc);
		/* fall through */
		case 2: /* erase whole display */
		case 3: /* (and scrollback buffer later) */
		count = vc->vc_cols * vc->vc_rows;
		start = (unsigned short *)vc->vc_origin;
		break;
		@@ -1194,7 +1187,12 @@ static void csi_J(struct vc_data *vc, int vpar)
		return;
		}
		scr_memsetw(start, vc->vc_video_erase_char, 2 * count);
		if (con_should_update(vc))
		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);
		vc->vc_need_wrap = 0;
		}

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