From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:35170 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755548AbeD3T17 (ORCPT ); Mon, 30 Apr 2018 15:27:59 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Marc Zyngier Subject: [PATCH 4.16 019/113] serial: mvebu-uart: Fix local flags handling on termios update Date: Mon, 30 Apr 2018 12:23:50 -0700 Message-Id: <20180430184015.892092940@linuxfoundation.org> In-Reply-To: <20180430184015.043892819@linuxfoundation.org> References: <20180430184015.043892819@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Marc Zyngier commit 46c6975a1fd9794ed979565235d24b2f5004e014 upstream. Commit 68a0db1d7da2 reworked the baud rate selection, but also added a (not so) subtle change in the way the local flags (c_lflag in the termios structure) are handled, forcing the new flags to always be the same as the old ones. The reason for that particular change is both obscure and undocumented. It also completely breaks userspace. Something as trivial as getty is unusable: Debian GNU/Linux 9 sy-borg ttyMV0 sy-borg login: root root [timeout] Debian GNU/Linux 9 sy-borg ttyMV0 which is quite obvious in retrospect: getty cannot get in control of the echo mode, is stuck in canonical mode, and times out without ever seeing anything valid. It also begs the question of how this change was ever tested. The fix is pretty obvious: stop messing with c_lflag, and the world will be a happier place. Cc: stable@vger.kernel.org # 4.15+ Fixes: 68a0db1d7da2 ("serial: mvebu-uart: add function to change baudrate") Signed-off-by: Marc Zyngier Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/mvebu-uart.c | 1 - 1 file changed, 1 deletion(-) --- a/drivers/tty/serial/mvebu-uart.c +++ b/drivers/tty/serial/mvebu-uart.c @@ -495,7 +495,6 @@ static void mvebu_uart_set_termios(struc termios->c_iflag |= old->c_iflag & ~(INPCK | IGNPAR); termios->c_cflag &= CREAD | CBAUD; termios->c_cflag |= old->c_cflag & ~(CREAD | CBAUD); - termios->c_lflag = old->c_lflag; } spin_unlock_irqrestore(&port->lock, flags);