Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754829AbaGKQP5 (ORCPT ); Fri, 11 Jul 2014 12:15:57 -0400 Received: from mailout32.mail01.mtsvc.net ([216.70.64.70]:47880 "EHLO n23.mail01.mtsvc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754807AbaGKQPz (ORCPT ); Fri, 11 Jul 2014 12:15:55 -0400 Message-ID: <53C00DB5.600@hurleysoftware.com> Date: Fri, 11 Jul 2014 12:15:49 -0400 From: Peter Hurley User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Greg Kroah-Hartman CC: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, One Thousand Gnomes Subject: Re: [PATCH tty-next 21/22] serial: core: Remove superfluous ldisc flush from uart_close() References: <1402924639-5164-1-git-send-email-peter@hurleysoftware.com> <1402924639-5164-22-git-send-email-peter@hurleysoftware.com> In-Reply-To: <1402924639-5164-22-git-send-email-peter@hurleysoftware.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated-User: 990527 peter@hurleysoftware.com X-MT-ID: 8FA290C2A27252AACF65DBC4A42F3CE3735FB2A4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/16/2014 09:17 AM, Peter Hurley wrote: > The tty_ldisc_flush() after port hardware shutdown is unnecessary; > the ldisc flush was just performed before the hardware shutdown > in tty_port_close_start() and the ldisc will be released when > uart_close() returns (because the last port close implies the > last tty close). > > Signed-off-by: Peter Hurley > --- > drivers/tty/serial/serial_core.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c > index 212ee07..15212d7 100644 > --- a/drivers/tty/serial/serial_core.c > +++ b/drivers/tty/serial/serial_core.c > @@ -1351,9 +1351,6 @@ static void uart_close(struct tty_struct *tty, struct file *filp) > > mutex_lock(&port->mutex); > uart_shutdown(tty, state); > - > - tty_ldisc_flush(tty); > - This isn't exactly correct. There is a small window of time between the ldisc flush being performed in tty_port_close_start() and the subsequent stop_rx() in uart_close(). This might allow for data to be received, and a racing tty reopen to receive that stale data. Unlikely, but possible. > tty_port_tty_set(port, NULL); > tty->closing = 0; > spin_lock_irqsave(&port->lock, flags); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/