From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: [PATCH 7/7] n_tty: Buffer work should not reschedule itself Date: Wed, 6 Mar 2013 08:38:25 -0500 Message-ID: <1362577105-19757-8-git-send-email-peter@hurleysoftware.com> References: <1362577105-19757-1-git-send-email-peter@hurleysoftware.com> Return-path: Received: from mailout01.c08.mtsvc.net ([205.186.168.189]:50390 "EHLO mailout01.c08.mtsvc.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755999Ab3CFNjG (ORCPT ); Wed, 6 Mar 2013 08:39:06 -0500 In-Reply-To: <1362577105-19757-1-git-send-email-peter@hurleysoftware.com> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Greg Kroah-Hartman Cc: Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Hurley Although the driver-side input path must update the available buffer space, it should not reschedule itself. If space is still available and the flip buffers are not empty, flush_to_ldisc() will loop again. Signed-off-by: Peter Hurley --- drivers/tty/n_tty.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 61a55f4..6f9694d 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -118,14 +118,14 @@ static inline int tty_put_user(struct tty_struct *tty, unsigned char x, * n_tty_set_room - receive space * @tty: terminal * - * Sets tty->receive_room to reflect the currently available space + * Updates tty->receive_room to reflect the currently available space * in the input buffer, and re-schedules the flip buffer work if space * just became available. * * Locks: Concurrent update is protected with read_lock */ -static void n_tty_set_room(struct tty_struct *tty) +static int set_room(struct tty_struct *tty) { struct n_tty_data *ldata = tty->disc_data; int left; @@ -155,8 +155,13 @@ static void n_tty_set_room(struct tty_struct *tty) raw_spin_unlock_irqrestore(&ldata->read_lock, flags); + return left && !old_left; +} + +static void n_tty_set_room(struct tty_struct *tty) +{ /* Did this open up the receive buffer? We may need to flip */ - if (left && !old_left) { + if (set_room(tty)) { WARN_RATELIMIT(tty->port->itty == NULL, "scheduling with invalid itty\n"); /* see if ldisc has been killed - if so, this means that @@ -1475,7 +1480,7 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, tty->ops->flush_chars(tty); } - n_tty_set_room(tty); + set_room(tty); if ((!ldata->icanon && (ldata->read_cnt >= ldata->minimum_to_wake)) || L_EXTPROC(tty)) { -- 1.8.1.2