From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932477Ab3APJIS (ORCPT ); Wed, 16 Jan 2013 04:08:18 -0500 Received: from 95-31-19-74.broadband.corbina.ru ([95.31.19.74]:56351 "EHLO 95-31-19-74.broadband.corbina.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932426Ab3APJHx (ORCPT ); Wed, 16 Jan 2013 04:07:53 -0500 Message-ID: <50F66DE6.6080101@ilyx.ru> Date: Wed, 16 Jan 2013 13:07:50 +0400 From: Ilya Zykov User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Alan Cox CC: Greg Kroah-Hartman , Alan Cox , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] tty: Add driver unthrottle in ioctl(...,TCFLSH,..). References: <50B45A49.2040104@ilyx.ru> <20121127172406.GE24592@kroah.com> <50B50AA0.7070603@ilyx.ru> <20121127193208.331673ae@pyramind.ukuu.org.uk> In-Reply-To: <20121127193208.331673ae@pyramind.ukuu.org.uk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Regression 'tty: fix "IRQ45: nobody cared"' Regression commit 7b292b4bf9a9d6098440d85616d6ca4c608b8304 Function reset_buffer_flags() also invoked during the ioctl(...,TCFLSH,..). At the time of request we can have full buffers and throttled driver too. If we don't unthrottle driver, we can get forever throttled driver, because, after request, we will have empty buffers and throttled driver and there is no place to unthrottle driver. It simple reproduce with "pty" pair then one side sleep on tty->write_wait, and other side do ioctl(...,TCFLSH,..). Then there is no place to do writers wake up. Signed-off-by: Ilya Zykov --- drivers/tty/tty_ioctl.c | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c index 8481b29..cc0fc52 100644 --- a/drivers/tty/tty_ioctl.c +++ b/drivers/tty/tty_ioctl.c @@ -1096,12 +1096,16 @@ int tty_perform_flush(struct tty_struct *tty, unsigned long arg) ld = tty_ldisc_ref_wait(tty); switch (arg) { case TCIFLUSH: - if (ld && ld->ops->flush_buffer) + if (ld && ld->ops->flush_buffer) { ld->ops->flush_buffer(tty); + tty_unthrottle(tty); + } break; case TCIOFLUSH: - if (ld && ld->ops->flush_buffer) + if (ld && ld->ops->flush_buffer) { ld->ops->flush_buffer(tty); + tty_unthrottle(tty); + } /* fall through */ case TCOFLUSH: tty_driver_flush_buffer(tty);