From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757317Ab2KZWJt (ORCPT ); Mon, 26 Nov 2012 17:09:49 -0500 Received: from 95-31-19-74.broadband.corbina.ru ([95.31.19.74]:46860 "EHLO 95-31-19-74.broadband.corbina.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755818Ab2KZWJr (ORCPT ); Mon, 26 Nov 2012 17:09:47 -0500 Message-ID: <50B3E897.3020901@ilyx.ru> Date: Tue, 27 Nov 2012 02:09:27 +0400 From: Ilya Zykov User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:16.0) Gecko/20121026 Thunderbird/16.0.2 MIME-Version: 1.0 To: Alan Cox CC: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, ilya@ilyx.ru Subject: [PATCH v3] tty: Add driver unthrottle in ioctl(...,TCFLSH,..). 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 --- diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c index 12b1fa0..a038be1 100644 --- a/drivers/tty/tty_ioctl.c +++ b/drivers/tty/tty_ioctl.c @@ -1098,10 +1098,12 @@ int tty_perform_flush(struct tty_struct *tty, unsigned long arg) case TCIFLUSH: if (ld && ld->ops->flush_buffer) ld->ops->flush_buffer(tty); + tty_unthrottle(tty); break; case TCIOFLUSH: if (ld && ld->ops->flush_buffer) ld->ops->flush_buffer(tty); + tty_unthrottle(tty); /* fall through */ case TCOFLUSH: tty_driver_flush_buffer(tty);