From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965014Ab2KVTZH (ORCPT ); Thu, 22 Nov 2012 14:25:07 -0500 Received: from 95-31-19-74.broadband.corbina.ru ([95.31.19.74]:45034 "EHLO 95-31-19-74.broadband.corbina.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753895Ab2KVTZF (ORCPT ); Thu, 22 Nov 2012 14:25:05 -0500 Message-ID: <50AD4A01.7060500@ilyx.ru> Date: Thu, 22 Nov 2012 01:39:13 +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: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Andrew McGregor Subject: Re: [PATCH] tty: Add driver unthrottle in ioctl(...,TCFLSH,..). References: <50AD43DB.4030800@ilyx.ru> <20121121213037.154306da@pyramind.ukuu.org.uk> In-Reply-To: <20121121213037.154306da@pyramind.ukuu.org.uk> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22.11.2012 1:30, Alan Cox wrote: >> 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. > > > So instead of revertng it why not just fix it ? Just add an argument to > the reset_buffer_flags function to indicate if unthrottling is permitted. > > Alan > Because in my opinion, unthrottling permitted always, except release last filp (tty->count == 0)