From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752572Ab2CLK0I (ORCPT ); Mon, 12 Mar 2012 06:26:08 -0400 Received: from a.ns.miles-group.at ([95.130.255.143]:47834 "EHLO radon.swed.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751749Ab2CLK0G (ORCPT ); Mon, 12 Mar 2012 06:26:06 -0400 Message-ID: <4F5DCF39.8080308@nod.at> Date: Mon, 12 Mar 2012 11:26:01 +0100 From: Richard Weinberger User-Agent: Mozilla/5.0 (X11; Linux i686; rv:10.0.2) Gecko/20120215 Thunderbird/10.0.2 MIME-Version: 1.0 To: Jiri Slaby CC: linux-kernel@vger.kernel.org, alan@lxorguk.ukuu.org.uk, gregkh@linuxfoundation.org, Jiri Slaby Subject: Re: TTY: tty_port questions References: <4F5BD51B.7030907@nod.at> <4F5BDB09.3020407@suse.cz> <4F5BE1E6.9000201@nod.at> <4F5C861F.2000507@nod.at> In-Reply-To: <4F5C861F.2000507@nod.at> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11.03.2012 12:01, Richard Weinberger wrote: > Am 11.03.2012 00:21, schrieb Richard Weinberger: >> Am 10.03.2012 23:51, schrieb Jiri Slaby: >>> On 03/10/2012 11:26 PM, Richard Weinberger wrote: >>>> Hi! >>> >>>> While moving UML's console driver to tty_port some strange things >>>> happened. So, I have a few questions. :-) >>> >>>> The original driver did not implement tty_operations->hangup(). If >>>> I implement it and call tty_port_hangup(), as Alan suggested, the >>>> login fails on all TTYs except tty0. It fails because the opened >>>> TTY returns EIO upon read()/write() after /bin/login called >>>> vhangup(). >>> >>>> The call chain is: vhangup() -> tty_vhangup_self() -> tty_vhangup() >>>> -> __tty_hangup() >>> >>>> Within __tty_hangup() something happens that I don't fully >>>> understand: >>> >>>> if (cons_filp) { if (tty->ops->close) for (n = 0; n< closecount; >>>> n++) tty->ops->close(tty, cons_filp); } else if (tty->ops->hangup) >>>> (tty->ops->hangup)(tty); >>> >>>> Login on tty0 works because cons_filp is not NULL and >>>> tty->ops->close() is called. On the other hand login fails on every >>>> other TTY because cons_filp remains NULL and the TTY hangs up. >>> >>>> Is there something missing in my hangup function? >>> >>>> If I omit tty_operations->hangup() and leave it, like the old >>>> driver, NULL non-tty0 TTYs cannot be opened. (getty terminates >>>> immediately because it cannot open any TTY.) open() retuns -EIO >>>> because the TTY_CLOSING is set in tty->flags. >>> >>>> How can this be? >>> >>> Hmm, it looks like some process is sitting on a TTY which was hung. >>> And the system offers this hung TTY to others on further opens. Could >>> you check that there is no process with open TTY after the vhangup? >>> >> >> "lsof | grep tty" does not show anything else than tty0. :-\ >> > > BTW: When I start the kernel with /bin/sh as init, opening and writing to any TTY works fine. > It looks like Fedora 16's userspace does something that makes the TTYs unhappy. > > Thanks, > //richard Another question, what is the purpose of tty_port->console? It seems to have no user. Is tty_port really the right thing for a console driver like in the UML case? Thanks, //richard