From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752173Ab2CKLCE (ORCPT ); Sun, 11 Mar 2012 07:02:04 -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 S1751716Ab2CKLCA (ORCPT ); Sun, 11 Mar 2012 07:02:00 -0400 Message-ID: <4F5C861F.2000507@nod.at> Date: Sun, 11 Mar 2012 12:01:51 +0100 From: Richard Weinberger User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111105 Thunderbird/8.0 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> In-Reply-To: <4F5BE1E6.9000201@nod.at> X-Enigmail-Version: 1.3.4 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig11959E9072910D4D260E0A8F" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig11959E9072910D4D260E0A8F Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable 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 =3D 0; n < closecount; >>> n++) tty->ops->close(tty, cons_filp); } else if (tty->ops->hangup)=20 >>> (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? >> >=20 > "lsof | grep tty" does not show anything else than tty0. :-\ >=20 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 un= happy. Thanks, //richard --------------enig11959E9072910D4D260E0A8F Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQEcBAEBAgAGBQJPXIYjAAoJEN9758yqZn9eA0AIAIUDJDFS9g5btNZI0Si0vrq3 830vnVrsAhn1aty7DCsEWUX5xz7LxMH79lST/2mqDugVHODCpFpM+gJWul1AaGfp a4cmPehEfbWpSAdq7KMb8udRwYoMOp8L9aAieh6XA0yi7DYXLZO6vFQreg7Quf87 UTerSH08fIYudiO3gstCPGCng506ozcaODeUVQLBXq+7j/49cNqGi1Hobsd2mCHC X49PafYj2jj5cukwPJWai5HMZvpxs5P1rOcoirfy9FnH9Dy3M+P95066QsK4k9Mb 6FWlg9qnquBVoLe+W4u/9n5bOIA34O5p8ZQqkz3KwmVb3yD56nOGQUVZqyUtgkw= =aZie -----END PGP SIGNATURE----- --------------enig11959E9072910D4D260E0A8F--