From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933142AbdEVSQ3 (ORCPT ); Mon, 22 May 2017 14:16:29 -0400 Received: from www.llwyncelyn.cymru ([82.70.14.225]:49924 "EHLO fuzix.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759987AbdEVSQ0 (ORCPT ); Mon, 22 May 2017 14:16:26 -0400 Date: Mon, 22 May 2017 19:16:17 +0100 From: Alan Cox To: Sascha Hauer Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Jiri Slaby , kernel@pengutronix.de Subject: Re: tty: n_gsm: fix closing multiplexer mode Message-ID: <20170522191617.35dd508f@alans-desktop> In-Reply-To: <20170522081500.21335-1-s.hauer@pengutronix.de> References: <20170522081500.21335-1-s.hauer@pengutronix.de> Organization: Intel Corporation X-Mailer: Claws Mail 3.14.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > disconnect frame before initialising multiplex mode. Since it's not so > nice that userspace has to know the layout of a disconnect frame, > the second patch introduces a disconnect ioctl which can be issued > right before closing the physical port during the first session. > This ioctl is only useful when during the second session it is known > the the first session has been closed properly, so I'm not sure > how useful it is to introduce such an ioctl. I don't think it justifies an ioctl and the likely use case is that the tty is hung up when the process dies so would already be in N_TTY at the point anyone tried to clean up. A more interesting question - and I don't have enough hardware to test this any more - would be whether we can safely send that sequence if our initial connects failed a few times so we try disconnect/reconnect. Alan