From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754140AbdCMWNI (ORCPT ); Mon, 13 Mar 2017 18:13:08 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:42466 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752235AbdCMWNB (ORCPT ); Mon, 13 Mar 2017 18:13:01 -0400 Date: Tue, 14 Mar 2017 06:12:47 +0800 From: Greg Kroah-Hartman To: okash.khawaja@gmail.com Cc: Jiri Slaby , Samuel Thibault , linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, Kirk Reiser , speakup@linux-speakup.org, alan@linux.intel.com, Chris Brannon Subject: Re: [patch 1/7] tty_port: allow a port to be opened with a tty that has no file handle Message-ID: <20170313221247.GA22823@kroah.com> References: <20170313220551.312820470@gmail.com> <20170313220926.390471547@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170313220926.390471547@gmail.com> User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 13, 2017 at 10:05:52PM +0000, okash.khawaja@gmail.com wrote: > Allow access to TTY device from kernel. This is based on Alan Cox's patch > (http://www.mail-archive.com/linux-kernel at vger.kernel.org/msg1215095.html), > with description quoted below. > > "tty_port: allow a port to be opened with a tty that has no file handle > > Let us create tty objects entirely in kernel space. > > With this a kernel created non file backed tty object could be used to handle > data, and set terminal modes. Not all ldiscs can cope with this as N_TTY in > particular has to work back to the fs/tty layer. > > The tty_port code is however otherwise clean of file handles as far as I can > tell as is the low level tty port write path used by the ldisc, the > configuration low level interfaces and most of the ldiscs. > > Currently you don't have any exposure to see tty hangups because those are > built around the file layer. However a) it's a fixed port so you probably > don't care about that b) if you do we can add a callback and c) you almost > certainly don't want the userspace tear down/rebuild behaviour anyway. > > This should however be sufficient if we wanted for example to enumerate all > the bluetooth bound fixed ports via ACPI and make them directly available. > > It doesn't deal with the case of a user opening a port that's also kernel > opened and that would need some locking out (so it returned EBUSY if bound > to a kernel device of some kind). That needs resolving along with how you > "up" or "down" your new bluetooth device, or enumerate it while providing > the existing tty API to avoid regressions (and to debug)." > > Signed-off-by: Okash Khawaja > > Reviewed-by: Samuel Thibault You do know this is already in 4.11-rc1, right? Please rebase your patch set on 4.11-rc2 at the least and resend. thanks, greg k-h