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From: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: linux-kernel@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>,
	kernel@pengutronix.de
Subject: Re: tty: n_gsm: fix closing multiplexer mode
Date: Mon, 22 May 2017 19:16:17 +0100	[thread overview]
Message-ID: <20170522191617.35dd508f@alans-desktop> (raw)
In-Reply-To: <20170522081500.21335-1-s.hauer@pengutronix.de>

> 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

  parent reply	other threads:[~2017-05-22 18:16 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-22  8:14 tty: n_gsm: fix closing multiplexer mode Sascha Hauer
2017-05-22  8:14 ` [PATCH 1/2] tty: n_gsm: do not send/receive in ldisc close path Sascha Hauer
2017-05-22  8:15 ` [PATCH 2/2] tty: n_gsm: Add GSMIOC_DISCONNECT ioctl to disconnect the multiplexer Sascha Hauer
2017-05-22  9:25   ` Greg Kroah-Hartman
2017-05-22  9:29     ` Sascha Hauer
2017-05-22 18:16 ` Alan Cox [this message]
2017-05-23  7:55   ` tty: n_gsm: fix closing multiplexer mode Sascha Hauer

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