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From: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To: Okash Khawaja <okash.khawaja@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>,
	Samuel Thibault <samuel.thibault@ens-lyon.org>,
	linux-kernel@vger.kernel.org, William Hubbs <w.d.hubbs@gmail.com>,
	Chris Brannon <chris@the-brannons.com>,
	Kirk Reiser <kirk@reisers.ca>,
	speakup@linux-speakup.org, devel@driverdev.osuosl.org
Subject: Re: [patch 0/3] Re: tty contention resulting from tty_open_by_device export
Date: Mon, 10 Jul 2017 12:52:33 +0100	[thread overview]
Message-ID: <20170710125233.2006733e@alans-desktop> (raw)
In-Reply-To: <20170709114153.157783481@gmail.com>

On Sun, 09 Jul 2017 12:41:53 +0100
Okash Khawaja <okash.khawaja@gmail.com> wrote:

> On Sat, Jul 08, 2017 at 10:38:03AM +0200, Greg Kroah-Hartman wrote:
> > Overall, the idea looks sane to me.  Keeping userspace from opening a
> > tty that the kernel has opened internally makes sense, hopefully
> > userspace doesn't get too confused when that happens.  I don't think we
> > normally return -EBUSY from an open call, have you seen what happens
> > with apps when you do this (like minicom?)
> >  
> I tested this wil minincom, picocom and commands like "echo foo >
> /dev/ttyS0". They all correctly report "Device or resource busy".
> 
> I have addressed all the comments you made. I have also split the patch
> into three. Following is summary of each.

If the tty counts are being misreported then it would be better to fix
the code to actually manage the counts properly. The core tty code is
telling you that the tty is not in a valid state. While this is of
itself a good API to have, the underlying reference miscounting ought
IMHO to be fixed as well.

Also you don't need a new TTY_KOPENED flag as far as I can see. All tty's
have a usage count and active bit flags already. Use those.

Alan

  parent reply	other threads:[~2017-07-10 11:53 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-07 20:28 tty contention resulting from tty_open_by_device export Okash Khawaja
2017-07-08  8:38 ` Greg Kroah-Hartman
2017-07-08  9:01   ` Okash Khawaja
2017-07-09 11:41   ` [patch 0/3] " Okash Khawaja
2017-07-09 11:41     ` [patch 1/3] tty: resolve tty contention between kernel and user space Okash Khawaja
2017-07-09 11:51       ` Greg Kroah-Hartman
2017-07-09 15:04       ` Andy Shevchenko
2017-07-09 19:08         ` Okash Khawaja
2017-07-10  8:31         ` Okash Khawaja
2017-07-10 15:21           ` Andy Shevchenko
2017-07-10 16:12             ` Okash Khawaja
2017-07-09 11:41     ` [patch 2/3] staging: speakup: use tty_kopen instead of tty_open_by_driver Okash Khawaja
2017-07-09 11:50       ` Greg Kroah-Hartman
2017-07-09 12:28         ` Okash Khawaja
2017-07-09 11:41     ` [patch 3/3] tty: undo export " Okash Khawaja
2017-07-09 11:57     ` [patch 0/3] Re: tty contention resulting from tty_open_by_device export Greg Kroah-Hartman
2017-07-09 12:32     ` [patch 4/3] tty: make tty_kopen return ENODEV in case of no TTY Okash Khawaja
2017-07-10 11:52     ` Alan Cox [this message]
2017-07-10 12:33       ` [patch 0/3] Re: tty contention resulting from tty_open_by_device export Okash Khawaja
2017-07-10 16:22         ` Okash Khawaja
2017-07-12 18:20         ` Alan Cox
2017-07-13 11:29           ` Okash Khawaja
2017-07-17 12:31             ` Greg Kroah-Hartman
2017-07-17 13:23               ` Okash Khawaja
2017-07-17 22:04                 ` Alan Cox
2017-07-18 11:29                   ` Okash Khawaja
2017-07-18 12:26                     ` Dan Carpenter
2017-07-18 19:22                       ` Okash Khawaja
2017-07-18 13:49                     ` Alan Cox
2017-07-20  7:22                       ` [patch v3 0/3] tty contention resulting from tty_open_by_driver export Okash Khawaja
2017-07-20  7:22                         ` [patch v3 1/3] tty: resolve tty contention between kernel and user space Okash Khawaja
2017-07-20  7:22                         ` [patch v3 2/3] staging: speakup: use tty_kopen and tty_kclose Okash Khawaja
2017-07-20  7:22                         ` [patch v3 3/3] tty: undo export of tty_open_by_driver Okash Khawaja
2017-07-17 21:04               ` [patch v2 0/3] tty contention resulting from tty_open_by_driver export Okash Khawaja
2017-07-17 21:04                 ` [patch v2 1/3] tty: resolve tty contention between kernel and user space Okash Khawaja
2017-07-17 21:04                 ` [patch v2 2/3] staging: speakup: use tty_kopen instead of tty_open_by_driver Okash Khawaja
2017-07-17 21:04                 ` [patch v2 3/3] tty: undo export " Okash Khawaja

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