From: shuah <shuah@kernel.org>
To: Johan Hovold <johan@kernel.org>, Marcel Holtmann <marcel@holtmann.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
"open list:NFC SUBSYSTEM" <linux-wireless@vger.kernel.org>,
chris@the-brannons.com, devel@driverdev.osuosl.org,
Rob Herring <robh@kernel.org>,
Samuel Ortiz <sameo@linux.intel.com>,
"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
Jiri Slaby <jslaby@suse.com>,
santhameena13@gmail.com, kirk@reisers.ca,
Johan Hedberg <johan.hedberg@gmail.com>,
Arnd Bergmann <arnd@arndb.de>,
samuel.thibault@ens-lyon.org, m.maya.nakamura@gmail.com,
zhongjiang@huawei.com, Greg KH <gregkh@linuxfoundation.org>,
speakup@linux-speakup.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Bluez mailing list <linux-bluetooth@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
nishka.dasgupta_ug18@ashoka.edu.in,
"David S. Miller" <davem@davemloft.net>, shuah <shuah@kernel.org>
Subject: Re: [PATCH] tty: Fix WARNING in tty_set_termios
Date: Thu, 31 Jan 2019 16:23:02 -0700 [thread overview]
Message-ID: <2812690e-d9d6-9755-ecb1-045e2acb4323@kernel.org> (raw)
In-Reply-To: <20190131153306.GT3691@localhost>
On 1/31/19 8:33 AM, Johan Hovold wrote:
> On Thu, Jan 31, 2019 at 04:18:33PM +0100, Marcel Holtmann wrote:
>
>>> I agree with Al that this change doesn't make much sense. The WARN_ON
>>> is there to catch any bugs leading to the termios being changed for a
>>> master side pty. Those should bugs should be fixed, and not worked
>>> around in order to silence a WARN_ON.
>>>
>>> The problem started with 7721383f4199 ("Bluetooth: hci_uart: Support
>>> operational speed during setup") which introduced a new way for how
>>> tty_set_termios() could end up being called for a master pty.
>>>
>>> As Al hinted at, setting these ldiscs for a master pty really makes no
>>> sense and perhaps that is what we should prevent unless simply making
>>> sure they do not call tty_set_termios() is sufficient for the time
>>> being.
>>>
>>> Finally, note that serdev never operates on a pty, and that this is only
>>> an issue for (the three) line disciplines.
>>
>> I think for PTYs we should just fail setting the HCI line discipline.
>> Fail early and just move on with life.
>
> Sounds good to me. At least for the pty master. There may be some people
> trying to use a bluetooth device connected to a remote serial port (I've
> seen descriptions of such setups at least), and maybe we need not prevent
> that.
>
Thanks for the feedback on the patch. Changes to prevent setting the HCI
line discipline from hci_uart fixes the problem.
I am sending v2 in a just a bit.
thanks,
-- Shuah
prev parent reply other threads:[~2019-01-31 23:23 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-25 23:29 [PATCH] tty: Fix WARNING in tty_set_termios Shuah Khan
2019-01-26 4:14 ` Al Viro
2019-01-28 21:29 ` shuah
2019-01-30 10:32 ` Johan Hovold
2019-01-31 0:35 ` shuah
2019-01-31 15:18 ` Marcel Holtmann
2019-01-31 15:33 ` Johan Hovold
2019-01-31 23:23 ` shuah [this message]
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