Subject: Re: [PATCH] serial: flush ldisc after hangup
To: Josef Bacik <jbacik@fb.com>, gregkh@linuxfoundation.org, jslaby@suse.com,
        linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
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 <56D5DCA0.2040201@hurleysoftware.com> <56D5DDA6.5080605@fb.com>
From: Peter Hurley <peter@hurleysoftware.com>
Message-ID: <56D5E714.7030900@hurleysoftware.com>
Date: Tue, 1 Mar 2016 11:01:40 -0800
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On 03/01/2016 10:21 AM, Josef Bacik wrote:
> On 03/01/2016 01:17 PM, Peter Hurley wrote:

>> Yeah, the race is that the ldisc should not be attempting i/o to 
>> the driver at all. This problem is fixed in -next already, but in
>> the tty core rather than in each individual tty driver.
>> 
> 
> Great!  Which patch/patches fix this?  I looked at linux-next and
> there's a lot of refactoring stuff, do I need all the things or is
> there a specific one that fixes this problem?  Thanks,

The series that fixes this design problem introduce in 3.10 are these
patches:

  staging: digi: Replace open-coded tty_wakeup()
  serial: 68328: Remove bogus ldisc reset
  bluetooth: hci_ldisc: Remove dead code
  NFC: nci: Remove dead code
  tty: Remove chars_in_buffer() line discipline method
  tty: Fix unsafe ldisc reference via ioctl(TIOCGETD)
  n_tty: Fix unsafe reference to "other" ldisc
  tty: Reset c_line from driver's init_termios
  staging/speakup: Use tty_ldisc_ref() for paste kworker
  tty: Fix comments for tty_ldisc_get()
  tty: Fix comments for tty_ldisc_release()
  tty: Prepare for destroying line discipline on hangup
  tty: Handle NULL tty->ldisc
  tty: Move tty_ldisc_kill()
  tty: Use 'disc' for line discipline index name
  tty: Refactor tty_ldisc_reinit() for reuse
  tty: Destroy ldisc instance on hangup

'tty: Fix unsafe ldisc reference via ioctl(TIOCGETD)' and
'tty: Fix unsafe reference to "other" ldisc' have already
made their way to most stable trees, afaict.

I doubt I'll submit any more of this series for stable;
it's just too invasive. I'll probably do it per-driver, like
your patch. Just an fyi.

Regards,
Peter Hurley