From mboxrd@z Thu Jan  1 00:00:00 1970
From: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH] tty: Only hangup once
Date: Mon, 18 Nov 2013 23:03:39 +0000
Message-ID: <20131118230339.5402fac4@alan.etchedpixels.co.uk>
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To: Peter Hurley <peter@hurleysoftware.com>
Cc: Heorhi Valakhanovich <valahanovich@tut.by>, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, gregkh@linuxfoundation.org

> I doubt this is caused by a race condition; the first hangup would do most
> of the destruction regardless, and a second hangup can't really race with
> the first because of the tty_lock() held for most of the hangup.
> 
> In any event, it's worth discovering what state a subsequent hangup can
> effect that the first hangup left incomplete. I'll look into it.
> 
> Regards,
> Peter Hurley

disassociate_ctty races with tty_hangup.

tty->pgrp is only protected by ctrl_lock

See no_tty and the FIXME note. Sorry the FIXME wasn't clearer.


Alan