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Date: Tue, 17 Jun 2014 12:54:41 +0100
From: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
To: Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH tty-next 14/22] tty: Remove
 tty_wait_until_sent_from_close()
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Cc: Karsten Keil <isdn@linux-pingi.de>,
 'Peter Hurley' <peter@hurleysoftware.com>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
 "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
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> Before the patch, I believe tty_reopen() would return -EIO because
> the TTY_CLOSING flag is set. After the patch, tty_open() blocks
> on tty_lock() before calling tty_reopen(). AFAICT, this is independent
> of O_NONBLOCK.

That would be a bug then. Returning -EIO is fine (if unfriendly). The
O_NONBLOCK can't block in this case though because the port could take a
long time to give up trying to dribble its bits (up to 30 seconds or so)

Alan