linux-kernel - Re: [PATCH tty-next 0/4] tty: Fix ^C echo

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Message-ID: <20131209011220.GA7671@kroah.com>
Date:	Sun, 8 Dec 2013 17:12:20 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Peter Hurley <peter@...leysoftware.com>,
	Karl Dahlke <eklhad@...cast.net>
Cc:	Jiri Slaby <jslaby@...e.cz>,
	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org
Subject: Re: [PATCH tty-next 0/4] tty: Fix ^C echo

On Mon, Dec 02, 2013 at 04:12:01PM -0500, Peter Hurley wrote:
> Greg,
> 
> Sometimes when interrupting terminal output, the '^C' won't be echoed
> until more output is echoed. This is fairly repeatable by interrupting
> 'cat large-file'.
> 
> The common reason for this is because the tty write buffer is full,
> even though the write buffer _should_ have been flushed already.
> Because of a known deadlock, the pty driver does not perform a
> write buffer flush in its flush_buffer() method.
> 
> [Refer to the FIXME in pty_flush_buffer() from commit
> d945cb9cce20ac7143c2de8d88b187f62db99bdc,
> 'pty: Rework the pty layer to use the normal buffering logic']
> 
> Patch 1 fixes a stale comment.
> Patch 2 adds the necessary interfaces to avoid direct linkage
> between the N_TTY line discipline and the pty driver.
> Patch 3 avoids the deadlock while performing the write buffer flush.
> Patch 4 fixes a less common condition introduced by the echo batch
> processing added in 3.12.
> 
> Alan,
> 
> I cc'd you because of your recent involvement in other
> tty patches/bug fixes and because it's your FIXME comment.
> Feel free to ignore and/or let me know you would prefer not to
> be bothered.

Peter, this series doesn't fix the ^C echo problem that Karl recently
reported, so I'll hold off in applying it for now.

thanks,

greg k-h
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