From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751350AbZHJSIA (ORCPT ); Mon, 10 Aug 2009 14:08:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751156AbZHJSH7 (ORCPT ); Mon, 10 Aug 2009 14:07:59 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:36804 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751009AbZHJSH7 (ORCPT ); Mon, 10 Aug 2009 14:07:59 -0400 Date: Mon, 10 Aug 2009 11:07:20 -0700 (PDT) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: Ray Lee cc: Artur Skawina , Alan Cox , "Rafael J. Wysocki" , LKML Subject: Re: xterm loses data (pty regression) In-Reply-To: Message-ID: References: <4A803CE7.20201@gmail.com> <2c0942db0908101007t54c39b64k2800b2c320969318@mail.gmail.com> User-Agent: Alpine 2.01 (LFD 1184 2008-12-16) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 10 Aug 2009, Linus Torvalds wrote: > > On Mon, 10 Aug 2009, Ray Lee wrote: > > On Mon, Aug 10, 2009 at 8:29 AM, Artur Skawina wrote: > > > > > > First noticed it after upgrading to v2.6.31-rc5-246-g90bc1a6, still happens > > > in rc5-381-g7b2aa03. > > > If i press ^S in an xterm the output stops as expected, but after a ^Q i see > > > only the newly written data, everything in between is lost. > > Yup, I can confirm that. > > > > > for i in `seq 1 111`; do echo $i; sleep 1; done > > (Do ^S/^Q, see data loss) > > Will take a look asap, thanks. Although I bet it's the same old commit > (d945cb9cc: "pty: Rework the pty layer to use the normal buffering logic") > again. I think it's really this trivial. That pty commit removed the checking for tty->stopped in pty_write_buffer() for no clear reason. And when it did that, it broke all the pausing logic in drivers/char/n_tty.c. Can you confirm? Linus --- drivers/char/pty.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/drivers/char/pty.c b/drivers/char/pty.c index 6e6942c..d083c73 100644 --- a/drivers/char/pty.c +++ b/drivers/char/pty.c @@ -144,6 +144,8 @@ static int pty_write(struct tty_struct *tty, const unsigned char *buf, static int pty_write_room(struct tty_struct *tty) { + if (tty->stopped) + return 0; return pty_space(tty->link); }