From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932503AbYBFX7Y (ORCPT ); Wed, 6 Feb 2008 18:59:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764168AbYBFXyd (ORCPT ); Wed, 6 Feb 2008 18:54:33 -0500 Received: from mail.suse.de ([195.135.220.2]:45148 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1764131AbYBFXyb (ORCPT ); Wed, 6 Feb 2008 18:54:31 -0500 Date: Wed, 6 Feb 2008 15:51:17 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org, torvalds@linux-foundation.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, ctusar@videon-central.com, jirislaby@gmail.com Subject: [patch 11/73] tty: fix logic change introduced by wait_event_interruptible_timeout() Message-ID: <20080206235117.GL13121@suse.de> References: <20080206234302.769849277@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="tty-fix-logic-change-introduced-by-wait_event_interruptible_timeout.patch" In-Reply-To: <20080206235015.GA13121@suse.de> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.23-stable review patch. If anyone has any objections, please let us know. ------------------ From: "Cory T. Tusar" patch db99247ac68fc352100090ad7704fb5efb9327b6 in mainline. Commit 5a52bd4a2dcb570333ce6fe2e16cd311650dbdc8 introduced a subtle logic change in tty_wait_until_sent(). The original version would only error out of the 'do { ... } while (timeout)' loop if signal_pending() evaluated to true; a timeout or break due to an empty buffer would fall out of the loop and into the tty->driver->wait_until_sent handling. The current implementation will error out on either a pending signal or an empty buffer, falling through to the tty->driver->wait_until_sent handling only on a timeout. The ->wait_until_sent() will not be reached if the buffer empties before timeout jiffies have elapsed. This behavior differs from that prior to commit 5a52bd4a2dcb570333ce6fe2e16cd311650dbdc8. I turned this up while using a little serial download utility to bootstrap an ARM-based eval board. The util worked fine on 2.6.22.x, but consistently failed on 2.6.23.x. Once I'd determined that, I narrowed things down with git bisect, and found the above difference in logic in tty_wait_until_sent() by inspection. This change reverts the logic flow in tty_wait_until_sent() to match that prior to the aforementioned commit. Signed-off-by: Cory T. Tusar Cc: Alan Cox Acked-by: Jiri Slaby Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- drivers/char/tty_ioctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/char/tty_ioctl.c +++ b/drivers/char/tty_ioctl.c @@ -62,7 +62,7 @@ void tty_wait_until_sent(struct tty_stru if (!timeout) timeout = MAX_SCHEDULE_TIMEOUT; if (wait_event_interruptible_timeout(tty->write_wait, - !tty->driver->chars_in_buffer(tty), timeout)) + !tty->driver->chars_in_buffer(tty), timeout) < 0) return; if (tty->driver->wait_until_sent) tty->driver->wait_until_sent(tty, timeout); --