From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751733AbaGJXMI (ORCPT ); Thu, 10 Jul 2014 19:12:08 -0400 Received: from shards.monkeyblade.net ([149.20.54.216]:45851 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750857AbaGJXMG (ORCPT ); Thu, 10 Jul 2014 19:12:06 -0400 Date: Thu, 10 Jul 2014 16:12:05 -0700 (PDT) Message-Id: <20140710.161205.2079073830695357277.davem@davemloft.net> To: gregkh@linuxfoundation.org Cc: peter@hurleysoftware.com, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, sethb@digi.com, aaro.koskinen@iki.fi, sam@ravnborg.org, tsbogend@alpha.franken.de Subject: Re: [PATCH 0/2] fixes for empty tx buffer breakage From: David Miller In-Reply-To: <20140710231432.GA9423@kroah.com> References: <20140609205917.GA913@drone.musicnaut.iki.fi> <1404660593-12172-1-git-send-email-peter@hurleysoftware.com> <20140710231432.GA9423@kroah.com> X-Mailer: Mew version 6.5 on Emacs 24.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.7 (shards.monkeyblade.net [149.20.54.216]); Thu, 10 Jul 2014 16:12:05 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Greg Kroah-Hartman Date: Thu, 10 Jul 2014 16:14:32 -0700 > On Sun, Jul 06, 2014 at 11:29:51AM -0400, Peter Hurley wrote: >> Cc: Seth Bollinger >> Cc: Aaro Koskinen >> Cc: Sam Ravnborg >> Cc: "David S. Miller" >> Cc: Thomas Bogendoerfer >> >> Greg, >> >> I completed the audit of serial drivers after reports that >> several Sun serial drivers were broken by >> commit 717f3bbab3c7628736ef738fdbf3d9a28578c26c, >> 'serial_core: Fix conditional start_tx on ring buffer not empty'. >> >> I apologize for not submitting this sooner. The delay was due to >> an ongoing analysis of serial flow control prompted by Sam Ravnborg's >> question: >> >> On 06/10/2014 03:24 PM, Sam Ravnborg wrote: >> > I also noticed the typical pattern is: >> > >> > if (uart_circ_empty(xmit) || uart_tx_stopped(port)) >> > >> > Should you use this pattern also in sunsab.c? >> >> Unfortunately, that analysis revealed that tx flow control is >> largely SMP-unsafe, and it's fairly easy to corrupt the hardware >> state wrt. the tty flow control state. >> >> I'm still working on the solutions to that; they're too >> extensive to submit for 3.16 anyway. > > So these should go into 3.16-final? Or 3.17? Definitely 3.16, this regression is several releases old.