From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965804AbbLPPnR (ORCPT ); Wed, 16 Dec 2015 10:43:17 -0500 Received: from mail-pa0-f42.google.com ([209.85.220.42]:32832 "EHLO mail-pa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752442AbbLPPnN (ORCPT ); Wed, 16 Dec 2015 10:43:13 -0500 Subject: Re: [PATCH 00/12] Rework tty_reopen() To: Greg Kroah-Hartman References: <1448677557-16420-1-git-send-email-peter@hurleysoftware.com> Cc: Jiri Slaby , linux-kernel@vger.kernel.org From: Peter Hurley Message-ID: <5671868F.6090508@hurleysoftware.com> Date: Wed, 16 Dec 2015 07:43:11 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: <1448677557-16420-1-git-send-email-peter@hurleysoftware.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Greg, This series has been reported to fix a regression with Redhat's kdump systemd service redirecting to /dev/console, when /dev/console is a serial port. The redirection consistently fails with EIO since "tty: Remove tty_wait_until_sent_from_close", which is new to 4.4-rc Prior to that patch, redirection would only occasionally fail with EIO. :) [ The systemd repeated hangup of /dev/console also seems to be the [ trigger for the serial driver crashes on hangup as well, which is [ fixed by the 19-patch "Fix driver crashes on hangup" series. [ That problem goes back to 3.10, but has only been reported recently, [ which leads me to believe recent changes in systemd /dev/console [ handling is a contributing factor (which I'm checking right now) Here are what I think are the options to resolve the regression: #1. Respin this series w/o the tty-next dependencies #2. Split this series into the minimum necessary to fix the regression #3. Revert from 4.4-rc (in revert order) "tty: Remove wait_event_interruptible_tty()" "tty: r3964: Replace/remove bogus tty lock use" "tty: r3964: Use tty->read_wait waitqueue" "tty: Remove tty_port::close_wait" "usb: gadget: gserial: Privatize close_wait" "tty: Remove ASYNC_CLOSING check in open()/hangup() methods" "tty: Remove tty_wait_until_sent_from_close()" Let me know how you'd like me to handle this. Sorry, Peter Hurley On 11/27/2015 06:25 PM, Peter Hurley wrote: > This patch series implements two important improvements to tty open() > behavior: interruptible open() and automatic retry when tty teardown > has already commenced. > > Interruptible open() allows signals to cancel the open wait if stalled > waiting for tty teardown to complete. > > Automatic retry of tty open() when racing a tty teardown now makes tty > open() fully POSIX compliant. For some time, the Linux kernel has > returned EIO from open() under certain circumstances. This happens when > tty_open() observes a valid tty from driver lookup but the tty is > being released (in final close) and teardown is about to commence. > > The observable userspace change is that userspace will no longer need > to retry open() on EIO error. > > This series also continues the ongoing effort to cleanup and reduce the > kernel tty interface. > > Lastly, this series lays important groundwork for implementing ptmx_open() > in tty_open(), trivially with driver lookup (still a work-in-progress). > > Regards, > > Peter Hurley (12): > tty: Fix ldisc leak in failed tty_init_dev() > tty: Remove !tty check from free_tty_struct() > tty: Fix tty_init_termios() declaration > tty: Re-declare tty_driver_remove_tty() file scope > pty: Remove pty_unix98_shutdown() > tty: Remove __lockfunc annotation from tty lock functions > tty: Wait interruptibly for tty lock on reopen > pty: Prepare to redefine tty driver remove() interface > tty: Re-define tty driver remove() interface > tty: Consolidate noctty checks in tty_open() > tty: Refactor tty_open() > tty: Retry failed reopen if tty teardown in-progress > > drivers/tty/pty.c | 40 +++------- > drivers/tty/tty_io.c | 180 +++++++++++++++++++++---------------------- > drivers/tty/tty_ldisc.c | 21 +++-- > drivers/tty/tty_mutex.c | 16 +++- > drivers/usb/serial/console.c | 6 +- > include/linux/tty.h | 19 ++--- > include/linux/tty_driver.h | 4 +- > 7 files changed, 128 insertions(+), 158 deletions(-) >