From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755965AbcAJFPC (ORCPT ); Sun, 10 Jan 2016 00:15:02 -0500 Received: from mail-pa0-f43.google.com ([209.85.220.43]:36318 "EHLO mail-pa0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750893AbcAJFOA (ORCPT ); Sun, 10 Jan 2016 00:14:00 -0500 From: Peter Hurley To: Greg Kroah-Hartman Cc: Jiri Slaby , linux-kernel@vger.kernel.org, Peter Hurley Subject: [PATCH v2 02/10] tty: Retry failed reopen if tty teardown in-progress Date: Sat, 9 Jan 2016 21:13:45 -0800 Message-Id: <1452402833-8652-3-git-send-email-peter@hurleysoftware.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1452402833-8652-1-git-send-email-peter@hurleysoftware.com> References: <1448677557-16420-1-git-send-email-peter@hurleysoftware.com> <1452402833-8652-1-git-send-email-peter@hurleysoftware.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A small window exists where a tty reopen will observe the tty just prior to imminent teardown (tty->count == 0); in this case, open() returns EIO to userspace. Instead, retry the open after checking for signals and yielding; this interruptible retry loop allows teardown to commence and initialize a new tty on retry. Never retry the BSD master pty reopen; there is no guarantee the pty pair teardown is imminent since the slave file descriptors may remain open indefinitely. Signed-off-by: Peter Hurley --- drivers/tty/tty_io.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 1bf67a2..93fe10d 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1468,13 +1468,13 @@ static int tty_reopen(struct tty_struct *tty) { struct tty_driver *driver = tty->driver; - if (!tty->count) - return -EIO; - if (driver->type == TTY_DRIVER_TYPE_PTY && driver->subtype == PTY_TYPE_MASTER) return -EIO; + if (!tty->count) + return -EAGAIN; + if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN)) return -EBUSY; @@ -2094,7 +2094,11 @@ retry_open: if (IS_ERR(tty)) { retval = PTR_ERR(tty); - goto err_file; + if (retval != -EAGAIN || signal_pending(current)) + goto err_file; + tty_free_file(filp); + schedule(); + goto retry_open; } tty_add_file(tty, filp); -- 2.7.0