From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756825Ab3BEUnu (ORCPT ); Tue, 5 Feb 2013 15:43:50 -0500 Received: from mailout39.mail01.mtsvc.net ([216.70.64.83]:33556 "EHLO n12.mail01.mtsvc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756363Ab3BEUnq (ORCPT ); Tue, 5 Feb 2013 15:43:46 -0500 From: Peter Hurley To: Greg Kroah-Hartman , Alan Cox , Jiri Slaby , Sasha Levin , Sebastian Andrzej Siewior Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Ilya Zykov , Dave Jones , Peter Hurley Subject: [PATCH v3 15/23] tty: Don't restart ldisc on hangup if racing ldisc kill Date: Tue, 5 Feb 2013 15:20:30 -0500 Message-Id: <1360095638-6624-16-git-send-email-peter@hurleysoftware.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1360095638-6624-1-git-send-email-peter@hurleysoftware.com> References: <1355509370-5883-1-git-send-email-peter@hurleysoftware.com> <1360095638-6624-1-git-send-email-peter@hurleysoftware.com> X-Authenticated-User: 125194 peter@hurleysoftware.com X-MT-ID: 8fa290c2a27252aacf65dbc4a42f3ce3735fb2a4 X-MT-INTERNAL-ID: 8fa290c2a27252aacf65dbc4a42f3ce3735fb2a4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Asynchronous hangups (such as from carrier loss) can race with the final tty release. Because there is no mechanism to prevent an async hangup from being scheduled, waiting for the hangup to complete is insufficient to prevent racing between ldisc hangup and ldisc kill. Eg., immediately after flush_work() returns, an async hangup could be scheduled, thus restarting a new ldisc. Instead, prevent hangup from restarting a new ldisc when the tty is being destroyed. Signed-off-by: Peter Hurley --- drivers/tty/tty_ldisc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index 8a86a72..e0fdfec 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -884,7 +884,7 @@ void tty_ldisc_hangup(struct tty_struct *tty) * Shutdown the current line discipline, and reset it to * N_TTY if need be. * - * Avoid racing set_ldisc or tty_ldisc_release + * Avoid racing set_ldisc or tty_ldisc_kill */ mutex_lock(&tty->ldisc_mutex); @@ -892,7 +892,7 @@ void tty_ldisc_hangup(struct tty_struct *tty) reopen it. We could defer this to the next open but it means auditing a lot of other paths so this is a FIXME */ - if (tty_ldisc_hangup_halt(tty)) { + if (tty_ldisc_hangup_halt(tty) && !test_bit(TTY_CLOSING, &tty->flags)) { if (reset == 0) { if (!tty_ldisc_reinit(tty, tty->termios.c_line)) -- 1.8.1.2