From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752506AbdDIQy3 (ORCPT ); Sun, 9 Apr 2017 12:54:29 -0400 Received: from mail-pg0-f67.google.com ([74.125.83.67]:36651 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752270AbdDIQyY (ORCPT ); Sun, 9 Apr 2017 12:54:24 -0400 Date: Mon, 10 Apr 2017 00:52:27 +0800 From: Wang YanQing To: gregkh@linuxfoundation.org Cc: jslaby@suse.com, linux-kernel@vger.kernel.org, mikey@neuling.org, viro@ZenIV.linux.org.uk, johan@kernel.org, peter@hurleysoftware.com, alex.popov@linux.com, robh@kernel.org, mpatocka@redhat.com, dvyukov@google.com, benh@kernel.crashing.org Subject: [PATCH] tty:tty_ldisc: add tty_ldisc_lock|unlock to prevent concurrent update to ldisc in tty_ldisc_reinit Message-ID: <20170409165227.GA7945@udknight> Mail-Followup-To: Wang YanQing , gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, mikey@neuling.org, viro@ZenIV.linux.org.uk, johan@kernel.org, peter@hurleysoftware.com, alex.popov@linux.com, robh@kernel.org, mpatocka@redhat.com, dvyukov@google.com, benh@kernel.crashing.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch could fix the issue that tty_reopen in tty_io calling tty_ldisc_reinit without holding tty->ldisc_sem. Signed-off-by: Wang YanQing --- drivers/tty/tty_ldisc.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index b0500a0..b1f7fa5 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -616,6 +616,10 @@ int tty_ldisc_reinit(struct tty_struct *tty, int disc) if (IS_ERR(ld)) return PTR_ERR(ld); + /* + * Avoid racing set_ldisc or tty_ldisc_release + */ + tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT); if (tty->ldisc) { tty_ldisc_close(tty, tty->ldisc); tty_ldisc_put(tty->ldisc); @@ -629,6 +633,7 @@ int tty_ldisc_reinit(struct tty_struct *tty, int disc) tty_ldisc_put(tty->ldisc); tty->ldisc = NULL; } + tty_ldisc_unlock(tty); return retval; } @@ -672,22 +677,18 @@ void tty_ldisc_hangup(struct tty_struct *tty, bool reinit) /* * Shutdown the current line discipline, and reset it to * N_TTY if need be. - * - * Avoid racing set_ldisc or tty_ldisc_release */ - tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT); - if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) tty_reset_termios(tty); - if (tty->ldisc) { - if (reinit) { - if (tty_ldisc_reinit(tty, tty->termios.c_line) < 0) - tty_ldisc_reinit(tty, N_TTY); - } else - tty_ldisc_kill(tty); + if (reinit) { + if (tty_ldisc_reinit(tty, tty->termios.c_line) < 0) + tty_ldisc_reinit(tty, N_TTY); + } else { + tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT); + tty_ldisc_kill(tty); + tty_ldisc_unlock(tty); } - tty_ldisc_unlock(tty); } /** -- 1.8.5.6.2.g3d8a54e.dirty