Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755034Ab0LLXqk (ORCPT ); Sun, 12 Dec 2010 18:46:40 -0500 Received: from one.firstfloor.org ([213.235.205.2]:36084 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754980Ab0LLXqh (ORCPT ); Sun, 12 Dec 2010 18:46:37 -0500 From: Andi Kleen References: <201012131244.547034648@firstfloor.org> In-Reply-To: <201012131244.547034648@firstfloor.org> To: philippe.retornaz@epfl.ch, philippe.retornaz@epfl.ch, philippe.retornaz@epfl.ch, alan@linux.intel.com, gregkh@suse.de, ak@linux.intel.com, linux-kernel@vger.kernel.org, stable@kernel.org Subject: [PATCH] [95/223] tty_ldisc: Fix BUG() on hangup Message-Id: <20101212234635.36C7AB27BF@basil.firstfloor.org> Date: Mon, 13 Dec 2010 00:46:35 +0100 (CET) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2553 Lines: 80 2.6.35-longterm review patch. If anyone has any objections, please let me know. ------------------ From: =?UTF-8?q?Philippe=20R=C3=A9tornaz?= commit 1c95ba1e1de7edffc0c4e275e147f1a9eb1f81ae upstream. A kernel BUG when bluetooth rfcomm connection drop while the associated serial port is open is sometime triggered. It seems that the line discipline can disappear between the tty_ldisc_put and tty_ldisc_get. This patch fall back to the N_TTY line discipline if the previous discipline is not available anymore. Signed-off-by: Philippe Retornaz Acked-by: Alan Cox Signed-off-by: Greg Kroah-Hartman Signed-off-by: Andi Kleen --- drivers/char/tty_ldisc.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) Index: linux/drivers/char/tty_ldisc.c =================================================================== --- linux.orig/drivers/char/tty_ldisc.c +++ linux/drivers/char/tty_ldisc.c @@ -741,9 +741,12 @@ static void tty_reset_termios(struct tty * state closed */ -static void tty_ldisc_reinit(struct tty_struct *tty, int ldisc) +static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc) { - struct tty_ldisc *ld; + struct tty_ldisc *ld = tty_ldisc_get(ldisc); + + if (IS_ERR(ld)) + return -1; tty_ldisc_close(tty, tty->ldisc); tty_ldisc_put(tty->ldisc); @@ -751,10 +754,10 @@ static void tty_ldisc_reinit(struct tty_ /* * Switch the line discipline back */ - ld = tty_ldisc_get(ldisc); - BUG_ON(IS_ERR(ld)); tty_ldisc_assign(tty, ld); tty_set_termios_ldisc(tty, ldisc); + + return 0; } /** @@ -816,13 +819,16 @@ void tty_ldisc_hangup(struct tty_struct a FIXME */ if (tty->ldisc) { /* Not yet closed */ if (reset == 0) { - tty_ldisc_reinit(tty, tty->termios->c_line); - err = tty_ldisc_open(tty, tty->ldisc); + + if (!tty_ldisc_reinit(tty, tty->termios->c_line)) + err = tty_ldisc_open(tty, tty->ldisc); + else + err = 1; } /* If the re-open fails or we reset then go to N_TTY. The N_TTY open cannot fail */ if (reset || err) { - tty_ldisc_reinit(tty, N_TTY); + BUG_ON(tty_ldisc_reinit(tty, N_TTY)); WARN_ON(tty_ldisc_open(tty, tty->ldisc)); } tty_ldisc_enable(tty); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/