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Date: Wed, 27 Oct 2010 17:13:21 +0200 From: Philippe Rétornaz <philippe.retornaz@...l.ch> To: "Greg Kroah-Hartman" <gregkh@...e.de> Cc: Alan Cox <alan@...ux.intel.com>, linux-kernel@...r.kernel.org Subject: [PATCH] tty_ldisc: Fix BUG() on hangup 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 <philippe.retornaz@...l.ch> Acked-by: Alan Cox <alan@...ux.intel.com> --- --- linux-2.6.34.x86_64/drivers/char/tty_ldisc.c.orig 2010-05-16 23:17:36.000000000 +0200 +++ linux-2.6.34.x86_64/drivers/char/tty_ldisc.c 2010-10-15 10:48:01.871721197 +0200 @@ -712,9 +712,12 @@ 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); @@ -722,10 +725,10 @@ 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; } /** @@ -787,13 +790,16 @@ 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@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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