| Date | Tue, 07 Dec 2010 16:58:34 -0800 | From | Greg KH <> | Subject | [137/289] tty_ldisc: Fix BUG() on hangup |
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2.6.36-stable review patch. If anyone has any objections, please let us know.
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From: =?UTF-8?q?Philippe=20R=C3=A9tornaz?= <philippe.retornaz@epfl.ch>
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 <philippe.retornaz@epfl.ch> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/char/tty_ldisc.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-)
--- a/drivers/char/tty_ldisc.c +++ b/drivers/char/tty_ldisc.c @@ -743,9 +743,12 @@ 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); @@ -753,10 +756,10 @@ 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; } /** @@ -831,13 +834,16 @@ 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);
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