From ece3150dea382c7c961fe2604332ed3474960d25 Mon Sep 17 00:00:00 2001 From: Gianluca Anzolin Date: Mon, 29 Jul 2013 17:08:12 +0200 Subject: [PATCH] Bluetooth: Fix the reference counting of tty_port The tty_port can be released in two cases: when we get a HUP in the functions rfcomm_tty_hangup() and rfcomm_dev_state_change(). Or when the user releases the device in rfcomm_release_dev(). In these cases we set the flag RFCOMM_TTY_RELEASED so that no other function can get a reference to the tty_port. The use of !test_and_set_bit(RFCOMM_TTY_RELEASED) ensures that the 'initial' tty_port reference is only dropped once. The rfcomm_dev_del function is removed becase it isn't used anymore. Signed-off-by: Gianluca Anzolin Reviewed-by: Peter Hurley Signed-off-by: Gustavo Padovan --- net/bluetooth/rfcomm/tty.c | 46 ++++++++++---------------------------- 1 file changed, 12 insertions(+), 34 deletions(-) diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c index 583f7135c811..3e078b73cc22 100644 --- a/net/bluetooth/rfcomm/tty.c +++ b/net/bluetooth/rfcomm/tty.c @@ -324,23 +324,6 @@ free: return err; } -static void rfcomm_dev_del(struct rfcomm_dev *dev) -{ - unsigned long flags; - BT_DBG("dev %p", dev); - - BUG_ON(test_and_set_bit(RFCOMM_TTY_RELEASED, &dev->flags)); - - spin_lock_irqsave(&dev->port.lock, flags); - if (dev->port.count > 0) { - spin_unlock_irqrestore(&dev->port.lock, flags); - return; - } - spin_unlock_irqrestore(&dev->port.lock, flags); - - tty_port_put(&dev->port); -} - /* ---- Send buffer ---- */ static inline unsigned int rfcomm_room(struct rfcomm_dlc *dlc) { @@ -454,8 +437,9 @@ static int rfcomm_release_dev(void __user *arg) tty_kref_put(tty); } - if (!test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags)) - rfcomm_dev_del(dev); + if (!test_and_set_bit(RFCOMM_TTY_RELEASED, &dev->flags)) + tty_port_put(&dev->port); + tty_port_put(&dev->port); return 0; } @@ -607,6 +591,9 @@ static void rfcomm_dev_state_change(struct rfcomm_dlc *dlc, int err) * rfcomm_dev_lock -> dlc lock * 2. tty_port_put will deadlock if it's * the last reference + * + * FIXME: when we release the lock anything + * could happen to dev, even its destruction */ rfcomm_dlc_unlock(dlc); if (rfcomm_dev_get(dev->id) == NULL) { @@ -614,7 +601,10 @@ static void rfcomm_dev_state_change(struct rfcomm_dlc *dlc, int err) return; } - rfcomm_dev_del(dev); + if (!test_and_set_bit(RFCOMM_TTY_RELEASED, + &dev->flags)) + tty_port_put(&dev->port); + tty_port_put(&dev->port); rfcomm_dlc_lock(dlc); } @@ -741,16 +731,10 @@ static void rfcomm_tty_close(struct tty_struct *tty, struct file *filp) { struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data; - if (!dev) - return; - BT_DBG("tty %p dev %p dlc %p opened %d", tty, dev, dev->dlc, dev->port.count); tty_port_close(&dev->port, tty, filp); - - if (test_bit(RFCOMM_TTY_RELEASED, &dev->flags)) - tty_port_put(&dev->port); } static int rfcomm_tty_write(struct tty_struct *tty, const unsigned char *buf, int count) @@ -1050,17 +1034,11 @@ static void rfcomm_tty_hangup(struct tty_struct *tty) BT_DBG("tty %p dev %p", tty, dev); - if (!dev) - return; - tty_port_hangup(&dev->port); - if (test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags)) { - if (rfcomm_dev_get(dev->id) == NULL) - return; - rfcomm_dev_del(dev); + if (test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags) && + !test_and_set_bit(RFCOMM_TTY_RELEASED, &dev->flags)) tty_port_put(&dev->port); - } } static int rfcomm_tty_tiocmget(struct tty_struct *tty) -- 2.39.2