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author | Gianluca Anzolin <gianluca@sottospazio.it> | 2013-07-29 19:08:12 +0400 |
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committer | Gustavo Padovan <gustavo.padovan@collabora.co.uk> | 2013-08-21 18:47:07 +0400 |
commit | ece3150dea382c7c961fe2604332ed3474960d25 (patch) | |
tree | 169cd2b7e414a06f7e35b522ab3a4fa4105ea8ca /net/bluetooth/rfcomm/tty.c | |
parent | cad348a17e170451ea8688b532a6ca3e98c63b60 (diff) | |
download | linux-ece3150dea382c7c961fe2604332ed3474960d25.tar.xz |
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 <gianluca@sottospazio.it>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Diffstat (limited to 'net/bluetooth/rfcomm/tty.c')
-rw-r--r-- | net/bluetooth/rfcomm/tty.c | 46 |
1 files 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) |