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authorGianluca Anzolin <gianluca@sottospazio.it>2013-07-29 19:08:12 +0400
committerGustavo Padovan <gustavo.padovan@collabora.co.uk>2013-08-21 18:47:07 +0400
commitece3150dea382c7c961fe2604332ed3474960d25 (patch)
tree169cd2b7e414a06f7e35b522ab3a4fa4105ea8ca /net/bluetooth
parentcad348a17e170451ea8688b532a6ca3e98c63b60 (diff)
downloadlinux-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')
-rw-r--r--net/bluetooth/rfcomm/tty.c46
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)