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authorGianluca Anzolin <gianluca@sottospazio.it>2013-08-27 18:28:46 +0200
committerGustavo Padovan <gustavo.padovan@collabora.co.uk>2013-09-20 14:17:54 -0500
commit29cd718beba999bda4bdbbf59b5a4d25c07e1547 (patch)
tree7178b36b8086d21b09dd3d21b281eb5770753c63 /net/bluetooth/rfcomm
parentbf5430360ebe4b2d0c51d91f782e649107b502eb (diff)
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Bluetooth: don't release the port in rfcomm_dev_state_change()
When the dlc is closed, rfcomm_dev_state_change() tries to release the port in the case it cannot get a reference to the tty. However this is racy and not even needed. Infact as Peter Hurley points out: 1. Only consider dlcs that are 'stolen' from a connected socket, ie. reused. Allocated dlcs cannot have been closed prior to port activate and so for these dlcs a tty reference will always be avail in rfcomm_dev_state_change() -- except for the conditions covered by #2b below. 2. If a tty was at some point previously created for this rfcomm, then either (a) the tty reference is still avail, so rfcomm_dev_state_change() will perform a hangup. So nothing to do, or, (b) the tty reference is no longer avail, and the tty_port will be destroyed by the last tty_port_put() in rfcomm_tty_cleanup. Again, no action required. 3. Prior to obtaining the dlc lock in rfcomm_dev_add(), rfcomm_dev_state_change() will not 'see' a rfcomm_dev so nothing to do here. 4. After releasing the dlc lock in rfcomm_dev_add(), rfcomm_dev_state_change() will 'see' an incomplete rfcomm_dev if a tty reference could not be obtained. Again, the best thing to do here is nothing. Any future attempted open() will block on rfcomm_dev_carrier_raised(). The unconnected device will exist until released by ioctl(RFCOMMRELEASEDEV). The patch removes the aforementioned code and uses the tty_port_tty_hangup() helper to hangup the tty. 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')
-rw-r--r--net/bluetooth/rfcomm/tty.c35
1 files changed, 2 insertions, 33 deletions
diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index 6d126faf145f..84fcf9fff3ea 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -569,7 +569,6 @@ static void rfcomm_dev_data_ready(struct rfcomm_dlc *dlc, struct sk_buff *skb)
static void rfcomm_dev_state_change(struct rfcomm_dlc *dlc, int err)
{
struct rfcomm_dev *dev = dlc->owner;
- struct tty_struct *tty;
if (!dev)
return;
@@ -581,38 +580,8 @@ static void rfcomm_dev_state_change(struct rfcomm_dlc *dlc, int err)
DPM_ORDER_DEV_AFTER_PARENT);
wake_up_interruptible(&dev->port.open_wait);
- } else if (dlc->state == BT_CLOSED) {
- tty = tty_port_tty_get(&dev->port);
- if (!tty) {
- if (test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags)) {
- /* Drop DLC lock here to avoid deadlock
- * 1. rfcomm_dev_get will take rfcomm_dev_lock
- * but in rfcomm_dev_add there's lock order:
- * 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) {
- rfcomm_dlc_lock(dlc);
- return;
- }
-
- if (!test_and_set_bit(RFCOMM_TTY_RELEASED,
- &dev->flags))
- tty_port_put(&dev->port);
-
- tty_port_put(&dev->port);
- rfcomm_dlc_lock(dlc);
- }
- } else {
- tty_hangup(tty);
- tty_kref_put(tty);
- }
- }
+ } else if (dlc->state == BT_CLOSED)
+ tty_port_tty_hangup(&dev->port, false);
}
static void rfcomm_dev_modem_status(struct rfcomm_dlc *dlc, u8 v24_sig)