[BLUETOOTH]: rfcomm tty BUG_ON() code fix

1) In tty.c the BUG_ON at line 115 will never be called, because the the
   before list_del_init in this same function.
	115          BUG_ON(!list_empty(&dev->list));
   So move the list_del_init to rfcomm_dev_del

2) The rfcomm_dev_del could be called from diffrent path
   (rfcomm_tty_hangup/rfcomm_dev_state_change/rfcomm_release_dev),

   So add another BUG_ON when the rfcomm_dev_del is called more than
   one time.

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index e447651..a6a758d 100644 (file)
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -95,9 +95,10 @@ static void rfcomm_dev_destruct(struct rfcomm_dev *dev)
 
        BT_DBG("dev %p dlc %p", dev, dlc);
 
-       write_lock_bh(&rfcomm_dev_lock);
-       list_del_init(&dev->list);
-       write_unlock_bh(&rfcomm_dev_lock);
+       /* Refcount should only hit zero when called from rfcomm_dev_del()
+          which will have taken us off the list. Everything else are
+          refcounting bugs. */
+       BUG_ON(!list_empty(&dev->list));
 
        rfcomm_dlc_lock(dlc);
        /* Detach DLC if it's owned by this dev */
@@ -109,11 +110,6 @@ static void rfcomm_dev_destruct(struct rfcomm_dev *dev)
 
        tty_unregister_device(rfcomm_tty_driver, dev->id);
 
-       /* Refcount should only hit zero when called from rfcomm_dev_del()
-          which will have taken us off the list. Everything else are
-          refcounting bugs. */
-       BUG_ON(!list_empty(&dev->list));
-
        kfree(dev);
 
        /* It's safe to call module_put() here because socket still
@@ -313,7 +309,15 @@ static void rfcomm_dev_del(struct rfcomm_dev *dev)
 {
        BT_DBG("dev %p", dev);
 
-       set_bit(RFCOMM_TTY_RELEASED, &dev->flags);
+       if (test_bit(RFCOMM_TTY_RELEASED, &dev->flags))
+               BUG_ON(1);
+       else
+               set_bit(RFCOMM_TTY_RELEASED, &dev->flags);
+
+       write_lock_bh(&rfcomm_dev_lock);
+       list_del_init(&dev->list);
+       write_unlock_bh(&rfcomm_dev_lock);
+
        rfcomm_dev_put(dev);
 }