[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>

1 files changed, 13 insertions, 9 deletions

diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index e447651a2dbe..a6a758dd1f7d 100644
--- 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);
 }