[Bluetooth] Keep rfcomm_dev on the list until it is freed

This patch changes the RFCOMM TTY release process so that the TTY is kept
on the list until it is really freed. A new device flag is used to keep
track of released TTYs.
Signed-off-by: NVille Tervo <ville.tervo@nokia.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/rfcomm.h

@@ -323,6 +323,7 @@ int  rfcomm_connect_ind(struct rfcomm_session *s, u8 channel, struct rfcomm_dlc
 #define RFCOMM_RELEASE_ONHUP  1
 #define RFCOMM_HANGUP_NOW     2
 #define RFCOMM_TTY_ATTACHED   3
+#define RFCOMM_TTY_RELEASED   4
 
 struct rfcomm_dev_req {
 	s16      dev_id;

net/bluetooth/rfcomm/tty.c

@@ -95,6 +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);
+
 	rfcomm_dlc_lock(dlc);
 	/* Detach DLC if it's owned by this dev */
 	if (dlc->owner == dev)
@@ -156,8 +160,13 @@ static inline struct rfcomm_dev *rfcomm_dev_get(int id)
 	read_lock(&rfcomm_dev_lock);
 
 	dev = __rfcomm_dev_get(id);
-	if (dev)
+
+	if (dev) {
+		if (test_bit(RFCOMM_TTY_RELEASED, &dev->flags))
+			dev = NULL;
+		else
 			rfcomm_dev_hold(dev);
+	}
 
 	read_unlock(&rfcomm_dev_lock);
 
@@ -265,6 +274,12 @@ static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc)
 
 	dev->tty_dev = tty_register_device(rfcomm_tty_driver, dev->id, NULL);
 
+	if (IS_ERR(dev->tty_dev)) {
+		list_del(&dev->list);
+		kfree(dev);
+		return PTR_ERR(dev->tty_dev);
+	}
+
 	return dev->id;
 }
 
@@ -272,10 +287,7 @@ static void rfcomm_dev_del(struct rfcomm_dev *dev)
 {
 	BT_DBG("dev %p", dev);
 
-	write_lock_bh(&rfcomm_dev_lock);
-	list_del_init(&dev->list);
-	write_unlock_bh(&rfcomm_dev_lock);
-
+	set_bit(RFCOMM_TTY_RELEASED, &dev->flags);
 	rfcomm_dev_put(dev);
 }
 
@@ -329,7 +341,7 @@ static int rfcomm_create_dev(struct sock *sk, void __user *arg)
 	if (copy_from_user(&req, arg, sizeof(req)))
 		return -EFAULT;
 
-	BT_DBG("sk %p dev_id %id flags 0x%x", sk, req.dev_id, req.flags);
+	BT_DBG("sk %p dev_id %d flags 0x%x", sk, req.dev_id, req.flags);
 
 	if (req.flags != NOCAP_FLAGS && !capable(CAP_NET_ADMIN))
 		return -EPERM;
@@ -370,7 +382,7 @@ static int rfcomm_release_dev(void __user *arg)
 	if (copy_from_user(&req, arg, sizeof(req)))
 		return -EFAULT;
 
-	BT_DBG("dev_id %id flags 0x%x", req.dev_id, req.flags);
+	BT_DBG("dev_id %d flags 0x%x", req.dev_id, req.flags);
 
 	if (!(dev = rfcomm_dev_get(req.dev_id)))
 		return -ENODEV;
@@ -419,6 +431,8 @@ static int rfcomm_get_dev_list(void __user *arg)
 
 	list_for_each(p, &rfcomm_dev_list) {
 		struct rfcomm_dev *dev = list_entry(p, struct rfcomm_dev, list);
+		if (test_bit(RFCOMM_TTY_RELEASED, &dev->flags))
+			continue;
 		(di + n)->id      = dev->id;
 		(di + n)->flags   = dev->flags;
 		(di + n)->state   = dev->dlc->state;