mwifiex: fix memory leak issue when driver unload

After unregister_netdevice() call the request is queued and
reg_state is changed to NETREG_UNREGISTERING.
As we check for NETREG_UNREGISTERED state, free_netdev() never
gets executed causing memory leak.

Initialize "dev->destructor" to free_netdev() to free device
data after unregistration.

Cc: <stable@vger.kernel.org>
Reported-by: NDaniel Drake <dsd@laptop.org>
Tested-by: NDaniel Drake <dsd@laptop.org>
Signed-off-by: NAmitkumar Karwar <akarwar@marvell.com>
Signed-off-by: NBing Zhao <bzhao@marvell.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/cfg80211.c

@@ -2234,9 +2234,6 @@ int mwifiex_del_virtual_intf(struct wiphy *wiphy, struct wireless_dev *wdev)
 	if (wdev->netdev->reg_state == NETREG_REGISTERED)
 		unregister_netdevice(wdev->netdev);
 
-	if (wdev->netdev->reg_state == NETREG_UNREGISTERED)
-		free_netdev(wdev->netdev);
-
 	/* Clear the priv in adapter */
 	priv->netdev = NULL;
 

drivers/net/wireless/mwifiex/main.c

@@ -655,6 +655,7 @@ void mwifiex_init_priv_params(struct mwifiex_private *priv,
 						struct net_device *dev)
 {
 	dev->netdev_ops = &mwifiex_netdev_ops;
+	dev->destructor = free_netdev;
 	/* Initialize private structure */
 	priv->current_key_index = 0;
 	priv->media_connected = false;