Use hotplug support to notify persistent reference holders when a

net_device is unregistered.

src/include/gpxe/netdevice.h

 #include <stdint.h>
 #include <gpxe/list.h>
 #include <gpxe/tables.h>
+#include <gpxe/hotplug.h>
 
 struct pk_buff;
 struct net_device;
 struct net_device {
 	/** List of network devices */
 	struct list_head list;
+
+	/** List of persistent reference holders */
+	struct list_head references;
+
 	/** Transmit packet
 	 *
 	 * @v netdev	Network device

src/net/netdevice.c

 
 	netdev = calloc ( 1, sizeof ( *netdev ) + priv_size );
 	if ( netdev ) {
+		INIT_LIST_HEAD ( &netdev->references );
 		INIT_LIST_HEAD ( &netdev->rx_queue );
 		netdev->priv = ( ( ( void * ) netdev ) + sizeof ( *netdev ) );
 	}
 		free_pkb ( pkb );
 	}
 
+	/* Kill off any persistent references to this device */
+	forget_references ( &netdev->references );
+
 	/* Remove from device list */
 	list_del ( &netdev->list );
 	DBG ( "%s unregistered\n", netdev_name ( netdev ) );