eth: remove usb-ethernet devices before re-enumerating them

Fix the crash when running several times usb_init() with a USB ethernet
device plugged.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
Tested-by: Wolfgang Grandegger <wg@denx.de>

drivers/usb/eth/usb_ether.c

@@ -127,8 +127,11 @@ int usb_host_eth_scan(int mode)
 
 	old_async = usb_disable_asynch(1); /* asynch transfer not allowed */
 
-	for (i = 0; i < USB_MAX_ETH_DEV; i++)
-		memset(&usb_eth[i], 0, sizeof(usb_eth[i]));
+	/* unregister a previously detected device */
+	for (i = 0; i < usb_max_eth_dev; i++)
+		eth_unregister(&usb_eth[i].eth_dev);
+
+	memset(usb_eth, 0, sizeof(usb_eth));
 
 	for (i = 0; prob_dev[i].probe; i++) {
 		if (prob_dev[i].before_probe)

include/net.h

@@ -96,6 +96,7 @@ struct eth_device {
 
 extern int eth_initialize(bd_t *bis);	/* Initialize network subsystem */
 extern int eth_register(struct eth_device* dev);/* Register network device */
+extern int eth_unregister(struct eth_device *dev);/* Remove network device */
 extern void eth_try_another(int first_restart);	/* Change the device */
 extern void eth_set_current(void);		/* set nterface to ethcur var */
 extern struct eth_device *eth_get_dev(void);	/* get the current device MAC */

net/eth.c

@@ -224,6 +224,35 @@ int eth_register(struct eth_device *dev)
 	return 0;
 }
 
+int eth_unregister(struct eth_device *dev)
+{
+	struct eth_device *cur;
+
+	/* No device */
+	if (!eth_devices)
+		return -1;
+
+	for (cur = eth_devices; cur->next != eth_devices && cur->next != dev;
+	     cur = cur->next)
+		;
+
+	/* Device not found */
+	if (cur->next != dev)
+		return -1;
+
+	cur->next = dev->next;
+
+	if (eth_devices == dev)
+		eth_devices = dev->next == eth_devices ? NULL : dev->next;
+
+	if (eth_current == dev) {
+		eth_current = eth_devices;
+		eth_current_changed();
+	}
+
+	return 0;
+}
+
 int eth_initialize(bd_t *bis)
 {
 	int num_devices = 0;