net: usbnet: Leverage core stats allocator

With commit 34d21de9 ("net: Move {l,t,d}stats allocation to core and
convert veth & vrf"), stats allocation could be done on net core
instead of in this driver.

With this new approach, the driver doesn't have to bother with error
handling (allocation failure checking, making sure free happens in the
right spot, etc). This is core responsibility now.

Remove the allocation in the usbnet driver and leverage the network
core allocation instead.
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Oliver Neukum <oneukum@suse.com>
Link: https://lore.kernel.org/r/20240306142643.2429409-1-leitao@debian.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/usb/usbnet.c

@@ -1633,7 +1633,6 @@ void usbnet_disconnect (struct usb_interface *intf)
 	usb_free_urb(dev->interrupt);
 	kfree(dev->padding_pkt);
 
-	free_percpu(net->tstats);
 	free_netdev(net);
 }
 EXPORT_SYMBOL_GPL(usbnet_disconnect);
@@ -1710,10 +1709,6 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
 	dev->rx_speed = SPEED_UNSET;
 	dev->tx_speed = SPEED_UNSET;
 
-	net->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
-	if (!net->tstats)
-		goto out0;
-
 	dev->msg_enable = netif_msg_init (msg_level, NETIF_MSG_DRV
 				| NETIF_MSG_PROBE | NETIF_MSG_LINK);
 	init_waitqueue_head(&dev->wait);
@@ -1743,6 +1738,7 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
 	net->netdev_ops = &usbnet_netdev_ops;
 	net->watchdog_timeo = TX_TIMEOUT_JIFFIES;
 	net->ethtool_ops = &usbnet_ethtool_ops;
+	net->pcpu_stat_type = NETDEV_PCPU_STAT_TSTATS;
 
 	// allow device-specific bind/init procedures
 	// NOTE net->name still not usable ...
@@ -1861,8 +1857,6 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
 	 */
 	cancel_work_sync(&dev->kevent);
 	del_timer_sync(&dev->delay);
-	free_percpu(net->tstats);
-out0:
 	free_netdev(net);
 out:
 	return status;