net: usbnet: Fix the wrong netif_carrier_on() call

The commit referenced in the Fixes tag causes usbnet to malfunction
(identified via git bisect). Post-commit, my external RJ45 LAN cable
fails to connect. Linus also reported the same issue after pulling that
commit.

The code has a logic error: netif_carrier_on() is only called when the
link is already on. Fix this by moving the netif_carrier_on() call
outside the if-statement entirely. This ensures it is always called
when EVENT_LINK_CARRIER_ON is set and properly clears it regardless
of the link state.

Cc: [email protected]
Cc: Armando Budianto <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Suggested-by: Linus Torvalds <[email protected]>
Link: https://lore.kernel.org/all/CAHk-=wjqL4uF0MG_c8+xHX1Vv8==sPYQrtzbdA3kzi96284nuQ@mail.gmail.com
Closes: https://lore.kernel.org/netdev/CAHk-=wjKh8X4PT_mU1kD4GQrbjivMfPn-_hXa6han_BTDcXddw@mail.gmail.com
Closes: https://lore.kernel.org/netdev/[email protected]
Fixes: 0d9cfc9 ("net: usbnet: Avoid potential RCU stall on LINK_CHANGE event")
Signed-off-by: Ammar Faizi <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: ammarfaizi2

drivers/net/usb/usbnet.c

@@ -1120,6 +1120,9 @@ static void __handle_link_change(struct usbnet *dev)
 	if (!test_bit(EVENT_DEV_OPEN, &dev->flags))
 		return;
 
+	if (test_and_clear_bit(EVENT_LINK_CARRIER_ON, &dev->flags))
+		netif_carrier_on(dev->net);
+
 	if (!netif_carrier_ok(dev->net)) {
 		/* kill URBs for reading packets to save bus bandwidth */
 		unlink_urbs(dev, &dev->rxq);
@@ -1129,9 +1132,6 @@ static void __handle_link_change(struct usbnet *dev)
 		 * tx queue is stopped by netcore after link becomes off
 		 */
 	} else {
-		if (test_and_clear_bit(EVENT_LINK_CARRIER_ON, &dev->flags))
-			netif_carrier_on(dev->net);
-
 		/* submitting URBs for reading packets */
 		queue_work(system_bh_wq, &dev->bh_work);
 	}