quoted

+static void ngbe_reinit_locked(struct wx *wx)
+{
+	int err = 0;
+
+	netif_trans_update(wx->netdev);
+
+	err = wx_set_state_reset(wx);
+	if (err) {
+		wx_err(wx, "wait device reset timeout\n");
+		return;
+	}
+
+	ngbe_down(wx);
+	ngbe_up(wx);
+
+	clear_bit(WX_STATE_RESETTING, wx->state);
+}

Is it possible to use a standard kernel mutex here instead of a bit flag for
synchronization?

Looking at the underlying implementation of wx_set_state_reset(), it relies
on an open-coded polling loop:

static inline int wx_set_state_reset(struct wx *wx)
{
        u8 timeout = 50;

        while (test_and_set_bit(WX_STATE_RESETTING, wx->state)) {
                timeout--;
                if (!timeout)
                        return -EBUSY;

                usleep_range(1000, 2000);
        }

        return 0;
}

Using a bit flag and a sleep-polling loop to guard a teardown and bringup
section acts as an ad-hoc lock. This approach bypasses standard kernel
synchronization guarantees and prevents lockdep from analyzing the lock
ordering.

Since this context is allowed to sleep, could this section be protected by
a standard mutex instead?

I think using a state flag here would be better. Because other code paths
(like watchdog) need to check if a reset is in process without taking a lock.