tg3: Fix race condition in tg3_get_stats64()

Spinlock should be taken before checking for tp->hw_stats.

Signed-off-by: Michael Chan <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/broadcom/tg3.c

···
 {
 	struct tg3 *tp = netdev_priv(dev);
 
-	if (!tp->hw_stats)
-		return &tp->net_stats_prev;
-
 	spin_lock_bh(&tp->lock);
+	if (!tp->hw_stats) {
+		spin_unlock_bh(&tp->lock);
+		return &tp->net_stats_prev;
+	}
+
 	tg3_get_nstats(tp, stats);
 	spin_unlock_bh(&tp->lock);