diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index 3b43bfd..cf17238 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -85,7 +85,7 @@ static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
 		return 0;
 	}
 #endif
-	dev->last_rx = jiffies;
+	netif_set_last_rx(dev);
 
 	/* it's OK to use per_cpu_ptr() because BHs are off */
 	pcpu_lstats = dev->ml_priv;
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c8bcb59..6729865 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -849,6 +849,22 @@ static inline void *netdev_priv(const struct net_device *dev)
 #define SET_NETDEV_DEV(net, pdev)	((net)->dev.parent = (pdev))
 
 /**
+ *	netif_set_last_rx - Set last_rx field of a device
+ *	@dev:  network device
+ *
+ * Instead of setting net->last_rx to jiffies, drivers should call this helper
+ * to avoid dirtying a cache line if last_rx already has the current jiffies
+ */
+static inline void netif_set_last_rx(struct net_device *dev)
+{
+#ifdef CONFIG_SMP
+	if (dev->last_rx == jiffies)
+		return;
+#endif
+	dev->last_rx = jiffies;
+}
+
+/**
  *	netif_napi_add - initialize a napi context
  *	@dev:  network device
  *	@napi: napi context