[NET] loopback: minor statistics optimization

The loopback device status structure is a singleton and doesn't
need to be allocated. Add ethtool_ops hooks to show checksum always on,
and make ethtool_ops const.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index f429b19..4178b4b 100644 (file)
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -161,15 +161,13 @@ static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
        return(0);
 }
 
+static struct net_device_stats loopback_stats;
+
 static struct net_device_stats *get_stats(struct net_device *dev)
 {
-       struct net_device_stats *stats = dev->priv;
+       struct net_device_stats *stats = &loopback_stats;
        int i;
 
-       if (!stats) {
-               return NULL;
-       }
-
        memset(stats, 0, sizeof(struct net_device_stats));
 
        for_each_possible_cpu(i) {
@@ -185,19 +183,28 @@ static struct net_device_stats *get_stats(struct net_device *dev)
        return stats;
 }
 
-static u32 loopback_get_link(struct net_device *dev)
+static u32 always_on(struct net_device *dev)
 {
        return 1;
 }
 
 static const struct ethtool_ops loopback_ethtool_ops = {
-       .get_link               = loopback_get_link,
+       .get_link               = always_on,
        .get_tso                = ethtool_op_get_tso,
        .set_tso                = ethtool_op_set_tso,
+       .get_tx_csum            = always_on,
+       .get_sg                 = always_on,
+       .get_rx_csum            = always_on,
 };
 
+/*
+ * The loopback device is special. There is only one instance and
+ * it is statically allocated. Don't do this for other devices.
+ */
 struct net_device loopback_dev = {
        .name                   = "lo",
+       .get_stats              = &get_stats,
+       .priv                   = &loopback_stats,
        .mtu                    = (16 * 1024) + 20 + 20 + 12,
        .hard_start_xmit        = loopback_xmit,
        .hard_header            = eth_header,
@@ -221,16 +228,6 @@ struct net_device loopback_dev = {
 /* Setup and register the loopback device. */
 int __init loopback_init(void)
 {
-       struct net_device_stats *stats;
-
-       /* Can survive without statistics */
-       stats = kmalloc(sizeof(struct net_device_stats), GFP_KERNEL);
-       if (stats) {
-               memset(stats, 0, sizeof(struct net_device_stats));
-               loopback_dev.priv = stats;
-               loopback_dev.get_stats = &get_stats;
-       }
-
        return register_netdev(&loopback_dev);
 };