dummy: percpu stats and lockless xmit

Converts dummy network device driver to :

- percpu stats

- 64bit stats

- lockless xmit (NETIF_F_LLTX)

- performance features added (NETIF_F_SG | NETIF_F_FRAGLIST |
NETIF_F_TSO | NETIF_F_NO_CSUM | NETIF_F_HIGHDMA)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 55 insertions, 3 deletions

diff --git a/drivers/net/dummy.c b/drivers/net/dummy.c
index 37dcfdc63456..ff2d29b17858 100644
--- a/drivers/net/dummy.c
+++ b/drivers/net/dummy.c
@@ -36,6 +36,7 @@
 #include <linux/moduleparam.h>
 #include <linux/rtnetlink.h>
 #include <net/rtnetlink.h>
+#include <linux/u64_stats_sync.h>
 
 static int numdummies = 1;
 
@@ -55,21 +56,69 @@ static void set_multicast_list(struct net_device *dev)
 {
 }
 
+struct pcpu_dstats {
+        u64                     tx_packets;
+        u64                     tx_bytes;
+        struct u64_stats_sync   syncp;
+};
+
+static struct rtnl_link_stats64 *dummy_get_stats64(struct net_device *dev,
+                                                   struct rtnl_link_stats64 *stats)
+{
+        int i;
+
+        for_each_possible_cpu(i) {
+                const struct pcpu_dstats *dstats;
+                u64 tbytes, tpackets;
+                unsigned int start;
+
+                dstats = per_cpu_ptr(dev->dstats, i);
+                do {
+                        start = u64_stats_fetch_begin(&dstats->syncp);
+                        tbytes = dstats->tx_bytes;
+                        tpackets = dstats->tx_packets;
+                } while (u64_stats_fetch_retry(&dstats->syncp, start));
+                stats->tx_bytes += tbytes;
+                stats->tx_packets += tpackets;
+        }
+        return stats;
+}
 
 static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev)
 {
-        dev->stats.tx_packets++;
-        dev->stats.tx_bytes += skb->len;
+        struct pcpu_dstats *dstats = this_cpu_ptr(dev->dstats);
+
+        u64_stats_update_begin(&dstats->syncp);
+        dstats->tx_packets++;
+        dstats->tx_bytes += skb->len;
+        u64_stats_update_end(&dstats->syncp);
 
         dev_kfree_skb(skb);
         return NETDEV_TX_OK;
 }
 
+static int dummy_dev_init(struct net_device *dev)
+{
+        dev->dstats = alloc_percpu(struct pcpu_dstats);
+        if (!dev->dstats)
+                return -ENOMEM;
+
+        return 0;
+}
+
+static void dummy_dev_free(struct net_device *dev)
+{
+        free_percpu(dev->dstats);
+        free_netdev(dev);
+}
+
 static const struct net_device_ops dummy_netdev_ops = {
+        .ndo_init               = dummy_dev_init,
         .ndo_start_xmit         = dummy_xmit,
         .ndo_validate_addr      = eth_validate_addr,
         .ndo_set_multicast_list = set_multicast_list,
         .ndo_set_mac_address    = dummy_set_address,
+        .ndo_get_stats64        = dummy_get_stats64,
 };
 
 static void dummy_setup(struct net_device *dev)
@@ -78,14 +127,17 @@ static void dummy_setup(struct net_device *dev)
 
         /* Initialize the device structure. */
         dev->netdev_ops = &dummy_netdev_ops;
-        dev->destructor = free_netdev;
+        dev->destructor = dummy_dev_free;
 
         /* Fill in device structure with ethernet-generic values. */
         dev->tx_queue_len = 0;
         dev->flags |= IFF_NOARP;
         dev->flags &= ~IFF_MULTICAST;
+        dev->features   |= NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_TSO;
+        dev->features   |= NETIF_F_NO_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX;
         random_ether_addr(dev->dev_addr);
 }
+
 static int dummy_validate(struct nlattr *tb[], struct nlattr *data[])
 {
         if (tb[IFLA_ADDRESS]) {