sit: percpu stats accounting

Maintain per_cpu tx_bytes, tx_packets, rx_bytes, rx_packets.

Other seldom used fields are kept in netdev->stats structure, possibly
unsafe.

This is a preliminary work to support lockless transmit path, and
correct RX stats, that are already unsafe.

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

1 files changed, 64 insertions, 18 deletions

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 8a0399822230..011ecf55d34e 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -63,8 +63,9 @@
 #define HASH_SIZE  16
 #define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF)
 
-static void ipip6_tunnel_init(struct net_device *dev);
+static int ipip6_tunnel_init(struct net_device *dev);
 static void ipip6_tunnel_setup(struct net_device *dev);
+static void ipip6_dev_free(struct net_device *dev);
 
 static int sit_net_id __read_mostly;
 struct sit_net {
@@ -84,6 +85,33 @@ struct sit_net {
 #define for_each_ip_tunnel_rcu(start) \
         for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
 
+/* often modified stats are per cpu, other are shared (netdev->stats) */
+struct pcpu_tstats {
+        unsigned long   rx_packets;
+        unsigned long   rx_bytes;
+        unsigned long   tx_packets;
+        unsigned long   tx_bytes;
+};
+
+static struct net_device_stats *ipip6_get_stats(struct net_device *dev)
+{
+        struct pcpu_tstats sum = { 0 };
+        int i;
+
+        for_each_possible_cpu(i) {
+                const struct pcpu_tstats *tstats = per_cpu_ptr(dev->tstats, i);
+
+                sum.rx_packets += tstats->rx_packets;
+                sum.rx_bytes   += tstats->rx_bytes;
+                sum.tx_packets += tstats->tx_packets;
+                sum.tx_bytes   += tstats->tx_bytes;
+        }
+        dev->stats.rx_packets = sum.rx_packets;
+        dev->stats.rx_bytes   = sum.rx_bytes;
+        dev->stats.tx_packets = sum.tx_packets;
+        dev->stats.tx_bytes   = sum.tx_bytes;
+        return &dev->stats;
+}
 /*
  * Must be invoked with rcu_read_lock
  */
@@ -214,7 +242,7 @@ static struct ip_tunnel *ipip6_tunnel_locate(struct net *net,
         if (parms->name[0])
                 strlcpy(name, parms->name, IFNAMSIZ);
         else
-                sprintf(name, "sit%%d");
+                strcpy(name, "sit%d");
 
         dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
         if (dev == NULL)
@@ -230,7 +258,8 @@ static struct ip_tunnel *ipip6_tunnel_locate(struct net *net,
         nt = netdev_priv(dev);
 
         nt->parms = *parms;
-        ipip6_tunnel_init(dev);
+        if (ipip6_tunnel_init(dev) < 0)
+                goto failed_free;
         ipip6_tunnel_clone_6rd(dev, sitn);
 
         if (parms->i_flags & SIT_ISATAP)
@@ -245,7 +274,7 @@ static struct ip_tunnel *ipip6_tunnel_locate(struct net *net,
         return nt;
 
 failed_free:
-        free_netdev(dev);
+        ipip6_dev_free(dev);
 failed:
         return NULL;
 }
@@ -546,6 +575,8 @@ static int ipip6_rcv(struct sk_buff *skb)
         tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
                                      iph->saddr, iph->daddr);
         if (tunnel != NULL) {
+                struct pcpu_tstats *tstats;
+
                 secpath_reset(skb);
                 skb->mac_header = skb->network_header;
                 skb_reset_network_header(skb);
@@ -561,7 +592,11 @@ static int ipip6_rcv(struct sk_buff *skb)
                         return 0;
                 }
 
-                skb_tunnel_rx(skb, tunnel->dev);
+                tstats = this_cpu_ptr(tunnel->dev->tstats);
+                tstats->rx_packets++;
+                tstats->rx_bytes += skb->len;
+
+                __skb_tunnel_rx(skb, tunnel->dev);
 
                 ipip6_ecn_decapsulate(iph, skb);
 
@@ -626,14 +661,13 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
                                      struct net_device *dev)
 {
         struct ip_tunnel *tunnel = netdev_priv(dev);
-        struct net_device_stats *stats = &dev->stats;
-        struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
+        struct pcpu_tstats *tstats;
         struct iphdr  *tiph = &tunnel->parms.iph;
         struct ipv6hdr *iph6 = ipv6_hdr(skb);
         u8     tos = tunnel->parms.iph.tos;
         __be16 df = tiph->frag_off;
         struct rtable *rt;                      /* Route to the other host */
-        struct net_device *tdev;                        /* Device to other host */
+        struct net_device *tdev;                /* Device to other host */
         struct iphdr  *iph;                     /* Our new IP header */
         unsigned int max_headroom;              /* The extra header space needed */
         __be32 dst = tiph->daddr;
@@ -704,20 +738,20 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
                                     .oif = tunnel->parms.link,
                                     .proto = IPPROTO_IPV6 };
                 if (ip_route_output_key(dev_net(dev), &rt, &fl)) {
-                        stats->tx_carrier_errors++;
+                        dev->stats.tx_carrier_errors++;
                         goto tx_error_icmp;
                 }
         }
         if (rt->rt_type != RTN_UNICAST) {
                 ip_rt_put(rt);
-                stats->tx_carrier_errors++;
+                dev->stats.tx_carrier_errors++;
                 goto tx_error_icmp;
         }
         tdev = rt->dst.dev;
 
         if (tdev == dev) {
                 ip_rt_put(rt);
-                stats->collisions++;
+                dev->stats.collisions++;
                 goto tx_error;
         }
 
@@ -725,7 +759,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
                 mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr);
 
                 if (mtu < 68) {
-                        stats->collisions++;
+                        dev->stats.collisions++;
                         ip_rt_put(rt);
                         goto tx_error;
                 }
@@ -764,7 +798,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
                 if (!new_skb) {
                         ip_rt_put(rt);
-                        txq->tx_dropped++;
+                        dev->stats.tx_dropped++;
                         dev_kfree_skb(skb);
                         return NETDEV_TX_OK;
                 }
@@ -800,14 +834,14 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
                 iph->ttl        =       iph6->hop_limit;
 
         nf_reset(skb);
-
-        IPTUNNEL_XMIT();
+        tstats = this_cpu_ptr(dev->tstats);
+        __IPTUNNEL_XMIT(tstats, &dev->stats);
         return NETDEV_TX_OK;
 
 tx_error_icmp:
         dst_link_failure(skb);
 tx_error:
-        stats->tx_errors++;
+        dev->stats.tx_errors++;
         dev_kfree_skb(skb);
         return NETDEV_TX_OK;
 }
@@ -1084,12 +1118,19 @@ static const struct net_device_ops ipip6_netdev_ops = {
         .ndo_start_xmit = ipip6_tunnel_xmit,
         .ndo_do_ioctl   = ipip6_tunnel_ioctl,
         .ndo_change_mtu = ipip6_tunnel_change_mtu,
+        .ndo_get_stats  = ipip6_get_stats,
 };
 
+static void ipip6_dev_free(struct net_device *dev)
+{
+        free_percpu(dev->tstats);
+        free_netdev(dev);
+}
+
 static void ipip6_tunnel_setup(struct net_device *dev)
 {
         dev->netdev_ops         = &ipip6_netdev_ops;
-        dev->destructor         = free_netdev;
+        dev->destructor         = ipip6_dev_free;
 
         dev->type               = ARPHRD_SIT;
         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
@@ -1101,7 +1142,7 @@ static void ipip6_tunnel_setup(struct net_device *dev)
         dev->features           |= NETIF_F_NETNS_LOCAL;
 }
 
-static void ipip6_tunnel_init(struct net_device *dev)
+static int ipip6_tunnel_init(struct net_device *dev)
 {
         struct ip_tunnel *tunnel = netdev_priv(dev);
 
@@ -1112,6 +1153,11 @@ static void ipip6_tunnel_init(struct net_device *dev)
         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
 
         ipip6_tunnel_bind_dev(dev);
+        dev->tstats = alloc_percpu(struct pcpu_tstats);
+        if (!dev->tstats)
+                return -ENOMEM;
+
+        return 0;
 }
 
 static void __net_init ipip6_fb_tunnel_init(struct net_device *dev)