xen: convert to 64 bit stats interface

Convert xen driver to 64 bit statistics interface.
Use stats_sync to ensure that 64 bit update is read atomically on 32 bit platform.
Put hot statistics into per-cpu table.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 64 insertions, 5 deletions

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index d29365a232a1..d7c8a98daff6 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -70,6 +70,14 @@ struct netfront_cb {
 #define NET_RX_RING_SIZE __CONST_RING_SIZE(xen_netif_rx, PAGE_SIZE)
 #define TX_MAX_TARGET min_t(int, NET_RX_RING_SIZE, 256)
 
+struct netfront_stats {
+        u64                     rx_packets;
+        u64                     tx_packets;
+        u64                     rx_bytes;
+        u64                     tx_bytes;
+        struct u64_stats_sync   syncp;
+};
+
 struct netfront_info {
         struct list_head list;
         struct net_device *netdev;
@@ -122,6 +130,8 @@ struct netfront_info {
         struct mmu_update rx_mmu[NET_RX_RING_SIZE];
 
         /* Statistics */
+        struct netfront_stats __percpu *stats;
+
         unsigned long rx_gso_checksum_fixup;
 };
 
@@ -468,6 +478,7 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
         unsigned short id;
         struct netfront_info *np = netdev_priv(dev);
+        struct netfront_stats *stats = this_cpu_ptr(np->stats);
         struct xen_netif_tx_request *tx;
         struct xen_netif_extra_info *extra;
         char *data = skb->data;
@@ -552,8 +563,10 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
         if (notify)
                 notify_remote_via_irq(np->netdev->irq);
 
-        dev->stats.tx_bytes += skb->len;
-        dev->stats.tx_packets++;
+        u64_stats_update_begin(&stats->syncp);
+        stats->tx_bytes += skb->len;
+        stats->tx_packets++;
+        u64_stats_update_end(&stats->syncp);
 
         /* Note: It is not safe to access skb after xennet_tx_buf_gc()! */
         xennet_tx_buf_gc(dev);
@@ -847,6 +860,8 @@ out:
 static int handle_incoming_queue(struct net_device *dev,
                                  struct sk_buff_head *rxq)
 {
+        struct netfront_info *np = netdev_priv(dev);
+        struct netfront_stats *stats = this_cpu_ptr(np->stats);
         int packets_dropped = 0;
         struct sk_buff *skb;
 
@@ -871,8 +886,10 @@ static int handle_incoming_queue(struct net_device *dev,
                         continue;
                 }
 
-                dev->stats.rx_packets++;
-                dev->stats.rx_bytes += skb->len;
+                u64_stats_update_begin(&stats->syncp);
+                stats->rx_packets++;
+                stats->rx_bytes += skb->len;
+                u64_stats_update_end(&stats->syncp);
 
                 /* Pass it up. */
                 netif_receive_skb(skb);
@@ -1034,6 +1051,38 @@ static int xennet_change_mtu(struct net_device *dev, int mtu)
         return 0;
 }
 
+static struct rtnl_link_stats64 *xennet_get_stats64(struct net_device *dev,
+                                                    struct rtnl_link_stats64 *tot)
+{
+        struct netfront_info *np = netdev_priv(dev);
+        int cpu;
+
+        for_each_possible_cpu(cpu) {
+                struct netfront_stats *stats = per_cpu_ptr(np->stats, cpu);
+                u64 rx_packets, rx_bytes, tx_packets, tx_bytes;
+                unsigned int start;
+
+                do {
+                        start = u64_stats_fetch_begin_bh(&stats->syncp);
+
+                        rx_packets = stats->rx_packets;
+                        tx_packets = stats->tx_packets;
+                        rx_bytes = stats->rx_bytes;
+                        tx_bytes = stats->tx_bytes;
+                } while (u64_stats_fetch_retry_bh(&stats->syncp, start));
+
+                tot->rx_packets += rx_packets;
+                tot->tx_packets += tx_packets;
+                tot->rx_bytes   += rx_bytes;
+                tot->tx_bytes   += tx_bytes;
+        }
+
+        tot->rx_errors  = dev->stats.rx_errors;
+        tot->tx_dropped = dev->stats.tx_dropped;
+
+        return tot;
+}
+
 static void xennet_release_tx_bufs(struct netfront_info *np)
 {
         struct sk_buff *skb;
@@ -1182,6 +1231,7 @@ static const struct net_device_ops xennet_netdev_ops = {
         .ndo_stop            = xennet_close,
         .ndo_start_xmit      = xennet_start_xmit,
         .ndo_change_mtu      = xennet_change_mtu,
+        .ndo_get_stats64     = xennet_get_stats64,
         .ndo_set_mac_address = eth_mac_addr,
         .ndo_validate_addr   = eth_validate_addr,
         .ndo_fix_features    = xennet_fix_features,
@@ -1216,6 +1266,11 @@ static struct net_device * __devinit xennet_create_dev(struct xenbus_device *dev
         np->rx_refill_timer.data = (unsigned long)netdev;
         np->rx_refill_timer.function = rx_refill_timeout;
 
+        err = -ENOMEM;
+        np->stats = alloc_percpu(struct netfront_stats);
+        if (np->stats == NULL)
+                goto exit;
+
         /* Initialise tx_skbs as a free chain containing every entry. */
         np->tx_skb_freelist = 0;
         for (i = 0; i < NET_TX_RING_SIZE; i++) {
@@ -1234,7 +1289,7 @@ static struct net_device * __devinit xennet_create_dev(struct xenbus_device *dev
                                           &np->gref_tx_head) < 0) {
                 printk(KERN_ALERT "#### netfront can't alloc tx grant refs\n");
                 err = -ENOMEM;
-                goto exit;
+                goto exit_free_stats;
         }
         /* A grant for every rx ring slot */
         if (gnttab_alloc_grant_references(RX_MAX_TARGET,
@@ -1270,6 +1325,8 @@ static struct net_device * __devinit xennet_create_dev(struct xenbus_device *dev
 
  exit_free_tx:
         gnttab_free_grant_references(np->gref_tx_head);
+ exit_free_stats:
+        free_percpu(np->stats);
  exit:
         free_netdev(netdev);
         return ERR_PTR(err);
@@ -1869,6 +1926,8 @@ static int __devexit xennet_remove(struct xenbus_device *dev)
 
         xennet_sysfs_delif(info->netdev);
 
+        free_percpu(info->stats);
+
         free_netdev(info->netdev);
 
         return 0;