net: dsa: User per-cpu 64-bit statistics

During testing with a background iperf pushing 1Gbit/sec worth of
traffic and having both ifconfig and ethtool collect statistics, we
could see quite frequent deadlocks. Convert the often accessed DSA slave
network devices statistics to per-cpu 64-bit statistics to remove these
deadlocks and provide fast efficient statistics updates.

Fixes: f613ed665bb3 ("net: dsa: Add support for 64-bit statistics")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 0ba842c08dd308cb953d74b7efef5d505584d004..a91e520e735feea054ffbdee59a7a173b7d691ea 100644 (file)
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -190,6 +190,7 @@ static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
 {
        struct dsa_switch_tree *dst = dev->dsa_ptr;
        struct sk_buff *nskb = NULL;
+       struct pcpu_sw_netstats *s;
        struct dsa_slave_priv *p;
 
        if (unlikely(dst == NULL)) {
@@ -213,10 +214,11 @@ static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
        skb->pkt_type = PACKET_HOST;
        skb->protocol = eth_type_trans(skb, skb->dev);
 
-       u64_stats_update_begin(&p->stats64.syncp);
-       p->stats64.rx_packets++;
-       p->stats64.rx_bytes += skb->len;
-       u64_stats_update_end(&p->stats64.syncp);
+       s = this_cpu_ptr(p->stats64);
+       u64_stats_update_begin(&s->syncp);
+       s->rx_packets++;
+       s->rx_bytes += skb->len;
+       u64_stats_update_end(&s->syncp);
 
        netif_receive_skb(skb);
 

diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index 7aa0656296c283fcc4b1c61c5845544e030cd1e5..306cff229def9d67480508d2eef63518698035cc 100644 (file)
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -77,7 +77,7 @@ struct dsa_slave_priv {
        struct sk_buff *        (*xmit)(struct sk_buff *skb,
                                        struct net_device *dev);
 
-       struct pcpu_sw_netstats stats64;
+       struct pcpu_sw_netstats *stats64;
 
        /* DSA port data, such as switch, port index, etc. */
        struct dsa_port         *dp;

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 83252e8426d7d74f6291de01376829156639278a..75c5c5808220cb41e8c8036e6416f70455a15acb 100644 (file)
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -352,12 +352,14 @@ static inline netdev_tx_t dsa_netpoll_send_skb(struct dsa_slave_priv *p,
 static netdev_tx_t dsa_slave_xmit(struct sk_buff *skb, struct net_device *dev)
 {
        struct dsa_slave_priv *p = netdev_priv(dev);
+       struct pcpu_sw_netstats *s;
        struct sk_buff *nskb;
 
-       u64_stats_update_begin(&p->stats64.syncp);
-       p->stats64.tx_packets++;
-       p->stats64.tx_bytes += skb->len;
-       u64_stats_update_end(&p->stats64.syncp);
+       s = this_cpu_ptr(p->stats64);
+       u64_stats_update_begin(&s->syncp);
+       s->tx_packets++;
+       s->tx_bytes += skb->len;
+       u64_stats_update_end(&s->syncp);
 
        /* Transmit function may have to reallocate the original SKB,
         * in which case it must have freed it. Only free it here on error.
@@ -596,15 +598,26 @@ static void dsa_slave_get_ethtool_stats(struct net_device *dev,
 {
        struct dsa_slave_priv *p = netdev_priv(dev);
        struct dsa_switch *ds = p->dp->ds;
+       struct pcpu_sw_netstats *s;
        unsigned int start;
-
-       do {
-               start = u64_stats_fetch_begin_irq(&p->stats64.syncp);
-               data[0] = p->stats64.tx_packets;
-               data[1] = p->stats64.tx_bytes;
-               data[2] = p->stats64.rx_packets;
-               data[3] = p->stats64.rx_bytes;
-       } while (u64_stats_fetch_retry_irq(&p->stats64.syncp, start));
+       int i;
+
+       for_each_possible_cpu(i) {
+               u64 tx_packets, tx_bytes, rx_packets, rx_bytes;
+
+               s = per_cpu_ptr(p->stats64, i);
+               do {
+                       start = u64_stats_fetch_begin_irq(&s->syncp);
+                       tx_packets = s->tx_packets;
+                       tx_bytes = s->tx_bytes;
+                       rx_packets = s->rx_packets;
+                       rx_bytes = s->rx_bytes;
+               } while (u64_stats_fetch_retry_irq(&s->syncp, start));
+               data[0] += tx_packets;
+               data[1] += tx_bytes;
+               data[2] += rx_packets;
+               data[3] += rx_bytes;
+       }
        if (ds->ops->get_ethtool_stats)
                ds->ops->get_ethtool_stats(ds, p->dp->index, data + 4);
 }
@@ -879,16 +892,28 @@ static void dsa_slave_get_stats64(struct net_device *dev,
                                  struct rtnl_link_stats64 *stats)
 {
        struct dsa_slave_priv *p = netdev_priv(dev);
+       struct pcpu_sw_netstats *s;
        unsigned int start;
+       int i;
 
        netdev_stats_to_stats64(stats, &dev->stats);
-       do {
-               start = u64_stats_fetch_begin_irq(&p->stats64.syncp);
-               stats->tx_packets = p->stats64.tx_packets;
-               stats->tx_bytes = p->stats64.tx_bytes;
-               stats->rx_packets = p->stats64.rx_packets;
-               stats->rx_bytes = p->stats64.rx_bytes;
-       } while (u64_stats_fetch_retry_irq(&p->stats64.syncp, start));
+       for_each_possible_cpu(i) {
+               u64 tx_packets, tx_bytes, rx_packets, rx_bytes;
+
+               s = per_cpu_ptr(p->stats64, i);
+               do {
+                       start = u64_stats_fetch_begin_irq(&s->syncp);
+                       tx_packets = s->tx_packets;
+                       tx_bytes = s->tx_bytes;
+                       rx_packets = s->rx_packets;
+                       rx_bytes = s->rx_bytes;
+               } while (u64_stats_fetch_retry_irq(&s->syncp, start));
+
+               stats->tx_packets += tx_packets;
+               stats->tx_bytes += tx_bytes;
+               stats->rx_packets += rx_packets;
+               stats->rx_bytes += rx_bytes;
+       }
 }
 
 void dsa_cpu_port_ethtool_init(struct ethtool_ops *ops)
@@ -1202,7 +1227,11 @@ int dsa_slave_create(struct dsa_switch *ds, struct device *parent,
        slave_dev->vlan_features = master->vlan_features;
 
        p = netdev_priv(slave_dev);
-       u64_stats_init(&p->stats64.syncp);
+       p->stats64 = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
+       if (!p->stats64) {
+               free_netdev(slave_dev);
+               return -ENOMEM;
+       }
        p->dp = &ds->ports[port];
        INIT_LIST_HEAD(&p->mall_tc_list);
        p->xmit = dst->tag_ops->xmit;
@@ -1217,6 +1246,7 @@ int dsa_slave_create(struct dsa_switch *ds, struct device *parent,
                netdev_err(master, "error %d registering interface %s\n",
                           ret, slave_dev->name);
                ds->ports[port].netdev = NULL;
+               free_percpu(p->stats64);
                free_netdev(slave_dev);
                return ret;
        }
@@ -1227,6 +1257,7 @@ int dsa_slave_create(struct dsa_switch *ds, struct device *parent,
        if (ret) {
                netdev_err(master, "error %d setting up slave phy\n", ret);
                unregister_netdev(slave_dev);
+               free_percpu(p->stats64);
                free_netdev(slave_dev);
                return ret;
        }
@@ -1249,6 +1280,7 @@ void dsa_slave_destroy(struct net_device *slave_dev)
                        of_phy_deregister_fixed_link(port_dn);
        }
        unregister_netdev(slave_dev);
+       free_percpu(p->stats64);
        free_netdev(slave_dev);
 }