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>

1 files changed, 6 insertions, 4 deletions

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 0ba842c08dd3..a91e520e735f 100644
--- 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);