Commit 5f6b4e14 authored by Florian Fainelli's avatar Florian Fainelli Committed by David S. Miller
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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: f613ed66 ("net: dsa: Add support for 64-bit statistics")
Signed-off-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent eaf6dc03

net/dsa/dsa.c

+6 −4
Original line number Diff line number Diff line
@@ -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);

net/dsa/dsa_priv.h

+1 −1
Original line number Diff line number Diff line
@@ -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;

net/dsa/slave.c

+52 −20
Original line number Diff line number Diff line
@@ -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;

	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(&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));

			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);

	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(&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));

			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);

}

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