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SubjectRe: [PATCH net-next] net: dsa: Add support for 64-bit statistics
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On 08/01/2017 03:00 PM, Florian Fainelli wrote:
> DSA slave network devices maintain a pair of bytes and packets counters
> for each directions, but these are not 64-bit capable. Re-use
> pcpu_sw_netstats which contains exactly what we need for that purpose
> and update the code path to report 64-bit capable statistics.

Humm, I do see a long time for ifconfig/ethtool -S to complete after
having transfered over 250GiB of data, the locking looks correct to me
in that statistics for the RX path are updated from softIRQ context
(napi_gro_receive/netif_receive_skb) but maybe I did misunderstand
whether the softirq/IRQ context applies to the producer and not the
reader...

>
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---
> net/dsa/dsa.c | 8 ++++++--
> net/dsa/dsa_priv.h | 2 ++
> net/dsa/slave.c | 38 +++++++++++++++++++++++++++++++-------
> 3 files changed, 39 insertions(+), 9 deletions(-)
>
> diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
> index a55e2e4087a4..0ba842c08dd3 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 dsa_slave_priv *p;
>
> if (unlikely(dst == NULL)) {
> kfree_skb(skb);
> @@ -207,12 +208,15 @@ static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
> }
>
> skb = nskb;
> + p = netdev_priv(skb->dev);
> skb_push(skb, ETH_HLEN);
> skb->pkt_type = PACKET_HOST;
> skb->protocol = eth_type_trans(skb, skb->dev);
>
> - skb->dev->stats.rx_packets++;
> - skb->dev->stats.rx_bytes += skb->len;
> + u64_stats_update_begin(&p->stats64.syncp);
> + p->stats64.rx_packets++;
> + p->stats64.rx_bytes += skb->len;
> + u64_stats_update_end(&p->stats64.syncp);
>
> netif_receive_skb(skb);
>
> diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
> index 55982cc39b24..7aa0656296c2 100644
> --- a/net/dsa/dsa_priv.h
> +++ b/net/dsa/dsa_priv.h
> @@ -77,6 +77,8 @@ struct dsa_slave_priv {
> struct sk_buff * (*xmit)(struct sk_buff *skb,
> struct net_device *dev);
>
> + 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 9507bd38cf04..65f3cef85976 100644
> --- a/net/dsa/slave.c
> +++ b/net/dsa/slave.c
> @@ -354,8 +354,10 @@ static netdev_tx_t dsa_slave_xmit(struct sk_buff *skb, struct net_device *dev)
> struct dsa_slave_priv *p = netdev_priv(dev);
> struct sk_buff *nskb;
>
> - dev->stats.tx_packets++;
> - dev->stats.tx_bytes += skb->len;
> + u64_stats_update_begin(&p->stats64.syncp);
> + p->stats64.tx_packets++;
> + p->stats64.tx_bytes += skb->len;
> + u64_stats_update_end(&p->stats64.syncp);
>
> /* Transmit function may have to reallocate the original SKB,
> * in which case it must have freed it. Only free it here on error.
> @@ -594,11 +596,15 @@ 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;
> -
> - data[0] = dev->stats.tx_packets;
> - data[1] = dev->stats.tx_bytes;
> - data[2] = dev->stats.rx_packets;
> - data[3] = dev->stats.rx_bytes;
> + 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));
> if (ds->ops->get_ethtool_stats)
> ds->ops->get_ethtool_stats(ds, p->dp->index, data + 4);
> }
> @@ -861,6 +867,22 @@ static int dsa_slave_setup_tc(struct net_device *dev, u32 handle,
> }
> }
>
> +static void dsa_slave_get_stats64(struct net_device *dev,
> + struct rtnl_link_stats64 *stats)
> +{
> + struct dsa_slave_priv *p = netdev_priv(dev);
> + unsigned int start;
> +
> + 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));
> +}
> +
> void dsa_cpu_port_ethtool_init(struct ethtool_ops *ops)
> {
> ops->get_sset_count = dsa_cpu_port_get_sset_count;
> @@ -936,6 +958,7 @@ static const struct net_device_ops dsa_slave_netdev_ops = {
> .ndo_bridge_dellink = switchdev_port_bridge_dellink,
> .ndo_get_phys_port_name = dsa_slave_get_phys_port_name,
> .ndo_setup_tc = dsa_slave_setup_tc,
> + .ndo_get_stats64 = dsa_slave_get_stats64,
> };
>
> static const struct switchdev_ops dsa_slave_switchdev_ops = {
> @@ -1171,6 +1194,7 @@ 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->dp = &ds->ports[port];
> INIT_LIST_HEAD(&p->mall_tc_list);
> p->xmit = dst->tag_ops->xmit;
>


--
Florian

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