netdevsim: migrate to dstats stats collection

Replace custom statistics tracking with the kernel's dstats infrastructure
to simplify code and improve consistency with other network drivers.

This change:
- Sets dev->pcpu_stat_type = NETDEV_PCPU_STAT_DSTATS for automatic
  automatic allocation and deallocation.
- Removes manual stats fields and their update
- Replaces custom nsim_get_stats64() with dev_get_stats()
- Uses dev_dstats_tx_add() and dev_dstats_tx_dropped() helpers
- Eliminates the need for manual synchronization primitives

The dstats framework provides the same functionality with less code.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Joe Damato <joe@dama.to>
Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20250618-netdevsim_stat-v4-1-19fe0d35e28e@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
index fa5fbd97ad69e39399ef39a7de6f807a10efe213..5010d8eefc8548b2afcbf8f2ebe6a9f80fba3c4c 100644 (file)
--- a/drivers/net/netdevsim/netdev.c
+++ b/drivers/net/netdevsim/netdev.c
@@ -93,19 +93,14 @@ static netdev_tx_t nsim_start_xmit(struct sk_buff *skb, struct net_device *dev)
                hrtimer_start(&rq->napi_timer, us_to_ktime(5), HRTIMER_MODE_REL);
 
        rcu_read_unlock();
-       u64_stats_update_begin(&ns->syncp);
-       ns->tx_packets++;
-       ns->tx_bytes += len;
-       u64_stats_update_end(&ns->syncp);
+       dev_dstats_tx_add(dev, skb->len);
        return NETDEV_TX_OK;
 
 out_drop_free:
        dev_kfree_skb(skb);
 out_drop_cnt:
        rcu_read_unlock();
-       u64_stats_update_begin(&ns->syncp);
-       ns->tx_dropped++;
-       u64_stats_update_end(&ns->syncp);
+       dev_dstats_tx_dropped(dev);
        return NETDEV_TX_OK;
 }
 
@@ -126,20 +121,6 @@ static int nsim_change_mtu(struct net_device *dev, int new_mtu)
        return 0;
 }
 
-static void
-nsim_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
-{
-       struct netdevsim *ns = netdev_priv(dev);
-       unsigned int start;
-
-       do {
-               start = u64_stats_fetch_begin(&ns->syncp);
-               stats->tx_bytes = ns->tx_bytes;
-               stats->tx_packets = ns->tx_packets;
-               stats->tx_dropped = ns->tx_dropped;
-       } while (u64_stats_fetch_retry(&ns->syncp, start));
-}
-
 static int
 nsim_setup_tc_block_cb(enum tc_setup_type type, void *type_data, void *cb_priv)
 {
@@ -556,7 +537,6 @@ static const struct net_device_ops nsim_netdev_ops = {
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_change_mtu         = nsim_change_mtu,
-       .ndo_get_stats64        = nsim_get_stats64,
        .ndo_set_vf_mac         = nsim_set_vf_mac,
        .ndo_set_vf_vlan        = nsim_set_vf_vlan,
        .ndo_set_vf_rate        = nsim_set_vf_rate,
@@ -580,7 +560,6 @@ static const struct net_device_ops nsim_vf_netdev_ops = {
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_change_mtu         = nsim_change_mtu,
-       .ndo_get_stats64        = nsim_get_stats64,
        .ndo_setup_tc           = nsim_setup_tc,
        .ndo_set_features       = nsim_set_features,
 };
@@ -594,7 +573,7 @@ static void nsim_get_queue_stats_rx(struct net_device *dev, int idx,
        struct rtnl_link_stats64 rtstats = {};
 
        if (!idx)
-               nsim_get_stats64(dev, &rtstats);
+               dev_get_stats(dev, &rtstats);
 
        stats->packets = rtstats.rx_packets - !!rtstats.rx_packets;
        stats->bytes = rtstats.rx_bytes;
@@ -606,7 +585,7 @@ static void nsim_get_queue_stats_tx(struct net_device *dev, int idx,
        struct rtnl_link_stats64 rtstats = {};
 
        if (!idx)
-               nsim_get_stats64(dev, &rtstats);
+               dev_get_stats(dev, &rtstats);
 
        stats->packets = rtstats.tx_packets - !!rtstats.tx_packets;
        stats->bytes = rtstats.tx_bytes;
@@ -618,7 +597,7 @@ static void nsim_get_base_stats(struct net_device *dev,
 {
        struct rtnl_link_stats64 rtstats = {};
 
-       nsim_get_stats64(dev, &rtstats);
+       dev_get_stats(dev, &rtstats);
 
        rx->packets = !!rtstats.rx_packets;
        rx->bytes = 0;
@@ -890,6 +869,7 @@ static void nsim_setup(struct net_device *dev)
                            NETIF_F_HW_CSUM |
                            NETIF_F_LRO |
                            NETIF_F_TSO;
+       dev->pcpu_stat_type = NETDEV_PCPU_STAT_DSTATS;
        dev->max_mtu = ETH_MAX_MTU;
        dev->xdp_features = NETDEV_XDP_ACT_HW_OFFLOAD;
 }
@@ -1022,7 +1002,6 @@ nsim_create(struct nsim_dev *nsim_dev, struct nsim_dev_port *nsim_dev_port)
        dev_net_set(dev, nsim_dev_net(nsim_dev));
        ns = netdev_priv(dev);
        ns->netdev = dev;
-       u64_stats_init(&ns->syncp);
        ns->nsim_dev = nsim_dev;
        ns->nsim_dev_port = nsim_dev_port;
        ns->nsim_bus_dev = nsim_dev->nsim_bus_dev;

diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index 511ed72a93ce67ec9ec6336e29634fdaa24dcd49..4a0c48c7a384e2036883c84dc847b82f992f1481 100644 (file)
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h
@@ -108,11 +108,6 @@ struct netdevsim {
 
        int rq_reset_mode;
 
-       u64 tx_packets;
-       u64 tx_bytes;
-       u64 tx_dropped;
-       struct u64_stats_sync syncp;
-
        struct nsim_bus_dev *nsim_bus_dev;
 
        struct bpf_prog *bpf_offloaded;