[PATCH v6 04/11] net/rtap: add statistics and device info

[Stephen Hemminger <stephen@networkplumber.org>]

Implement basic and per-queue statistics collection.
Usual statistics per queue: packets, bytes, errors.

The imissed counter reports kernel rx_dropped (packets dropped
before reaching the interface) retrieved via netlink IFLA_STATS64.
The rx_drop_base field captures the baseline value at stats_reset.

Device info reports ifindex, max queue counts, and default
burst/ring sizes.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 doc/guides/nics/features/rtap.ini |   2 +
 drivers/net/rtap/rtap.h           |   2 +
 drivers/net/rtap/rtap_ethdev.c    | 120 ++++++++++++++++++++++++++++++
 3 files changed, 124 insertions(+)

diff --git a/doc/guides/nics/features/rtap.ini b/doc/guides/nics/features/rtap.ini
index c064e1e0b9..9bef9e341d 100644
--- a/doc/guides/nics/features/rtap.ini
+++ b/doc/guides/nics/features/rtap.ini
@@ -5,6 +5,8 @@
 ;
 [Features]
 Scattered Rx         = P
+Basic stats          = Y
+Stats per queue      = Y
 Linux                = Y
 ARMv7                = Y
 ARMv8                = Y
diff --git a/drivers/net/rtap/rtap.h b/drivers/net/rtap/rtap.h
index 823b8c59f7..abfde20e60 100644
--- a/drivers/net/rtap/rtap.h
+++ b/drivers/net/rtap/rtap.h
@@ -62,6 +62,8 @@ struct rtap_pmd {
 	int if_index;			/* interface index */
 	int nlsk_fd;			/* netlink control socket */
 	struct rte_ether_addr eth_addr; /* address assigned by kernel */
+
+	uint64_t rx_drop_base;		/* value of rx_dropped when reset */
 };
 
 /* rtap_ethdev.c */
diff --git a/drivers/net/rtap/rtap_ethdev.c b/drivers/net/rtap/rtap_ethdev.c
index 463e24a6e1..888f8e7f39 100644
--- a/drivers/net/rtap/rtap_ethdev.c
+++ b/drivers/net/rtap/rtap_ethdev.c
@@ -2,6 +2,7 @@
  * Copyright (c) 2026 Stephen Hemminger
  */
 
+#include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <stdlib.h>
@@ -11,6 +12,7 @@
 #include <sys/ioctl.h>
 #include <net/if.h>
 #include <linux/if_tun.h>
+#include <linux/if_link.h>
 #include <linux/virtio_net.h>
 
 #include <rte_config.h>
@@ -29,6 +31,14 @@
 
 #define RTAP_DEFAULT_IFNAME	"rtap%d"
 
+#define RTAP_DEFAULT_BURST	64
+#define RTAP_NUM_BUFFERS	1024
+#define RTAP_MAX_QUEUES		128
+#define RTAP_MIN_RX_BUFSIZE	RTE_ETHER_MIN_LEN
+#define RTAP_MAX_RX_PKTLEN	RTE_ETHER_MAX_JUMBO_FRAME_LEN
+
+static_assert(RTAP_MAX_QUEUES <= RTE_MP_MAX_FD_NUM, "Max queues exceeds MP fd limit");
+
 #define RTAP_IFACE_ARG		"iface"
 #define RTAP_PERSIST_ARG	"persist"
 
@@ -157,6 +167,112 @@ rtap_dev_configure(struct rte_eth_dev *dev)
 	return 0;
 }
 
+static int
+rtap_dev_info(struct rte_eth_dev *dev, struct rte_eth_dev_info *dev_info)
+{
+	struct rtap_pmd *pmd = dev->data->dev_private;
+
+	dev_info->if_index = pmd->if_index;
+	dev_info->max_mac_addrs = 1;
+	dev_info->max_rx_pktlen = RTAP_MAX_RX_PKTLEN;
+	dev_info->min_rx_bufsize = RTAP_MIN_RX_BUFSIZE;
+	dev_info->max_rx_queues = RTAP_MAX_QUEUES;
+	dev_info->max_tx_queues = RTAP_MAX_QUEUES;
+
+	dev_info->default_rxportconf = (struct rte_eth_dev_portconf) {
+		.burst_size = RTAP_DEFAULT_BURST,
+		.ring_size = RTAP_NUM_BUFFERS,
+		.nb_queues = 1,
+	};
+	dev_info->default_txportconf = (struct rte_eth_dev_portconf) {
+		.burst_size = RTAP_DEFAULT_BURST,
+		.ring_size = RTAP_NUM_BUFFERS,
+		.nb_queues = 1,
+	};
+	return 0;
+}
+
+static int
+rtap_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats,
+	       struct eth_queue_stats *qstats)
+{
+	struct rtap_pmd *pmd = dev->data->dev_private;
+	struct rtnl_link_stats64 kstats;
+	uint16_t i;
+
+	for (i = 0; i < dev->data->nb_rx_queues; i++) {
+		struct rtap_rx_queue *rxq = dev->data->rx_queues[i];
+		if (rxq == NULL)
+			continue;
+
+		stats->ipackets += rxq->rx_packets;
+		stats->ibytes += rxq->rx_bytes;
+		stats->ierrors += rxq->rx_errors;
+
+		if (qstats != NULL && i < RTE_ETHDEV_QUEUE_STAT_CNTRS) {
+			qstats->q_ipackets[i] = rxq->rx_packets;
+			qstats->q_ibytes[i] = rxq->rx_bytes;
+			qstats->q_errors[i] = rxq->rx_errors;
+		}
+	}
+
+	for (i = 0; i < dev->data->nb_tx_queues; i++) {
+		struct rtap_tx_queue *txq = dev->data->tx_queues[i];
+		if (txq == NULL)
+			continue;
+
+		stats->opackets += txq->tx_packets;
+		stats->obytes += txq->tx_bytes;
+		stats->oerrors += txq->tx_errors;
+
+		if (qstats != NULL && i < RTE_ETHDEV_QUEUE_STAT_CNTRS) {
+			qstats->q_opackets[i] = txq->tx_packets;
+			qstats->q_obytes[i] = txq->tx_bytes;
+		}
+	}
+
+	/* Get kernel rx_dropped counter via netlink */
+	if (rtap_nl_get_stats(pmd->if_index, &kstats) == 0 &&
+	    kstats.rx_dropped > pmd->rx_drop_base)
+		stats->imissed = kstats.rx_dropped - pmd->rx_drop_base;
+
+	return 0;
+}
+
+static int
+rtap_stats_reset(struct rte_eth_dev *dev)
+{
+	struct rtap_pmd *pmd = dev->data->dev_private;
+	struct rtnl_link_stats64 kstats;
+	uint16_t i;
+
+	for (i = 0; i < dev->data->nb_rx_queues; i++) {
+		struct rtap_rx_queue *rxq = dev->data->rx_queues[i];
+		if (rxq == NULL)
+			continue;
+
+		rxq->rx_packets = 0;
+		rxq->rx_bytes = 0;
+		rxq->rx_errors = 0;
+	}
+
+	for (i = 0; i < dev->data->nb_tx_queues; i++) {
+		struct rtap_tx_queue *txq = dev->data->tx_queues[i];
+		if (txq == NULL)
+			continue;
+
+		txq->tx_packets = 0;
+		txq->tx_bytes = 0;
+		txq->tx_errors = 0;
+	}
+
+	/* Capture current rx_dropped as baseline via netlink */
+	if (rtap_nl_get_stats(pmd->if_index, &kstats) == 0)
+		pmd->rx_drop_base = kstats.rx_dropped;
+
+	return 0;
+}
+
 static int
 rtap_dev_close(struct rte_eth_dev *dev)
 {
@@ -247,7 +363,10 @@ static const struct eth_dev_ops rtap_ops = {
 	.dev_start		= rtap_dev_start,
 	.dev_stop		= rtap_dev_stop,
 	.dev_configure		= rtap_dev_configure,
+	.dev_infos_get		= rtap_dev_info,
 	.dev_close		= rtap_dev_close,
+	.stats_get		= rtap_stats_get,
+	.stats_reset		= rtap_stats_reset,
 	.rx_queue_setup		= rtap_rx_queue_setup,
 	.rx_queue_release	= rtap_rx_queue_release,
 	.tx_queue_setup		= rtap_tx_queue_setup,
@@ -262,6 +381,7 @@ rtap_create(struct rte_eth_dev *dev, const char *tap_name, uint8_t persist)
 
 	pmd->keep_fd = -1;
 	pmd->nlsk_fd = -1;
+	pmd->rx_drop_base = 0;
 
 	dev->dev_ops = &rtap_ops;
 
-- 
2.51.0