[v2,net-next,2/2] veth: rely on peer veth_rq for ndo_xdp_xmit accounting

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 2041152da716..aece0e5eec8c 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -45,8 +45,8 @@  struct veth_stats {
 	u64	xdp_drops;
 	u64	xdp_tx;
 	u64	xdp_tx_err;
-	u64	xdp_xmit;
-	u64	xdp_xmit_err;
+	u64	peer_tq_xdp_xmit;
+	u64	peer_tq_xdp_xmit_err;
 };
 
 struct veth_rq_stats {
@@ -92,17 +92,22 @@  struct veth_q_stat_desc {
 static const struct veth_q_stat_desc veth_rq_stats_desc[] = {
 	{ "xdp_packets",	VETH_RQ_STAT(xdp_packets) },
 	{ "xdp_bytes",		VETH_RQ_STAT(xdp_bytes) },
-	{ "rx_drops",		VETH_RQ_STAT(rx_drops) },
-	{ "rx_xdp_redirect",	VETH_RQ_STAT(xdp_redirect) },
-	{ "rx_xdp_drops",	VETH_RQ_STAT(xdp_drops) },
-	{ "rx_xdp_tx",		VETH_RQ_STAT(xdp_tx) },
-	{ "rx_xdp_tx_errors",	VETH_RQ_STAT(xdp_tx_err) },
-	{ "tx_xdp_xmit",	VETH_RQ_STAT(xdp_xmit) },
-	{ "tx_xdp_xmit_errors",	VETH_RQ_STAT(xdp_xmit_err) },
+	{ "drops",		VETH_RQ_STAT(rx_drops) },
+	{ "xdp_redirect",	VETH_RQ_STAT(xdp_redirect) },
+	{ "xdp_drops",		VETH_RQ_STAT(xdp_drops) },
+	{ "xdp_tx",		VETH_RQ_STAT(xdp_tx) },
+	{ "xdp_tx_errors",	VETH_RQ_STAT(xdp_tx_err) },
 };
 
 #define VETH_RQ_STATS_LEN	ARRAY_SIZE(veth_rq_stats_desc)
 
+static const struct veth_q_stat_desc veth_tq_stats_desc[] = {
+	{ "xdp_xmit",		VETH_RQ_STAT(peer_tq_xdp_xmit) },
+	{ "xdp_xmit_errors",	VETH_RQ_STAT(peer_tq_xdp_xmit_err) },
+};
+
+#define VETH_TQ_STATS_LEN	ARRAY_SIZE(veth_tq_stats_desc)
+
 static struct {
 	const char string[ETH_GSTRING_LEN];
 } ethtool_stats_keys[] = {
@@ -142,6 +147,14 @@  static void veth_get_strings(struct net_device *dev, u32 stringset, u8 *buf)
 				p += ETH_GSTRING_LEN;
 			}
 		}
+		for (i = 0; i < dev->real_num_tx_queues; i++) {
+			for (j = 0; j < VETH_TQ_STATS_LEN; j++) {
+				snprintf(p, ETH_GSTRING_LEN,
+					 "tx_queue_%u_%.18s",
+					 i, veth_tq_stats_desc[j].desc);
+				p += ETH_GSTRING_LEN;
+			}
+		}
 		break;
 	}
 }
@@ -151,7 +164,8 @@  static int veth_get_sset_count(struct net_device *dev, int sset)
 	switch (sset) {
 	case ETH_SS_STATS:
 		return ARRAY_SIZE(ethtool_stats_keys) +
-		       VETH_RQ_STATS_LEN * dev->real_num_rx_queues;
+		       VETH_RQ_STATS_LEN * dev->real_num_rx_queues +
+		       VETH_TQ_STATS_LEN * dev->real_num_tx_queues;
 	default:
 		return -EOPNOTSUPP;
 	}
@@ -160,7 +174,7 @@  static int veth_get_sset_count(struct net_device *dev, int sset)
 static void veth_get_ethtool_stats(struct net_device *dev,
 		struct ethtool_stats *stats, u64 *data)
 {
-	struct veth_priv *priv = netdev_priv(dev);
+	struct veth_priv *rcv_priv, *priv = netdev_priv(dev);
 	struct net_device *peer = rtnl_dereference(priv->peer);
 	int i, j, idx;
 
@@ -181,6 +195,26 @@  static void veth_get_ethtool_stats(struct net_device *dev,
 		} while (u64_stats_fetch_retry_irq(&rq_stats->syncp, start));
 		idx += VETH_RQ_STATS_LEN;
 	}
+
+	if (!peer)
+		return;
+
+	rcv_priv = netdev_priv(peer);
+	for (i = 0; i < peer->real_num_rx_queues; i++) {
+		const struct veth_rq_stats *rq_stats = &rcv_priv->rq[i].stats;
+		const void *base = (void *)&rq_stats->vs;
+		unsigned int start, tx_idx = idx;
+		size_t offset;
+
+		tx_idx += (i % dev->real_num_tx_queues) * VETH_TQ_STATS_LEN;
+		do {
+			start = u64_stats_fetch_begin_irq(&rq_stats->syncp);
+			for (j = 0; j < VETH_TQ_STATS_LEN; j++) {
+				offset = veth_tq_stats_desc[j].offset;
+				data[tx_idx + j] += *(u64 *)(base + offset);
+			}
+		} while (u64_stats_fetch_retry_irq(&rq_stats->syncp, start));
+	}
 }
 
 static const struct ethtool_ops veth_ethtool_ops = {
@@ -301,25 +335,25 @@  static void veth_stats_rx(struct veth_stats *result, struct net_device *dev)
 	struct veth_priv *priv = netdev_priv(dev);
 	int i;
 
-	result->xdp_xmit_err = 0;
+	result->peer_tq_xdp_xmit_err = 0;
 	result->xdp_packets = 0;
 	result->xdp_tx_err = 0;
 	result->xdp_bytes = 0;
 	result->rx_drops = 0;
 	for (i = 0; i < dev->num_rx_queues; i++) {
-		u64 packets, bytes, drops, xdp_tx_err, xdp_xmit_err;
+		u64 packets, bytes, drops, xdp_tx_err, peer_tq_xdp_xmit_err;
 		struct veth_rq_stats *stats = &priv->rq[i].stats;
 		unsigned int start;
 
 		do {
 			start = u64_stats_fetch_begin_irq(&stats->syncp);
-			xdp_xmit_err = stats->vs.xdp_xmit_err;
+			peer_tq_xdp_xmit_err = stats->vs.peer_tq_xdp_xmit_err;
 			xdp_tx_err = stats->vs.xdp_tx_err;
 			packets = stats->vs.xdp_packets;
 			bytes = stats->vs.xdp_bytes;
 			drops = stats->vs.rx_drops;
 		} while (u64_stats_fetch_retry_irq(&stats->syncp, start));
-		result->xdp_xmit_err += xdp_xmit_err;
+		result->peer_tq_xdp_xmit_err += peer_tq_xdp_xmit_err;
 		result->xdp_tx_err += xdp_tx_err;
 		result->xdp_packets += packets;
 		result->xdp_bytes += bytes;
@@ -340,8 +374,8 @@  static void veth_get_stats64(struct net_device *dev,
 	tot->tx_packets = packets;
 
 	veth_stats_rx(&rx, dev);
-	tot->tx_dropped += rx.xdp_xmit_err + rx.xdp_tx_err;
-	tot->rx_dropped = rx.rx_drops;
+	tot->tx_dropped += rx.xdp_tx_err;
+	tot->rx_dropped = rx.rx_drops + rx.peer_tq_xdp_xmit_err;
 	tot->rx_bytes = rx.xdp_bytes;
 	tot->rx_packets = rx.xdp_packets;
 
@@ -353,7 +387,8 @@  static void veth_get_stats64(struct net_device *dev,
 		tot->rx_packets += packets;
 
 		veth_stats_rx(&rx, peer);
-		tot->rx_dropped += rx.xdp_xmit_err + rx.xdp_tx_err;
+		tot->tx_dropped += rx.peer_tq_xdp_xmit_err;
+		tot->rx_dropped += rx.xdp_tx_err;
 		tot->tx_bytes += rx.xdp_bytes;
 		tot->tx_packets += rx.xdp_packets;
 	}
@@ -394,38 +429,28 @@  static int veth_xdp_xmit(struct net_device *dev, int n,
 			 u32 flags, bool ndo_xmit)
 {
 	struct veth_priv *rcv_priv, *priv = netdev_priv(dev);
-	unsigned int qidx, max_len;
+	int i, ret = -ENXIO, drops = 0;
 	struct net_device *rcv;
-	int i, ret, drops = n;
+	unsigned int max_len;
 	struct veth_rq *rq;
 
-	rcu_read_lock();
-	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK)) {
-		rcu_read_unlock();
-		atomic64_add(drops, &priv->dropped);
+	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
 		return -EINVAL;
-	}
 
+	rcu_read_lock();
 	rcv = rcu_dereference(priv->peer);
-	if (unlikely(!rcv)) {
-		rcu_read_unlock();
-		atomic64_add(drops, &priv->dropped);
-		return -ENXIO;
-	}
+	if (unlikely(!rcv))
+		goto out;
 
 	rcv_priv = netdev_priv(rcv);
-	qidx = veth_select_rxq(rcv);
-	rq = &rcv_priv->rq[qidx];
+	rq = &rcv_priv->rq[veth_select_rxq(rcv)];
 	/* Non-NULL xdp_prog ensures that xdp_ring is initialized on receive
 	 * side. This means an XDP program is loaded on the peer and the peer
 	 * device is up.
 	 */
-	if (!rcu_access_pointer(rq->xdp_prog)) {
-		ret = -ENXIO;
-		goto drop;
-	}
+	if (!rcu_access_pointer(rq->xdp_prog))
+		goto out;
 
-	drops = 0;
 	max_len = rcv->mtu + rcv->hard_header_len + VLAN_HLEN;
 
 	spin_lock(&rq->xdp_ring.producer_lock);
@@ -445,18 +470,14 @@  static int veth_xdp_xmit(struct net_device *dev, int n,
 		__veth_xdp_flush(rq);
 
 	ret = n - drops;
-drop:
-	rq = &priv->rq[qidx];
-	u64_stats_update_begin(&rq->stats.syncp);
 	if (ndo_xmit) {
-		rq->stats.vs.xdp_xmit += n - drops;
-		rq->stats.vs.xdp_xmit_err += drops;
-	} else {
-		rq->stats.vs.xdp_tx += n - drops;
-		rq->stats.vs.xdp_tx_err += drops;
+		u64_stats_update_begin(&rq->stats.syncp);
+		rq->stats.vs.peer_tq_xdp_xmit += n - drops;
+		rq->stats.vs.peer_tq_xdp_xmit_err += drops;
+		u64_stats_update_end(&rq->stats.syncp);
 	}
-	u64_stats_update_end(&rq->stats.syncp);
 
+out:
 	rcu_read_unlock();
 
 	return ret;
@@ -465,7 +486,16 @@  static int veth_xdp_xmit(struct net_device *dev, int n,
 static int veth_ndo_xdp_xmit(struct net_device *dev, int n,
 			     struct xdp_frame **frames, u32 flags)
 {
-	return veth_xdp_xmit(dev, n, frames, flags, true);
+	int err;
+
+	err = veth_xdp_xmit(dev, n, frames, flags, true);
+	if (err < 0) {
+		struct veth_priv *priv = netdev_priv(dev);
+
+		atomic64_add(n, &priv->dropped);
+	}
+
+	return err;
 }
 
 static void veth_xdp_flush_bq(struct veth_rq *rq, struct veth_xdp_tx_bq *bq)
@@ -481,6 +511,11 @@  static void veth_xdp_flush_bq(struct veth_rq *rq, struct veth_xdp_tx_bq *bq)
 	}
 	trace_xdp_bulk_tx(rq->dev, sent, bq->count - sent, err);
 
+	u64_stats_update_begin(&rq->stats.syncp);
+	rq->stats.vs.xdp_tx += sent;
+	rq->stats.vs.xdp_tx_err += bq->count - sent;
+	u64_stats_update_end(&rq->stats.syncp);
+
 	bq->count = 0;
 }