net/sched: taprio: report class offload stats per TXQ, not per TC

The taprio Qdisc creates child classes per netdev TX queue, but
taprio_dump_class_stats() currently reports offload statistics per
traffic class. Traffic classes are groups of TXQs sharing the same
dequeue priority, so this is incorrect and we shouldn't be bundling up
the TXQ stats when reporting them, as we currently do in enetc.

Modify the API from taprio to drivers such that they report TXQ offload
stats and not TC offload stats.

There is no change in the UAPI or in the global Qdisc stats.

Fixes: 6c1adb6 ("net/sched: taprio: add netlink reporting for offload statistics counters")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: vladimiroltean

drivers/net/ethernet/freescale/enetc/enetc_qos.c

@@ -160,20 +160,14 @@ static void enetc_taprio_stats(struct net_device *ndev,
 	stats->window_drops = window_drops;
 }
 
-static void enetc_taprio_tc_stats(struct net_device *ndev,
-				  struct tc_taprio_qopt_tc_stats *tc_stats)
+static void enetc_taprio_queue_stats(struct net_device *ndev,
+				     struct tc_taprio_qopt_queue_stats *queue_stats)
 {
-	struct tc_taprio_qopt_stats *stats = &tc_stats->stats;
+	struct tc_taprio_qopt_stats *stats = &queue_stats->stats;
 	struct enetc_ndev_priv *priv = netdev_priv(ndev);
-	int tc = tc_stats->tc;
-	u64 window_drops = 0;
-	int i;
+	int queue = queue_stats->queue;
 
-	for (i = 0; i < priv->num_tx_rings; i++)
-		if (priv->tx_ring[i]->prio == tc)
-			window_drops += priv->tx_ring[i]->stats.win_drop;
-
-	stats->window_drops = window_drops;
+	stats->window_drops = priv->tx_ring[queue]->stats.win_drop;
 }
 
 static int enetc_taprio_replace(struct net_device *ndev,
@@ -208,8 +202,8 @@ int enetc_setup_tc_taprio(struct net_device *ndev, void *type_data)
 	case TAPRIO_CMD_STATS:
 		enetc_taprio_stats(ndev, &offload->stats);
 		break;
-	case TAPRIO_CMD_TC_STATS:
-		enetc_taprio_tc_stats(ndev, &offload->tc_stats);
+	case TAPRIO_CMD_QUEUE_STATS:
+		enetc_taprio_queue_stats(ndev, &offload->queue_stats);
 		break;
 	default:
 		err = -EOPNOTSUPP;

include/net/pkt_sched.h

@@ -191,7 +191,7 @@ enum tc_taprio_qopt_cmd {
 	TAPRIO_CMD_REPLACE,
 	TAPRIO_CMD_DESTROY,
 	TAPRIO_CMD_STATS,
-	TAPRIO_CMD_TC_STATS,
+	TAPRIO_CMD_QUEUE_STATS,
 };
 
 /**
@@ -208,8 +208,8 @@ struct tc_taprio_qopt_stats {
 	u64 tx_overruns;
 };
 
-struct tc_taprio_qopt_tc_stats {
-	int tc;
+struct tc_taprio_qopt_queue_stats {
+	int queue;
 	struct tc_taprio_qopt_stats stats;
 };
 
@@ -227,8 +227,8 @@ struct tc_taprio_qopt_offload {
 	union {
 		/* TAPRIO_CMD_STATS */
 		struct tc_taprio_qopt_stats stats;
-		/* TAPRIO_CMD_TC_STATS */
-		struct tc_taprio_qopt_tc_stats tc_stats;
+		/* TAPRIO_CMD_QUEUE_STATS */
+		struct tc_taprio_qopt_queue_stats queue_stats;
 		/* TAPRIO_CMD_REPLACE */
 		struct {
 			struct tc_mqprio_qopt_offload mqprio;

net/sched/sch_taprio.c

@@ -2458,9 +2458,9 @@ static int taprio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 {
 	struct netdev_queue *dev_queue = taprio_queue_get(sch, cl);
 	struct tc_taprio_qopt_offload offload = {
-		.cmd = TAPRIO_CMD_TC_STATS,
-		.tc_stats = {
-			.tc = cl - 1,
+		.cmd = TAPRIO_CMD_QUEUE_STATS,
+		.queue_stats = {
+			.queue = cl - 1,
 		},
 	};
 	struct Qdisc *child;
@@ -2470,7 +2470,7 @@ static int taprio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 	    qdisc_qstats_copy(d, child) < 0)
 		return -1;
 
-	return taprio_dump_xstats(sch, d, &offload, &offload.tc_stats.stats);
+	return taprio_dump_xstats(sch, d, &offload, &offload.queue_stats.stats);
 }
 
 static void taprio_walk(struct Qdisc *sch, struct qdisc_walker *arg)