net: sched: gred: support reporting stats from offloads

Allow drivers which offload GRED to report back statistics.  Since
A lot of GRED stats is fairly ad hoc in nature pass to drivers the
standard struct gnet_stats_basic/gnet_stats_queue pairs, and
untangle the values in the core.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/pkt_cls.h

@@ -871,6 +871,7 @@ struct tc_red_qopt_offload {
 enum tc_gred_command {
 	TC_GRED_REPLACE,
 	TC_GRED_DESTROY,
+	TC_GRED_STATS,
 };
 
 struct tc_gred_vq_qopt_offload_params {
@@ -895,12 +896,19 @@ struct tc_gred_qopt_offload_params {
 	struct tc_gred_vq_qopt_offload_params tab[MAX_DPs];
 };
 
+struct tc_gred_qopt_offload_stats {
+	struct gnet_stats_basic_packed bstats[MAX_DPs];
+	struct gnet_stats_queue qstats[MAX_DPs];
+	struct red_stats *xstats[MAX_DPs];
+};
+
 struct tc_gred_qopt_offload {
 	enum tc_gred_command command;
 	u32 handle;
 	u32 parent;
 	union {
 		struct tc_gred_qopt_offload_params set;
+		struct tc_gred_qopt_offload_stats stats;
 	};
 };
 

net/sched/sch_gred.c

@@ -354,6 +354,50 @@ static void gred_offload(struct Qdisc *sch, enum tc_gred_command command)
 	dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_GRED, &opt);
 }
 
+static int gred_offload_dump_stats(struct Qdisc *sch)
+{
+	struct gred_sched *table = qdisc_priv(sch);
+	struct tc_gred_qopt_offload *hw_stats;
+	unsigned int i;
+	int ret;
+
+	hw_stats = kzalloc(sizeof(*hw_stats), GFP_KERNEL);
+	if (!hw_stats)
+		return -ENOMEM;
+
+	hw_stats->command = TC_GRED_STATS;
+	hw_stats->handle = sch->handle;
+	hw_stats->parent = sch->parent;
+
+	for (i = 0; i < MAX_DPs; i++)
+		if (table->tab[i])
+			hw_stats->stats.xstats[i] = &table->tab[i]->stats;
+
+	ret = qdisc_offload_dump_helper(sch, TC_SETUP_QDISC_GRED, hw_stats);
+	/* Even if driver returns failure adjust the stats - in case offload
+	 * ended but driver still wants to adjust the values.
+	 */
+	for (i = 0; i < MAX_DPs; i++) {
+		if (!table->tab[i])
+			continue;
+		table->tab[i]->packetsin += hw_stats->stats.bstats[i].packets;
+		table->tab[i]->bytesin += hw_stats->stats.bstats[i].bytes;
+		table->tab[i]->backlog += hw_stats->stats.qstats[i].backlog;
+
+		_bstats_update(&sch->bstats,
+			       hw_stats->stats.bstats[i].bytes,
+			       hw_stats->stats.bstats[i].packets);
+		sch->qstats.qlen += hw_stats->stats.qstats[i].qlen;
+		sch->qstats.backlog += hw_stats->stats.qstats[i].backlog;
+		sch->qstats.drops += hw_stats->stats.qstats[i].drops;
+		sch->qstats.requeues += hw_stats->stats.qstats[i].requeues;
+		sch->qstats.overlimits += hw_stats->stats.qstats[i].overlimits;
+	}
+
+	kfree(hw_stats);
+	return ret;
+}
+
 static inline void gred_destroy_vq(struct gred_sched_data *q)
 {
 	kfree(q);
@@ -725,6 +769,9 @@ static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
 		.flags	= table->red_flags,
 	};
 
+	if (gred_offload_dump_stats(sch))
+		goto nla_put_failure;
+
 	opts = nla_nest_start(skb, TCA_OPTIONS);
 	if (opts == NULL)
 		goto nla_put_failure;