net_sched: sch_fq: add TCA_FQ_WEIGHTS attribute

This attribute can be used to tune the per band weight
and report them in "tc qdisc show" output:

qdisc fq 802f: parent 1:9 limit 100000p flow_limit 500p buckets 1024 orphan_mask 1023
quantum 8364b initial_quantum 41820b low_rate_threshold 550Kbit
refill_delay 40ms timer_slack 10us horizon 10s horizon_drop
bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1 weights 589824 196608 65536
Sent 236460814 bytes 792991 pkt (dropped 0, overlimits 0 requeues 0)
rate 25816bit 10pps backlog 0b 0p requeues 0
flows 4 (inactive 4 throttled 0)
gc 0 throttled 19 latency 17.6us fastpath 773882

Signed-off-by: Eric Dumazet <[e-mail]>
Acked-by: Dave Taht <[e-mail]>
Reviewed-by: Willem de Bruijn <[e-mail]>
Reviewed-by: Toke Høiland-Jørgensen <[e-mail]>
Signed-off-by: Paolo Abeni <[e-mail]>

include/uapi/linux/pkt_sched.h

···
 
 	TCA_FQ_PRIOMAP,		/* prio2band */
 
+	TCA_FQ_WEIGHTS,		/* Weights for each band */
+
 	__TCA_FQ_MAX
 };
 
 #define TCA_FQ_MAX	(__TCA_FQ_MAX - 1)
 
 #define FQ_BANDS 3
+#define FQ_MIN_WEIGHT 16384
 
 struct tc_fq_qd_stats {
 	__u64	gc_flows;

net/sched/sch_fq.c

···
 			.type = NLA_BINARY,
 			.len = sizeof(struct tc_prio_qopt),
 		},
+	[TCA_FQ_WEIGHTS]		= {
+			.type = NLA_BINARY,
+			.len = FQ_BANDS * sizeof(s32),
+		},
 };
 
 /* compress a u8 array with all elems <= 3 to an array of 2-bit fields */
···
 
 	for (i = 0; i < num_elems; i++)
 		out[i] = fq_prio2band(in, i);
+}
+
+static int fq_load_weights(struct fq_sched_data *q,
+			   const struct nlattr *attr,
+			   struct netlink_ext_ack *extack)
+{
+	s32 *weights = nla_data(attr);
+	int i;
+
+	for (i = 0; i < FQ_BANDS; i++) {
+		if (weights[i] < FQ_MIN_WEIGHT) {
+			NL_SET_ERR_MSG_FMT_MOD(extack, "Weight %d less that minimum allowed %d",
+					       weights[i], FQ_MIN_WEIGHT);
+			return -EINVAL;
+		}
+	}
+	for (i = 0; i < FQ_BANDS; i++)
+		q->band_flows[i].quantum = weights[i];
+	return 0;
 }
 
 static int fq_load_priomap(struct fq_sched_data *q,
···
 
 	if (!err && tb[TCA_FQ_PRIOMAP])
 		err = fq_load_priomap(q, tb[TCA_FQ_PRIOMAP], extack);
+
+	if (!err && tb[TCA_FQ_WEIGHTS])
+		err = fq_load_weights(q, tb[TCA_FQ_WEIGHTS], extack);
 
 	if (tb[TCA_FQ_ORPHAN_MASK])
 		q->orphan_mask = nla_get_u32(tb[TCA_FQ_ORPHAN_MASK]);
···
 	};
 	u64 horizon = q->horizon;
 	struct nlattr *opts;
+	s32 weights[3];
 
 	opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
 	if (opts == NULL)
···
 
 	fq_prio2band_decompress_crumb(q->prio2band, prio.priomap);
 	if (nla_put(skb, TCA_FQ_PRIOMAP, sizeof(prio), &prio))
+		goto nla_put_failure;
+
+	weights[0] = q->band_flows[0].quantum;
+	weights[1] = q->band_flows[1].quantum;
+	weights[2] = q->band_flows[2].quantum;
+	if (nla_put(skb, TCA_FQ_WEIGHTS, sizeof(weights), &weights))
 		goto nla_put_failure;
 
 	return nla_nest_end(skb, opts);