net/sched: refactor mqprio qopt reconstruction to a library function

The taprio qdisc will need to reconstruct a struct tc_mqprio_qopt from
netdev settings once more in a future patch, but this code was already
written twice, once in taprio and once in mqprio.

Refactor the code to a helper in the common mqprio library.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_mqprio.c

@@ -406,7 +406,7 @@ static int mqprio_dump(struct Qdisc *sch, struct sk_buff *skb)
 	struct nlattr *nla = (struct nlattr *)skb_tail_pointer(skb);
 	struct tc_mqprio_qopt opt = { 0 };
 	struct Qdisc *qdisc;
-	unsigned int ntx, tc;
+	unsigned int ntx;
 
 	sch->q.qlen = 0;
 	gnet_stats_basic_sync_init(&sch->bstats);
@@ -430,15 +430,9 @@ static int mqprio_dump(struct Qdisc *sch, struct sk_buff *skb)
 		spin_unlock_bh(qdisc_lock(qdisc));
 	}
 
-	opt.num_tc = netdev_get_num_tc(dev);
-	memcpy(opt.prio_tc_map, dev->prio_tc_map, sizeof(opt.prio_tc_map));
+	mqprio_qopt_reconstruct(dev, &opt);
 	opt.hw = priv->hw_offload;
 
-	for (tc = 0; tc < netdev_get_num_tc(dev); tc++) {
-		opt.count[tc] = dev->tc_to_txq[tc].count;
-		opt.offset[tc] = dev->tc_to_txq[tc].offset;
-	}
-
 	if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 		goto nla_put_failure;
 

net/sched/sch_mqprio_lib.c

@@ -100,4 +100,18 @@ int mqprio_validate_qopt(struct net_device *dev, struct tc_mqprio_qopt *qopt,
 }
 EXPORT_SYMBOL_GPL(mqprio_validate_qopt);
 
+void mqprio_qopt_reconstruct(struct net_device *dev, struct tc_mqprio_qopt *qopt)
+{
+	int tc, num_tc = netdev_get_num_tc(dev);
+
+	qopt->num_tc = num_tc;
+	memcpy(qopt->prio_tc_map, dev->prio_tc_map, sizeof(qopt->prio_tc_map));
+
+	for (tc = 0; tc < num_tc; tc++) {
+		qopt->count[tc] = dev->tc_to_txq[tc].count;
+		qopt->offset[tc] = dev->tc_to_txq[tc].offset;
+	}
+}
+EXPORT_SYMBOL_GPL(mqprio_qopt_reconstruct);
+
 MODULE_LICENSE("GPL");

net/sched/sch_mqprio_lib.h

@@ -12,5 +12,7 @@ int mqprio_validate_qopt(struct net_device *dev, struct tc_mqprio_qopt *qopt,
 			 bool validate_queue_counts,
 			 bool allow_overlapping_txqs,
 			 struct netlink_ext_ack *extack);
+void mqprio_qopt_reconstruct(struct net_device *dev,
+			     struct tc_mqprio_qopt *qopt);
 
 #endif

net/sched/sch_taprio.c

@@ -1948,18 +1948,11 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb)
 	struct sched_gate_list *oper, *admin;
 	struct tc_mqprio_qopt opt = { 0 };
 	struct nlattr *nest, *sched_nest;
-	unsigned int i;
 
 	oper = rtnl_dereference(q->oper_sched);
 	admin = rtnl_dereference(q->admin_sched);
 
-	opt.num_tc = netdev_get_num_tc(dev);
-	memcpy(opt.prio_tc_map, dev->prio_tc_map, sizeof(opt.prio_tc_map));
-
-	for (i = 0; i < netdev_get_num_tc(dev); i++) {
-		opt.count[i] = dev->tc_to_txq[i].count;
-		opt.offset[i] = dev->tc_to_txq[i].offset;
-	}
+	mqprio_qopt_reconstruct(dev, &opt);
 
 	nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
 	if (!nest)