[Cake] [PATCH RFC net-next 3/4] net/sched: sch_cake: Share config across cake_mq sub-qdiscs

["Toke Høiland-Jørgensen" <toke@redhat.com>]

This adds support for configuring the cake_mq instance directly, sharing
the config across the cake sub-qdiscs.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 net/sched/sch_cake.c | 147 +++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 118 insertions(+), 29 deletions(-)

diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c
index d17d7669de389bb21ca6ce3b209e0272cfaa5112..7ceccbfaa9b6b4cdeaf17b416c2b65709c22a60a 100644
--- a/net/sched/sch_cake.c
+++ b/net/sched/sch_cake.c
@@ -211,6 +211,7 @@ struct cake_sched_config {
 	u8		flow_mode;
 	u8		atm_mode;
 	u8		ack_filter;
+	u8		is_shared;
 };
 
 struct cake_sched_data {
@@ -2585,11 +2586,9 @@ static void cake_reconfigure(struct Qdisc *sch)
 				   q->buffer_config_limit));
 }
 
-static int cake_change(struct Qdisc *sch, struct nlattr *opt,
-		       struct netlink_ext_ack *extack)
+static int cake_config_change(struct cake_sched_config *q, struct nlattr *opt,
+			      struct netlink_ext_ack *extack, bool *overhead_changed)
 {
-	struct cake_sched_data *qd = qdisc_priv(sch);
-	struct cake_sched_config *q = qd->config;
 	struct nlattr *tb[TCA_CAKE_MAX + 1];
 	u16 rate_flags;
 	u8 flow_mode;
@@ -2642,20 +2641,12 @@ static int cake_change(struct Qdisc *sch, struct nlattr *opt,
 		WRITE_ONCE(q->rate_overhead,
 			   nla_get_s32(tb[TCA_CAKE_OVERHEAD]));
 		rate_flags |= CAKE_FLAG_OVERHEAD;
-
-		qd->max_netlen = 0;
-		qd->max_adjlen = 0;
-		qd->min_netlen = ~0;
-		qd->min_adjlen = ~0;
+		*overhead_changed = true;
 	}
 
 	if (tb[TCA_CAKE_RAW]) {
 		rate_flags &= ~CAKE_FLAG_OVERHEAD;
-
-		qd->max_netlen = 0;
-		qd->max_adjlen = 0;
-		qd->min_netlen = ~0;
-		qd->min_adjlen = ~0;
+		*overhead_changed = true;
 	}
 
 	if (tb[TCA_CAKE_MPU])
@@ -2711,6 +2702,34 @@ static int cake_change(struct Qdisc *sch, struct nlattr *opt,
 
 	WRITE_ONCE(q->rate_flags, rate_flags);
 	WRITE_ONCE(q->flow_mode, flow_mode);
+
+	return 0;
+}
+
+static int cake_change(struct Qdisc *sch, struct nlattr *opt,
+		       struct netlink_ext_ack *extack)
+{
+	struct cake_sched_data *qd = qdisc_priv(sch);
+	struct cake_sched_config *q = qd->config;
+	bool overhead_changed = false;
+	int ret;
+
+	if (q->is_shared) {
+		NL_SET_ERR_MSG(extack, "can't reconfigure cake_mq sub-qdiscs");
+		return -EOPNOTSUPP;
+	}
+
+	ret = cake_config_change(q, opt, extack, &overhead_changed);
+	if (ret)
+		return ret;
+
+	if (overhead_changed) {
+		qd->max_netlen = 0;
+		qd->max_adjlen = 0;
+		qd->min_netlen = ~0;
+		qd->min_adjlen = ~0;
+	}
+
 	if (qd->tins) {
 		sch_tree_lock(sch);
 		cake_reconfigure(sch);
@@ -2727,7 +2746,23 @@ static void cake_destroy(struct Qdisc *sch)
 	qdisc_watchdog_cancel(&q->watchdog);
 	tcf_block_put(q->block);
 	kvfree(q->tins);
-	kvfree(q->config);
+	if (!q->config->is_shared)
+		kvfree(q->config);
+}
+
+static void cake_config_init(struct cake_sched_config *q, bool is_shared)
+{
+	q->tin_mode = CAKE_DIFFSERV_DIFFSERV3;
+	q->flow_mode  = CAKE_FLOW_TRIPLE;
+
+	q->rate_bps = 0; /* unlimited by default */
+
+	q->interval = 100000; /* 100ms default */
+	q->target   =   5000; /* 5ms: codel RFC argues
+			       * for 5 to 10% of interval
+			       */
+	q->rate_flags |= CAKE_FLAG_SPLIT_GSO;
+	q->is_shared = is_shared;
 }
 
 static int cake_init(struct Qdisc *sch, struct nlattr *opt,
@@ -2741,17 +2776,9 @@ static int cake_init(struct Qdisc *sch, struct nlattr *opt,
 	if (!q)
 		return -ENOMEM;
 
+	cake_config_init(q, false);
+
 	sch->limit = 10240;
-	q->tin_mode = CAKE_DIFFSERV_DIFFSERV3;
-	q->flow_mode  = CAKE_FLOW_TRIPLE;
-
-	q->rate_bps = 0; /* unlimited by default */
-
-	q->interval = 100000; /* 100ms default */
-	q->target   =   5000; /* 5ms: codel RFC argues
-			       * for 5 to 10% of interval
-			       */
-	q->rate_flags |= CAKE_FLAG_SPLIT_GSO;
 	qd->cur_tin = 0;
 	qd->cur_flow  = 0;
 	qd->config = q;
@@ -2814,10 +2841,21 @@ static int cake_init(struct Qdisc *sch, struct nlattr *opt,
 	return err;
 }
 
-static int cake_dump(struct Qdisc *sch, struct sk_buff *skb)
+static void cake_config_replace(struct Qdisc *sch, struct cake_sched_config *cfg)
 {
 	struct cake_sched_data *qd = qdisc_priv(sch);
 	struct cake_sched_config *q = qd->config;
+
+	qd->config = cfg;
+
+	if (!q->is_shared)
+		kvfree(q);
+
+	cake_reconfigure(sch);
+}
+
+static int cake_config_dump(struct cake_sched_config *q, struct sk_buff *skb)
+{
 	struct nlattr *opts;
 	u16 rate_flags;
 	u8 flow_mode;
@@ -2893,6 +2931,14 @@ static int cake_dump(struct Qdisc *sch, struct sk_buff *skb)
 	return -1;
 }
 
+static int cake_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+	struct cake_sched_data *qd = qdisc_priv(sch);
+	struct cake_sched_config *q = qd->config;
+
+	return cake_config_dump(q, skb);
+}
+
 static int cake_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 {
 	struct nlattr *stats = nla_nest_start_noflag(d->skb, TCA_STATS_APP);
@@ -3155,7 +3201,8 @@ static struct Qdisc_ops cake_qdisc_ops __read_mostly = {
 MODULE_ALIAS_NET_SCH("cake");
 
 struct cake_mq_sched {
-	struct Qdisc		**qdiscs;
+	struct Qdisc **qdiscs;
+	struct cake_sched_config cake_config;
 };
 
 static void cake_mq_destroy(struct Qdisc *sch)
@@ -3179,6 +3226,8 @@ static int cake_mq_init(struct Qdisc *sch, struct nlattr *opt,
 	struct netdev_queue *dev_queue;
 	struct Qdisc *qdisc;
 	unsigned int ntx;
+	bool _unused;
+	int ret;
 
 	if (sch->parent != TC_H_ROOT)
 		return -EOPNOTSUPP;
@@ -3186,6 +3235,11 @@ static int cake_mq_init(struct Qdisc *sch, struct nlattr *opt,
 	if (!netif_is_multiqueue(dev))
 		return -EOPNOTSUPP;
 
+	cake_config_init(&priv->cake_config, true);
+	ret = cake_config_change(&priv->cake_config, opt, extack, &_unused);
+	if (ret)
+		return ret;
+
 	/* pre-allocate qdiscs, attachment can't fail */
 	priv->qdiscs = kcalloc(dev->num_tx_queues, sizeof(priv->qdiscs[0]),
 			       GFP_KERNEL);
@@ -3204,6 +3258,7 @@ static int cake_mq_init(struct Qdisc *sch, struct nlattr *opt,
 		}
 		priv->qdiscs[ntx] = qdisc;
 		qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
+		cake_config_replace(qdisc, &priv->cake_config);
 	}
 
 	sch->flags |= TCQ_F_MQROOT;
@@ -3232,8 +3287,42 @@ static void cake_mq_attach(struct Qdisc *sch)
 	priv->qdiscs = NULL;
 }
 
+static int cake_mq_change(struct Qdisc *sch, struct nlattr *opt,
+			  struct netlink_ext_ack *extack)
+{
+	struct net_device *dev = qdisc_dev(sch);
+	struct cake_mq_sched *priv = qdisc_priv(sch);
+	bool overhead_changed = false;
+	unsigned int ntx;
+	int ret;
+
+	ret = cake_config_change(&priv->cake_config, opt, extack, &overhead_changed);
+	if (ret)
+		return ret;
+
+	sch_tree_lock(sch);
+	for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
+		struct Qdisc *chld = rtnl_dereference(netdev_get_tx_queue(dev, ntx)->qdisc_sleeping);
+		struct cake_sched_data *qd = qdisc_priv(chld);
+
+		if (overhead_changed) {
+			qd->max_netlen = 0;
+			qd->max_adjlen = 0;
+			qd->min_netlen = ~0;
+			qd->min_adjlen = ~0;
+		}
+
+		if (qd->tins)
+			cake_reconfigure(chld);
+	}
+	sch_tree_unlock(sch);
+
+	return 0;
+}
+
 static int cake_mq_dump(struct Qdisc *sch, struct sk_buff *skb)
 {
+	struct cake_mq_sched *qd = qdisc_priv(sch);
 	struct net_device *dev = qdisc_dev(sch);
 	struct Qdisc *qdisc;
 	unsigned int ntx;
@@ -3260,7 +3349,7 @@ static int cake_mq_dump(struct Qdisc *sch, struct sk_buff *skb)
 		spin_unlock_bh(qdisc_lock(qdisc));
 	}
 
-	return 0;
+	return cake_config_dump(&qd->cake_config, skb);
 }
 
 static struct netdev_queue *cake_mq_queue_get(struct Qdisc *sch, unsigned long cl)
@@ -3357,7 +3446,7 @@ static struct Qdisc_ops cake_mq_qdisc_ops __read_mostly = {
 	.init		=	cake_mq_init,
 	.destroy	=	cake_mq_destroy,
 	.attach		= cake_mq_attach,
-	//	.change		=	cake_mq_change,
+	.change		=	cake_mq_change,
 	.change_real_num_tx = mq_change_real_num_tx,
 	.dump		=	cake_mq_dump,
 	.owner		=	THIS_MODULE,

-- 
2.51.0