net_sched: gen_estimator: complete rewrite of rate estimators

1) Old code was hard to maintain, due to complex lock chains.
   (We probably will be able to remove some kfree_rcu() in callers)

2) Using a single timer to update all estimators does not scale.

3) Code was buggy on 32bit kernel (WRITE_ONCE() on 64bit quantity
   is not supposed to work well)

In this rewrite :

- I removed the RB tree that had to be scanned in
  gen_estimator_active(). qdisc dumps should be much faster.

- Each estimator has its own timer.

- Estimations are maintained in net_rate_estimator structure,
  instead of dirtying the qdisc. Minor, but part of the simplification.

- Reading the estimator uses RCU and a seqcount to provide proper
  support for 32bit kernels.

- We reduce memory need when estimators are not used, since
  we store a pointer, instead of the bytes/packets counters.

- xt_rateest_mt() no longer has to grab a spinlock.
  (In the future, xt_rateest_tg() could be switched to per cpu counters)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

9 files changed, 33 insertions, 33 deletions

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index f893d180da1c..2095c83ce773 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -41,8 +41,7 @@ static void tcf_hash_destroy(struct tcf_hashinfo *hinfo, struct tc_action *p)
 	spin_lock_bh(&hinfo->lock);
 	hlist_del(&p->tcfa_head);
 	spin_unlock_bh(&hinfo->lock);
-	gen_kill_estimator(&p->tcfa_bstats,
-			   &p->tcfa_rate_est);
+	gen_kill_estimator(&p->tcfa_rate_est);
 	/*
 	 * gen_estimator est_timer() might access p->tcfa_lock
 	 * or bstats, wait a RCU grace period before freeing p
@@ -237,8 +236,7 @@ EXPORT_SYMBOL(tcf_hash_check);
 void tcf_hash_cleanup(struct tc_action *a, struct nlattr *est)
 {
 	if (est)
-		gen_kill_estimator(&a->tcfa_bstats,
-				   &a->tcfa_rate_est);
+		gen_kill_estimator(&a->tcfa_rate_est);
 	call_rcu(&a->tcfa_rcu, free_tcf);
 }
 EXPORT_SYMBOL(tcf_hash_cleanup);
@@ -670,8 +668,7 @@ int tcf_action_copy_stats(struct sk_buff *skb, struct tc_action *p,
 		goto errout;
 
 	if (gnet_stats_copy_basic(NULL, &d, p->cpu_bstats, &p->tcfa_bstats) < 0 ||
-	    gnet_stats_copy_rate_est(&d, &p->tcfa_bstats,
-				     &p->tcfa_rate_est) < 0 ||
+	    gnet_stats_copy_rate_est(&d, &p->tcfa_rate_est) < 0 ||
 	    gnet_stats_copy_queue(&d, p->cpu_qstats,
 				  &p->tcfa_qstats,
 				  p->tcfa_qstats.qlen) < 0)
diff --git a/net/sched/act_police.c b/net/sched/act_police.c
index c990b73a6c85..0ba91d1ce994 100644
--- a/net/sched/act_police.c
+++ b/net/sched/act_police.c
@@ -142,8 +142,7 @@ static int tcf_act_police_init(struct net *net, struct nlattr *nla,
 			goto failure_unlock;
 	} else if (tb[TCA_POLICE_AVRATE] &&
 		   (ret == ACT_P_CREATED ||
-		    !gen_estimator_active(&police->tcf_bstats,
-					  &police->tcf_rate_est))) {
+		    !gen_estimator_active(&police->tcf_rate_est))) {
 		err = -EINVAL;
 		goto failure_unlock;
 	}
@@ -216,13 +215,17 @@ static int tcf_act_police(struct sk_buff *skb, const struct tc_action *a,
 	bstats_update(&police->tcf_bstats, skb);
 	tcf_lastuse_update(&police->tcf_tm);
 
-	if (police->tcfp_ewma_rate &&
-	    police->tcf_rate_est.bps >= police->tcfp_ewma_rate) {
-		police->tcf_qstats.overlimits++;
-		if (police->tcf_action == TC_ACT_SHOT)
-			police->tcf_qstats.drops++;
-		spin_unlock(&police->tcf_lock);
-		return police->tcf_action;
+	if (police->tcfp_ewma_rate) {
+		struct gnet_stats_rate_est64 sample;
+
+		if (!gen_estimator_read(&police->tcf_rate_est, &sample) ||
+		    sample.bps >= police->tcfp_ewma_rate) {
+			police->tcf_qstats.overlimits++;
+			if (police->tcf_action == TC_ACT_SHOT)
+				police->tcf_qstats.drops++;
+			spin_unlock(&police->tcf_lock);
+			return police->tcf_action;
+		}
 	}
 
 	if (qdisc_pkt_len(skb) <= police->tcfp_mtu) {
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index f337f1bdd1d4..d7b93429f0cc 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1395,7 +1395,7 @@ static int tc_fill_qdisc(struct sk_buff *skb, struct Qdisc *q, u32 clid,
 
 	if (gnet_stats_copy_basic(qdisc_root_sleeping_running(q),
 				  &d, cpu_bstats, &q->bstats) < 0 ||
-	    gnet_stats_copy_rate_est(&d, &q->bstats, &q->rate_est) < 0 ||
+	    gnet_stats_copy_rate_est(&d, &q->rate_est) < 0 ||
 	    gnet_stats_copy_queue(&d, cpu_qstats, &q->qstats, qlen) < 0)
 		goto nla_put_failure;
 
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index beb554aa8cfb..9ffe1c220b02 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -122,7 +122,7 @@ struct cbq_class {
 	psched_time_t		penalized;
 	struct gnet_stats_basic_packed bstats;
 	struct gnet_stats_queue qstats;
-	struct gnet_stats_rate_est64 rate_est;
+	struct net_rate_estimator __rcu *rate_est;
 	struct tc_cbq_xstats	xstats;
 
 	struct tcf_proto __rcu	*filter_list;
@@ -1346,7 +1346,7 @@ cbq_dump_class_stats(struct Qdisc *sch, unsigned long arg,
 
 	if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
 				  d, NULL, &cl->bstats) < 0 ||
-	    gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
+	    gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
 	    gnet_stats_copy_queue(d, NULL, &cl->qstats, cl->q->q.qlen) < 0)
 		return -1;
 
@@ -1405,7 +1405,7 @@ static void cbq_destroy_class(struct Qdisc *sch, struct cbq_class *cl)
 	tcf_destroy_chain(&cl->filter_list);
 	qdisc_destroy(cl->q);
 	qdisc_put_rtab(cl->R_tab);
-	gen_kill_estimator(&cl->bstats, &cl->rate_est);
+	gen_kill_estimator(&cl->rate_est);
 	if (cl != &q->link)
 		kfree(cl);
 }
diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c
index 8af5c59eef84..bb4cbdf75004 100644
--- a/net/sched/sch_drr.c
+++ b/net/sched/sch_drr.c
@@ -25,7 +25,7 @@ struct drr_class {
 
 	struct gnet_stats_basic_packed		bstats;
 	struct gnet_stats_queue		qstats;
-	struct gnet_stats_rate_est64	rate_est;
+	struct net_rate_estimator __rcu *rate_est;
 	struct list_head		alist;
 	struct Qdisc			*qdisc;
 
@@ -142,7 +142,7 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 
 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl)
 {
-	gen_kill_estimator(&cl->bstats, &cl->rate_est);
+	gen_kill_estimator(&cl->rate_est);
 	qdisc_destroy(cl->qdisc);
 	kfree(cl);
 }
@@ -283,7 +283,7 @@ static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
 
 	if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
 				  d, NULL, &cl->bstats) < 0 ||
-	    gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
+	    gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
 	    gnet_stats_copy_queue(d, NULL, &cl->qdisc->qstats, qlen) < 0)
 		return -1;
 
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 6cfb6e9038c2..6eb9c8e88519 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -709,7 +709,7 @@ void qdisc_destroy(struct Qdisc *qdisc)
 
 	qdisc_put_stab(rtnl_dereference(qdisc->stab));
 #endif
-	gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
+	gen_kill_estimator(&qdisc->rate_est);
 	if (ops->reset)
 		ops->reset(qdisc);
 	if (ops->destroy)
diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index 000f1d36128e..3ffaa6fb0990 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -114,7 +114,7 @@ struct hfsc_class {
 
 	struct gnet_stats_basic_packed bstats;
 	struct gnet_stats_queue qstats;
-	struct gnet_stats_rate_est64 rate_est;
+	struct net_rate_estimator __rcu *rate_est;
 	struct tcf_proto __rcu *filter_list; /* filter list */
 	unsigned int	filter_cnt;	/* filter count */
 	unsigned int	level;		/* class level in hierarchy */
@@ -1091,7 +1091,7 @@ hfsc_destroy_class(struct Qdisc *sch, struct hfsc_class *cl)
 
 	tcf_destroy_chain(&cl->filter_list);
 	qdisc_destroy(cl->qdisc);
-	gen_kill_estimator(&cl->bstats, &cl->rate_est);
+	gen_kill_estimator(&cl->rate_est);
 	if (cl != &q->root)
 		kfree(cl);
 }
@@ -1348,7 +1348,7 @@ hfsc_dump_class_stats(struct Qdisc *sch, unsigned long arg,
 	xstats.rtwork  = cl->cl_cumul;
 
 	if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), d, NULL, &cl->bstats) < 0 ||
-	    gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
+	    gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
 	    gnet_stats_copy_queue(d, NULL, &cl->qstats, cl->qdisc->q.qlen) < 0)
 		return -1;
 
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 9926fe4f3b6f..760f39e7caee 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -111,7 +111,7 @@ struct htb_class {
 	unsigned int		children;
 	struct htb_class	*parent;	/* parent class */
 
-	struct gnet_stats_rate_est64 rate_est;
+	struct net_rate_estimator __rcu *rate_est;
 
 	/*
 	 * Written often fields
@@ -1145,7 +1145,7 @@ htb_dump_class_stats(struct Qdisc *sch, unsigned long arg, struct gnet_dump *d)
 
 	if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
 				  d, NULL, &cl->bstats) < 0 ||
-	    gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
+	    gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
 	    gnet_stats_copy_queue(d, NULL, &qs, qlen) < 0)
 		return -1;
 
@@ -1228,7 +1228,7 @@ static void htb_destroy_class(struct Qdisc *sch, struct htb_class *cl)
 		WARN_ON(!cl->un.leaf.q);
 		qdisc_destroy(cl->un.leaf.q);
 	}
-	gen_kill_estimator(&cl->bstats, &cl->rate_est);
+	gen_kill_estimator(&cl->rate_est);
 	tcf_destroy_chain(&cl->filter_list);
 	kfree(cl);
 }
diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index ca0516e6f743..f9e712ce2d15 100644
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -137,7 +137,7 @@ struct qfq_class {
 
 	struct gnet_stats_basic_packed bstats;
 	struct gnet_stats_queue qstats;
-	struct gnet_stats_rate_est64 rate_est;
+	struct net_rate_estimator __rcu *rate_est;
 	struct Qdisc *qdisc;
 	struct list_head alist;		/* Link for active-classes list. */
 	struct qfq_aggregate *agg;	/* Parent aggregate. */
@@ -508,7 +508,7 @@ set_change_agg:
 		new_agg = kzalloc(sizeof(*new_agg), GFP_KERNEL);
 		if (new_agg == NULL) {
 			err = -ENOBUFS;
-			gen_kill_estimator(&cl->bstats, &cl->rate_est);
+			gen_kill_estimator(&cl->rate_est);
 			goto destroy_class;
 		}
 		sch_tree_lock(sch);
@@ -533,7 +533,7 @@ static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl)
 	struct qfq_sched *q = qdisc_priv(sch);
 
 	qfq_rm_from_agg(q, cl);
-	gen_kill_estimator(&cl->bstats, &cl->rate_est);
+	gen_kill_estimator(&cl->rate_est);
 	qdisc_destroy(cl->qdisc);
 	kfree(cl);
 }
@@ -667,7 +667,7 @@ static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg,
 
 	if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
 				  d, NULL, &cl->bstats) < 0 ||
-	    gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
+	    gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
 	    gnet_stats_copy_queue(d, NULL,
 				  &cl->qdisc->qstats, cl->qdisc->q.qlen) < 0)
 		return -1;