1 files changed, 951 insertions, 0 deletions

diff --git a/net/netfilter/ipvs/ip_vs_est.c b/net/netfilter/ipvs/ip_vs_est.c
new file mode 100644
index 000000000..c5970ba41
--- /dev/null
+++ b/net/netfilter/ipvs/ip_vs_est.c
@@ -0,0 +1,951 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * ip_vs_est.c: simple rate estimator for IPVS
+ *
+ * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
+ *
+ * Changes:     Hans Schillstrom <hans.schillstrom@ericsson.com>
+ *              Network name space (netns) aware.
+ *              Global data moved to netns i.e struct netns_ipvs
+ *              Affected data: est_list and est_lock.
+ *              estimation_timer() runs with timer per netns.
+ *              get_stats()) do the per cpu summing.
+ */
+
+#define KMSG_COMPONENT "IPVS"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/jiffies.h>
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/sysctl.h>
+#include <linux/list.h>
+
+#include <net/ip_vs.h>
+
+/*
+  This code is to estimate rate in a shorter interval (such as 8
+  seconds) for virtual services and real servers. For measure rate in a
+  long interval, it is easy to implement a user level daemon which
+  periodically reads those statistical counters and measure rate.
+
+  We measure rate during the last 8 seconds every 2 seconds:
+
+    avgrate = avgrate*(1-W) + rate*W
+
+    where W = 2^(-2)
+
+  NOTES.
+
+  * Average bps is scaled by 2^5, while average pps and cps are scaled by 2^10.
+
+  * Netlink users can see 64-bit values but sockopt users are restricted
+    to 32-bit values for conns, packets, bps, cps and pps.
+
+  * A lot of code is taken from net/core/gen_estimator.c
+
+  KEY POINTS:
+  - cpustats counters are updated per-cpu in SoftIRQ context with BH disabled
+  - kthreads read the cpustats to update the estimators (svcs, dests, total)
+  - the states of estimators can be read (get stats) or modified (zero stats)
+    from processes
+
+  KTHREADS:
+  - estimators are added initially to est_temp_list and later kthread 0
+    distributes them to one or many kthreads for estimation
+  - kthread contexts are created and attached to array
+  - the kthread tasks are started when first service is added, before that
+    the total stats are not estimated
+  - when configuration (cpulist/nice) is changed, the tasks are restarted
+    by work (est_reload_work)
+  - kthread tasks are stopped while the cpulist is empty
+  - the kthread context holds lists with estimators (chains) which are
+    processed every 2 seconds
+  - as estimators can be added dynamically and in bursts, we try to spread
+    them to multiple chains which are estimated at different time
+  - on start, kthread 0 enters calculation phase to determine the chain limits
+    and the limit of estimators per kthread
+  - est_add_ktid: ktid where to add new ests, can point to empty slot where
+    we should add kt data
+ */
+
+static struct lock_class_key __ipvs_est_key;
+
+static void ip_vs_est_calc_phase(struct netns_ipvs *ipvs);
+static void ip_vs_est_drain_temp_list(struct netns_ipvs *ipvs);
+
+static void ip_vs_chain_estimation(struct hlist_head *chain)
+{
+	struct ip_vs_estimator *e;
+	struct ip_vs_cpu_stats *c;
+	struct ip_vs_stats *s;
+	u64 rate;
+
+	hlist_for_each_entry_rcu(e, chain, list) {
+		u64 conns, inpkts, outpkts, inbytes, outbytes;
+		u64 kconns = 0, kinpkts = 0, koutpkts = 0;
+		u64 kinbytes = 0, koutbytes = 0;
+		unsigned int start;
+		int i;
+
+		if (kthread_should_stop())
+			break;
+
+		s = container_of(e, struct ip_vs_stats, est);
+		for_each_possible_cpu(i) {
+			c = per_cpu_ptr(s->cpustats, i);
+			do {
+				start = u64_stats_fetch_begin(&c->syncp);
+				conns = u64_stats_read(&c->cnt.conns);
+				inpkts = u64_stats_read(&c->cnt.inpkts);
+				outpkts = u64_stats_read(&c->cnt.outpkts);
+				inbytes = u64_stats_read(&c->cnt.inbytes);
+				outbytes = u64_stats_read(&c->cnt.outbytes);
+			} while (u64_stats_fetch_retry(&c->syncp, start));
+			kconns += conns;
+			kinpkts += inpkts;
+			koutpkts += outpkts;
+			kinbytes += inbytes;
+			koutbytes += outbytes;
+		}
+
+		spin_lock(&s->lock);
+
+		s->kstats.conns = kconns;
+		s->kstats.inpkts = kinpkts;
+		s->kstats.outpkts = koutpkts;
+		s->kstats.inbytes = kinbytes;
+		s->kstats.outbytes = koutbytes;
+
+		/* scaled by 2^10, but divided 2 seconds */
+		rate = (s->kstats.conns - e->last_conns) << 9;
+		e->last_conns = s->kstats.conns;
+		e->cps += ((s64)rate - (s64)e->cps) >> 2;
+
+		rate = (s->kstats.inpkts - e->last_inpkts) << 9;
+		e->last_inpkts = s->kstats.inpkts;
+		e->inpps += ((s64)rate - (s64)e->inpps) >> 2;
+
+		rate = (s->kstats.outpkts - e->last_outpkts) << 9;
+		e->last_outpkts = s->kstats.outpkts;
+		e->outpps += ((s64)rate - (s64)e->outpps) >> 2;
+
+		/* scaled by 2^5, but divided 2 seconds */
+		rate = (s->kstats.inbytes - e->last_inbytes) << 4;
+		e->last_inbytes = s->kstats.inbytes;
+		e->inbps += ((s64)rate - (s64)e->inbps) >> 2;
+
+		rate = (s->kstats.outbytes - e->last_outbytes) << 4;
+		e->last_outbytes = s->kstats.outbytes;
+		e->outbps += ((s64)rate - (s64)e->outbps) >> 2;
+		spin_unlock(&s->lock);
+	}
+}
+
+static void ip_vs_tick_estimation(struct ip_vs_est_kt_data *kd, int row)
+{
+	struct ip_vs_est_tick_data *td;
+	int cid;
+
+	rcu_read_lock();
+	td = rcu_dereference(kd->ticks[row]);
+	if (!td)
+		goto out;
+	for_each_set_bit(cid, td->present, IPVS_EST_TICK_CHAINS) {
+		if (kthread_should_stop())
+			break;
+		ip_vs_chain_estimation(&td->chains[cid]);
+		cond_resched_rcu();
+		td = rcu_dereference(kd->ticks[row]);
+		if (!td)
+			break;
+	}
+
+out:
+	rcu_read_unlock();
+}
+
+static int ip_vs_estimation_kthread(void *data)
+{
+	struct ip_vs_est_kt_data *kd = data;
+	struct netns_ipvs *ipvs = kd->ipvs;
+	int row = kd->est_row;
+	unsigned long now;
+	int id = kd->id;
+	long gap;
+
+	if (id > 0) {
+		if (!ipvs->est_chain_max)
+			return 0;
+	} else {
+		if (!ipvs->est_chain_max) {
+			ipvs->est_calc_phase = 1;
+			/* commit est_calc_phase before reading est_genid */
+			smp_mb();
+		}
+
+		/* kthread 0 will handle the calc phase */
+		if (ipvs->est_calc_phase)
+			ip_vs_est_calc_phase(ipvs);
+	}
+
+	while (1) {
+		if (!id && !hlist_empty(&ipvs->est_temp_list))
+			ip_vs_est_drain_temp_list(ipvs);
+		set_current_state(TASK_IDLE);
+		if (kthread_should_stop())
+			break;
+
+		/* before estimation, check if we should sleep */
+		now = jiffies;
+		gap = kd->est_timer - now;
+		if (gap > 0) {
+			if (gap > IPVS_EST_TICK) {
+				kd->est_timer = now - IPVS_EST_TICK;
+				gap = IPVS_EST_TICK;
+			}
+			schedule_timeout(gap);
+		} else {
+			__set_current_state(TASK_RUNNING);
+			if (gap < -8 * IPVS_EST_TICK)
+				kd->est_timer = now;
+		}
+
+		if (kd->tick_len[row])
+			ip_vs_tick_estimation(kd, row);
+
+		row++;
+		if (row >= IPVS_EST_NTICKS)
+			row = 0;
+		WRITE_ONCE(kd->est_row, row);
+		kd->est_timer += IPVS_EST_TICK;
+	}
+	__set_current_state(TASK_RUNNING);
+
+	return 0;
+}
+
+/* Schedule stop/start for kthread tasks */
+void ip_vs_est_reload_start(struct netns_ipvs *ipvs)
+{
+	/* Ignore reloads before first service is added */
+	if (!ipvs->enable)
+		return;
+	ip_vs_est_stopped_recalc(ipvs);
+	/* Bump the kthread configuration genid */
+	atomic_inc(&ipvs->est_genid);
+	queue_delayed_work(system_long_wq, &ipvs->est_reload_work, 0);
+}
+
+/* Start kthread task with current configuration */
+int ip_vs_est_kthread_start(struct netns_ipvs *ipvs,
+			    struct ip_vs_est_kt_data *kd)
+{
+	unsigned long now;
+	int ret = 0;
+	long gap;
+
+	lockdep_assert_held(&ipvs->est_mutex);
+
+	if (kd->task)
+		goto out;
+	now = jiffies;
+	gap = kd->est_timer - now;
+	/* Sync est_timer if task is starting later */
+	if (abs(gap) > 4 * IPVS_EST_TICK)
+		kd->est_timer = now;
+	kd->task = kthread_create(ip_vs_estimation_kthread, kd, "ipvs-e:%d:%d",
+				  ipvs->gen, kd->id);
+	if (IS_ERR(kd->task)) {
+		ret = PTR_ERR(kd->task);
+		kd->task = NULL;
+		goto out;
+	}
+
+	set_user_nice(kd->task, sysctl_est_nice(ipvs));
+	set_cpus_allowed_ptr(kd->task, sysctl_est_cpulist(ipvs));
+
+	pr_info("starting estimator thread %d...\n", kd->id);
+	wake_up_process(kd->task);
+
+out:
+	return ret;
+}
+
+void ip_vs_est_kthread_stop(struct ip_vs_est_kt_data *kd)
+{
+	if (kd->task) {
+		pr_info("stopping estimator thread %d...\n", kd->id);
+		kthread_stop(kd->task);
+		kd->task = NULL;
+	}
+}
+
+/* Apply parameters to kthread */
+static void ip_vs_est_set_params(struct netns_ipvs *ipvs,
+				 struct ip_vs_est_kt_data *kd)
+{
+	kd->chain_max = ipvs->est_chain_max;
+	/* We are using single chain on RCU preemption */
+	if (IPVS_EST_TICK_CHAINS == 1)
+		kd->chain_max *= IPVS_EST_CHAIN_FACTOR;
+	kd->tick_max = IPVS_EST_TICK_CHAINS * kd->chain_max;
+	kd->est_max_count = IPVS_EST_NTICKS * kd->tick_max;
+}
+
+/* Create and start estimation kthread in a free or new array slot */
+static int ip_vs_est_add_kthread(struct netns_ipvs *ipvs)
+{
+	struct ip_vs_est_kt_data *kd = NULL;
+	int id = ipvs->est_kt_count;
+	int ret = -ENOMEM;
+	void *arr = NULL;
+	int i;
+
+	if ((unsigned long)ipvs->est_kt_count >= ipvs->est_max_threads &&
+	    ipvs->enable && ipvs->est_max_threads)
+		return -EINVAL;
+
+	mutex_lock(&ipvs->est_mutex);
+
+	for (i = 0; i < id; i++) {
+		if (!ipvs->est_kt_arr[i])
+			break;
+	}
+	if (i >= id) {
+		arr = krealloc_array(ipvs->est_kt_arr, id + 1,
+				     sizeof(struct ip_vs_est_kt_data *),
+				     GFP_KERNEL);
+		if (!arr)
+			goto out;
+		ipvs->est_kt_arr = arr;
+	} else {
+		id = i;
+	}
+
+	kd = kzalloc(sizeof(*kd), GFP_KERNEL);
+	if (!kd)
+		goto out;
+	kd->ipvs = ipvs;
+	bitmap_fill(kd->avail, IPVS_EST_NTICKS);
+	kd->est_timer = jiffies;
+	kd->id = id;
+	ip_vs_est_set_params(ipvs, kd);
+
+	/* Pre-allocate stats used in calc phase */
+	if (!id && !kd->calc_stats) {
+		kd->calc_stats = ip_vs_stats_alloc();
+		if (!kd->calc_stats)
+			goto out;
+	}
+
+	/* Start kthread tasks only when services are present */
+	if (ipvs->enable && !ip_vs_est_stopped(ipvs)) {
+		ret = ip_vs_est_kthread_start(ipvs, kd);
+		if (ret < 0)
+			goto out;
+	}
+
+	if (arr)
+		ipvs->est_kt_count++;
+	ipvs->est_kt_arr[id] = kd;
+	kd = NULL;
+	/* Use most recent kthread for new ests */
+	ipvs->est_add_ktid = id;
+	ret = 0;
+
+out:
+	mutex_unlock(&ipvs->est_mutex);
+	if (kd) {
+		ip_vs_stats_free(kd->calc_stats);
+		kfree(kd);
+	}
+
+	return ret;
+}
+
+/* Select ktid where to add new ests: available, unused or new slot */
+static void ip_vs_est_update_ktid(struct netns_ipvs *ipvs)
+{
+	int ktid, best = ipvs->est_kt_count;
+	struct ip_vs_est_kt_data *kd;
+
+	for (ktid = 0; ktid < ipvs->est_kt_count; ktid++) {
+		kd = ipvs->est_kt_arr[ktid];
+		if (kd) {
+			if (kd->est_count < kd->est_max_count) {
+				best = ktid;
+				break;
+			}
+		} else if (ktid < best) {
+			best = ktid;
+		}
+	}
+	ipvs->est_add_ktid = best;
+}
+
+/* Add estimator to current kthread (est_add_ktid) */
+static int ip_vs_enqueue_estimator(struct netns_ipvs *ipvs,
+				   struct ip_vs_estimator *est)
+{
+	struct ip_vs_est_kt_data *kd = NULL;
+	struct ip_vs_est_tick_data *td;
+	int ktid, row, crow, cid, ret;
+	int delay = est->ktrow;
+
+	BUILD_BUG_ON_MSG(IPVS_EST_TICK_CHAINS > 127,
+			 "Too many chains for ktcid");
+
+	if (ipvs->est_add_ktid < ipvs->est_kt_count) {
+		kd = ipvs->est_kt_arr[ipvs->est_add_ktid];
+		if (kd)
+			goto add_est;
+	}
+
+	ret = ip_vs_est_add_kthread(ipvs);
+	if (ret < 0)
+		goto out;
+	kd = ipvs->est_kt_arr[ipvs->est_add_ktid];
+
+add_est:
+	ktid = kd->id;
+	/* For small number of estimators prefer to use few ticks,
+	 * otherwise try to add into the last estimated row.
+	 * est_row and add_row point after the row we should use
+	 */
+	if (kd->est_count >= 2 * kd->tick_max || delay < IPVS_EST_NTICKS - 1)
+		crow = READ_ONCE(kd->est_row);
+	else
+		crow = kd->add_row;
+	crow += delay;
+	if (crow >= IPVS_EST_NTICKS)
+		crow -= IPVS_EST_NTICKS;
+	/* Assume initial delay ? */
+	if (delay >= IPVS_EST_NTICKS - 1) {
+		/* Preserve initial delay or decrease it if no space in tick */
+		row = crow;
+		if (crow < IPVS_EST_NTICKS - 1) {
+			crow++;
+			row = find_last_bit(kd->avail, crow);
+		}
+		if (row >= crow)
+			row = find_last_bit(kd->avail, IPVS_EST_NTICKS);
+	} else {
+		/* Preserve delay or increase it if no space in tick */
+		row = IPVS_EST_NTICKS;
+		if (crow > 0)
+			row = find_next_bit(kd->avail, IPVS_EST_NTICKS, crow);
+		if (row >= IPVS_EST_NTICKS)
+			row = find_first_bit(kd->avail, IPVS_EST_NTICKS);
+	}
+
+	td = rcu_dereference_protected(kd->ticks[row], 1);
+	if (!td) {
+		td = kzalloc(sizeof(*td), GFP_KERNEL);
+		if (!td) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		rcu_assign_pointer(kd->ticks[row], td);
+	}
+
+	cid = find_first_zero_bit(td->full, IPVS_EST_TICK_CHAINS);
+
+	kd->est_count++;
+	kd->tick_len[row]++;
+	if (!td->chain_len[cid])
+		__set_bit(cid, td->present);
+	td->chain_len[cid]++;
+	est->ktid = ktid;
+	est->ktrow = row;
+	est->ktcid = cid;
+	hlist_add_head_rcu(&est->list, &td->chains[cid]);
+
+	if (td->chain_len[cid] >= kd->chain_max) {
+		__set_bit(cid, td->full);
+		if (kd->tick_len[row] >= kd->tick_max)
+			__clear_bit(row, kd->avail);
+	}
+
+	/* Update est_add_ktid to point to first available/empty kt slot */
+	if (kd->est_count == kd->est_max_count)
+		ip_vs_est_update_ktid(ipvs);
+
+	ret = 0;
+
+out:
+	return ret;
+}
+
+/* Start estimation for stats */
+int ip_vs_start_estimator(struct netns_ipvs *ipvs, struct ip_vs_stats *stats)
+{
+	struct ip_vs_estimator *est = &stats->est;
+	int ret;
+
+	if (!ipvs->est_max_threads && ipvs->enable)
+		ipvs->est_max_threads = ip_vs_est_max_threads(ipvs);
+
+	est->ktid = -1;
+	est->ktrow = IPVS_EST_NTICKS - 1;	/* Initial delay */
+
+	/* We prefer this code to be short, kthread 0 will requeue the
+	 * estimator to available chain. If tasks are disabled, we
+	 * will not allocate much memory, just for kt 0.
+	 */
+	ret = 0;
+	if (!ipvs->est_kt_count || !ipvs->est_kt_arr[0])
+		ret = ip_vs_est_add_kthread(ipvs);
+	if (ret >= 0)
+		hlist_add_head(&est->list, &ipvs->est_temp_list);
+	else
+		INIT_HLIST_NODE(&est->list);
+	return ret;
+}
+
+static void ip_vs_est_kthread_destroy(struct ip_vs_est_kt_data *kd)
+{
+	if (kd) {
+		if (kd->task) {
+			pr_info("stop unused estimator thread %d...\n", kd->id);
+			kthread_stop(kd->task);
+		}
+		ip_vs_stats_free(kd->calc_stats);
+		kfree(kd);
+	}
+}
+
+/* Unlink estimator from chain */
+void ip_vs_stop_estimator(struct netns_ipvs *ipvs, struct ip_vs_stats *stats)
+{
+	struct ip_vs_estimator *est = &stats->est;
+	struct ip_vs_est_tick_data *td;
+	struct ip_vs_est_kt_data *kd;
+	int ktid = est->ktid;
+	int row = est->ktrow;
+	int cid = est->ktcid;
+
+	/* Failed to add to chain ? */
+	if (hlist_unhashed(&est->list))
+		return;
+
+	/* On return, estimator can be freed, dequeue it now */
+
+	/* In est_temp_list ? */
+	if (ktid < 0) {
+		hlist_del(&est->list);
+		goto end_kt0;
+	}
+
+	hlist_del_rcu(&est->list);
+	kd = ipvs->est_kt_arr[ktid];
+	td = rcu_dereference_protected(kd->ticks[row], 1);
+	__clear_bit(cid, td->full);
+	td->chain_len[cid]--;
+	if (!td->chain_len[cid])
+		__clear_bit(cid, td->present);
+	kd->tick_len[row]--;
+	__set_bit(row, kd->avail);
+	if (!kd->tick_len[row]) {
+		RCU_INIT_POINTER(kd->ticks[row], NULL);
+		kfree_rcu(td, rcu_head);
+	}
+	kd->est_count--;
+	if (kd->est_count) {
+		/* This kt slot can become available just now, prefer it */
+		if (ktid < ipvs->est_add_ktid)
+			ipvs->est_add_ktid = ktid;
+		return;
+	}
+
+	if (ktid > 0) {
+		mutex_lock(&ipvs->est_mutex);
+		ip_vs_est_kthread_destroy(kd);
+		ipvs->est_kt_arr[ktid] = NULL;
+		if (ktid == ipvs->est_kt_count - 1) {
+			ipvs->est_kt_count--;
+			while (ipvs->est_kt_count > 1 &&
+			       !ipvs->est_kt_arr[ipvs->est_kt_count - 1])
+				ipvs->est_kt_count--;
+		}
+		mutex_unlock(&ipvs->est_mutex);
+
+		/* This slot is now empty, prefer another available kt slot */
+		if (ktid == ipvs->est_add_ktid)
+			ip_vs_est_update_ktid(ipvs);
+	}
+
+end_kt0:
+	/* kt 0 is freed after all other kthreads and chains are empty */
+	if (ipvs->est_kt_count == 1 && hlist_empty(&ipvs->est_temp_list)) {
+		kd = ipvs->est_kt_arr[0];
+		if (!kd || !kd->est_count) {
+			mutex_lock(&ipvs->est_mutex);
+			if (kd) {
+				ip_vs_est_kthread_destroy(kd);
+				ipvs->est_kt_arr[0] = NULL;
+			}
+			ipvs->est_kt_count--;
+			mutex_unlock(&ipvs->est_mutex);
+			ipvs->est_add_ktid = 0;
+		}
+	}
+}
+
+/* Register all ests from est_temp_list to kthreads */
+static void ip_vs_est_drain_temp_list(struct netns_ipvs *ipvs)
+{
+	struct ip_vs_estimator *est;
+
+	while (1) {
+		int max = 16;
+
+		mutex_lock(&__ip_vs_mutex);
+
+		while (max-- > 0) {
+			est = hlist_entry_safe(ipvs->est_temp_list.first,
+					       struct ip_vs_estimator, list);
+			if (est) {
+				if (kthread_should_stop())
+					goto unlock;
+				hlist_del_init(&est->list);
+				if (ip_vs_enqueue_estimator(ipvs, est) >= 0)
+					continue;
+				est->ktid = -1;
+				hlist_add_head(&est->list,
+					       &ipvs->est_temp_list);
+				/* Abort, some entries will not be estimated
+				 * until next attempt
+				 */
+			}
+			goto unlock;
+		}
+		mutex_unlock(&__ip_vs_mutex);
+		cond_resched();
+	}
+
+unlock:
+	mutex_unlock(&__ip_vs_mutex);
+}
+
+/* Calculate limits for all kthreads */
+static int ip_vs_est_calc_limits(struct netns_ipvs *ipvs, int *chain_max)
+{
+	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+	struct ip_vs_est_kt_data *kd;
+	struct hlist_head chain;
+	struct ip_vs_stats *s;
+	int cache_factor = 4;
+	int i, loops, ntest;
+	s32 min_est = 0;
+	ktime_t t1, t2;
+	int max = 8;
+	int ret = 1;
+	s64 diff;
+	u64 val;
+
+	INIT_HLIST_HEAD(&chain);
+	mutex_lock(&__ip_vs_mutex);
+	kd = ipvs->est_kt_arr[0];
+	mutex_unlock(&__ip_vs_mutex);
+	s = kd ? kd->calc_stats : NULL;
+	if (!s)
+		goto out;
+	hlist_add_head(&s->est.list, &chain);
+
+	loops = 1;
+	/* Get best result from many tests */
+	for (ntest = 0; ntest < 12; ntest++) {
+		if (!(ntest & 3)) {
+			/* Wait for cpufreq frequency transition */
+			wait_event_idle_timeout(wq, kthread_should_stop(),
+						HZ / 50);
+			if (!ipvs->enable || kthread_should_stop())
+				goto stop;
+		}
+
+		local_bh_disable();
+		rcu_read_lock();
+
+		/* Put stats in cache */
+		ip_vs_chain_estimation(&chain);
+
+		t1 = ktime_get();
+		for (i = loops * cache_factor; i > 0; i--)
+			ip_vs_chain_estimation(&chain);
+		t2 = ktime_get();
+
+		rcu_read_unlock();
+		local_bh_enable();
+
+		if (!ipvs->enable || kthread_should_stop())
+			goto stop;
+		cond_resched();
+
+		diff = ktime_to_ns(ktime_sub(t2, t1));
+		if (diff <= 1 * NSEC_PER_USEC) {
+			/* Do more loops on low time resolution */
+			loops *= 2;
+			continue;
+		}
+		if (diff >= NSEC_PER_SEC)
+			continue;
+		val = diff;
+		do_div(val, loops);
+		if (!min_est || val < min_est) {
+			min_est = val;
+			/* goal: 95usec per chain */
+			val = 95 * NSEC_PER_USEC;
+			if (val >= min_est) {
+				do_div(val, min_est);
+				max = (int)val;
+			} else {
+				max = 1;
+			}
+		}
+	}
+
+out:
+	if (s)
+		hlist_del_init(&s->est.list);
+	*chain_max = max;
+	return ret;
+
+stop:
+	ret = 0;
+	goto out;
+}
+
+/* Calculate the parameters and apply them in context of kt #0
+ * ECP: est_calc_phase
+ * ECM: est_chain_max
+ * ECP	ECM	Insert Chain	enable	Description
+ * ---------------------------------------------------------------------------
+ * 0	0	est_temp_list	0	create kt #0 context
+ * 0	0	est_temp_list	0->1	service added, start kthread #0 task
+ * 0->1	0	est_temp_list	1	kt task #0 started, enters calc phase
+ * 1	0	est_temp_list	1	kt #0: determine est_chain_max,
+ *					stop tasks, move ests to est_temp_list
+ *					and free kd for kthreads 1..last
+ * 1->0	0->N	kt chains	1	ests can go to kthreads
+ * 0	N	kt chains	1	drain est_temp_list, create new kthread
+ *					contexts, start tasks, estimate
+ */
+static void ip_vs_est_calc_phase(struct netns_ipvs *ipvs)
+{
+	int genid = atomic_read(&ipvs->est_genid);
+	struct ip_vs_est_tick_data *td;
+	struct ip_vs_est_kt_data *kd;
+	struct ip_vs_estimator *est;
+	struct ip_vs_stats *stats;
+	int id, row, cid, delay;
+	bool last, last_td;
+	int chain_max;
+	int step;
+
+	if (!ip_vs_est_calc_limits(ipvs, &chain_max))
+		return;
+
+	mutex_lock(&__ip_vs_mutex);
+
+	/* Stop all other tasks, so that we can immediately move the
+	 * estimators to est_temp_list without RCU grace period
+	 */
+	mutex_lock(&ipvs->est_mutex);
+	for (id = 1; id < ipvs->est_kt_count; id++) {
+		/* netns clean up started, abort */
+		if (!ipvs->enable)
+			goto unlock2;
+		kd = ipvs->est_kt_arr[id];
+		if (!kd)
+			continue;
+		ip_vs_est_kthread_stop(kd);
+	}
+	mutex_unlock(&ipvs->est_mutex);
+
+	/* Move all estimators to est_temp_list but carefully,
+	 * all estimators and kthread data can be released while
+	 * we reschedule. Even for kthread 0.
+	 */
+	step = 0;
+
+	/* Order entries in est_temp_list in ascending delay, so now
+	 * walk delay(desc), id(desc), cid(asc)
+	 */
+	delay = IPVS_EST_NTICKS;
+
+next_delay:
+	delay--;
+	if (delay < 0)
+		goto end_dequeue;
+
+last_kt:
+	/* Destroy contexts backwards */
+	id = ipvs->est_kt_count;
+
+next_kt:
+	if (!ipvs->enable || kthread_should_stop())
+		goto unlock;
+	id--;
+	if (id < 0)
+		goto next_delay;
+	kd = ipvs->est_kt_arr[id];
+	if (!kd)
+		goto next_kt;
+	/* kt 0 can exist with empty chains */
+	if (!id && kd->est_count <= 1)
+		goto next_delay;
+
+	row = kd->est_row + delay;
+	if (row >= IPVS_EST_NTICKS)
+		row -= IPVS_EST_NTICKS;
+	td = rcu_dereference_protected(kd->ticks[row], 1);
+	if (!td)
+		goto next_kt;
+
+	cid = 0;
+
+walk_chain:
+	if (kthread_should_stop())
+		goto unlock;
+	step++;
+	if (!(step & 63)) {
+		/* Give chance estimators to be added (to est_temp_list)
+		 * and deleted (releasing kthread contexts)
+		 */
+		mutex_unlock(&__ip_vs_mutex);
+		cond_resched();
+		mutex_lock(&__ip_vs_mutex);
+
+		/* Current kt released ? */
+		if (id >= ipvs->est_kt_count)
+			goto last_kt;
+		if (kd != ipvs->est_kt_arr[id])
+			goto next_kt;
+		/* Current td released ? */
+		if (td != rcu_dereference_protected(kd->ticks[row], 1))
+			goto next_kt;
+		/* No fatal changes on the current kd and td */
+	}
+	est = hlist_entry_safe(td->chains[cid].first, struct ip_vs_estimator,
+			       list);
+	if (!est) {
+		cid++;
+		if (cid >= IPVS_EST_TICK_CHAINS)
+			goto next_kt;
+		goto walk_chain;
+	}
+	/* We can cheat and increase est_count to protect kt 0 context
+	 * from release but we prefer to keep the last estimator
+	 */
+	last = kd->est_count <= 1;
+	/* Do not free kt #0 data */
+	if (!id && last)
+		goto next_delay;
+	last_td = kd->tick_len[row] <= 1;
+	stats = container_of(est, struct ip_vs_stats, est);
+	ip_vs_stop_estimator(ipvs, stats);
+	/* Tasks are stopped, move without RCU grace period */
+	est->ktid = -1;
+	est->ktrow = row - kd->est_row;
+	if (est->ktrow < 0)
+		est->ktrow += IPVS_EST_NTICKS;
+	hlist_add_head(&est->list, &ipvs->est_temp_list);
+	/* kd freed ? */
+	if (last)
+		goto next_kt;
+	/* td freed ? */
+	if (last_td)
+		goto next_kt;
+	goto walk_chain;
+
+end_dequeue:
+	/* All estimators removed while calculating ? */
+	if (!ipvs->est_kt_count)
+		goto unlock;
+	kd = ipvs->est_kt_arr[0];
+	if (!kd)
+		goto unlock;
+	kd->add_row = kd->est_row;
+	ipvs->est_chain_max = chain_max;
+	ip_vs_est_set_params(ipvs, kd);
+
+	pr_info("using max %d ests per chain, %d per kthread\n",
+		kd->chain_max, kd->est_max_count);
+
+	/* Try to keep tot_stats in kt0, enqueue it early */
+	if (ipvs->tot_stats && !hlist_unhashed(&ipvs->tot_stats->s.est.list) &&
+	    ipvs->tot_stats->s.est.ktid == -1) {
+		hlist_del(&ipvs->tot_stats->s.est.list);
+		hlist_add_head(&ipvs->tot_stats->s.est.list,
+			       &ipvs->est_temp_list);
+	}
+
+	mutex_lock(&ipvs->est_mutex);
+
+	/* We completed the calc phase, new calc phase not requested */
+	if (genid == atomic_read(&ipvs->est_genid))
+		ipvs->est_calc_phase = 0;
+
+unlock2:
+	mutex_unlock(&ipvs->est_mutex);
+
+unlock:
+	mutex_unlock(&__ip_vs_mutex);
+}
+
+void ip_vs_zero_estimator(struct ip_vs_stats *stats)
+{
+	struct ip_vs_estimator *est = &stats->est;
+	struct ip_vs_kstats *k = &stats->kstats;
+
+	/* reset counters, caller must hold the stats->lock lock */
+	est->last_inbytes = k->inbytes;
+	est->last_outbytes = k->outbytes;
+	est->last_conns = k->conns;
+	est->last_inpkts = k->inpkts;
+	est->last_outpkts = k->outpkts;
+	est->cps = 0;
+	est->inpps = 0;
+	est->outpps = 0;
+	est->inbps = 0;
+	est->outbps = 0;
+}
+
+/* Get decoded rates */
+void ip_vs_read_estimator(struct ip_vs_kstats *dst, struct ip_vs_stats *stats)
+{
+	struct ip_vs_estimator *e = &stats->est;
+
+	dst->cps = (e->cps + 0x1FF) >> 10;
+	dst->inpps = (e->inpps + 0x1FF) >> 10;
+	dst->outpps = (e->outpps + 0x1FF) >> 10;
+	dst->inbps = (e->inbps + 0xF) >> 5;
+	dst->outbps = (e->outbps + 0xF) >> 5;
+}
+
+int __net_init ip_vs_estimator_net_init(struct netns_ipvs *ipvs)
+{
+	INIT_HLIST_HEAD(&ipvs->est_temp_list);
+	ipvs->est_kt_arr = NULL;
+	ipvs->est_max_threads = 0;
+	ipvs->est_calc_phase = 0;
+	ipvs->est_chain_max = 0;
+	ipvs->est_kt_count = 0;
+	ipvs->est_add_ktid = 0;
+	atomic_set(&ipvs->est_genid, 0);
+	atomic_set(&ipvs->est_genid_done, 0);
+	__mutex_init(&ipvs->est_mutex, "ipvs->est_mutex", &__ipvs_est_key);
+	return 0;
+}
+
+void __net_exit ip_vs_estimator_net_cleanup(struct netns_ipvs *ipvs)
+{
+	int i;
+
+	for (i = 0; i < ipvs->est_kt_count; i++)
+		ip_vs_est_kthread_destroy(ipvs->est_kt_arr[i]);
+	kfree(ipvs->est_kt_arr);
+	mutex_destroy(&ipvs->est_mutex);
+}