1 files changed, 152 insertions, 193 deletions

diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c
index 6b5b6e7013ca..f112156db587 100644
--- a/net/core/gen_estimator.c
+++ b/net/core/gen_estimator.c
@@ -1,19 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * net/sched/gen_estimator.c	Simple rate estimator.
  *
- *		This program is free software; you can redistribute it and/or
- *		modify it under the terms of the GNU General Public License
- *		as published by the Free Software Foundation; either version
- *		2 of the License, or (at your option) any later version.
- *
  * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ *		Eric Dumazet <edumazet@google.com>
  *
  * Changes:
  *              Jamal Hadi Salim - moved it to net/core and reshulfed
  *              names to make it usable in general net subsystem.
  */
 
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
 #include <linux/bitops.h>
 #include <linux/module.h>
 #include <linux/types.h>
@@ -30,258 +27,204 @@
 #include <linux/skbuff.h>
 #include <linux/rtnetlink.h>
 #include <linux/init.h>
-#include <linux/rbtree.h>
 #include <linux/slab.h>
+#include <linux/seqlock.h>
 #include <net/sock.h>
 #include <net/gen_stats.h>
 
-/*
-   This code is NOT intended to be used for statistics collection,
-   its purpose is to provide a base for statistical multiplexing
-   for controlled load service.
-   If you need only statistics, run a user level daemon which
-   periodically reads byte counters.
-
-   Unfortunately, rate estimation is not a very easy task.
-   F.e. I did not find a simple way to estimate the current peak rate
-   and even failed to formulate the problem 8)8)
-
-   So I preferred not to built an estimator into the scheduler,
-   but run this task separately.
-   Ideally, it should be kernel thread(s), but for now it runs
-   from timers, which puts apparent top bounds on the number of rated
-   flows, has minimal overhead on small, but is enough
-   to handle controlled load service, sets of aggregates.
-
-   We measure rate over A=(1<<interval) seconds and evaluate EWMA:
-
-   avrate = avrate*(1-W) + rate*W
-
-   where W is chosen as negative power of 2: W = 2^(-ewma_log)
-
-   The resulting time constant is:
-
-   T = A/(-ln(1-W))
-
-
-   NOTES.
-
-   * avbps is scaled by 2^5, avpps is scaled by 2^10.
-   * both values are reported as 32 bit unsigned values. bps can
-     overflow for fast links : max speed being 34360Mbit/sec
-   * Minimal interval is HZ/4=250msec (it is the greatest common divisor
-     for HZ=100 and HZ=1024 8)), maximal interval
-     is (HZ*2^EST_MAX_INTERVAL)/4 = 8sec. Shorter intervals
-     are too expensive, longer ones can be implemented
-     at user level painlessly.
+/* This code is NOT intended to be used for statistics collection,
+ * its purpose is to provide a base for statistical multiplexing
+ * for controlled load service.
+ * If you need only statistics, run a user level daemon which
+ * periodically reads byte counters.
  */
 
-#define EST_MAX_INTERVAL	5
-
-struct gen_estimator
-{
-	struct list_head	list;
-	struct gnet_stats_basic_packed	*bstats;
-	struct gnet_stats_rate_est64	*rate_est;
+struct net_rate_estimator {
+	struct gnet_stats_basic_sync	*bstats;
 	spinlock_t		*stats_lock;
-	int			ewma_log;
+	bool			running;
+	struct gnet_stats_basic_sync __percpu *cpu_bstats;
+	u8			ewma_log;
+	u8			intvl_log; /* period : (250ms << intvl_log) */
+
+	seqcount_t		seq;
+	u64			last_packets;
 	u64			last_bytes;
+
+	u64			avpps;
 	u64			avbps;
-	u32			last_packets;
-	u32			avpps;
-	struct rcu_head		e_rcu;
-	struct rb_node		node;
-};
 
-struct gen_estimator_head
-{
-	struct timer_list	timer;
-	struct list_head	list;
+	unsigned long           next_jiffies;
+	struct timer_list       timer;
+	struct rcu_head		rcu;
 };
 
-static struct gen_estimator_head elist[EST_MAX_INTERVAL+1];
-
-/* Protects against NULL dereference */
-static DEFINE_RWLOCK(est_lock);
-
-/* Protects against soft lockup during large deletion */
-static struct rb_root est_root = RB_ROOT;
-static DEFINE_SPINLOCK(est_tree_lock);
-
-static void est_timer(unsigned long arg)
+static void est_fetch_counters(struct net_rate_estimator *e,
+			       struct gnet_stats_basic_sync *b)
 {
-	int idx = (int)arg;
-	struct gen_estimator *e;
+	gnet_stats_basic_sync_init(b);
+	if (e->stats_lock)
+		spin_lock(e->stats_lock);
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(e, &elist[idx].list, list) {
-		u64 nbytes;
-		u64 brate;
-		u32 npackets;
-		u32 rate;
+	gnet_stats_add_basic(b, e->cpu_bstats, e->bstats, e->running);
 
-		spin_lock(e->stats_lock);
-		read_lock(&est_lock);
-		if (e->bstats == NULL)
-			goto skip;
-
-		nbytes = e->bstats->bytes;
-		npackets = e->bstats->packets;
-		brate = (nbytes - e->last_bytes)<<(7 - idx);
-		e->last_bytes = nbytes;
-		e->avbps += (brate >> e->ewma_log) - (e->avbps >> e->ewma_log);
-		e->rate_est->bps = (e->avbps+0xF)>>5;
-
-		rate = (npackets - e->last_packets)<<(12 - idx);
-		e->last_packets = npackets;
-		e->avpps += (rate >> e->ewma_log) - (e->avpps >> e->ewma_log);
-		e->rate_est->pps = (e->avpps+0x1FF)>>10;
-skip:
-		read_unlock(&est_lock);
+	if (e->stats_lock)
 		spin_unlock(e->stats_lock);
-	}
 
-	if (!list_empty(&elist[idx].list))
-		mod_timer(&elist[idx].timer, jiffies + ((HZ/4) << idx));
-	rcu_read_unlock();
 }
 
-static void gen_add_node(struct gen_estimator *est)
+static void est_timer(struct timer_list *t)
 {
-	struct rb_node **p = &est_root.rb_node, *parent = NULL;
+	struct net_rate_estimator *est = timer_container_of(est, t, timer);
+	struct gnet_stats_basic_sync b;
+	u64 b_bytes, b_packets;
+	u64 rate, brate;
 
-	while (*p) {
-		struct gen_estimator *e;
+	est_fetch_counters(est, &b);
+	b_bytes = u64_stats_read(&b.bytes);
+	b_packets = u64_stats_read(&b.packets);
 
-		parent = *p;
-		e = rb_entry(parent, struct gen_estimator, node);
+	brate = (b_bytes - est->last_bytes) << (10 - est->intvl_log);
+	brate = (brate >> est->ewma_log) - (est->avbps >> est->ewma_log);
 
-		if (est->bstats > e->bstats)
-			p = &parent->rb_right;
-		else
-			p = &parent->rb_left;
-	}
-	rb_link_node(&est->node, parent, p);
-	rb_insert_color(&est->node, &est_root);
-}
+	rate = (b_packets - est->last_packets) << (10 - est->intvl_log);
+	rate = (rate >> est->ewma_log) - (est->avpps >> est->ewma_log);
 
-static
-struct gen_estimator *gen_find_node(const struct gnet_stats_basic_packed *bstats,
-				    const struct gnet_stats_rate_est64 *rate_est)
-{
-	struct rb_node *p = est_root.rb_node;
+	preempt_disable_nested();
+	write_seqcount_begin(&est->seq);
+	est->avbps += brate;
+	est->avpps += rate;
+	write_seqcount_end(&est->seq);
+	preempt_enable_nested();
 
-	while (p) {
-		struct gen_estimator *e;
+	est->last_bytes = b_bytes;
+	est->last_packets = b_packets;
 
-		e = rb_entry(p, struct gen_estimator, node);
+	est->next_jiffies += ((HZ/4) << est->intvl_log);
 
-		if (bstats > e->bstats)
-			p = p->rb_right;
-		else if (bstats < e->bstats || rate_est != e->rate_est)
-			p = p->rb_left;
-		else
-			return e;
+	if (unlikely(time_after_eq(jiffies, est->next_jiffies))) {
+		/* Ouch... timer was delayed. */
+		est->next_jiffies = jiffies + 1;
 	}
-	return NULL;
+	mod_timer(&est->timer, est->next_jiffies);
 }
 
 /**
  * gen_new_estimator - create a new rate estimator
  * @bstats: basic statistics
+ * @cpu_bstats: bstats per cpu
  * @rate_est: rate estimator statistics
- * @stats_lock: statistics lock
+ * @lock: lock for statistics and control path
+ * @running: true if @bstats represents a running qdisc, thus @bstats'
+ *           internal values might change during basic reads. Only used
+ *           if @bstats_cpu is NULL
  * @opt: rate estimator configuration TLV
  *
  * Creates a new rate estimator with &bstats as source and &rate_est
  * as destination. A new timer with the interval specified in the
  * configuration TLV is created. Upon each interval, the latest statistics
  * will be read from &bstats and the estimated rate will be stored in
- * &rate_est with the statistics lock grabed during this period.
+ * &rate_est with the statistics lock grabbed during this period.
  *
  * Returns 0 on success or a negative error code.
  *
  */
-int gen_new_estimator(struct gnet_stats_basic_packed *bstats,
-		      struct gnet_stats_rate_est64 *rate_est,
-		      spinlock_t *stats_lock,
+int gen_new_estimator(struct gnet_stats_basic_sync *bstats,
+		      struct gnet_stats_basic_sync __percpu *cpu_bstats,
+		      struct net_rate_estimator __rcu **rate_est,
+		      spinlock_t *lock,
+		      bool running,
 		      struct nlattr *opt)
 {
-	struct gen_estimator *est;
 	struct gnet_estimator *parm = nla_data(opt);
-	int idx;
+	struct net_rate_estimator *old, *est;
+	struct gnet_stats_basic_sync b;
+	int intvl_log;
 
 	if (nla_len(opt) < sizeof(*parm))
 		return -EINVAL;
 
+	/* allowed timer periods are :
+	 * -2 : 250ms,   -1 : 500ms,    0 : 1 sec
+	 *  1 : 2 sec,    2 : 4 sec,    3 : 8 sec
+	 */
 	if (parm->interval < -2 || parm->interval > 3)
 		return -EINVAL;
 
+	if (parm->ewma_log == 0 || parm->ewma_log >= 31)
+		return -EINVAL;
+
 	est = kzalloc(sizeof(*est), GFP_KERNEL);
-	if (est == NULL)
+	if (!est)
 		return -ENOBUFS;
 
-	idx = parm->interval + 2;
+	seqcount_init(&est->seq);
+	intvl_log = parm->interval + 2;
 	est->bstats = bstats;
-	est->rate_est = rate_est;
-	est->stats_lock = stats_lock;
+	est->stats_lock = lock;
+	est->running  = running;
 	est->ewma_log = parm->ewma_log;
-	est->last_bytes = bstats->bytes;
-	est->avbps = rate_est->bps<<5;
-	est->last_packets = bstats->packets;
-	est->avpps = rate_est->pps<<10;
-
-	spin_lock_bh(&est_tree_lock);
-	if (!elist[idx].timer.function) {
-		INIT_LIST_HEAD(&elist[idx].list);
-		setup_timer(&elist[idx].timer, est_timer, idx);
+	est->intvl_log = intvl_log;
+	est->cpu_bstats = cpu_bstats;
+
+	if (lock)
+		local_bh_disable();
+	est_fetch_counters(est, &b);
+	if (lock)
+		local_bh_enable();
+	est->last_bytes = u64_stats_read(&b.bytes);
+	est->last_packets = u64_stats_read(&b.packets);
+
+	if (lock)
+		spin_lock_bh(lock);
+	old = rcu_dereference_protected(*rate_est, 1);
+	if (old) {
+		timer_delete_sync(&old->timer);
+		est->avbps = old->avbps;
+		est->avpps = old->avpps;
 	}
 
-	if (list_empty(&elist[idx].list))
-		mod_timer(&elist[idx].timer, jiffies + ((HZ/4) << idx));
-
-	list_add_rcu(&est->list, &elist[idx].list);
-	gen_add_node(est);
-	spin_unlock_bh(&est_tree_lock);
+	est->next_jiffies = jiffies + ((HZ/4) << intvl_log);
+	timer_setup(&est->timer, est_timer, 0);
+	mod_timer(&est->timer, est->next_jiffies);
 
+	rcu_assign_pointer(*rate_est, est);
+	if (lock)
+		spin_unlock_bh(lock);
+	if (old)
+		kfree_rcu(old, rcu);
 	return 0;
 }
 EXPORT_SYMBOL(gen_new_estimator);
 
 /**
  * gen_kill_estimator - remove a rate estimator
- * @bstats: basic statistics
- * @rate_est: rate estimator statistics
+ * @rate_est: rate estimator
  *
- * Removes the rate estimator specified by &bstats and &rate_est.
+ * Removes the rate estimator.
  *
- * Note : Caller should respect an RCU grace period before freeing stats_lock
  */
-void gen_kill_estimator(struct gnet_stats_basic_packed *bstats,
-			struct gnet_stats_rate_est64 *rate_est)
+void gen_kill_estimator(struct net_rate_estimator __rcu **rate_est)
 {
-	struct gen_estimator *e;
-
-	spin_lock_bh(&est_tree_lock);
-	while ((e = gen_find_node(bstats, rate_est))) {
-		rb_erase(&e->node, &est_root);
+	struct net_rate_estimator *est;
 
-		write_lock(&est_lock);
-		e->bstats = NULL;
-		write_unlock(&est_lock);
-
-		list_del_rcu(&e->list);
-		kfree_rcu(e, e_rcu);
+	est = unrcu_pointer(xchg(rate_est, NULL));
+	if (est) {
+		timer_shutdown_sync(&est->timer);
+		kfree_rcu(est, rcu);
 	}
-	spin_unlock_bh(&est_tree_lock);
 }
 EXPORT_SYMBOL(gen_kill_estimator);
 
 /**
  * gen_replace_estimator - replace rate estimator configuration
  * @bstats: basic statistics
+ * @cpu_bstats: bstats per cpu
  * @rate_est: rate estimator statistics
- * @stats_lock: statistics lock
+ * @lock: lock for statistics and control path
+ * @running: true if @bstats represents a running qdisc, thus @bstats'
+ *           internal values might change during basic reads. Only used
+ *           if @cpu_bstats is NULL
  * @opt: rate estimator configuration TLV
  *
  * Replaces the configuration of a rate estimator by calling
@@ -289,33 +232,49 @@ EXPORT_SYMBOL(gen_kill_estimator);
  *
  * Returns 0 on success or a negative error code.
  */
-int gen_replace_estimator(struct gnet_stats_basic_packed *bstats,
-			  struct gnet_stats_rate_est64 *rate_est,
-			  spinlock_t *stats_lock, struct nlattr *opt)
+int gen_replace_estimator(struct gnet_stats_basic_sync *bstats,
+			  struct gnet_stats_basic_sync __percpu *cpu_bstats,
+			  struct net_rate_estimator __rcu **rate_est,
+			  spinlock_t *lock,
+			  bool running, struct nlattr *opt)
 {
-	gen_kill_estimator(bstats, rate_est);
-	return gen_new_estimator(bstats, rate_est, stats_lock, opt);
+	return gen_new_estimator(bstats, cpu_bstats, rate_est,
+				 lock, running, opt);
 }
 EXPORT_SYMBOL(gen_replace_estimator);
 
 /**
  * gen_estimator_active - test if estimator is currently in use
- * @bstats: basic statistics
- * @rate_est: rate estimator statistics
+ * @rate_est: rate estimator
  *
  * Returns true if estimator is active, and false if not.
  */
-bool gen_estimator_active(const struct gnet_stats_basic_packed *bstats,
-			  const struct gnet_stats_rate_est64 *rate_est)
+bool gen_estimator_active(struct net_rate_estimator __rcu **rate_est)
 {
-	bool res;
+	return !!rcu_access_pointer(*rate_est);
+}
+EXPORT_SYMBOL(gen_estimator_active);
 
-	ASSERT_RTNL();
+bool gen_estimator_read(struct net_rate_estimator __rcu **rate_est,
+			struct gnet_stats_rate_est64 *sample)
+{
+	struct net_rate_estimator *est;
+	unsigned seq;
 
-	spin_lock_bh(&est_tree_lock);
-	res = gen_find_node(bstats, rate_est) != NULL;
-	spin_unlock_bh(&est_tree_lock);
+	rcu_read_lock();
+	est = rcu_dereference(*rate_est);
+	if (!est) {
+		rcu_read_unlock();
+		return false;
+	}
+
+	do {
+		seq = read_seqcount_begin(&est->seq);
+		sample->bps = est->avbps >> 8;
+		sample->pps = est->avpps >> 8;
+	} while (read_seqcount_retry(&est->seq, seq));
 
-	return res;
+	rcu_read_unlock();
+	return true;
 }
-EXPORT_SYMBOL(gen_estimator_active);
+EXPORT_SYMBOL(gen_estimator_read);