// SPDX-License-Identifier: GPL-2.0-or-later
/*
* net/sched/gen_estimator.c Simple rate estimator.
*
* Authors: Alexey Kuznetsov, <[email protected]>
* Eric Dumazet <[email protected]>
*
* Changes:
* Jamal Hadi Salim - moved it to net/core and reshulfed
* names to make it usable in general net subsystem.
*/
#include <linux/uaccess.h>
#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/init.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.
*/
struct net_rate_estimator {
struct gnet_stats_basic_sync *bstats;
spinlock_t *stats_lock;
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;
unsigned long next_jiffies;
struct timer_list timer;
struct rcu_head rcu;
};
static void est_fetch_counters(struct net_rate_estimator *e,
struct gnet_stats_basic_sync *b)
{
gnet_stats_basic_sync_init(b);
if (e->stats_lock)
spin_lock(e->stats_lock);
gnet_stats_add_basic(b, e->cpu_bstats, e->bstats, e->running);
if (e->stats_lock)
spin_unlock(e->stats_lock);
}
static void est_timer(struct timer_list *t)
{
struct net_rate_estimator *est = from_timer(est, t, timer);
struct gnet_stats_basic_sync b;
u64 b_bytes, b_packets;
u64 rate, brate;
est_fetch_counters(est, &b);
b_bytes = u64_stats_read(&b.bytes);
b_packets = u64_stats_read(&b.packets);
brate = (b_bytes - est->last_bytes) << (10 - est->intvl_log);
brate = (brate >> est->ewma_log) - (est->avbps >> est->ewma_log);
rate = (b_packets - est->last_packets) << (10 - est->intvl_log);
rate = (rate >> est->ewma_log) - (est->avpps >> est->ewma_log);
write_seqcount_begin(&est->seq);
est->avbps += brate;
est->avpps += rate;
write_seqcount_end(&est->seq);
est->last_bytes = b_bytes;
est->last_packets = b_packets;
est->next_jiffies += ((HZ/4) << est->intvl_log);
if (unlikely(time_after_eq(jiffies, est->next_jiffies))) {
/* Ouch... timer was delayed. */
est->next_jiffies = jiffies + 1;
}
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
* @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 grabbed during this period.
*
* Returns 0 on success or a negative error code.
*
*/
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 gnet_estimator *parm = nla_data(opt);
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)
return -ENOBUFS;
seqcount_init(&est->seq);
intvl_log = parm->interval + 2;
est->bstats = bstats;
est->stats_lock = lock;
est->running = running;
est->ewma_log = parm->ewma_log;
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) {
del_timer_sync(&old->timer);
est->avbps = old->avbps;
est->avpps = old->avpps;
}
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
* @rate_est: rate estimator
*
* Removes the rate estimator.
*
*/
void gen_kill_estimator(struct net_rate_estimator __rcu **rate_est)
{
struct net_rate_estimator *est;
est = unrcu_pointer(xchg(rate_est, NULL));
if (est) {
timer_shutdown_sync(&est->timer);
kfree_rcu(est, rcu);
}
}
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
* @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
* gen_kill_estimator() and gen_new_estimator().
*
* Returns 0 on success or a negative error code.
*/
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)
{
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
* @rate_est: rate estimator
*
* Returns true if estimator is active, and false if not.
*/
bool gen_estimator_active(struct net_rate_estimator __rcu **rate_est)
{
return !!rcu_access_pointer(*rate_est);
}
EXPORT_SYMBOL(gen_estimator_active);
bool gen_estimator_read(struct net_rate_estimator __rcu **rate_est,
struct gnet_stats_rate_est64 *sample)
{
struct net_rate_estimator *est;
unsigned seq;
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));
rcu_read_unlock();
return true;
}
EXPORT_SYMBOL(gen_estimator_read);
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