1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * net/sched/gen_estimator.c Simple rate estimator.
4 *
5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
6 * Eric Dumazet <edumazet@google.com>
7 *
8 * Changes:
9 * Jamal Hadi Salim - moved it to net/core and reshulfed
10 * names to make it usable in general net subsystem.
11 */
12
13 #include <linux/uaccess.h>
14 #include <linux/bitops.h>
15 #include <linux/module.h>
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/jiffies.h>
19 #include <linux/string.h>
20 #include <linux/mm.h>
21 #include <linux/socket.h>
22 #include <linux/sockios.h>
23 #include <linux/in.h>
24 #include <linux/errno.h>
25 #include <linux/interrupt.h>
26 #include <linux/netdevice.h>
27 #include <linux/skbuff.h>
28 #include <linux/rtnetlink.h>
29 #include <linux/init.h>
30 #include <linux/slab.h>
31 #include <linux/seqlock.h>
32 #include <net/sock.h>
33 #include <net/gen_stats.h>
34
35 /* This code is NOT intended to be used for statistics collection,
36 * its purpose is to provide a base for statistical multiplexing
37 * for controlled load service.
38 * If you need only statistics, run a user level daemon which
39 * periodically reads byte counters.
40 */
41
42 struct net_rate_estimator {
43 struct gnet_stats_basic_sync *bstats;
44 spinlock_t *stats_lock;
45 bool running;
46 struct gnet_stats_basic_sync __percpu *cpu_bstats;
47 u8 ewma_log;
48 u8 intvl_log; /* period : (250ms << intvl_log) */
49
50 seqcount_t seq;
51 u64 last_packets;
52 u64 last_bytes;
53
54 u64 avpps;
55 u64 avbps;
56
57 unsigned long next_jiffies;
58 struct timer_list timer;
59 struct rcu_head rcu;
60 };
61
62 static void est_fetch_counters(struct net_rate_estimator *e,
63 struct gnet_stats_basic_sync *b)
64 {
65 gnet_stats_basic_sync_init(b);
66 if (e->stats_lock)
67 spin_lock(e->stats_lock);
68
69 gnet_stats_add_basic(b, e->cpu_bstats, e->bstats, e->running);
70
71 if (e->stats_lock)
72 spin_unlock(e->stats_lock);
73
74 }
75
76 static void est_timer(struct timer_list *t)
77 {
78 struct net_rate_estimator *est = from_timer(est, t, timer);
79 struct gnet_stats_basic_sync b;
80 u64 b_bytes, b_packets;
81 u64 rate, brate;
82
83 est_fetch_counters(est, &b);
84 b_bytes = u64_stats_read(&b.bytes);
85 b_packets = u64_stats_read(&b.packets);
86
87 brate = (b_bytes - est->last_bytes) << (10 - est->intvl_log);
88 brate = (brate >> est->ewma_log) - (est->avbps >> est->ewma_log);
89
90 rate = (b_packets - est->last_packets) << (10 - est->intvl_log);
91 rate = (rate >> est->ewma_log) - (est->avpps >> est->ewma_log);
92
93 write_seqcount_begin(&est->seq);
94 est->avbps += brate;
95 est->avpps += rate;
96 write_seqcount_end(&est->seq);
97
98 est->last_bytes = b_bytes;
99 est->last_packets = b_packets;
100
101 est->next_jiffies += ((HZ/4) << est->intvl_log);
102
103 if (unlikely(time_after_eq(jiffies, est->next_jiffies))) {
104 /* Ouch... timer was delayed. */
105 est->next_jiffies = jiffies + 1;
106 }
107 mod_timer(&est->timer, est->next_jiffies);
108 }
109
110 /**
111 * gen_new_estimator - create a new rate estimator
112 * @bstats: basic statistics
113 * @cpu_bstats: bstats per cpu
114 * @rate_est: rate estimator statistics
115 * @lock: lock for statistics and control path
116 * @running: true if @bstats represents a running qdisc, thus @bstats'
117 * internal values might change during basic reads. Only used
118 * if @bstats_cpu is NULL
119 * @opt: rate estimator configuration TLV
120 *
121 * Creates a new rate estimator with &bstats as source and &rate_est
122 * as destination. A new timer with the interval specified in the
123 * configuration TLV is created. Upon each interval, the latest statistics
124 * will be read from &bstats and the estimated rate will be stored in
125 * &rate_est with the statistics lock grabbed during this period.
126 *
127 * Returns 0 on success or a negative error code.
128 *
129 */
130 int gen_new_estimator(struct gnet_stats_basic_sync *bstats,
131 struct gnet_stats_basic_sync __percpu *cpu_bstats,
132 struct net_rate_estimator __rcu **rate_est,
133 spinlock_t *lock,
134 bool running,
135 struct nlattr *opt)
136 {
137 struct gnet_estimator *parm = nla_data(opt);
138 struct net_rate_estimator *old, *est;
139 struct gnet_stats_basic_sync b;
140 int intvl_log;
141
142 if (nla_len(opt) < sizeof(*parm))
143 return -EINVAL;
144
145 /* allowed timer periods are :
146 * -2 : 250ms, -1 : 500ms, 0 : 1 sec
147 * 1 : 2 sec, 2 : 4 sec, 3 : 8 sec
148 */
149 if (parm->interval < -2 || parm->interval > 3)
150 return -EINVAL;
151
152 if (parm->ewma_log == 0 || parm->ewma_log >= 31)
153 return -EINVAL;
154
155 est = kzalloc(sizeof(*est), GFP_KERNEL);
156 if (!est)
157 return -ENOBUFS;
158
159 seqcount_init(&est->seq);
160 intvl_log = parm->interval + 2;
161 est->bstats = bstats;
162 est->stats_lock = lock;
163 est->running = running;
164 est->ewma_log = parm->ewma_log;
165 est->intvl_log = intvl_log;
166 est->cpu_bstats = cpu_bstats;
167
168 if (lock)
169 local_bh_disable();
170 est_fetch_counters(est, &b);
171 if (lock)
172 local_bh_enable();
173 est->last_bytes = u64_stats_read(&b.bytes);
174 est->last_packets = u64_stats_read(&b.packets);
175
176 if (lock)
177 spin_lock_bh(lock);
178 old = rcu_dereference_protected(*rate_est, 1);
179 if (old) {
180 del_timer_sync(&old->timer);
181 est->avbps = old->avbps;
182 est->avpps = old->avpps;
183 }
184
185 est->next_jiffies = jiffies + ((HZ/4) << intvl_log);
186 timer_setup(&est->timer, est_timer, 0);
187 mod_timer(&est->timer, est->next_jiffies);
188
189 rcu_assign_pointer(*rate_est, est);
190 if (lock)
191 spin_unlock_bh(lock);
192 if (old)
193 kfree_rcu(old, rcu);
194 return 0;
195 }
196 EXPORT_SYMBOL(gen_new_estimator);
197
198 /**
199 * gen_kill_estimator - remove a rate estimator
200 * @rate_est: rate estimator
201 *
202 * Removes the rate estimator.
203 *
204 */
205 void gen_kill_estimator(struct net_rate_estimator __rcu **rate_est)
206 {
207 struct net_rate_estimator *est;
208
209 est = unrcu_pointer(xchg(rate_est, NULL));
210 if (est) {
211 timer_shutdown_sync(&est->timer);
212 kfree_rcu(est, rcu);
213 }
214 }
215 EXPORT_SYMBOL(gen_kill_estimator);
216
217 /**
218 * gen_replace_estimator - replace rate estimator configuration
219 * @bstats: basic statistics
220 * @cpu_bstats: bstats per cpu
221 * @rate_est: rate estimator statistics
222 * @lock: lock for statistics and control path
223 * @running: true if @bstats represents a running qdisc, thus @bstats'
224 * internal values might change during basic reads. Only used
225 * if @cpu_bstats is NULL
226 * @opt: rate estimator configuration TLV
227 *
228 * Replaces the configuration of a rate estimator by calling
229 * gen_kill_estimator() and gen_new_estimator().
230 *
231 * Returns 0 on success or a negative error code.
232 */
233 int gen_replace_estimator(struct gnet_stats_basic_sync *bstats,
234 struct gnet_stats_basic_sync __percpu *cpu_bstats,
235 struct net_rate_estimator __rcu **rate_est,
236 spinlock_t *lock,
237 bool running, struct nlattr *opt)
238 {
239 return gen_new_estimator(bstats, cpu_bstats, rate_est,
240 lock, running, opt);
241 }
242 EXPORT_SYMBOL(gen_replace_estimator);
243
244 /**
245 * gen_estimator_active - test if estimator is currently in use
246 * @rate_est: rate estimator
247 *
248 * Returns true if estimator is active, and false if not.
249 */
250 bool gen_estimator_active(struct net_rate_estimator __rcu **rate_est)
251 {
252 return !!rcu_access_pointer(*rate_est);
253 }
254 EXPORT_SYMBOL(gen_estimator_active);
255
256 bool gen_estimator_read(struct net_rate_estimator __rcu **rate_est,
257 struct gnet_stats_rate_est64 *sample)
258 {
259 struct net_rate_estimator *est;
260 unsigned seq;
261
262 rcu_read_lock();
263 est = rcu_dereference(*rate_est);
264 if (!est) {
265 rcu_read_unlock();
266 return false;
267 }
268
269 do {
270 seq = read_seqcount_begin(&est->seq);
271 sample->bps = est->avbps >> 8;
272 sample->pps = est->avpps >> 8;
273 } while (read_seqcount_retry(&est->seq, seq));
274
275 rcu_read_unlock();
276 return true;
277 }
278 EXPORT_SYMBOL(gen_estimator_read);
279
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