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_packed *bstats; 44 spinlock_t *stats_lock; 45 seqcount_t *running; 46 struct gnet_stats_basic_cpu __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_packed *b) 64 { 65 memset(b, 0, sizeof(*b)); 66 if (e->stats_lock) 67 spin_lock(e->stats_lock); 68 69 __gnet_stats_copy_basic(e->running, b, e->cpu_bstats, e->bstats); 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_packed b; 80 u64 rate, brate; 81 82 est_fetch_counters(est, &b); 83 brate = (b.bytes - est->last_bytes) << (10 - est->intvl_log); 84 brate = (brate >> est->ewma_log) - (est->avbps >> est->ewma_log); 85 86 rate = (b.packets - est->last_packets) << (10 - est->intvl_log); 87 rate = (rate >> est->ewma_log) - (est->avpps >> est->ewma_log); 88 89 write_seqcount_begin(&est->seq); 90 est->avbps += brate; 91 est->avpps += rate; 92 write_seqcount_end(&est->seq); 93 94 est->last_bytes = b.bytes; 95 est->last_packets = b.packets; 96 97 est->next_jiffies += ((HZ/4) << est->intvl_log); 98 99 if (unlikely(time_after_eq(jiffies, est->next_jiffies))) { 100 /* Ouch... timer was delayed. */ 101 est->next_jiffies = jiffies + 1; 102 } 103 mod_timer(&est->timer, est->next_jiffies); 104 } 105 106 /** 107 * gen_new_estimator - create a new rate estimator 108 * @bstats: basic statistics 109 * @cpu_bstats: bstats per cpu 110 * @rate_est: rate estimator statistics 111 * @lock: lock for statistics and control path 112 * @running: qdisc running seqcount 113 * @opt: rate estimator configuration TLV 114 * 115 * Creates a new rate estimator with &bstats as source and &rate_est 116 * as destination. A new timer with the interval specified in the 117 * configuration TLV is created. Upon each interval, the latest statistics 118 * will be read from &bstats and the estimated rate will be stored in 119 * &rate_est with the statistics lock grabbed during this period. 120 * 121 * Returns 0 on success or a negative error code. 122 * 123 */ 124 int gen_new_estimator(struct gnet_stats_basic_packed *bstats, 125 struct gnet_stats_basic_cpu __percpu *cpu_bstats, 126 struct net_rate_estimator __rcu **rate_est, 127 spinlock_t *lock, 128 seqcount_t *running, 129 struct nlattr *opt) 130 { 131 struct gnet_estimator *parm = nla_data(opt); 132 struct net_rate_estimator *old, *est; 133 struct gnet_stats_basic_packed b; 134 int intvl_log; 135 136 if (nla_len(opt) < sizeof(*parm)) 137 return -EINVAL; 138 139 /* allowed timer periods are : 140 * -2 : 250ms, -1 : 500ms, 0 : 1 sec 141 * 1 : 2 sec, 2 : 4 sec, 3 : 8 sec 142 */ 143 if (parm->interval < -2 || parm->interval > 3) 144 return -EINVAL; 145 146 if (parm->ewma_log == 0 || parm->ewma_log >= 31) 147 return -EINVAL; 148 149 est = kzalloc(sizeof(*est), GFP_KERNEL); 150 if (!est) 151 return -ENOBUFS; 152 153 seqcount_init(&est->seq); 154 intvl_log = parm->interval + 2; 155 est->bstats = bstats; 156 est->stats_lock = lock; 157 est->running = running; 158 est->ewma_log = parm->ewma_log; 159 est->intvl_log = intvl_log; 160 est->cpu_bstats = cpu_bstats; 161 162 if (lock) 163 local_bh_disable(); 164 est_fetch_counters(est, &b); 165 if (lock) 166 local_bh_enable(); 167 est->last_bytes = b.bytes; 168 est->last_packets = b.packets; 169 170 if (lock) 171 spin_lock_bh(lock); 172 old = rcu_dereference_protected(*rate_est, 1); 173 if (old) { 174 del_timer_sync(&old->timer); 175 est->avbps = old->avbps; 176 est->avpps = old->avpps; 177 } 178 179 est->next_jiffies = jiffies + ((HZ/4) << intvl_log); 180 timer_setup(&est->timer, est_timer, 0); 181 mod_timer(&est->timer, est->next_jiffies); 182 183 rcu_assign_pointer(*rate_est, est); 184 if (lock) 185 spin_unlock_bh(lock); 186 if (old) 187 kfree_rcu(old, rcu); 188 return 0; 189 } 190 EXPORT_SYMBOL(gen_new_estimator); 191 192 /** 193 * gen_kill_estimator - remove a rate estimator 194 * @rate_est: rate estimator 195 * 196 * Removes the rate estimator. 197 * 198 */ 199 void gen_kill_estimator(struct net_rate_estimator __rcu **rate_est) 200 { 201 struct net_rate_estimator *est; 202 203 est = xchg((__force struct net_rate_estimator **)rate_est, NULL); 204 if (est) { 205 del_timer_sync(&est->timer); 206 kfree_rcu(est, rcu); 207 } 208 } 209 EXPORT_SYMBOL(gen_kill_estimator); 210 211 /** 212 * gen_replace_estimator - replace rate estimator configuration 213 * @bstats: basic statistics 214 * @cpu_bstats: bstats per cpu 215 * @rate_est: rate estimator statistics 216 * @lock: lock for statistics and control path 217 * @running: qdisc running seqcount (might be NULL) 218 * @opt: rate estimator configuration TLV 219 * 220 * Replaces the configuration of a rate estimator by calling 221 * gen_kill_estimator() and gen_new_estimator(). 222 * 223 * Returns 0 on success or a negative error code. 224 */ 225 int gen_replace_estimator(struct gnet_stats_basic_packed *bstats, 226 struct gnet_stats_basic_cpu __percpu *cpu_bstats, 227 struct net_rate_estimator __rcu **rate_est, 228 spinlock_t *lock, 229 seqcount_t *running, struct nlattr *opt) 230 { 231 return gen_new_estimator(bstats, cpu_bstats, rate_est, 232 lock, running, opt); 233 } 234 EXPORT_SYMBOL(gen_replace_estimator); 235 236 /** 237 * gen_estimator_active - test if estimator is currently in use 238 * @rate_est: rate estimator 239 * 240 * Returns true if estimator is active, and false if not. 241 */ 242 bool gen_estimator_active(struct net_rate_estimator __rcu **rate_est) 243 { 244 return !!rcu_access_pointer(*rate_est); 245 } 246 EXPORT_SYMBOL(gen_estimator_active); 247 248 bool gen_estimator_read(struct net_rate_estimator __rcu **rate_est, 249 struct gnet_stats_rate_est64 *sample) 250 { 251 struct net_rate_estimator *est; 252 unsigned seq; 253 254 rcu_read_lock(); 255 est = rcu_dereference(*rate_est); 256 if (!est) { 257 rcu_read_unlock(); 258 return false; 259 } 260 261 do { 262 seq = read_seqcount_begin(&est->seq); 263 sample->bps = est->avbps >> 8; 264 sample->pps = est->avpps >> 8; 265 } while (read_seqcount_retry(&est->seq, seq)); 266 267 rcu_read_unlock(); 268 return true; 269 } 270 EXPORT_SYMBOL(gen_estimator_read); 271