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 u32 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->ewma_log - est->intvl_log); 84 brate -= (est->avbps >> est->ewma_log); 85 86 rate = (u64)(b.packets - est->last_packets) << (10 - est->ewma_log - est->intvl_log); 87 rate -= (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 est = kzalloc(sizeof(*est), GFP_KERNEL); 147 if (!est) 148 return -ENOBUFS; 149 150 seqcount_init(&est->seq); 151 intvl_log = parm->interval + 2; 152 est->bstats = bstats; 153 est->stats_lock = lock; 154 est->running = running; 155 est->ewma_log = parm->ewma_log; 156 est->intvl_log = intvl_log; 157 est->cpu_bstats = cpu_bstats; 158 159 if (lock) 160 local_bh_disable(); 161 est_fetch_counters(est, &b); 162 if (lock) 163 local_bh_enable(); 164 est->last_bytes = b.bytes; 165 est->last_packets = b.packets; 166 167 if (lock) 168 spin_lock_bh(lock); 169 old = rcu_dereference_protected(*rate_est, 1); 170 if (old) { 171 del_timer_sync(&old->timer); 172 est->avbps = old->avbps; 173 est->avpps = old->avpps; 174 } 175 176 est->next_jiffies = jiffies + ((HZ/4) << intvl_log); 177 timer_setup(&est->timer, est_timer, 0); 178 mod_timer(&est->timer, est->next_jiffies); 179 180 rcu_assign_pointer(*rate_est, est); 181 if (lock) 182 spin_unlock_bh(lock); 183 if (old) 184 kfree_rcu(old, rcu); 185 return 0; 186 } 187 EXPORT_SYMBOL(gen_new_estimator); 188 189 /** 190 * gen_kill_estimator - remove a rate estimator 191 * @rate_est: rate estimator 192 * 193 * Removes the rate estimator. 194 * 195 */ 196 void gen_kill_estimator(struct net_rate_estimator __rcu **rate_est) 197 { 198 struct net_rate_estimator *est; 199 200 est = xchg((__force struct net_rate_estimator **)rate_est, NULL); 201 if (est) { 202 del_timer_sync(&est->timer); 203 kfree_rcu(est, rcu); 204 } 205 } 206 EXPORT_SYMBOL(gen_kill_estimator); 207 208 /** 209 * gen_replace_estimator - replace rate estimator configuration 210 * @bstats: basic statistics 211 * @cpu_bstats: bstats per cpu 212 * @rate_est: rate estimator statistics 213 * @lock: lock for statistics and control path 214 * @running: qdisc running seqcount (might be NULL) 215 * @opt: rate estimator configuration TLV 216 * 217 * Replaces the configuration of a rate estimator by calling 218 * gen_kill_estimator() and gen_new_estimator(). 219 * 220 * Returns 0 on success or a negative error code. 221 */ 222 int gen_replace_estimator(struct gnet_stats_basic_packed *bstats, 223 struct gnet_stats_basic_cpu __percpu *cpu_bstats, 224 struct net_rate_estimator __rcu **rate_est, 225 spinlock_t *lock, 226 seqcount_t *running, struct nlattr *opt) 227 { 228 return gen_new_estimator(bstats, cpu_bstats, rate_est, 229 lock, running, opt); 230 } 231 EXPORT_SYMBOL(gen_replace_estimator); 232 233 /** 234 * gen_estimator_active - test if estimator is currently in use 235 * @rate_est: rate estimator 236 * 237 * Returns true if estimator is active, and false if not. 238 */ 239 bool gen_estimator_active(struct net_rate_estimator __rcu **rate_est) 240 { 241 return !!rcu_access_pointer(*rate_est); 242 } 243 EXPORT_SYMBOL(gen_estimator_active); 244 245 bool gen_estimator_read(struct net_rate_estimator __rcu **rate_est, 246 struct gnet_stats_rate_est64 *sample) 247 { 248 struct net_rate_estimator *est; 249 unsigned seq; 250 251 rcu_read_lock(); 252 est = rcu_dereference(*rate_est); 253 if (!est) { 254 rcu_read_unlock(); 255 return false; 256 } 257 258 do { 259 seq = read_seqcount_begin(&est->seq); 260 sample->bps = est->avbps >> 8; 261 sample->pps = est->avpps >> 8; 262 } while (read_seqcount_retry(&est->seq, seq)); 263 264 rcu_read_unlock(); 265 return true; 266 } 267 EXPORT_SYMBOL(gen_estimator_read); 268