net/core/gen_estimator.c

   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->ewma_log - est->intvl_log);
  84         brate -= (est->avbps >> est->ewma_log);
  85
  86         rate = (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);