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_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);