linux/net/ipv4/inetpeer.c
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   1/*
   2 *              INETPEER - A storage for permanent information about peers
   3 *
   4 *  This source is covered by the GNU GPL, the same as all kernel sources.
   5 *
   6 *  Authors:    Andrey V. Savochkin <saw@msu.ru>
   7 */
   8
   9#include <linux/module.h>
  10#include <linux/types.h>
  11#include <linux/slab.h>
  12#include <linux/interrupt.h>
  13#include <linux/spinlock.h>
  14#include <linux/random.h>
  15#include <linux/timer.h>
  16#include <linux/time.h>
  17#include <linux/kernel.h>
  18#include <linux/mm.h>
  19#include <linux/net.h>
  20#include <linux/workqueue.h>
  21#include <net/ip.h>
  22#include <net/inetpeer.h>
  23#include <net/secure_seq.h>
  24
  25/*
  26 *  Theory of operations.
  27 *  We keep one entry for each peer IP address.  The nodes contains long-living
  28 *  information about the peer which doesn't depend on routes.
  29 *  At this moment this information consists only of ID field for the next
  30 *  outgoing IP packet.  This field is incremented with each packet as encoded
  31 *  in inet_getid() function (include/net/inetpeer.h).
  32 *  At the moment of writing this notes identifier of IP packets is generated
  33 *  to be unpredictable using this code only for packets subjected
  34 *  (actually or potentially) to defragmentation.  I.e. DF packets less than
  35 *  PMTU in size uses a constant ID and do not use this code (see
  36 *  ip_select_ident() in include/net/ip.h).
  37 *
  38 *  Route cache entries hold references to our nodes.
  39 *  New cache entries get references via lookup by destination IP address in
  40 *  the avl tree.  The reference is grabbed only when it's needed i.e. only
  41 *  when we try to output IP packet which needs an unpredictable ID (see
  42 *  __ip_select_ident() in net/ipv4/route.c).
  43 *  Nodes are removed only when reference counter goes to 0.
  44 *  When it's happened the node may be removed when a sufficient amount of
  45 *  time has been passed since its last use.  The less-recently-used entry can
  46 *  also be removed if the pool is overloaded i.e. if the total amount of
  47 *  entries is greater-or-equal than the threshold.
  48 *
  49 *  Node pool is organised as an AVL tree.
  50 *  Such an implementation has been chosen not just for fun.  It's a way to
  51 *  prevent easy and efficient DoS attacks by creating hash collisions.  A huge
  52 *  amount of long living nodes in a single hash slot would significantly delay
  53 *  lookups performed with disabled BHs.
  54 *
  55 *  Serialisation issues.
  56 *  1.  Nodes may appear in the tree only with the pool lock held.
  57 *  2.  Nodes may disappear from the tree only with the pool lock held
  58 *      AND reference count being 0.
  59 *  3.  Global variable peer_total is modified under the pool lock.
  60 *  4.  struct inet_peer fields modification:
  61 *              avl_left, avl_right, avl_parent, avl_height: pool lock
  62 *              refcnt: atomically against modifications on other CPU;
  63 *                 usually under some other lock to prevent node disappearing
  64 *              daddr: unchangeable
  65 *              ip_id_count: atomic value (no lock needed)
  66 */
  67
  68static struct kmem_cache *peer_cachep __read_mostly;
  69
  70static LIST_HEAD(gc_list);
  71static const int gc_delay = 60 * HZ;
  72static struct delayed_work gc_work;
  73static DEFINE_SPINLOCK(gc_lock);
  74
  75#define node_height(x) x->avl_height
  76
  77#define peer_avl_empty ((struct inet_peer *)&peer_fake_node)
  78#define peer_avl_empty_rcu ((struct inet_peer __rcu __force *)&peer_fake_node)
  79static const struct inet_peer peer_fake_node = {
  80        .avl_left       = peer_avl_empty_rcu,
  81        .avl_right      = peer_avl_empty_rcu,
  82        .avl_height     = 0
  83};
  84
  85void inet_peer_base_init(struct inet_peer_base *bp)
  86{
  87        bp->root = peer_avl_empty_rcu;
  88        seqlock_init(&bp->lock);
  89        bp->flush_seq = ~0U;
  90        bp->total = 0;
  91}
  92EXPORT_SYMBOL_GPL(inet_peer_base_init);
  93
  94static atomic_t v4_seq = ATOMIC_INIT(0);
  95static atomic_t v6_seq = ATOMIC_INIT(0);
  96
  97static atomic_t *inetpeer_seq_ptr(int family)
  98{
  99        return (family == AF_INET ? &v4_seq : &v6_seq);
 100}
 101
 102static inline void flush_check(struct inet_peer_base *base, int family)
 103{
 104        atomic_t *fp = inetpeer_seq_ptr(family);
 105
 106        if (unlikely(base->flush_seq != atomic_read(fp))) {
 107                inetpeer_invalidate_tree(base);
 108                base->flush_seq = atomic_read(fp);
 109        }
 110}
 111
 112void inetpeer_invalidate_family(int family)
 113{
 114        atomic_t *fp = inetpeer_seq_ptr(family);
 115
 116        atomic_inc(fp);
 117}
 118
 119#define PEER_MAXDEPTH 40 /* sufficient for about 2^27 nodes */
 120
 121/* Exported for sysctl_net_ipv4.  */
 122int inet_peer_threshold __read_mostly = 65536 + 128;    /* start to throw entries more
 123                                         * aggressively at this stage */
 124int inet_peer_minttl __read_mostly = 120 * HZ;  /* TTL under high load: 120 sec */
 125int inet_peer_maxttl __read_mostly = 10 * 60 * HZ;      /* usual time to live: 10 min */
 126
 127static void inetpeer_gc_worker(struct work_struct *work)
 128{
 129        struct inet_peer *p, *n, *c;
 130        LIST_HEAD(list);
 131
 132        spin_lock_bh(&gc_lock);
 133        list_replace_init(&gc_list, &list);
 134        spin_unlock_bh(&gc_lock);
 135
 136        if (list_empty(&list))
 137                return;
 138
 139        list_for_each_entry_safe(p, n, &list, gc_list) {
 140
 141                if (need_resched())
 142                        cond_resched();
 143
 144                c = rcu_dereference_protected(p->avl_left, 1);
 145                if (c != peer_avl_empty) {
 146                        list_add_tail(&c->gc_list, &list);
 147                        p->avl_left = peer_avl_empty_rcu;
 148                }
 149
 150                c = rcu_dereference_protected(p->avl_right, 1);
 151                if (c != peer_avl_empty) {
 152                        list_add_tail(&c->gc_list, &list);
 153                        p->avl_right = peer_avl_empty_rcu;
 154                }
 155
 156                n = list_entry(p->gc_list.next, struct inet_peer, gc_list);
 157
 158                if (!atomic_read(&p->refcnt)) {
 159                        list_del(&p->gc_list);
 160                        kmem_cache_free(peer_cachep, p);
 161                }
 162        }
 163
 164        if (list_empty(&list))
 165                return;
 166
 167        spin_lock_bh(&gc_lock);
 168        list_splice(&list, &gc_list);
 169        spin_unlock_bh(&gc_lock);
 170
 171        schedule_delayed_work(&gc_work, gc_delay);
 172}
 173
 174/* Called from ip_output.c:ip_init  */
 175void __init inet_initpeers(void)
 176{
 177        struct sysinfo si;
 178
 179        /* Use the straight interface to information about memory. */
 180        si_meminfo(&si);
 181        /* The values below were suggested by Alexey Kuznetsov
 182         * <kuznet@ms2.inr.ac.ru>.  I don't have any opinion about the values
 183         * myself.  --SAW
 184         */
 185        if (si.totalram <= (32768*1024)/PAGE_SIZE)
 186                inet_peer_threshold >>= 1; /* max pool size about 1MB on IA32 */
 187        if (si.totalram <= (16384*1024)/PAGE_SIZE)
 188                inet_peer_threshold >>= 1; /* about 512KB */
 189        if (si.totalram <= (8192*1024)/PAGE_SIZE)
 190                inet_peer_threshold >>= 2; /* about 128KB */
 191
 192        peer_cachep = kmem_cache_create("inet_peer_cache",
 193                        sizeof(struct inet_peer),
 194                        0, SLAB_HWCACHE_ALIGN | SLAB_PANIC,
 195                        NULL);
 196
 197        INIT_DELAYED_WORK_DEFERRABLE(&gc_work, inetpeer_gc_worker);
 198}
 199
 200static int addr_compare(const struct inetpeer_addr *a,
 201                        const struct inetpeer_addr *b)
 202{
 203        int i, n = (a->family == AF_INET ? 1 : 4);
 204
 205        for (i = 0; i < n; i++) {
 206                if (a->addr.a6[i] == b->addr.a6[i])
 207                        continue;
 208                if ((__force u32)a->addr.a6[i] < (__force u32)b->addr.a6[i])
 209                        return -1;
 210                return 1;
 211        }
 212
 213        return 0;
 214}
 215
 216#define rcu_deref_locked(X, BASE)                               \
 217        rcu_dereference_protected(X, lockdep_is_held(&(BASE)->lock.lock))
 218
 219/*
 220 * Called with local BH disabled and the pool lock held.
 221 */
 222#define lookup(_daddr, _stack, _base)                           \
 223({                                                              \
 224        struct inet_peer *u;                                    \
 225        struct inet_peer __rcu **v;                             \
 226                                                                \
 227        stackptr = _stack;                                      \
 228        *stackptr++ = &_base->root;                             \
 229        for (u = rcu_deref_locked(_base->root, _base);          \
 230             u != peer_avl_empty; ) {                           \
 231                int cmp = addr_compare(_daddr, &u->daddr);      \
 232                if (cmp == 0)                                   \
 233                        break;                                  \
 234                if (cmp == -1)                                  \
 235                        v = &u->avl_left;                       \
 236                else                                            \
 237                        v = &u->avl_right;                      \
 238                *stackptr++ = v;                                \
 239                u = rcu_deref_locked(*v, _base);                \
 240        }                                                       \
 241        u;                                                      \
 242})
 243
 244/*
 245 * Called with rcu_read_lock()
 246 * Because we hold no lock against a writer, its quite possible we fall
 247 * in an endless loop.
 248 * But every pointer we follow is guaranteed to be valid thanks to RCU.
 249 * We exit from this function if number of links exceeds PEER_MAXDEPTH
 250 */
 251static struct inet_peer *lookup_rcu(const struct inetpeer_addr *daddr,
 252                                    struct inet_peer_base *base)
 253{
 254        struct inet_peer *u = rcu_dereference(base->root);
 255        int count = 0;
 256
 257        while (u != peer_avl_empty) {
 258                int cmp = addr_compare(daddr, &u->daddr);
 259                if (cmp == 0) {
 260                        /* Before taking a reference, check if this entry was
 261                         * deleted (refcnt=-1)
 262                         */
 263                        if (!atomic_add_unless(&u->refcnt, 1, -1))
 264                                u = NULL;
 265                        return u;
 266                }
 267                if (cmp == -1)
 268                        u = rcu_dereference(u->avl_left);
 269                else
 270                        u = rcu_dereference(u->avl_right);
 271                if (unlikely(++count == PEER_MAXDEPTH))
 272                        break;
 273        }
 274        return NULL;
 275}
 276
 277/* Called with local BH disabled and the pool lock held. */
 278#define lookup_rightempty(start, base)                          \
 279({                                                              \
 280        struct inet_peer *u;                                    \
 281        struct inet_peer __rcu **v;                             \
 282        *stackptr++ = &start->avl_left;                         \
 283        v = &start->avl_left;                                   \
 284        for (u = rcu_deref_locked(*v, base);                    \
 285             u->avl_right != peer_avl_empty_rcu; ) {            \
 286                v = &u->avl_right;                              \
 287                *stackptr++ = v;                                \
 288                u = rcu_deref_locked(*v, base);                 \
 289        }                                                       \
 290        u;                                                      \
 291})
 292
 293/* Called with local BH disabled and the pool lock held.
 294 * Variable names are the proof of operation correctness.
 295 * Look into mm/map_avl.c for more detail description of the ideas.
 296 */
 297static void peer_avl_rebalance(struct inet_peer __rcu **stack[],
 298                               struct inet_peer __rcu ***stackend,
 299                               struct inet_peer_base *base)
 300{
 301        struct inet_peer __rcu **nodep;
 302        struct inet_peer *node, *l, *r;
 303        int lh, rh;
 304
 305        while (stackend > stack) {
 306                nodep = *--stackend;
 307                node = rcu_deref_locked(*nodep, base);
 308                l = rcu_deref_locked(node->avl_left, base);
 309                r = rcu_deref_locked(node->avl_right, base);
 310                lh = node_height(l);
 311                rh = node_height(r);
 312                if (lh > rh + 1) { /* l: RH+2 */
 313                        struct inet_peer *ll, *lr, *lrl, *lrr;
 314                        int lrh;
 315                        ll = rcu_deref_locked(l->avl_left, base);
 316                        lr = rcu_deref_locked(l->avl_right, base);
 317                        lrh = node_height(lr);
 318                        if (lrh <= node_height(ll)) {   /* ll: RH+1 */
 319                                RCU_INIT_POINTER(node->avl_left, lr);   /* lr: RH or RH+1 */
 320                                RCU_INIT_POINTER(node->avl_right, r);   /* r: RH */
 321                                node->avl_height = lrh + 1; /* RH+1 or RH+2 */
 322                                RCU_INIT_POINTER(l->avl_left, ll);       /* ll: RH+1 */
 323                                RCU_INIT_POINTER(l->avl_right, node);   /* node: RH+1 or RH+2 */
 324                                l->avl_height = node->avl_height + 1;
 325                                RCU_INIT_POINTER(*nodep, l);
 326                        } else { /* ll: RH, lr: RH+1 */
 327                                lrl = rcu_deref_locked(lr->avl_left, base);/* lrl: RH or RH-1 */
 328                                lrr = rcu_deref_locked(lr->avl_right, base);/* lrr: RH or RH-1 */
 329                                RCU_INIT_POINTER(node->avl_left, lrr);  /* lrr: RH or RH-1 */
 330                                RCU_INIT_POINTER(node->avl_right, r);   /* r: RH */
 331                                node->avl_height = rh + 1; /* node: RH+1 */
 332                                RCU_INIT_POINTER(l->avl_left, ll);      /* ll: RH */
 333                                RCU_INIT_POINTER(l->avl_right, lrl);    /* lrl: RH or RH-1 */
 334                                l->avl_height = rh + 1; /* l: RH+1 */
 335                                RCU_INIT_POINTER(lr->avl_left, l);      /* l: RH+1 */
 336                                RCU_INIT_POINTER(lr->avl_right, node);  /* node: RH+1 */
 337                                lr->avl_height = rh + 2;
 338                                RCU_INIT_POINTER(*nodep, lr);
 339                        }
 340                } else if (rh > lh + 1) { /* r: LH+2 */
 341                        struct inet_peer *rr, *rl, *rlr, *rll;
 342                        int rlh;
 343                        rr = rcu_deref_locked(r->avl_right, base);
 344                        rl = rcu_deref_locked(r->avl_left, base);
 345                        rlh = node_height(rl);
 346                        if (rlh <= node_height(rr)) {   /* rr: LH+1 */
 347                                RCU_INIT_POINTER(node->avl_right, rl);  /* rl: LH or LH+1 */
 348                                RCU_INIT_POINTER(node->avl_left, l);    /* l: LH */
 349                                node->avl_height = rlh + 1; /* LH+1 or LH+2 */
 350                                RCU_INIT_POINTER(r->avl_right, rr);     /* rr: LH+1 */
 351                                RCU_INIT_POINTER(r->avl_left, node);    /* node: LH+1 or LH+2 */
 352                                r->avl_height = node->avl_height + 1;
 353                                RCU_INIT_POINTER(*nodep, r);
 354                        } else { /* rr: RH, rl: RH+1 */
 355                                rlr = rcu_deref_locked(rl->avl_right, base);/* rlr: LH or LH-1 */
 356                                rll = rcu_deref_locked(rl->avl_left, base);/* rll: LH or LH-1 */
 357                                RCU_INIT_POINTER(node->avl_right, rll); /* rll: LH or LH-1 */
 358                                RCU_INIT_POINTER(node->avl_left, l);    /* l: LH */
 359                                node->avl_height = lh + 1; /* node: LH+1 */
 360                                RCU_INIT_POINTER(r->avl_right, rr);     /* rr: LH */
 361                                RCU_INIT_POINTER(r->avl_left, rlr);     /* rlr: LH or LH-1 */
 362                                r->avl_height = lh + 1; /* r: LH+1 */
 363                                RCU_INIT_POINTER(rl->avl_right, r);     /* r: LH+1 */
 364                                RCU_INIT_POINTER(rl->avl_left, node);   /* node: LH+1 */
 365                                rl->avl_height = lh + 2;
 366                                RCU_INIT_POINTER(*nodep, rl);
 367                        }
 368                } else {
 369                        node->avl_height = (lh > rh ? lh : rh) + 1;
 370                }
 371        }
 372}
 373
 374/* Called with local BH disabled and the pool lock held. */
 375#define link_to_pool(n, base)                                   \
 376do {                                                            \
 377        n->avl_height = 1;                                      \
 378        n->avl_left = peer_avl_empty_rcu;                       \
 379        n->avl_right = peer_avl_empty_rcu;                      \
 380        /* lockless readers can catch us now */                 \
 381        rcu_assign_pointer(**--stackptr, n);                    \
 382        peer_avl_rebalance(stack, stackptr, base);              \
 383} while (0)
 384
 385static void inetpeer_free_rcu(struct rcu_head *head)
 386{
 387        kmem_cache_free(peer_cachep, container_of(head, struct inet_peer, rcu));
 388}
 389
 390static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base,
 391                             struct inet_peer __rcu **stack[PEER_MAXDEPTH])
 392{
 393        struct inet_peer __rcu ***stackptr, ***delp;
 394
 395        if (lookup(&p->daddr, stack, base) != p)
 396                BUG();
 397        delp = stackptr - 1; /* *delp[0] == p */
 398        if (p->avl_left == peer_avl_empty_rcu) {
 399                *delp[0] = p->avl_right;
 400                --stackptr;
 401        } else {
 402                /* look for a node to insert instead of p */
 403                struct inet_peer *t;
 404                t = lookup_rightempty(p, base);
 405                BUG_ON(rcu_deref_locked(*stackptr[-1], base) != t);
 406                **--stackptr = t->avl_left;
 407                /* t is removed, t->daddr > x->daddr for any
 408                 * x in p->avl_left subtree.
 409                 * Put t in the old place of p. */
 410                RCU_INIT_POINTER(*delp[0], t);
 411                t->avl_left = p->avl_left;
 412                t->avl_right = p->avl_right;
 413                t->avl_height = p->avl_height;
 414                BUG_ON(delp[1] != &p->avl_left);
 415                delp[1] = &t->avl_left; /* was &p->avl_left */
 416        }
 417        peer_avl_rebalance(stack, stackptr, base);
 418        base->total--;
 419        call_rcu(&p->rcu, inetpeer_free_rcu);
 420}
 421
 422/* perform garbage collect on all items stacked during a lookup */
 423static int inet_peer_gc(struct inet_peer_base *base,
 424                        struct inet_peer __rcu **stack[PEER_MAXDEPTH],
 425                        struct inet_peer __rcu ***stackptr)
 426{
 427        struct inet_peer *p, *gchead = NULL;
 428        __u32 delta, ttl;
 429        int cnt = 0;
 430
 431        if (base->total >= inet_peer_threshold)
 432                ttl = 0; /* be aggressive */
 433        else
 434                ttl = inet_peer_maxttl
 435                                - (inet_peer_maxttl - inet_peer_minttl) / HZ *
 436                                        base->total / inet_peer_threshold * HZ;
 437        stackptr--; /* last stack slot is peer_avl_empty */
 438        while (stackptr > stack) {
 439                stackptr--;
 440                p = rcu_deref_locked(**stackptr, base);
 441                if (atomic_read(&p->refcnt) == 0) {
 442                        smp_rmb();
 443                        delta = (__u32)jiffies - p->dtime;
 444                        if (delta >= ttl &&
 445                            atomic_cmpxchg(&p->refcnt, 0, -1) == 0) {
 446                                p->gc_next = gchead;
 447                                gchead = p;
 448                        }
 449                }
 450        }
 451        while ((p = gchead) != NULL) {
 452                gchead = p->gc_next;
 453                cnt++;
 454                unlink_from_pool(p, base, stack);
 455        }
 456        return cnt;
 457}
 458
 459struct inet_peer *inet_getpeer(struct inet_peer_base *base,
 460                               const struct inetpeer_addr *daddr,
 461                               int create)
 462{
 463        struct inet_peer __rcu **stack[PEER_MAXDEPTH], ***stackptr;
 464        struct inet_peer *p;
 465        unsigned int sequence;
 466        int invalidated, gccnt = 0;
 467
 468        flush_check(base, daddr->family);
 469
 470        /* Attempt a lockless lookup first.
 471         * Because of a concurrent writer, we might not find an existing entry.
 472         */
 473        rcu_read_lock();
 474        sequence = read_seqbegin(&base->lock);
 475        p = lookup_rcu(daddr, base);
 476        invalidated = read_seqretry(&base->lock, sequence);
 477        rcu_read_unlock();
 478
 479        if (p)
 480                return p;
 481
 482        /* If no writer did a change during our lookup, we can return early. */
 483        if (!create && !invalidated)
 484                return NULL;
 485
 486        /* retry an exact lookup, taking the lock before.
 487         * At least, nodes should be hot in our cache.
 488         */
 489        write_seqlock_bh(&base->lock);
 490relookup:
 491        p = lookup(daddr, stack, base);
 492        if (p != peer_avl_empty) {
 493                atomic_inc(&p->refcnt);
 494                write_sequnlock_bh(&base->lock);
 495                return p;
 496        }
 497        if (!gccnt) {
 498                gccnt = inet_peer_gc(base, stack, stackptr);
 499                if (gccnt && create)
 500                        goto relookup;
 501        }
 502        p = create ? kmem_cache_alloc(peer_cachep, GFP_ATOMIC) : NULL;
 503        if (p) {
 504                p->daddr = *daddr;
 505                atomic_set(&p->refcnt, 1);
 506                atomic_set(&p->rid, 0);
 507                atomic_set(&p->ip_id_count,
 508                                (daddr->family == AF_INET) ?
 509                                        secure_ip_id(daddr->addr.a4) :
 510                                        secure_ipv6_id(daddr->addr.a6));
 511                p->metrics[RTAX_LOCK-1] = INETPEER_METRICS_NEW;
 512                p->rate_tokens = 0;
 513                /* 60*HZ is arbitrary, but chosen enough high so that the first
 514                 * calculation of tokens is at its maximum.
 515                 */
 516                p->rate_last = jiffies - 60*HZ;
 517                INIT_LIST_HEAD(&p->gc_list);
 518
 519                /* Link the node. */
 520                link_to_pool(p, base);
 521                base->total++;
 522        }
 523        write_sequnlock_bh(&base->lock);
 524
 525        return p;
 526}
 527EXPORT_SYMBOL_GPL(inet_getpeer);
 528
 529void inet_putpeer(struct inet_peer *p)
 530{
 531        p->dtime = (__u32)jiffies;
 532        smp_mb__before_atomic_dec();
 533        atomic_dec(&p->refcnt);
 534}
 535EXPORT_SYMBOL_GPL(inet_putpeer);
 536
 537/*
 538 *      Check transmit rate limitation for given message.
 539 *      The rate information is held in the inet_peer entries now.
 540 *      This function is generic and could be used for other purposes
 541 *      too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
 542 *
 543 *      Note that the same inet_peer fields are modified by functions in
 544 *      route.c too, but these work for packet destinations while xrlim_allow
 545 *      works for icmp destinations. This means the rate limiting information
 546 *      for one "ip object" is shared - and these ICMPs are twice limited:
 547 *      by source and by destination.
 548 *
 549 *      RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
 550 *                        SHOULD allow setting of rate limits
 551 *
 552 *      Shared between ICMPv4 and ICMPv6.
 553 */
 554#define XRLIM_BURST_FACTOR 6
 555bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout)
 556{
 557        unsigned long now, token;
 558        bool rc = false;
 559
 560        if (!peer)
 561                return true;
 562
 563        token = peer->rate_tokens;
 564        now = jiffies;
 565        token += now - peer->rate_last;
 566        peer->rate_last = now;
 567        if (token > XRLIM_BURST_FACTOR * timeout)
 568                token = XRLIM_BURST_FACTOR * timeout;
 569        if (token >= timeout) {
 570                token -= timeout;
 571                rc = true;
 572        }
 573        peer->rate_tokens = token;
 574        return rc;
 575}
 576EXPORT_SYMBOL(inet_peer_xrlim_allow);
 577
 578static void inetpeer_inval_rcu(struct rcu_head *head)
 579{
 580        struct inet_peer *p = container_of(head, struct inet_peer, gc_rcu);
 581
 582        spin_lock_bh(&gc_lock);
 583        list_add_tail(&p->gc_list, &gc_list);
 584        spin_unlock_bh(&gc_lock);
 585
 586        schedule_delayed_work(&gc_work, gc_delay);
 587}
 588
 589void inetpeer_invalidate_tree(struct inet_peer_base *base)
 590{
 591        struct inet_peer *root;
 592
 593        write_seqlock_bh(&base->lock);
 594
 595        root = rcu_deref_locked(base->root, base);
 596        if (root != peer_avl_empty) {
 597                base->root = peer_avl_empty_rcu;
 598                base->total = 0;
 599                call_rcu(&root->gc_rcu, inetpeer_inval_rcu);
 600        }
 601
 602        write_sequnlock_bh(&base->lock);
 603}
 604EXPORT_SYMBOL(inetpeer_invalidate_tree);
 605
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