| /* |
| * INETPEER - A storage for permanent information about peers |
| * |
| * This source is covered by the GNU GPL, the same as all kernel sources. |
| * |
| * Authors: Andrey V. Savochkin <saw@msu.ru> |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/types.h> |
| #include <linux/slab.h> |
| #include <linux/interrupt.h> |
| #include <linux/spinlock.h> |
| #include <linux/random.h> |
| #include <linux/timer.h> |
| #include <linux/time.h> |
| #include <linux/kernel.h> |
| #include <linux/mm.h> |
| #include <linux/net.h> |
| #include <net/ip.h> |
| #include <net/inetpeer.h> |
| |
| /* |
| * Theory of operations. |
| * We keep one entry for each peer IP address. The nodes contains long-living |
| * information about the peer which doesn't depend on routes. |
| * At this moment this information consists only of ID field for the next |
| * outgoing IP packet. This field is incremented with each packet as encoded |
| * in inet_getid() function (include/net/inetpeer.h). |
| * At the moment of writing this notes identifier of IP packets is generated |
| * to be unpredictable using this code only for packets subjected |
| * (actually or potentially) to defragmentation. I.e. DF packets less than |
| * PMTU in size uses a constant ID and do not use this code (see |
| * ip_select_ident() in include/net/ip.h). |
| * |
| * Route cache entries hold references to our nodes. |
| * New cache entries get references via lookup by destination IP address in |
| * the avl tree. The reference is grabbed only when it's needed i.e. only |
| * when we try to output IP packet which needs an unpredictable ID (see |
| * __ip_select_ident() in net/ipv4/route.c). |
| * Nodes are removed only when reference counter goes to 0. |
| * When it's happened the node may be removed when a sufficient amount of |
| * time has been passed since its last use. The less-recently-used entry can |
| * also be removed if the pool is overloaded i.e. if the total amount of |
| * entries is greater-or-equal than the threshold. |
| * |
| * Node pool is organised as an AVL tree. |
| * Such an implementation has been chosen not just for fun. It's a way to |
| * prevent easy and efficient DoS attacks by creating hash collisions. A huge |
| * amount of long living nodes in a single hash slot would significantly delay |
| * lookups performed with disabled BHs. |
| * |
| * Serialisation issues. |
| * 1. Nodes may appear in the tree only with the pool lock held. |
| * 2. Nodes may disappear from the tree only with the pool lock held |
| * AND reference count being 0. |
| * 3. Nodes appears and disappears from unused node list only under |
| * "inet_peer_unused_lock". |
| * 4. Global variable peer_total is modified under the pool lock. |
| * 5. struct inet_peer fields modification: |
| * avl_left, avl_right, avl_parent, avl_height: pool lock |
| * unused: unused node list lock |
| * refcnt: atomically against modifications on other CPU; |
| * usually under some other lock to prevent node disappearing |
| * dtime: unused node list lock |
| * daddr: unchangeable |
| * ip_id_count: atomic value (no lock needed) |
| */ |
| |
| static struct kmem_cache *peer_cachep __read_mostly; |
| |
| #define node_height(x) x->avl_height |
| |
| #define peer_avl_empty ((struct inet_peer *)&peer_fake_node) |
| #define peer_avl_empty_rcu ((struct inet_peer __rcu __force *)&peer_fake_node) |
| static const struct inet_peer peer_fake_node = { |
| .avl_left = peer_avl_empty_rcu, |
| .avl_right = peer_avl_empty_rcu, |
| .avl_height = 0 |
| }; |
| |
| struct inet_peer_base { |
| struct inet_peer __rcu *root; |
| seqlock_t lock; |
| int total; |
| }; |
| |
| static struct inet_peer_base v4_peers = { |
| .root = peer_avl_empty_rcu, |
| .lock = __SEQLOCK_UNLOCKED(v4_peers.lock), |
| .total = 0, |
| }; |
| |
| static struct inet_peer_base v6_peers = { |
| .root = peer_avl_empty_rcu, |
| .lock = __SEQLOCK_UNLOCKED(v6_peers.lock), |
| .total = 0, |
| }; |
| |
| #define PEER_MAXDEPTH 40 /* sufficient for about 2^27 nodes */ |
| |
| /* Exported for sysctl_net_ipv4. */ |
| int inet_peer_threshold __read_mostly = 65536 + 128; /* start to throw entries more |
| * aggressively at this stage */ |
| int inet_peer_minttl __read_mostly = 120 * HZ; /* TTL under high load: 120 sec */ |
| int inet_peer_maxttl __read_mostly = 10 * 60 * HZ; /* usual time to live: 10 min */ |
| int inet_peer_gc_mintime __read_mostly = 10 * HZ; |
| int inet_peer_gc_maxtime __read_mostly = 120 * HZ; |
| |
| static struct { |
| struct list_head list; |
| spinlock_t lock; |
| } unused_peers = { |
| .list = LIST_HEAD_INIT(unused_peers.list), |
| .lock = __SPIN_LOCK_UNLOCKED(unused_peers.lock), |
| }; |
| |
| static void peer_check_expire(unsigned long dummy); |
| static DEFINE_TIMER(peer_periodic_timer, peer_check_expire, 0, 0); |
| |
| |
| /* Called from ip_output.c:ip_init */ |
| void __init inet_initpeers(void) |
| { |
| struct sysinfo si; |
| |
| /* Use the straight interface to information about memory. */ |
| si_meminfo(&si); |
| /* The values below were suggested by Alexey Kuznetsov |
| * <kuznet@ms2.inr.ac.ru>. I don't have any opinion about the values |
| * myself. --SAW |
| */ |
| if (si.totalram <= (32768*1024)/PAGE_SIZE) |
| inet_peer_threshold >>= 1; /* max pool size about 1MB on IA32 */ |
| if (si.totalram <= (16384*1024)/PAGE_SIZE) |
| inet_peer_threshold >>= 1; /* about 512KB */ |
| if (si.totalram <= (8192*1024)/PAGE_SIZE) |
| inet_peer_threshold >>= 2; /* about 128KB */ |
| |
| peer_cachep = kmem_cache_create("inet_peer_cache", |
| sizeof(struct inet_peer), |
| 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, |
| NULL); |
| |
| /* All the timers, started at system startup tend |
| to synchronize. Perturb it a bit. |
| */ |
| peer_periodic_timer.expires = jiffies |
| + net_random() % inet_peer_gc_maxtime |
| + inet_peer_gc_maxtime; |
| add_timer(&peer_periodic_timer); |
| } |
| |
| /* Called with or without local BH being disabled. */ |
| static void unlink_from_unused(struct inet_peer *p) |
| { |
| if (!list_empty(&p->unused)) { |
| spin_lock_bh(&unused_peers.lock); |
| list_del_init(&p->unused); |
| spin_unlock_bh(&unused_peers.lock); |
| } |
| } |
| |
| static int addr_compare(const struct inetpeer_addr *a, |
| const struct inetpeer_addr *b) |
| { |
| int i, n = (a->family == AF_INET ? 1 : 4); |
| |
| for (i = 0; i < n; i++) { |
| if (a->addr.a6[i] == b->addr.a6[i]) |
| continue; |
| if (a->addr.a6[i] < b->addr.a6[i]) |
| return -1; |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| #define rcu_deref_locked(X, BASE) \ |
| rcu_dereference_protected(X, lockdep_is_held(&(BASE)->lock.lock)) |
| |
| /* |
| * Called with local BH disabled and the pool lock held. |
| */ |
| #define lookup(_daddr, _stack, _base) \ |
| ({ \ |
| struct inet_peer *u; \ |
| struct inet_peer __rcu **v; \ |
| \ |
| stackptr = _stack; \ |
| *stackptr++ = &_base->root; \ |
| for (u = rcu_deref_locked(_base->root, _base); \ |
| u != peer_avl_empty; ) { \ |
| int cmp = addr_compare(_daddr, &u->daddr); \ |
| if (cmp == 0) \ |
| break; \ |
| if (cmp == -1) \ |
| v = &u->avl_left; \ |
| else \ |
| v = &u->avl_right; \ |
| *stackptr++ = v; \ |
| u = rcu_deref_locked(*v, _base); \ |
| } \ |
| u; \ |
| }) |
| |
| /* |
| * Called with rcu_read_lock() |
| * Because we hold no lock against a writer, its quite possible we fall |
| * in an endless loop. |
| * But every pointer we follow is guaranteed to be valid thanks to RCU. |
| * We exit from this function if number of links exceeds PEER_MAXDEPTH |
| */ |
| static struct inet_peer *lookup_rcu(const struct inetpeer_addr *daddr, |
| struct inet_peer_base *base) |
| { |
| struct inet_peer *u = rcu_dereference(base->root); |
| int count = 0; |
| |
| while (u != peer_avl_empty) { |
| int cmp = addr_compare(daddr, &u->daddr); |
| if (cmp == 0) { |
| /* Before taking a reference, check if this entry was |
| * deleted, unlink_from_pool() sets refcnt=-1 to make |
| * distinction between an unused entry (refcnt=0) and |
| * a freed one. |
| */ |
| if (unlikely(!atomic_add_unless(&u->refcnt, 1, -1))) |
| u = NULL; |
| return u; |
| } |
| if (cmp == -1) |
| u = rcu_dereference(u->avl_left); |
| else |
| u = rcu_dereference(u->avl_right); |
| if (unlikely(++count == PEER_MAXDEPTH)) |
| break; |
| } |
| return NULL; |
| } |
| |
| /* Called with local BH disabled and the pool lock held. */ |
| #define lookup_rightempty(start, base) \ |
| ({ \ |
| struct inet_peer *u; \ |
| struct inet_peer __rcu **v; \ |
| *stackptr++ = &start->avl_left; \ |
| v = &start->avl_left; \ |
| for (u = rcu_deref_locked(*v, base); \ |
| u->avl_right != peer_avl_empty_rcu; ) { \ |
| v = &u->avl_right; \ |
| *stackptr++ = v; \ |
| u = rcu_deref_locked(*v, base); \ |
| } \ |
| u; \ |
| }) |
| |
| /* Called with local BH disabled and the pool lock held. |
| * Variable names are the proof of operation correctness. |
| * Look into mm/map_avl.c for more detail description of the ideas. |
| */ |
| static void peer_avl_rebalance(struct inet_peer __rcu **stack[], |
| struct inet_peer __rcu ***stackend, |
| struct inet_peer_base *base) |
| { |
| struct inet_peer __rcu **nodep; |
| struct inet_peer *node, *l, *r; |
| int lh, rh; |
| |
| while (stackend > stack) { |
| nodep = *--stackend; |
| node = rcu_deref_locked(*nodep, base); |
| l = rcu_deref_locked(node->avl_left, base); |
| r = rcu_deref_locked(node->avl_right, base); |
| lh = node_height(l); |
| rh = node_height(r); |
| if (lh > rh + 1) { /* l: RH+2 */ |
| struct inet_peer *ll, *lr, *lrl, *lrr; |
| int lrh; |
| ll = rcu_deref_locked(l->avl_left, base); |
| lr = rcu_deref_locked(l->avl_right, base); |
| lrh = node_height(lr); |
| if (lrh <= node_height(ll)) { /* ll: RH+1 */ |
| RCU_INIT_POINTER(node->avl_left, lr); /* lr: RH or RH+1 */ |
| RCU_INIT_POINTER(node->avl_right, r); /* r: RH */ |
| node->avl_height = lrh + 1; /* RH+1 or RH+2 */ |
| RCU_INIT_POINTER(l->avl_left, ll); /* ll: RH+1 */ |
| RCU_INIT_POINTER(l->avl_right, node); /* node: RH+1 or RH+2 */ |
| l->avl_height = node->avl_height + 1; |
| RCU_INIT_POINTER(*nodep, l); |
| } else { /* ll: RH, lr: RH+1 */ |
| lrl = rcu_deref_locked(lr->avl_left, base);/* lrl: RH or RH-1 */ |
| lrr = rcu_deref_locked(lr->avl_right, base);/* lrr: RH or RH-1 */ |
| RCU_INIT_POINTER(node->avl_left, lrr); /* lrr: RH or RH-1 */ |
| RCU_INIT_POINTER(node->avl_right, r); /* r: RH */ |
| node->avl_height = rh + 1; /* node: RH+1 */ |
| RCU_INIT_POINTER(l->avl_left, ll); /* ll: RH */ |
| RCU_INIT_POINTER(l->avl_right, lrl); /* lrl: RH or RH-1 */ |
| l->avl_height = rh + 1; /* l: RH+1 */ |
| RCU_INIT_POINTER(lr->avl_left, l); /* l: RH+1 */ |
| RCU_INIT_POINTER(lr->avl_right, node); /* node: RH+1 */ |
| lr->avl_height = rh + 2; |
| RCU_INIT_POINTER(*nodep, lr); |
| } |
| } else if (rh > lh + 1) { /* r: LH+2 */ |
| struct inet_peer *rr, *rl, *rlr, *rll; |
| int rlh; |
| rr = rcu_deref_locked(r->avl_right, base); |
| rl = rcu_deref_locked(r->avl_left, base); |
| rlh = node_height(rl); |
| if (rlh <= node_height(rr)) { /* rr: LH+1 */ |
| RCU_INIT_POINTER(node->avl_right, rl); /* rl: LH or LH+1 */ |
| RCU_INIT_POINTER(node->avl_left, l); /* l: LH */ |
| node->avl_height = rlh + 1; /* LH+1 or LH+2 */ |
| RCU_INIT_POINTER(r->avl_right, rr); /* rr: LH+1 */ |
| RCU_INIT_POINTER(r->avl_left, node); /* node: LH+1 or LH+2 */ |
| r->avl_height = node->avl_height + 1; |
| RCU_INIT_POINTER(*nodep, r); |
| } else { /* rr: RH, rl: RH+1 */ |
| rlr = rcu_deref_locked(rl->avl_right, base);/* rlr: LH or LH-1 */ |
| rll = rcu_deref_locked(rl->avl_left, base);/* rll: LH or LH-1 */ |
| RCU_INIT_POINTER(node->avl_right, rll); /* rll: LH or LH-1 */ |
| RCU_INIT_POINTER(node->avl_left, l); /* l: LH */ |
| node->avl_height = lh + 1; /* node: LH+1 */ |
| RCU_INIT_POINTER(r->avl_right, rr); /* rr: LH */ |
| RCU_INIT_POINTER(r->avl_left, rlr); /* rlr: LH or LH-1 */ |
| r->avl_height = lh + 1; /* r: LH+1 */ |
| RCU_INIT_POINTER(rl->avl_right, r); /* r: LH+1 */ |
| RCU_INIT_POINTER(rl->avl_left, node); /* node: LH+1 */ |
| rl->avl_height = lh + 2; |
| RCU_INIT_POINTER(*nodep, rl); |
| } |
| } else { |
| node->avl_height = (lh > rh ? lh : rh) + 1; |
| } |
| } |
| } |
| |
| /* Called with local BH disabled and the pool lock held. */ |
| #define link_to_pool(n, base) \ |
| do { \ |
| n->avl_height = 1; \ |
| n->avl_left = peer_avl_empty_rcu; \ |
| n->avl_right = peer_avl_empty_rcu; \ |
| /* lockless readers can catch us now */ \ |
| rcu_assign_pointer(**--stackptr, n); \ |
| peer_avl_rebalance(stack, stackptr, base); \ |
| } while (0) |
| |
| static void inetpeer_free_rcu(struct rcu_head *head) |
| { |
| kmem_cache_free(peer_cachep, container_of(head, struct inet_peer, rcu)); |
| } |
| |
| /* May be called with local BH enabled. */ |
| static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base) |
| { |
| int do_free; |
| |
| do_free = 0; |
| |
| write_seqlock_bh(&base->lock); |
| /* Check the reference counter. It was artificially incremented by 1 |
| * in cleanup() function to prevent sudden disappearing. If we can |
| * atomically (because of lockless readers) take this last reference, |
| * it's safe to remove the node and free it later. |
| * We use refcnt=-1 to alert lockless readers this entry is deleted. |
| */ |
| if (atomic_cmpxchg(&p->refcnt, 1, -1) == 1) { |
| struct inet_peer __rcu **stack[PEER_MAXDEPTH]; |
| struct inet_peer __rcu ***stackptr, ***delp; |
| if (lookup(&p->daddr, stack, base) != p) |
| BUG(); |
| delp = stackptr - 1; /* *delp[0] == p */ |
| if (p->avl_left == peer_avl_empty_rcu) { |
| *delp[0] = p->avl_right; |
| --stackptr; |
| } else { |
| /* look for a node to insert instead of p */ |
| struct inet_peer *t; |
| t = lookup_rightempty(p, base); |
| BUG_ON(rcu_deref_locked(*stackptr[-1], base) != t); |
| **--stackptr = t->avl_left; |
| /* t is removed, t->daddr > x->daddr for any |
| * x in p->avl_left subtree. |
| * Put t in the old place of p. */ |
| RCU_INIT_POINTER(*delp[0], t); |
| t->avl_left = p->avl_left; |
| t->avl_right = p->avl_right; |
| t->avl_height = p->avl_height; |
| BUG_ON(delp[1] != &p->avl_left); |
| delp[1] = &t->avl_left; /* was &p->avl_left */ |
| } |
| peer_avl_rebalance(stack, stackptr, base); |
| base->total--; |
| do_free = 1; |
| } |
| write_sequnlock_bh(&base->lock); |
| |
| if (do_free) |
| call_rcu_bh(&p->rcu, inetpeer_free_rcu); |
| else |
| /* The node is used again. Decrease the reference counter |
| * back. The loop "cleanup -> unlink_from_unused |
| * -> unlink_from_pool -> putpeer -> link_to_unused |
| * -> cleanup (for the same node)" |
| * doesn't really exist because the entry will have a |
| * recent deletion time and will not be cleaned again soon. |
| */ |
| inet_putpeer(p); |
| } |
| |
| static struct inet_peer_base *family_to_base(int family) |
| { |
| return (family == AF_INET ? &v4_peers : &v6_peers); |
| } |
| |
| static struct inet_peer_base *peer_to_base(struct inet_peer *p) |
| { |
| return family_to_base(p->daddr.family); |
| } |
| |
| /* May be called with local BH enabled. */ |
| static int cleanup_once(unsigned long ttl) |
| { |
| struct inet_peer *p = NULL; |
| |
| /* Remove the first entry from the list of unused nodes. */ |
| spin_lock_bh(&unused_peers.lock); |
| if (!list_empty(&unused_peers.list)) { |
| __u32 delta; |
| |
| p = list_first_entry(&unused_peers.list, struct inet_peer, unused); |
| delta = (__u32)jiffies - p->dtime; |
| |
| if (delta < ttl) { |
| /* Do not prune fresh entries. */ |
| spin_unlock_bh(&unused_peers.lock); |
| return -1; |
| } |
| |
| list_del_init(&p->unused); |
| |
| /* Grab an extra reference to prevent node disappearing |
| * before unlink_from_pool() call. */ |
| atomic_inc(&p->refcnt); |
| } |
| spin_unlock_bh(&unused_peers.lock); |
| |
| if (p == NULL) |
| /* It means that the total number of USED entries has |
| * grown over inet_peer_threshold. It shouldn't really |
| * happen because of entry limits in route cache. */ |
| return -1; |
| |
| unlink_from_pool(p, peer_to_base(p)); |
| return 0; |
| } |
| |
| /* Called with or without local BH being disabled. */ |
| struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create) |
| { |
| struct inet_peer __rcu **stack[PEER_MAXDEPTH], ***stackptr; |
| struct inet_peer_base *base = family_to_base(daddr->family); |
| struct inet_peer *p; |
| unsigned int sequence; |
| int invalidated; |
| |
| /* Look up for the address quickly, lockless. |
| * Because of a concurrent writer, we might not find an existing entry. |
| */ |
| rcu_read_lock(); |
| sequence = read_seqbegin(&base->lock); |
| p = lookup_rcu(daddr, base); |
| invalidated = read_seqretry(&base->lock, sequence); |
| rcu_read_unlock(); |
| |
| if (p) { |
| /* The existing node has been found. |
| * Remove the entry from unused list if it was there. |
| */ |
| unlink_from_unused(p); |
| return p; |
| } |
| |
| /* If no writer did a change during our lookup, we can return early. */ |
| if (!create && !invalidated) |
| return NULL; |
| |
| /* retry an exact lookup, taking the lock before. |
| * At least, nodes should be hot in our cache. |
| */ |
| write_seqlock_bh(&base->lock); |
| p = lookup(daddr, stack, base); |
| if (p != peer_avl_empty) { |
| atomic_inc(&p->refcnt); |
| write_sequnlock_bh(&base->lock); |
| /* Remove the entry from unused list if it was there. */ |
| unlink_from_unused(p); |
| return p; |
| } |
| p = create ? kmem_cache_alloc(peer_cachep, GFP_ATOMIC) : NULL; |
| if (p) { |
| p->daddr = *daddr; |
| atomic_set(&p->refcnt, 1); |
| atomic_set(&p->rid, 0); |
| atomic_set(&p->ip_id_count, secure_ip_id(daddr->addr.a4)); |
| p->tcp_ts_stamp = 0; |
| p->metrics[RTAX_LOCK-1] = INETPEER_METRICS_NEW; |
| p->rate_tokens = 0; |
| p->rate_last = 0; |
| p->pmtu_expires = 0; |
| p->pmtu_orig = 0; |
| memset(&p->redirect_learned, 0, sizeof(p->redirect_learned)); |
| INIT_LIST_HEAD(&p->unused); |
| |
| |
| /* Link the node. */ |
| link_to_pool(p, base); |
| base->total++; |
| } |
| write_sequnlock_bh(&base->lock); |
| |
| if (base->total >= inet_peer_threshold) |
| /* Remove one less-recently-used entry. */ |
| cleanup_once(0); |
| |
| return p; |
| } |
| |
| static int compute_total(void) |
| { |
| return v4_peers.total + v6_peers.total; |
| } |
| EXPORT_SYMBOL_GPL(inet_getpeer); |
| |
| /* Called with local BH disabled. */ |
| static void peer_check_expire(unsigned long dummy) |
| { |
| unsigned long now = jiffies; |
| int ttl, total; |
| |
| total = compute_total(); |
| if (total >= inet_peer_threshold) |
| ttl = inet_peer_minttl; |
| else |
| ttl = inet_peer_maxttl |
| - (inet_peer_maxttl - inet_peer_minttl) / HZ * |
| total / inet_peer_threshold * HZ; |
| while (!cleanup_once(ttl)) { |
| if (jiffies != now) |
| break; |
| } |
| |
| /* Trigger the timer after inet_peer_gc_mintime .. inet_peer_gc_maxtime |
| * interval depending on the total number of entries (more entries, |
| * less interval). */ |
| total = compute_total(); |
| if (total >= inet_peer_threshold) |
| peer_periodic_timer.expires = jiffies + inet_peer_gc_mintime; |
| else |
| peer_periodic_timer.expires = jiffies |
| + inet_peer_gc_maxtime |
| - (inet_peer_gc_maxtime - inet_peer_gc_mintime) / HZ * |
| total / inet_peer_threshold * HZ; |
| add_timer(&peer_periodic_timer); |
| } |
| |
| void inet_putpeer(struct inet_peer *p) |
| { |
| local_bh_disable(); |
| |
| if (atomic_dec_and_lock(&p->refcnt, &unused_peers.lock)) { |
| list_add_tail(&p->unused, &unused_peers.list); |
| p->dtime = (__u32)jiffies; |
| spin_unlock(&unused_peers.lock); |
| } |
| |
| local_bh_enable(); |
| } |
| EXPORT_SYMBOL_GPL(inet_putpeer); |
| |
| /* |
| * Check transmit rate limitation for given message. |
| * The rate information is held in the inet_peer entries now. |
| * This function is generic and could be used for other purposes |
| * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov. |
| * |
| * Note that the same inet_peer fields are modified by functions in |
| * route.c too, but these work for packet destinations while xrlim_allow |
| * works for icmp destinations. This means the rate limiting information |
| * for one "ip object" is shared - and these ICMPs are twice limited: |
| * by source and by destination. |
| * |
| * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate |
| * SHOULD allow setting of rate limits |
| * |
| * Shared between ICMPv4 and ICMPv6. |
| */ |
| #define XRLIM_BURST_FACTOR 6 |
| bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout) |
| { |
| unsigned long now, token; |
| bool rc = false; |
| |
| if (!peer) |
| return true; |
| |
| token = peer->rate_tokens; |
| now = jiffies; |
| token += now - peer->rate_last; |
| peer->rate_last = now; |
| if (token > XRLIM_BURST_FACTOR * timeout) |
| token = XRLIM_BURST_FACTOR * timeout; |
| if (token >= timeout) { |
| token -= timeout; |
| rc = true; |
| } |
| peer->rate_tokens = token; |
| return rc; |
| } |
| EXPORT_SYMBOL(inet_peer_xrlim_allow); |