Commit | Line | Data |
---|---|---|
1da177e4 LT |
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 | * | |
1da177e4 LT |
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> | |
1da177e4 LT |
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> | |
20380731 | 20 | #include <net/ip.h> |
1da177e4 LT |
21 | #include <net/inetpeer.h> |
22 | ||
23 | /* | |
24 | * Theory of operations. | |
25 | * We keep one entry for each peer IP address. The nodes contains long-living | |
26 | * information about the peer which doesn't depend on routes. | |
27 | * At this moment this information consists only of ID field for the next | |
28 | * outgoing IP packet. This field is incremented with each packet as encoded | |
29 | * in inet_getid() function (include/net/inetpeer.h). | |
30 | * At the moment of writing this notes identifier of IP packets is generated | |
31 | * to be unpredictable using this code only for packets subjected | |
32 | * (actually or potentially) to defragmentation. I.e. DF packets less than | |
33 | * PMTU in size uses a constant ID and do not use this code (see | |
34 | * ip_select_ident() in include/net/ip.h). | |
35 | * | |
36 | * Route cache entries hold references to our nodes. | |
37 | * New cache entries get references via lookup by destination IP address in | |
38 | * the avl tree. The reference is grabbed only when it's needed i.e. only | |
39 | * when we try to output IP packet which needs an unpredictable ID (see | |
40 | * __ip_select_ident() in net/ipv4/route.c). | |
41 | * Nodes are removed only when reference counter goes to 0. | |
42 | * When it's happened the node may be removed when a sufficient amount of | |
43 | * time has been passed since its last use. The less-recently-used entry can | |
44 | * also be removed if the pool is overloaded i.e. if the total amount of | |
45 | * entries is greater-or-equal than the threshold. | |
46 | * | |
47 | * Node pool is organised as an AVL tree. | |
48 | * Such an implementation has been chosen not just for fun. It's a way to | |
49 | * prevent easy and efficient DoS attacks by creating hash collisions. A huge | |
50 | * amount of long living nodes in a single hash slot would significantly delay | |
51 | * lookups performed with disabled BHs. | |
52 | * | |
53 | * Serialisation issues. | |
aa1039e7 ED |
54 | * 1. Nodes may appear in the tree only with the pool lock held. |
55 | * 2. Nodes may disappear from the tree only with the pool lock held | |
1da177e4 LT |
56 | * AND reference count being 0. |
57 | * 3. Nodes appears and disappears from unused node list only under | |
58 | * "inet_peer_unused_lock". | |
59 | * 4. Global variable peer_total is modified under the pool lock. | |
60 | * 5. struct inet_peer fields modification: | |
61 | * avl_left, avl_right, avl_parent, avl_height: pool lock | |
d71209de | 62 | * unused: unused node list lock |
1da177e4 LT |
63 | * refcnt: atomically against modifications on other CPU; |
64 | * usually under some other lock to prevent node disappearing | |
65 | * dtime: unused node list lock | |
66 | * v4daddr: unchangeable | |
317fe0e6 | 67 | * ip_id_count: atomic value (no lock needed) |
1da177e4 LT |
68 | */ |
69 | ||
e18b890b | 70 | static struct kmem_cache *peer_cachep __read_mostly; |
1da177e4 LT |
71 | |
72 | #define node_height(x) x->avl_height | |
d6cc1d64 ED |
73 | |
74 | #define peer_avl_empty ((struct inet_peer *)&peer_fake_node) | |
75 | static const struct inet_peer peer_fake_node = { | |
76 | .avl_left = peer_avl_empty, | |
77 | .avl_right = peer_avl_empty, | |
1da177e4 LT |
78 | .avl_height = 0 |
79 | }; | |
d6cc1d64 ED |
80 | |
81 | static struct { | |
82 | struct inet_peer *root; | |
aa1039e7 | 83 | spinlock_t lock; |
d6cc1d64 ED |
84 | int total; |
85 | } peers = { | |
86 | .root = peer_avl_empty, | |
aa1039e7 | 87 | .lock = __SPIN_LOCK_UNLOCKED(peers.lock), |
d6cc1d64 ED |
88 | .total = 0, |
89 | }; | |
1da177e4 LT |
90 | #define PEER_MAXDEPTH 40 /* sufficient for about 2^27 nodes */ |
91 | ||
1da177e4 | 92 | /* Exported for sysctl_net_ipv4. */ |
243bbcaa | 93 | int inet_peer_threshold __read_mostly = 65536 + 128; /* start to throw entries more |
1da177e4 | 94 | * aggressively at this stage */ |
243bbcaa ED |
95 | int inet_peer_minttl __read_mostly = 120 * HZ; /* TTL under high load: 120 sec */ |
96 | int inet_peer_maxttl __read_mostly = 10 * 60 * HZ; /* usual time to live: 10 min */ | |
97 | int inet_peer_gc_mintime __read_mostly = 10 * HZ; | |
98 | int inet_peer_gc_maxtime __read_mostly = 120 * HZ; | |
1da177e4 | 99 | |
d6cc1d64 ED |
100 | static struct { |
101 | struct list_head list; | |
102 | spinlock_t lock; | |
103 | } unused_peers = { | |
104 | .list = LIST_HEAD_INIT(unused_peers.list), | |
105 | .lock = __SPIN_LOCK_UNLOCKED(unused_peers.lock), | |
106 | }; | |
1da177e4 LT |
107 | |
108 | static void peer_check_expire(unsigned long dummy); | |
8d06afab | 109 | static DEFINE_TIMER(peer_periodic_timer, peer_check_expire, 0, 0); |
1da177e4 | 110 | |
1da177e4 LT |
111 | |
112 | /* Called from ip_output.c:ip_init */ | |
113 | void __init inet_initpeers(void) | |
114 | { | |
115 | struct sysinfo si; | |
116 | ||
117 | /* Use the straight interface to information about memory. */ | |
118 | si_meminfo(&si); | |
119 | /* The values below were suggested by Alexey Kuznetsov | |
120 | * <kuznet@ms2.inr.ac.ru>. I don't have any opinion about the values | |
121 | * myself. --SAW | |
122 | */ | |
123 | if (si.totalram <= (32768*1024)/PAGE_SIZE) | |
124 | inet_peer_threshold >>= 1; /* max pool size about 1MB on IA32 */ | |
125 | if (si.totalram <= (16384*1024)/PAGE_SIZE) | |
126 | inet_peer_threshold >>= 1; /* about 512KB */ | |
127 | if (si.totalram <= (8192*1024)/PAGE_SIZE) | |
128 | inet_peer_threshold >>= 2; /* about 128KB */ | |
129 | ||
130 | peer_cachep = kmem_cache_create("inet_peer_cache", | |
131 | sizeof(struct inet_peer), | |
317fe0e6 | 132 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, |
20c2df83 | 133 | NULL); |
1da177e4 | 134 | |
1da177e4 LT |
135 | /* All the timers, started at system startup tend |
136 | to synchronize. Perturb it a bit. | |
137 | */ | |
138 | peer_periodic_timer.expires = jiffies | |
139 | + net_random() % inet_peer_gc_maxtime | |
140 | + inet_peer_gc_maxtime; | |
141 | add_timer(&peer_periodic_timer); | |
142 | } | |
143 | ||
144 | /* Called with or without local BH being disabled. */ | |
145 | static void unlink_from_unused(struct inet_peer *p) | |
146 | { | |
d6cc1d64 ED |
147 | if (!list_empty(&p->unused)) { |
148 | spin_lock_bh(&unused_peers.lock); | |
149 | list_del_init(&p->unused); | |
150 | spin_unlock_bh(&unused_peers.lock); | |
151 | } | |
1da177e4 LT |
152 | } |
153 | ||
243bbcaa ED |
154 | /* |
155 | * Called with local BH disabled and the pool lock held. | |
243bbcaa | 156 | */ |
d9319100 | 157 | #define lookup(_daddr, _stack) \ |
1da177e4 LT |
158 | ({ \ |
159 | struct inet_peer *u, **v; \ | |
aa1039e7 ED |
160 | \ |
161 | stackptr = _stack; \ | |
162 | *stackptr++ = &peers.root; \ | |
d6cc1d64 | 163 | for (u = peers.root; u != peer_avl_empty; ) { \ |
243bbcaa | 164 | if (_daddr == u->v4daddr) \ |
1da177e4 | 165 | break; \ |
243bbcaa | 166 | if ((__force __u32)_daddr < (__force __u32)u->v4daddr) \ |
1da177e4 LT |
167 | v = &u->avl_left; \ |
168 | else \ | |
169 | v = &u->avl_right; \ | |
aa1039e7 | 170 | *stackptr++ = v; \ |
1da177e4 LT |
171 | u = *v; \ |
172 | } \ | |
173 | u; \ | |
174 | }) | |
175 | ||
aa1039e7 ED |
176 | /* |
177 | * Called with rcu_read_lock_bh() | |
178 | * Because we hold no lock against a writer, its quite possible we fall | |
179 | * in an endless loop. | |
180 | * But every pointer we follow is guaranteed to be valid thanks to RCU. | |
181 | * We exit from this function if number of links exceeds PEER_MAXDEPTH | |
182 | */ | |
183 | static struct inet_peer *lookup_rcu_bh(__be32 daddr) | |
184 | { | |
185 | struct inet_peer *u = rcu_dereference_bh(peers.root); | |
186 | int count = 0; | |
187 | ||
188 | while (u != peer_avl_empty) { | |
189 | if (daddr == u->v4daddr) { | |
5f2f8920 ED |
190 | /* Before taking a reference, check if this entry was |
191 | * deleted, unlink_from_pool() sets refcnt=-1 to make | |
192 | * distinction between an unused entry (refcnt=0) and | |
193 | * a freed one. | |
194 | */ | |
195 | if (unlikely(!atomic_add_unless(&u->refcnt, 1, -1))) | |
aa1039e7 ED |
196 | u = NULL; |
197 | return u; | |
198 | } | |
199 | if ((__force __u32)daddr < (__force __u32)u->v4daddr) | |
200 | u = rcu_dereference_bh(u->avl_left); | |
201 | else | |
202 | u = rcu_dereference_bh(u->avl_right); | |
203 | if (unlikely(++count == PEER_MAXDEPTH)) | |
204 | break; | |
205 | } | |
206 | return NULL; | |
207 | } | |
208 | ||
209 | /* Called with local BH disabled and the pool lock held. */ | |
1da177e4 LT |
210 | #define lookup_rightempty(start) \ |
211 | ({ \ | |
212 | struct inet_peer *u, **v; \ | |
213 | *stackptr++ = &start->avl_left; \ | |
214 | v = &start->avl_left; \ | |
215 | for (u = *v; u->avl_right != peer_avl_empty; ) { \ | |
216 | v = &u->avl_right; \ | |
217 | *stackptr++ = v; \ | |
218 | u = *v; \ | |
219 | } \ | |
220 | u; \ | |
221 | }) | |
222 | ||
aa1039e7 | 223 | /* Called with local BH disabled and the pool lock held. |
1da177e4 | 224 | * Variable names are the proof of operation correctness. |
aa1039e7 ED |
225 | * Look into mm/map_avl.c for more detail description of the ideas. |
226 | */ | |
1da177e4 LT |
227 | static void peer_avl_rebalance(struct inet_peer **stack[], |
228 | struct inet_peer ***stackend) | |
229 | { | |
230 | struct inet_peer **nodep, *node, *l, *r; | |
231 | int lh, rh; | |
232 | ||
233 | while (stackend > stack) { | |
234 | nodep = *--stackend; | |
235 | node = *nodep; | |
236 | l = node->avl_left; | |
237 | r = node->avl_right; | |
238 | lh = node_height(l); | |
239 | rh = node_height(r); | |
240 | if (lh > rh + 1) { /* l: RH+2 */ | |
241 | struct inet_peer *ll, *lr, *lrl, *lrr; | |
242 | int lrh; | |
243 | ll = l->avl_left; | |
244 | lr = l->avl_right; | |
245 | lrh = node_height(lr); | |
246 | if (lrh <= node_height(ll)) { /* ll: RH+1 */ | |
247 | node->avl_left = lr; /* lr: RH or RH+1 */ | |
248 | node->avl_right = r; /* r: RH */ | |
249 | node->avl_height = lrh + 1; /* RH+1 or RH+2 */ | |
250 | l->avl_left = ll; /* ll: RH+1 */ | |
251 | l->avl_right = node; /* node: RH+1 or RH+2 */ | |
252 | l->avl_height = node->avl_height + 1; | |
253 | *nodep = l; | |
254 | } else { /* ll: RH, lr: RH+1 */ | |
255 | lrl = lr->avl_left; /* lrl: RH or RH-1 */ | |
256 | lrr = lr->avl_right; /* lrr: RH or RH-1 */ | |
257 | node->avl_left = lrr; /* lrr: RH or RH-1 */ | |
258 | node->avl_right = r; /* r: RH */ | |
259 | node->avl_height = rh + 1; /* node: RH+1 */ | |
260 | l->avl_left = ll; /* ll: RH */ | |
261 | l->avl_right = lrl; /* lrl: RH or RH-1 */ | |
262 | l->avl_height = rh + 1; /* l: RH+1 */ | |
263 | lr->avl_left = l; /* l: RH+1 */ | |
264 | lr->avl_right = node; /* node: RH+1 */ | |
265 | lr->avl_height = rh + 2; | |
266 | *nodep = lr; | |
267 | } | |
268 | } else if (rh > lh + 1) { /* r: LH+2 */ | |
269 | struct inet_peer *rr, *rl, *rlr, *rll; | |
270 | int rlh; | |
271 | rr = r->avl_right; | |
272 | rl = r->avl_left; | |
273 | rlh = node_height(rl); | |
274 | if (rlh <= node_height(rr)) { /* rr: LH+1 */ | |
275 | node->avl_right = rl; /* rl: LH or LH+1 */ | |
276 | node->avl_left = l; /* l: LH */ | |
277 | node->avl_height = rlh + 1; /* LH+1 or LH+2 */ | |
278 | r->avl_right = rr; /* rr: LH+1 */ | |
279 | r->avl_left = node; /* node: LH+1 or LH+2 */ | |
280 | r->avl_height = node->avl_height + 1; | |
281 | *nodep = r; | |
282 | } else { /* rr: RH, rl: RH+1 */ | |
283 | rlr = rl->avl_right; /* rlr: LH or LH-1 */ | |
284 | rll = rl->avl_left; /* rll: LH or LH-1 */ | |
285 | node->avl_right = rll; /* rll: LH or LH-1 */ | |
286 | node->avl_left = l; /* l: LH */ | |
287 | node->avl_height = lh + 1; /* node: LH+1 */ | |
288 | r->avl_right = rr; /* rr: LH */ | |
289 | r->avl_left = rlr; /* rlr: LH or LH-1 */ | |
290 | r->avl_height = lh + 1; /* r: LH+1 */ | |
291 | rl->avl_right = r; /* r: LH+1 */ | |
292 | rl->avl_left = node; /* node: LH+1 */ | |
293 | rl->avl_height = lh + 2; | |
294 | *nodep = rl; | |
295 | } | |
296 | } else { | |
297 | node->avl_height = (lh > rh ? lh : rh) + 1; | |
298 | } | |
299 | } | |
300 | } | |
301 | ||
aa1039e7 | 302 | /* Called with local BH disabled and the pool lock held. */ |
1da177e4 LT |
303 | #define link_to_pool(n) \ |
304 | do { \ | |
305 | n->avl_height = 1; \ | |
306 | n->avl_left = peer_avl_empty; \ | |
307 | n->avl_right = peer_avl_empty; \ | |
aa1039e7 | 308 | smp_wmb(); /* lockless readers can catch us now */ \ |
1da177e4 LT |
309 | **--stackptr = n; \ |
310 | peer_avl_rebalance(stack, stackptr); \ | |
d6cc1d64 | 311 | } while (0) |
1da177e4 | 312 | |
aa1039e7 ED |
313 | static void inetpeer_free_rcu(struct rcu_head *head) |
314 | { | |
315 | kmem_cache_free(peer_cachep, container_of(head, struct inet_peer, rcu)); | |
316 | } | |
317 | ||
1da177e4 LT |
318 | /* May be called with local BH enabled. */ |
319 | static void unlink_from_pool(struct inet_peer *p) | |
320 | { | |
321 | int do_free; | |
322 | ||
323 | do_free = 0; | |
324 | ||
aa1039e7 | 325 | spin_lock_bh(&peers.lock); |
1da177e4 | 326 | /* Check the reference counter. It was artificially incremented by 1 |
aa1039e7 ED |
327 | * in cleanup() function to prevent sudden disappearing. If we can |
328 | * atomically (because of lockless readers) take this last reference, | |
329 | * it's safe to remove the node and free it later. | |
5f2f8920 | 330 | * We use refcnt=-1 to alert lockless readers this entry is deleted. |
aa1039e7 | 331 | */ |
5f2f8920 | 332 | if (atomic_cmpxchg(&p->refcnt, 1, -1) == 1) { |
1da177e4 LT |
333 | struct inet_peer **stack[PEER_MAXDEPTH]; |
334 | struct inet_peer ***stackptr, ***delp; | |
243bbcaa | 335 | if (lookup(p->v4daddr, stack) != p) |
1da177e4 LT |
336 | BUG(); |
337 | delp = stackptr - 1; /* *delp[0] == p */ | |
338 | if (p->avl_left == peer_avl_empty) { | |
339 | *delp[0] = p->avl_right; | |
340 | --stackptr; | |
341 | } else { | |
342 | /* look for a node to insert instead of p */ | |
343 | struct inet_peer *t; | |
344 | t = lookup_rightempty(p); | |
09a62660 | 345 | BUG_ON(*stackptr[-1] != t); |
1da177e4 LT |
346 | **--stackptr = t->avl_left; |
347 | /* t is removed, t->v4daddr > x->v4daddr for any | |
348 | * x in p->avl_left subtree. | |
349 | * Put t in the old place of p. */ | |
350 | *delp[0] = t; | |
351 | t->avl_left = p->avl_left; | |
352 | t->avl_right = p->avl_right; | |
353 | t->avl_height = p->avl_height; | |
09a62660 | 354 | BUG_ON(delp[1] != &p->avl_left); |
1da177e4 LT |
355 | delp[1] = &t->avl_left; /* was &p->avl_left */ |
356 | } | |
357 | peer_avl_rebalance(stack, stackptr); | |
d6cc1d64 | 358 | peers.total--; |
1da177e4 LT |
359 | do_free = 1; |
360 | } | |
aa1039e7 | 361 | spin_unlock_bh(&peers.lock); |
1da177e4 LT |
362 | |
363 | if (do_free) | |
aa1039e7 | 364 | call_rcu_bh(&p->rcu, inetpeer_free_rcu); |
1da177e4 LT |
365 | else |
366 | /* The node is used again. Decrease the reference counter | |
367 | * back. The loop "cleanup -> unlink_from_unused | |
368 | * -> unlink_from_pool -> putpeer -> link_to_unused | |
369 | * -> cleanup (for the same node)" | |
370 | * doesn't really exist because the entry will have a | |
aa1039e7 ED |
371 | * recent deletion time and will not be cleaned again soon. |
372 | */ | |
1da177e4 LT |
373 | inet_putpeer(p); |
374 | } | |
375 | ||
376 | /* May be called with local BH enabled. */ | |
377 | static int cleanup_once(unsigned long ttl) | |
378 | { | |
d71209de | 379 | struct inet_peer *p = NULL; |
1da177e4 LT |
380 | |
381 | /* Remove the first entry from the list of unused nodes. */ | |
d6cc1d64 ED |
382 | spin_lock_bh(&unused_peers.lock); |
383 | if (!list_empty(&unused_peers.list)) { | |
d71209de PE |
384 | __u32 delta; |
385 | ||
d6cc1d64 | 386 | p = list_first_entry(&unused_peers.list, struct inet_peer, unused); |
d71209de PE |
387 | delta = (__u32)jiffies - p->dtime; |
388 | ||
4663afe2 | 389 | if (delta < ttl) { |
1da177e4 | 390 | /* Do not prune fresh entries. */ |
d6cc1d64 | 391 | spin_unlock_bh(&unused_peers.lock); |
1da177e4 LT |
392 | return -1; |
393 | } | |
d71209de PE |
394 | |
395 | list_del_init(&p->unused); | |
396 | ||
1da177e4 LT |
397 | /* Grab an extra reference to prevent node disappearing |
398 | * before unlink_from_pool() call. */ | |
399 | atomic_inc(&p->refcnt); | |
400 | } | |
d6cc1d64 | 401 | spin_unlock_bh(&unused_peers.lock); |
1da177e4 LT |
402 | |
403 | if (p == NULL) | |
404 | /* It means that the total number of USED entries has | |
405 | * grown over inet_peer_threshold. It shouldn't really | |
406 | * happen because of entry limits in route cache. */ | |
407 | return -1; | |
408 | ||
409 | unlink_from_pool(p); | |
410 | return 0; | |
411 | } | |
412 | ||
413 | /* Called with or without local BH being disabled. */ | |
53576d9b | 414 | struct inet_peer *inet_getpeer(__be32 daddr, int create) |
1da177e4 | 415 | { |
aa1039e7 | 416 | struct inet_peer *p; |
1da177e4 LT |
417 | struct inet_peer **stack[PEER_MAXDEPTH], ***stackptr; |
418 | ||
aa1039e7 ED |
419 | /* Look up for the address quickly, lockless. |
420 | * Because of a concurrent writer, we might not find an existing entry. | |
421 | */ | |
422 | rcu_read_lock_bh(); | |
423 | p = lookup_rcu_bh(daddr); | |
424 | rcu_read_unlock_bh(); | |
425 | ||
426 | if (p) { | |
427 | /* The existing node has been found. | |
428 | * Remove the entry from unused list if it was there. | |
429 | */ | |
430 | unlink_from_unused(p); | |
431 | return p; | |
432 | } | |
1da177e4 | 433 | |
aa1039e7 ED |
434 | /* retry an exact lookup, taking the lock before. |
435 | * At least, nodes should be hot in our cache. | |
436 | */ | |
437 | spin_lock_bh(&peers.lock); | |
438 | p = lookup(daddr, stack); | |
1da177e4 | 439 | if (p != peer_avl_empty) { |
aa1039e7 ED |
440 | atomic_inc(&p->refcnt); |
441 | spin_unlock_bh(&peers.lock); | |
1da177e4 LT |
442 | /* Remove the entry from unused list if it was there. */ |
443 | unlink_from_unused(p); | |
444 | return p; | |
445 | } | |
aa1039e7 ED |
446 | p = create ? kmem_cache_alloc(peer_cachep, GFP_ATOMIC) : NULL; |
447 | if (p) { | |
448 | p->v4daddr = daddr; | |
449 | atomic_set(&p->refcnt, 1); | |
450 | atomic_set(&p->rid, 0); | |
451 | atomic_set(&p->ip_id_count, secure_ip_id(daddr)); | |
452 | p->tcp_ts_stamp = 0; | |
453 | INIT_LIST_HEAD(&p->unused); | |
454 | ||
455 | ||
456 | /* Link the node. */ | |
457 | link_to_pool(p); | |
458 | peers.total++; | |
459 | } | |
460 | spin_unlock_bh(&peers.lock); | |
1da177e4 | 461 | |
d6cc1d64 | 462 | if (peers.total >= inet_peer_threshold) |
1da177e4 LT |
463 | /* Remove one less-recently-used entry. */ |
464 | cleanup_once(0); | |
465 | ||
1da177e4 LT |
466 | return p; |
467 | } | |
468 | ||
469 | /* Called with local BH disabled. */ | |
470 | static void peer_check_expire(unsigned long dummy) | |
471 | { | |
4663afe2 | 472 | unsigned long now = jiffies; |
1da177e4 LT |
473 | int ttl; |
474 | ||
d6cc1d64 | 475 | if (peers.total >= inet_peer_threshold) |
1da177e4 LT |
476 | ttl = inet_peer_minttl; |
477 | else | |
478 | ttl = inet_peer_maxttl | |
479 | - (inet_peer_maxttl - inet_peer_minttl) / HZ * | |
d6cc1d64 | 480 | peers.total / inet_peer_threshold * HZ; |
4663afe2 ED |
481 | while (!cleanup_once(ttl)) { |
482 | if (jiffies != now) | |
483 | break; | |
484 | } | |
1da177e4 LT |
485 | |
486 | /* Trigger the timer after inet_peer_gc_mintime .. inet_peer_gc_maxtime | |
487 | * interval depending on the total number of entries (more entries, | |
488 | * less interval). */ | |
d6cc1d64 | 489 | if (peers.total >= inet_peer_threshold) |
1344a416 DJ |
490 | peer_periodic_timer.expires = jiffies + inet_peer_gc_mintime; |
491 | else | |
492 | peer_periodic_timer.expires = jiffies | |
493 | + inet_peer_gc_maxtime | |
494 | - (inet_peer_gc_maxtime - inet_peer_gc_mintime) / HZ * | |
d6cc1d64 | 495 | peers.total / inet_peer_threshold * HZ; |
1da177e4 LT |
496 | add_timer(&peer_periodic_timer); |
497 | } | |
4663afe2 ED |
498 | |
499 | void inet_putpeer(struct inet_peer *p) | |
500 | { | |
d6cc1d64 ED |
501 | local_bh_disable(); |
502 | ||
503 | if (atomic_dec_and_lock(&p->refcnt, &unused_peers.lock)) { | |
504 | list_add_tail(&p->unused, &unused_peers.list); | |
4663afe2 | 505 | p->dtime = (__u32)jiffies; |
d6cc1d64 | 506 | spin_unlock(&unused_peers.lock); |
4663afe2 | 507 | } |
d6cc1d64 ED |
508 | |
509 | local_bh_enable(); | |
4663afe2 | 510 | } |