Commit | Line | Data |
---|---|---|
e48c414e ACM |
1 | /* |
2 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
3 | * operating system. INET is implemented using the BSD Socket | |
4 | * interface as the means of communication with the user level. | |
5 | * | |
6 | * Generic TIME_WAIT sockets functions | |
7 | * | |
8 | * From code orinally in TCP | |
9 | */ | |
10 | ||
172589cc | 11 | #include <linux/kernel.h> |
e48c414e ACM |
12 | #include <net/inet_hashtables.h> |
13 | #include <net/inet_timewait_sock.h> | |
696ab2d3 | 14 | #include <net/ip.h> |
e48c414e ACM |
15 | |
16 | /* Must be called with locally disabled BHs. */ | |
acd159b6 AB |
17 | static void __inet_twsk_kill(struct inet_timewait_sock *tw, |
18 | struct inet_hashinfo *hashinfo) | |
e48c414e ACM |
19 | { |
20 | struct inet_bind_hashbucket *bhead; | |
21 | struct inet_bind_bucket *tb; | |
22 | /* Unlink from established hashes. */ | |
230140cf | 23 | rwlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash); |
e48c414e | 24 | |
230140cf | 25 | write_lock(lock); |
e48c414e | 26 | if (hlist_unhashed(&tw->tw_node)) { |
230140cf | 27 | write_unlock(lock); |
e48c414e ACM |
28 | return; |
29 | } | |
30 | __hlist_del(&tw->tw_node); | |
31 | sk_node_init(&tw->tw_node); | |
230140cf | 32 | write_unlock(lock); |
e48c414e ACM |
33 | |
34 | /* Disassociate with bind bucket. */ | |
35 | bhead = &hashinfo->bhash[inet_bhashfn(tw->tw_num, hashinfo->bhash_size)]; | |
36 | spin_lock(&bhead->lock); | |
37 | tb = tw->tw_tb; | |
38 | __hlist_del(&tw->tw_bind_node); | |
39 | tw->tw_tb = NULL; | |
40 | inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb); | |
41 | spin_unlock(&bhead->lock); | |
42 | #ifdef SOCK_REFCNT_DEBUG | |
43 | if (atomic_read(&tw->tw_refcnt) != 1) { | |
44 | printk(KERN_DEBUG "%s timewait_sock %p refcnt=%d\n", | |
45 | tw->tw_prot->name, tw, atomic_read(&tw->tw_refcnt)); | |
46 | } | |
47 | #endif | |
48 | inet_twsk_put(tw); | |
49 | } | |
50 | ||
7054fb93 PE |
51 | void inet_twsk_put(struct inet_timewait_sock *tw) |
52 | { | |
53 | if (atomic_dec_and_test(&tw->tw_refcnt)) { | |
54 | struct module *owner = tw->tw_prot->owner; | |
55 | twsk_destructor((struct sock *)tw); | |
56 | #ifdef SOCK_REFCNT_DEBUG | |
57 | printk(KERN_DEBUG "%s timewait_sock %p released\n", | |
58 | tw->tw_prot->name, tw); | |
59 | #endif | |
60 | kmem_cache_free(tw->tw_prot->twsk_prot->twsk_slab, tw); | |
61 | module_put(owner); | |
62 | } | |
63 | } | |
64 | EXPORT_SYMBOL_GPL(inet_twsk_put); | |
65 | ||
e48c414e ACM |
66 | /* |
67 | * Enter the time wait state. This is called with locally disabled BH. | |
68 | * Essentially we whip up a timewait bucket, copy the relevant info into it | |
69 | * from the SK, and mess with hash chains and list linkage. | |
70 | */ | |
71 | void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk, | |
72 | struct inet_hashinfo *hashinfo) | |
73 | { | |
74 | const struct inet_sock *inet = inet_sk(sk); | |
463c84b9 | 75 | const struct inet_connection_sock *icsk = inet_csk(sk); |
81c3d547 | 76 | struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, sk->sk_hash); |
230140cf | 77 | rwlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash); |
e48c414e ACM |
78 | struct inet_bind_hashbucket *bhead; |
79 | /* Step 1: Put TW into bind hash. Original socket stays there too. | |
80 | Note, that any socket with inet->num != 0 MUST be bound in | |
81 | binding cache, even if it is closed. | |
82 | */ | |
83 | bhead = &hashinfo->bhash[inet_bhashfn(inet->num, hashinfo->bhash_size)]; | |
84 | spin_lock(&bhead->lock); | |
463c84b9 ACM |
85 | tw->tw_tb = icsk->icsk_bind_hash; |
86 | BUG_TRAP(icsk->icsk_bind_hash); | |
e48c414e ACM |
87 | inet_twsk_add_bind_node(tw, &tw->tw_tb->owners); |
88 | spin_unlock(&bhead->lock); | |
89 | ||
230140cf | 90 | write_lock(lock); |
e48c414e ACM |
91 | |
92 | /* Step 2: Remove SK from established hash. */ | |
93 | if (__sk_del_node_init(sk)) | |
65f76517 | 94 | sock_prot_inuse_add(sk->sk_prot, -1); |
e48c414e | 95 | |
dbca9b27 ED |
96 | /* Step 3: Hash TW into TIMEWAIT chain. */ |
97 | inet_twsk_add_node(tw, &ehead->twchain); | |
e48c414e ACM |
98 | atomic_inc(&tw->tw_refcnt); |
99 | ||
230140cf | 100 | write_unlock(lock); |
e48c414e | 101 | } |
c676270b | 102 | |
696ab2d3 ACM |
103 | EXPORT_SYMBOL_GPL(__inet_twsk_hashdance); |
104 | ||
c676270b ACM |
105 | struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int state) |
106 | { | |
6d6ee43e ACM |
107 | struct inet_timewait_sock *tw = |
108 | kmem_cache_alloc(sk->sk_prot_creator->twsk_prot->twsk_slab, | |
54e6ecb2 | 109 | GFP_ATOMIC); |
c676270b ACM |
110 | if (tw != NULL) { |
111 | const struct inet_sock *inet = inet_sk(sk); | |
112 | ||
113 | /* Give us an identity. */ | |
114 | tw->tw_daddr = inet->daddr; | |
115 | tw->tw_rcv_saddr = inet->rcv_saddr; | |
116 | tw->tw_bound_dev_if = sk->sk_bound_dev_if; | |
117 | tw->tw_num = inet->num; | |
118 | tw->tw_state = TCP_TIME_WAIT; | |
119 | tw->tw_substate = state; | |
120 | tw->tw_sport = inet->sport; | |
121 | tw->tw_dport = inet->dport; | |
122 | tw->tw_family = sk->sk_family; | |
123 | tw->tw_reuse = sk->sk_reuse; | |
81c3d547 | 124 | tw->tw_hash = sk->sk_hash; |
c676270b ACM |
125 | tw->tw_ipv6only = 0; |
126 | tw->tw_prot = sk->sk_prot_creator; | |
127 | atomic_set(&tw->tw_refcnt, 1); | |
128 | inet_twsk_dead_node_init(tw); | |
eeb2b856 | 129 | __module_get(tw->tw_prot->owner); |
c676270b ACM |
130 | } |
131 | ||
132 | return tw; | |
133 | } | |
696ab2d3 ACM |
134 | |
135 | EXPORT_SYMBOL_GPL(inet_twsk_alloc); | |
136 | ||
137 | /* Returns non-zero if quota exceeded. */ | |
138 | static int inet_twdr_do_twkill_work(struct inet_timewait_death_row *twdr, | |
139 | const int slot) | |
140 | { | |
141 | struct inet_timewait_sock *tw; | |
142 | struct hlist_node *node; | |
143 | unsigned int killed; | |
144 | int ret; | |
145 | ||
146 | /* NOTE: compare this to previous version where lock | |
147 | * was released after detaching chain. It was racy, | |
148 | * because tw buckets are scheduled in not serialized context | |
149 | * in 2.3 (with netfilter), and with softnet it is common, because | |
150 | * soft irqs are not sequenced. | |
151 | */ | |
152 | killed = 0; | |
153 | ret = 0; | |
154 | rescan: | |
155 | inet_twsk_for_each_inmate(tw, node, &twdr->cells[slot]) { | |
156 | __inet_twsk_del_dead_node(tw); | |
157 | spin_unlock(&twdr->death_lock); | |
158 | __inet_twsk_kill(tw, twdr->hashinfo); | |
159 | inet_twsk_put(tw); | |
160 | killed++; | |
161 | spin_lock(&twdr->death_lock); | |
162 | if (killed > INET_TWDR_TWKILL_QUOTA) { | |
163 | ret = 1; | |
164 | break; | |
165 | } | |
166 | ||
167 | /* While we dropped twdr->death_lock, another cpu may have | |
168 | * killed off the next TW bucket in the list, therefore | |
169 | * do a fresh re-read of the hlist head node with the | |
170 | * lock reacquired. We still use the hlist traversal | |
171 | * macro in order to get the prefetches. | |
172 | */ | |
173 | goto rescan; | |
174 | } | |
175 | ||
176 | twdr->tw_count -= killed; | |
177 | NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITED, killed); | |
178 | ||
179 | return ret; | |
180 | } | |
181 | ||
182 | void inet_twdr_hangman(unsigned long data) | |
183 | { | |
184 | struct inet_timewait_death_row *twdr; | |
185 | int unsigned need_timer; | |
186 | ||
187 | twdr = (struct inet_timewait_death_row *)data; | |
188 | spin_lock(&twdr->death_lock); | |
189 | ||
190 | if (twdr->tw_count == 0) | |
191 | goto out; | |
192 | ||
193 | need_timer = 0; | |
194 | if (inet_twdr_do_twkill_work(twdr, twdr->slot)) { | |
195 | twdr->thread_slots |= (1 << twdr->slot); | |
696ab2d3 ACM |
196 | schedule_work(&twdr->twkill_work); |
197 | need_timer = 1; | |
198 | } else { | |
199 | /* We purged the entire slot, anything left? */ | |
200 | if (twdr->tw_count) | |
201 | need_timer = 1; | |
202 | } | |
203 | twdr->slot = ((twdr->slot + 1) & (INET_TWDR_TWKILL_SLOTS - 1)); | |
204 | if (need_timer) | |
205 | mod_timer(&twdr->tw_timer, jiffies + twdr->period); | |
206 | out: | |
207 | spin_unlock(&twdr->death_lock); | |
208 | } | |
209 | ||
210 | EXPORT_SYMBOL_GPL(inet_twdr_hangman); | |
211 | ||
65f27f38 | 212 | void inet_twdr_twkill_work(struct work_struct *work) |
696ab2d3 | 213 | { |
65f27f38 DH |
214 | struct inet_timewait_death_row *twdr = |
215 | container_of(work, struct inet_timewait_death_row, twkill_work); | |
696ab2d3 ACM |
216 | int i; |
217 | ||
95c9382a PE |
218 | BUILD_BUG_ON((INET_TWDR_TWKILL_SLOTS - 1) > |
219 | (sizeof(twdr->thread_slots) * 8)); | |
696ab2d3 ACM |
220 | |
221 | while (twdr->thread_slots) { | |
222 | spin_lock_bh(&twdr->death_lock); | |
223 | for (i = 0; i < INET_TWDR_TWKILL_SLOTS; i++) { | |
224 | if (!(twdr->thread_slots & (1 << i))) | |
225 | continue; | |
226 | ||
227 | while (inet_twdr_do_twkill_work(twdr, i) != 0) { | |
228 | if (need_resched()) { | |
229 | spin_unlock_bh(&twdr->death_lock); | |
230 | schedule(); | |
231 | spin_lock_bh(&twdr->death_lock); | |
232 | } | |
233 | } | |
234 | ||
235 | twdr->thread_slots &= ~(1 << i); | |
236 | } | |
237 | spin_unlock_bh(&twdr->death_lock); | |
238 | } | |
239 | } | |
240 | ||
241 | EXPORT_SYMBOL_GPL(inet_twdr_twkill_work); | |
242 | ||
243 | /* These are always called from BH context. See callers in | |
244 | * tcp_input.c to verify this. | |
245 | */ | |
246 | ||
247 | /* This is for handling early-kills of TIME_WAIT sockets. */ | |
248 | void inet_twsk_deschedule(struct inet_timewait_sock *tw, | |
249 | struct inet_timewait_death_row *twdr) | |
250 | { | |
251 | spin_lock(&twdr->death_lock); | |
252 | if (inet_twsk_del_dead_node(tw)) { | |
253 | inet_twsk_put(tw); | |
254 | if (--twdr->tw_count == 0) | |
255 | del_timer(&twdr->tw_timer); | |
256 | } | |
257 | spin_unlock(&twdr->death_lock); | |
258 | __inet_twsk_kill(tw, twdr->hashinfo); | |
259 | } | |
260 | ||
261 | EXPORT_SYMBOL(inet_twsk_deschedule); | |
262 | ||
263 | void inet_twsk_schedule(struct inet_timewait_sock *tw, | |
264 | struct inet_timewait_death_row *twdr, | |
265 | const int timeo, const int timewait_len) | |
266 | { | |
267 | struct hlist_head *list; | |
268 | int slot; | |
269 | ||
270 | /* timeout := RTO * 3.5 | |
271 | * | |
272 | * 3.5 = 1+2+0.5 to wait for two retransmits. | |
273 | * | |
274 | * RATIONALE: if FIN arrived and we entered TIME-WAIT state, | |
275 | * our ACK acking that FIN can be lost. If N subsequent retransmitted | |
276 | * FINs (or previous seqments) are lost (probability of such event | |
277 | * is p^(N+1), where p is probability to lose single packet and | |
278 | * time to detect the loss is about RTO*(2^N - 1) with exponential | |
279 | * backoff). Normal timewait length is calculated so, that we | |
280 | * waited at least for one retransmitted FIN (maximal RTO is 120sec). | |
281 | * [ BTW Linux. following BSD, violates this requirement waiting | |
282 | * only for 60sec, we should wait at least for 240 secs. | |
283 | * Well, 240 consumes too much of resources 8) | |
284 | * ] | |
285 | * This interval is not reduced to catch old duplicate and | |
286 | * responces to our wandering segments living for two MSLs. | |
287 | * However, if we use PAWS to detect | |
288 | * old duplicates, we can reduce the interval to bounds required | |
289 | * by RTO, rather than MSL. So, if peer understands PAWS, we | |
290 | * kill tw bucket after 3.5*RTO (it is important that this number | |
291 | * is greater than TS tick!) and detect old duplicates with help | |
292 | * of PAWS. | |
293 | */ | |
294 | slot = (timeo + (1 << INET_TWDR_RECYCLE_TICK) - 1) >> INET_TWDR_RECYCLE_TICK; | |
295 | ||
296 | spin_lock(&twdr->death_lock); | |
297 | ||
298 | /* Unlink it, if it was scheduled */ | |
299 | if (inet_twsk_del_dead_node(tw)) | |
300 | twdr->tw_count--; | |
301 | else | |
302 | atomic_inc(&tw->tw_refcnt); | |
303 | ||
304 | if (slot >= INET_TWDR_RECYCLE_SLOTS) { | |
305 | /* Schedule to slow timer */ | |
306 | if (timeo >= timewait_len) { | |
307 | slot = INET_TWDR_TWKILL_SLOTS - 1; | |
308 | } else { | |
172589cc | 309 | slot = DIV_ROUND_UP(timeo, twdr->period); |
696ab2d3 ACM |
310 | if (slot >= INET_TWDR_TWKILL_SLOTS) |
311 | slot = INET_TWDR_TWKILL_SLOTS - 1; | |
312 | } | |
313 | tw->tw_ttd = jiffies + timeo; | |
314 | slot = (twdr->slot + slot) & (INET_TWDR_TWKILL_SLOTS - 1); | |
315 | list = &twdr->cells[slot]; | |
316 | } else { | |
317 | tw->tw_ttd = jiffies + (slot << INET_TWDR_RECYCLE_TICK); | |
318 | ||
319 | if (twdr->twcal_hand < 0) { | |
320 | twdr->twcal_hand = 0; | |
321 | twdr->twcal_jiffie = jiffies; | |
322 | twdr->twcal_timer.expires = twdr->twcal_jiffie + | |
323 | (slot << INET_TWDR_RECYCLE_TICK); | |
324 | add_timer(&twdr->twcal_timer); | |
325 | } else { | |
326 | if (time_after(twdr->twcal_timer.expires, | |
327 | jiffies + (slot << INET_TWDR_RECYCLE_TICK))) | |
328 | mod_timer(&twdr->twcal_timer, | |
329 | jiffies + (slot << INET_TWDR_RECYCLE_TICK)); | |
330 | slot = (twdr->twcal_hand + slot) & (INET_TWDR_RECYCLE_SLOTS - 1); | |
331 | } | |
332 | list = &twdr->twcal_row[slot]; | |
333 | } | |
334 | ||
335 | hlist_add_head(&tw->tw_death_node, list); | |
336 | ||
337 | if (twdr->tw_count++ == 0) | |
338 | mod_timer(&twdr->tw_timer, jiffies + twdr->period); | |
339 | spin_unlock(&twdr->death_lock); | |
340 | } | |
341 | ||
342 | EXPORT_SYMBOL_GPL(inet_twsk_schedule); | |
343 | ||
344 | void inet_twdr_twcal_tick(unsigned long data) | |
345 | { | |
346 | struct inet_timewait_death_row *twdr; | |
347 | int n, slot; | |
348 | unsigned long j; | |
349 | unsigned long now = jiffies; | |
350 | int killed = 0; | |
351 | int adv = 0; | |
352 | ||
353 | twdr = (struct inet_timewait_death_row *)data; | |
354 | ||
355 | spin_lock(&twdr->death_lock); | |
356 | if (twdr->twcal_hand < 0) | |
357 | goto out; | |
358 | ||
359 | slot = twdr->twcal_hand; | |
360 | j = twdr->twcal_jiffie; | |
361 | ||
362 | for (n = 0; n < INET_TWDR_RECYCLE_SLOTS; n++) { | |
363 | if (time_before_eq(j, now)) { | |
364 | struct hlist_node *node, *safe; | |
365 | struct inet_timewait_sock *tw; | |
366 | ||
367 | inet_twsk_for_each_inmate_safe(tw, node, safe, | |
368 | &twdr->twcal_row[slot]) { | |
369 | __inet_twsk_del_dead_node(tw); | |
370 | __inet_twsk_kill(tw, twdr->hashinfo); | |
371 | inet_twsk_put(tw); | |
372 | killed++; | |
373 | } | |
374 | } else { | |
375 | if (!adv) { | |
376 | adv = 1; | |
377 | twdr->twcal_jiffie = j; | |
378 | twdr->twcal_hand = slot; | |
379 | } | |
380 | ||
381 | if (!hlist_empty(&twdr->twcal_row[slot])) { | |
382 | mod_timer(&twdr->twcal_timer, j); | |
383 | goto out; | |
384 | } | |
385 | } | |
386 | j += 1 << INET_TWDR_RECYCLE_TICK; | |
387 | slot = (slot + 1) & (INET_TWDR_RECYCLE_SLOTS - 1); | |
388 | } | |
389 | twdr->twcal_hand = -1; | |
390 | ||
391 | out: | |
392 | if ((twdr->tw_count -= killed) == 0) | |
393 | del_timer(&twdr->tw_timer); | |
394 | NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITKILLED, killed); | |
395 | spin_unlock(&twdr->death_lock); | |
396 | } | |
397 | ||
398 | EXPORT_SYMBOL_GPL(inet_twdr_twcal_tick); |