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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 | ||
11 | #include <linux/config.h> | |
12 | ||
13 | #include <net/inet_hashtables.h> | |
14 | #include <net/inet_timewait_sock.h> | |
696ab2d3 | 15 | #include <net/ip.h> |
e48c414e ACM |
16 | |
17 | /* Must be called with locally disabled BHs. */ | |
18 | void __inet_twsk_kill(struct inet_timewait_sock *tw, struct inet_hashinfo *hashinfo) | |
19 | { | |
20 | struct inet_bind_hashbucket *bhead; | |
21 | struct inet_bind_bucket *tb; | |
22 | /* Unlink from established hashes. */ | |
23 | struct inet_ehash_bucket *ehead = &hashinfo->ehash[tw->tw_hashent]; | |
24 | ||
25 | write_lock(&ehead->lock); | |
26 | if (hlist_unhashed(&tw->tw_node)) { | |
27 | write_unlock(&ehead->lock); | |
28 | return; | |
29 | } | |
30 | __hlist_del(&tw->tw_node); | |
31 | sk_node_init(&tw->tw_node); | |
32 | write_unlock(&ehead->lock); | |
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 | ||
d8c97a94 ACM |
51 | EXPORT_SYMBOL_GPL(__inet_twsk_kill); |
52 | ||
e48c414e ACM |
53 | /* |
54 | * Enter the time wait state. This is called with locally disabled BH. | |
55 | * Essentially we whip up a timewait bucket, copy the relevant info into it | |
56 | * from the SK, and mess with hash chains and list linkage. | |
57 | */ | |
58 | void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk, | |
59 | struct inet_hashinfo *hashinfo) | |
60 | { | |
61 | const struct inet_sock *inet = inet_sk(sk); | |
463c84b9 | 62 | const struct inet_connection_sock *icsk = inet_csk(sk); |
e48c414e ACM |
63 | struct inet_ehash_bucket *ehead = &hashinfo->ehash[sk->sk_hashent]; |
64 | struct inet_bind_hashbucket *bhead; | |
65 | /* Step 1: Put TW into bind hash. Original socket stays there too. | |
66 | Note, that any socket with inet->num != 0 MUST be bound in | |
67 | binding cache, even if it is closed. | |
68 | */ | |
69 | bhead = &hashinfo->bhash[inet_bhashfn(inet->num, hashinfo->bhash_size)]; | |
70 | spin_lock(&bhead->lock); | |
463c84b9 ACM |
71 | tw->tw_tb = icsk->icsk_bind_hash; |
72 | BUG_TRAP(icsk->icsk_bind_hash); | |
e48c414e ACM |
73 | inet_twsk_add_bind_node(tw, &tw->tw_tb->owners); |
74 | spin_unlock(&bhead->lock); | |
75 | ||
76 | write_lock(&ehead->lock); | |
77 | ||
78 | /* Step 2: Remove SK from established hash. */ | |
79 | if (__sk_del_node_init(sk)) | |
80 | sock_prot_dec_use(sk->sk_prot); | |
81 | ||
82 | /* Step 3: Hash TW into TIMEWAIT half of established hash table. */ | |
83 | inet_twsk_add_node(tw, &(ehead + hashinfo->ehash_size)->chain); | |
84 | atomic_inc(&tw->tw_refcnt); | |
85 | ||
86 | write_unlock(&ehead->lock); | |
87 | } | |
c676270b | 88 | |
696ab2d3 ACM |
89 | EXPORT_SYMBOL_GPL(__inet_twsk_hashdance); |
90 | ||
c676270b ACM |
91 | struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int state) |
92 | { | |
93 | struct inet_timewait_sock *tw = kmem_cache_alloc(sk->sk_prot_creator->twsk_slab, | |
94 | SLAB_ATOMIC); | |
95 | if (tw != NULL) { | |
96 | const struct inet_sock *inet = inet_sk(sk); | |
97 | ||
98 | /* Give us an identity. */ | |
99 | tw->tw_daddr = inet->daddr; | |
100 | tw->tw_rcv_saddr = inet->rcv_saddr; | |
101 | tw->tw_bound_dev_if = sk->sk_bound_dev_if; | |
102 | tw->tw_num = inet->num; | |
103 | tw->tw_state = TCP_TIME_WAIT; | |
104 | tw->tw_substate = state; | |
105 | tw->tw_sport = inet->sport; | |
106 | tw->tw_dport = inet->dport; | |
107 | tw->tw_family = sk->sk_family; | |
108 | tw->tw_reuse = sk->sk_reuse; | |
109 | tw->tw_hashent = sk->sk_hashent; | |
110 | tw->tw_ipv6only = 0; | |
111 | tw->tw_prot = sk->sk_prot_creator; | |
112 | atomic_set(&tw->tw_refcnt, 1); | |
113 | inet_twsk_dead_node_init(tw); | |
114 | } | |
115 | ||
116 | return tw; | |
117 | } | |
696ab2d3 ACM |
118 | |
119 | EXPORT_SYMBOL_GPL(inet_twsk_alloc); | |
120 | ||
121 | /* Returns non-zero if quota exceeded. */ | |
122 | static int inet_twdr_do_twkill_work(struct inet_timewait_death_row *twdr, | |
123 | const int slot) | |
124 | { | |
125 | struct inet_timewait_sock *tw; | |
126 | struct hlist_node *node; | |
127 | unsigned int killed; | |
128 | int ret; | |
129 | ||
130 | /* NOTE: compare this to previous version where lock | |
131 | * was released after detaching chain. It was racy, | |
132 | * because tw buckets are scheduled in not serialized context | |
133 | * in 2.3 (with netfilter), and with softnet it is common, because | |
134 | * soft irqs are not sequenced. | |
135 | */ | |
136 | killed = 0; | |
137 | ret = 0; | |
138 | rescan: | |
139 | inet_twsk_for_each_inmate(tw, node, &twdr->cells[slot]) { | |
140 | __inet_twsk_del_dead_node(tw); | |
141 | spin_unlock(&twdr->death_lock); | |
142 | __inet_twsk_kill(tw, twdr->hashinfo); | |
143 | inet_twsk_put(tw); | |
144 | killed++; | |
145 | spin_lock(&twdr->death_lock); | |
146 | if (killed > INET_TWDR_TWKILL_QUOTA) { | |
147 | ret = 1; | |
148 | break; | |
149 | } | |
150 | ||
151 | /* While we dropped twdr->death_lock, another cpu may have | |
152 | * killed off the next TW bucket in the list, therefore | |
153 | * do a fresh re-read of the hlist head node with the | |
154 | * lock reacquired. We still use the hlist traversal | |
155 | * macro in order to get the prefetches. | |
156 | */ | |
157 | goto rescan; | |
158 | } | |
159 | ||
160 | twdr->tw_count -= killed; | |
161 | NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITED, killed); | |
162 | ||
163 | return ret; | |
164 | } | |
165 | ||
166 | void inet_twdr_hangman(unsigned long data) | |
167 | { | |
168 | struct inet_timewait_death_row *twdr; | |
169 | int unsigned need_timer; | |
170 | ||
171 | twdr = (struct inet_timewait_death_row *)data; | |
172 | spin_lock(&twdr->death_lock); | |
173 | ||
174 | if (twdr->tw_count == 0) | |
175 | goto out; | |
176 | ||
177 | need_timer = 0; | |
178 | if (inet_twdr_do_twkill_work(twdr, twdr->slot)) { | |
179 | twdr->thread_slots |= (1 << twdr->slot); | |
180 | mb(); | |
181 | schedule_work(&twdr->twkill_work); | |
182 | need_timer = 1; | |
183 | } else { | |
184 | /* We purged the entire slot, anything left? */ | |
185 | if (twdr->tw_count) | |
186 | need_timer = 1; | |
187 | } | |
188 | twdr->slot = ((twdr->slot + 1) & (INET_TWDR_TWKILL_SLOTS - 1)); | |
189 | if (need_timer) | |
190 | mod_timer(&twdr->tw_timer, jiffies + twdr->period); | |
191 | out: | |
192 | spin_unlock(&twdr->death_lock); | |
193 | } | |
194 | ||
195 | EXPORT_SYMBOL_GPL(inet_twdr_hangman); | |
196 | ||
197 | extern void twkill_slots_invalid(void); | |
198 | ||
199 | void inet_twdr_twkill_work(void *data) | |
200 | { | |
201 | struct inet_timewait_death_row *twdr = data; | |
202 | int i; | |
203 | ||
204 | if ((INET_TWDR_TWKILL_SLOTS - 1) > (sizeof(twdr->thread_slots) * 8)) | |
205 | twkill_slots_invalid(); | |
206 | ||
207 | while (twdr->thread_slots) { | |
208 | spin_lock_bh(&twdr->death_lock); | |
209 | for (i = 0; i < INET_TWDR_TWKILL_SLOTS; i++) { | |
210 | if (!(twdr->thread_slots & (1 << i))) | |
211 | continue; | |
212 | ||
213 | while (inet_twdr_do_twkill_work(twdr, i) != 0) { | |
214 | if (need_resched()) { | |
215 | spin_unlock_bh(&twdr->death_lock); | |
216 | schedule(); | |
217 | spin_lock_bh(&twdr->death_lock); | |
218 | } | |
219 | } | |
220 | ||
221 | twdr->thread_slots &= ~(1 << i); | |
222 | } | |
223 | spin_unlock_bh(&twdr->death_lock); | |
224 | } | |
225 | } | |
226 | ||
227 | EXPORT_SYMBOL_GPL(inet_twdr_twkill_work); | |
228 | ||
229 | /* These are always called from BH context. See callers in | |
230 | * tcp_input.c to verify this. | |
231 | */ | |
232 | ||
233 | /* This is for handling early-kills of TIME_WAIT sockets. */ | |
234 | void inet_twsk_deschedule(struct inet_timewait_sock *tw, | |
235 | struct inet_timewait_death_row *twdr) | |
236 | { | |
237 | spin_lock(&twdr->death_lock); | |
238 | if (inet_twsk_del_dead_node(tw)) { | |
239 | inet_twsk_put(tw); | |
240 | if (--twdr->tw_count == 0) | |
241 | del_timer(&twdr->tw_timer); | |
242 | } | |
243 | spin_unlock(&twdr->death_lock); | |
244 | __inet_twsk_kill(tw, twdr->hashinfo); | |
245 | } | |
246 | ||
247 | EXPORT_SYMBOL(inet_twsk_deschedule); | |
248 | ||
249 | void inet_twsk_schedule(struct inet_timewait_sock *tw, | |
250 | struct inet_timewait_death_row *twdr, | |
251 | const int timeo, const int timewait_len) | |
252 | { | |
253 | struct hlist_head *list; | |
254 | int slot; | |
255 | ||
256 | /* timeout := RTO * 3.5 | |
257 | * | |
258 | * 3.5 = 1+2+0.5 to wait for two retransmits. | |
259 | * | |
260 | * RATIONALE: if FIN arrived and we entered TIME-WAIT state, | |
261 | * our ACK acking that FIN can be lost. If N subsequent retransmitted | |
262 | * FINs (or previous seqments) are lost (probability of such event | |
263 | * is p^(N+1), where p is probability to lose single packet and | |
264 | * time to detect the loss is about RTO*(2^N - 1) with exponential | |
265 | * backoff). Normal timewait length is calculated so, that we | |
266 | * waited at least for one retransmitted FIN (maximal RTO is 120sec). | |
267 | * [ BTW Linux. following BSD, violates this requirement waiting | |
268 | * only for 60sec, we should wait at least for 240 secs. | |
269 | * Well, 240 consumes too much of resources 8) | |
270 | * ] | |
271 | * This interval is not reduced to catch old duplicate and | |
272 | * responces to our wandering segments living for two MSLs. | |
273 | * However, if we use PAWS to detect | |
274 | * old duplicates, we can reduce the interval to bounds required | |
275 | * by RTO, rather than MSL. So, if peer understands PAWS, we | |
276 | * kill tw bucket after 3.5*RTO (it is important that this number | |
277 | * is greater than TS tick!) and detect old duplicates with help | |
278 | * of PAWS. | |
279 | */ | |
280 | slot = (timeo + (1 << INET_TWDR_RECYCLE_TICK) - 1) >> INET_TWDR_RECYCLE_TICK; | |
281 | ||
282 | spin_lock(&twdr->death_lock); | |
283 | ||
284 | /* Unlink it, if it was scheduled */ | |
285 | if (inet_twsk_del_dead_node(tw)) | |
286 | twdr->tw_count--; | |
287 | else | |
288 | atomic_inc(&tw->tw_refcnt); | |
289 | ||
290 | if (slot >= INET_TWDR_RECYCLE_SLOTS) { | |
291 | /* Schedule to slow timer */ | |
292 | if (timeo >= timewait_len) { | |
293 | slot = INET_TWDR_TWKILL_SLOTS - 1; | |
294 | } else { | |
295 | slot = (timeo + twdr->period - 1) / twdr->period; | |
296 | if (slot >= INET_TWDR_TWKILL_SLOTS) | |
297 | slot = INET_TWDR_TWKILL_SLOTS - 1; | |
298 | } | |
299 | tw->tw_ttd = jiffies + timeo; | |
300 | slot = (twdr->slot + slot) & (INET_TWDR_TWKILL_SLOTS - 1); | |
301 | list = &twdr->cells[slot]; | |
302 | } else { | |
303 | tw->tw_ttd = jiffies + (slot << INET_TWDR_RECYCLE_TICK); | |
304 | ||
305 | if (twdr->twcal_hand < 0) { | |
306 | twdr->twcal_hand = 0; | |
307 | twdr->twcal_jiffie = jiffies; | |
308 | twdr->twcal_timer.expires = twdr->twcal_jiffie + | |
309 | (slot << INET_TWDR_RECYCLE_TICK); | |
310 | add_timer(&twdr->twcal_timer); | |
311 | } else { | |
312 | if (time_after(twdr->twcal_timer.expires, | |
313 | jiffies + (slot << INET_TWDR_RECYCLE_TICK))) | |
314 | mod_timer(&twdr->twcal_timer, | |
315 | jiffies + (slot << INET_TWDR_RECYCLE_TICK)); | |
316 | slot = (twdr->twcal_hand + slot) & (INET_TWDR_RECYCLE_SLOTS - 1); | |
317 | } | |
318 | list = &twdr->twcal_row[slot]; | |
319 | } | |
320 | ||
321 | hlist_add_head(&tw->tw_death_node, list); | |
322 | ||
323 | if (twdr->tw_count++ == 0) | |
324 | mod_timer(&twdr->tw_timer, jiffies + twdr->period); | |
325 | spin_unlock(&twdr->death_lock); | |
326 | } | |
327 | ||
328 | EXPORT_SYMBOL_GPL(inet_twsk_schedule); | |
329 | ||
330 | void inet_twdr_twcal_tick(unsigned long data) | |
331 | { | |
332 | struct inet_timewait_death_row *twdr; | |
333 | int n, slot; | |
334 | unsigned long j; | |
335 | unsigned long now = jiffies; | |
336 | int killed = 0; | |
337 | int adv = 0; | |
338 | ||
339 | twdr = (struct inet_timewait_death_row *)data; | |
340 | ||
341 | spin_lock(&twdr->death_lock); | |
342 | if (twdr->twcal_hand < 0) | |
343 | goto out; | |
344 | ||
345 | slot = twdr->twcal_hand; | |
346 | j = twdr->twcal_jiffie; | |
347 | ||
348 | for (n = 0; n < INET_TWDR_RECYCLE_SLOTS; n++) { | |
349 | if (time_before_eq(j, now)) { | |
350 | struct hlist_node *node, *safe; | |
351 | struct inet_timewait_sock *tw; | |
352 | ||
353 | inet_twsk_for_each_inmate_safe(tw, node, safe, | |
354 | &twdr->twcal_row[slot]) { | |
355 | __inet_twsk_del_dead_node(tw); | |
356 | __inet_twsk_kill(tw, twdr->hashinfo); | |
357 | inet_twsk_put(tw); | |
358 | killed++; | |
359 | } | |
360 | } else { | |
361 | if (!adv) { | |
362 | adv = 1; | |
363 | twdr->twcal_jiffie = j; | |
364 | twdr->twcal_hand = slot; | |
365 | } | |
366 | ||
367 | if (!hlist_empty(&twdr->twcal_row[slot])) { | |
368 | mod_timer(&twdr->twcal_timer, j); | |
369 | goto out; | |
370 | } | |
371 | } | |
372 | j += 1 << INET_TWDR_RECYCLE_TICK; | |
373 | slot = (slot + 1) & (INET_TWDR_RECYCLE_SLOTS - 1); | |
374 | } | |
375 | twdr->twcal_hand = -1; | |
376 | ||
377 | out: | |
378 | if ((twdr->tw_count -= killed) == 0) | |
379 | del_timer(&twdr->tw_timer); | |
380 | NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITKILLED, killed); | |
381 | spin_unlock(&twdr->death_lock); | |
382 | } | |
383 | ||
384 | EXPORT_SYMBOL_GPL(inet_twdr_twcal_tick); |