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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 | ||
e48c414e ACM |
11 | |
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. */ | |
17 | void __inet_twsk_kill(struct inet_timewait_sock *tw, struct inet_hashinfo *hashinfo) | |
18 | { | |
19 | struct inet_bind_hashbucket *bhead; | |
20 | struct inet_bind_bucket *tb; | |
21 | /* Unlink from established hashes. */ | |
81c3d547 | 22 | struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, tw->tw_hash); |
e48c414e ACM |
23 | |
24 | write_lock(&ehead->lock); | |
25 | if (hlist_unhashed(&tw->tw_node)) { | |
26 | write_unlock(&ehead->lock); | |
27 | return; | |
28 | } | |
29 | __hlist_del(&tw->tw_node); | |
30 | sk_node_init(&tw->tw_node); | |
31 | write_unlock(&ehead->lock); | |
32 | ||
33 | /* Disassociate with bind bucket. */ | |
34 | bhead = &hashinfo->bhash[inet_bhashfn(tw->tw_num, hashinfo->bhash_size)]; | |
35 | spin_lock(&bhead->lock); | |
36 | tb = tw->tw_tb; | |
37 | __hlist_del(&tw->tw_bind_node); | |
38 | tw->tw_tb = NULL; | |
39 | inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb); | |
40 | spin_unlock(&bhead->lock); | |
41 | #ifdef SOCK_REFCNT_DEBUG | |
42 | if (atomic_read(&tw->tw_refcnt) != 1) { | |
43 | printk(KERN_DEBUG "%s timewait_sock %p refcnt=%d\n", | |
44 | tw->tw_prot->name, tw, atomic_read(&tw->tw_refcnt)); | |
45 | } | |
46 | #endif | |
47 | inet_twsk_put(tw); | |
48 | } | |
49 | ||
d8c97a94 ACM |
50 | EXPORT_SYMBOL_GPL(__inet_twsk_kill); |
51 | ||
e48c414e ACM |
52 | /* |
53 | * Enter the time wait state. This is called with locally disabled BH. | |
54 | * Essentially we whip up a timewait bucket, copy the relevant info into it | |
55 | * from the SK, and mess with hash chains and list linkage. | |
56 | */ | |
57 | void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk, | |
58 | struct inet_hashinfo *hashinfo) | |
59 | { | |
60 | const struct inet_sock *inet = inet_sk(sk); | |
463c84b9 | 61 | const struct inet_connection_sock *icsk = inet_csk(sk); |
81c3d547 | 62 | struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, sk->sk_hash); |
e48c414e ACM |
63 | struct inet_bind_hashbucket *bhead; |
64 | /* Step 1: Put TW into bind hash. Original socket stays there too. | |
65 | Note, that any socket with inet->num != 0 MUST be bound in | |
66 | binding cache, even if it is closed. | |
67 | */ | |
68 | bhead = &hashinfo->bhash[inet_bhashfn(inet->num, hashinfo->bhash_size)]; | |
69 | spin_lock(&bhead->lock); | |
463c84b9 ACM |
70 | tw->tw_tb = icsk->icsk_bind_hash; |
71 | BUG_TRAP(icsk->icsk_bind_hash); | |
e48c414e ACM |
72 | inet_twsk_add_bind_node(tw, &tw->tw_tb->owners); |
73 | spin_unlock(&bhead->lock); | |
74 | ||
75 | write_lock(&ehead->lock); | |
76 | ||
77 | /* Step 2: Remove SK from established hash. */ | |
78 | if (__sk_del_node_init(sk)) | |
79 | sock_prot_dec_use(sk->sk_prot); | |
80 | ||
81 | /* Step 3: Hash TW into TIMEWAIT half of established hash table. */ | |
82 | inet_twsk_add_node(tw, &(ehead + hashinfo->ehash_size)->chain); | |
83 | atomic_inc(&tw->tw_refcnt); | |
84 | ||
85 | write_unlock(&ehead->lock); | |
86 | } | |
c676270b | 87 | |
696ab2d3 ACM |
88 | EXPORT_SYMBOL_GPL(__inet_twsk_hashdance); |
89 | ||
c676270b ACM |
90 | struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int state) |
91 | { | |
6d6ee43e ACM |
92 | struct inet_timewait_sock *tw = |
93 | kmem_cache_alloc(sk->sk_prot_creator->twsk_prot->twsk_slab, | |
54e6ecb2 | 94 | GFP_ATOMIC); |
c676270b ACM |
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; | |
81c3d547 | 109 | tw->tw_hash = sk->sk_hash; |
c676270b ACM |
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); | |
eeb2b856 | 114 | __module_get(tw->tw_prot->owner); |
c676270b ACM |
115 | } |
116 | ||
117 | return tw; | |
118 | } | |
696ab2d3 ACM |
119 | |
120 | EXPORT_SYMBOL_GPL(inet_twsk_alloc); | |
121 | ||
122 | /* Returns non-zero if quota exceeded. */ | |
123 | static int inet_twdr_do_twkill_work(struct inet_timewait_death_row *twdr, | |
124 | const int slot) | |
125 | { | |
126 | struct inet_timewait_sock *tw; | |
127 | struct hlist_node *node; | |
128 | unsigned int killed; | |
129 | int ret; | |
130 | ||
131 | /* NOTE: compare this to previous version where lock | |
132 | * was released after detaching chain. It was racy, | |
133 | * because tw buckets are scheduled in not serialized context | |
134 | * in 2.3 (with netfilter), and with softnet it is common, because | |
135 | * soft irqs are not sequenced. | |
136 | */ | |
137 | killed = 0; | |
138 | ret = 0; | |
139 | rescan: | |
140 | inet_twsk_for_each_inmate(tw, node, &twdr->cells[slot]) { | |
141 | __inet_twsk_del_dead_node(tw); | |
142 | spin_unlock(&twdr->death_lock); | |
143 | __inet_twsk_kill(tw, twdr->hashinfo); | |
144 | inet_twsk_put(tw); | |
145 | killed++; | |
146 | spin_lock(&twdr->death_lock); | |
147 | if (killed > INET_TWDR_TWKILL_QUOTA) { | |
148 | ret = 1; | |
149 | break; | |
150 | } | |
151 | ||
152 | /* While we dropped twdr->death_lock, another cpu may have | |
153 | * killed off the next TW bucket in the list, therefore | |
154 | * do a fresh re-read of the hlist head node with the | |
155 | * lock reacquired. We still use the hlist traversal | |
156 | * macro in order to get the prefetches. | |
157 | */ | |
158 | goto rescan; | |
159 | } | |
160 | ||
161 | twdr->tw_count -= killed; | |
162 | NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITED, killed); | |
163 | ||
164 | return ret; | |
165 | } | |
166 | ||
167 | void inet_twdr_hangman(unsigned long data) | |
168 | { | |
169 | struct inet_timewait_death_row *twdr; | |
170 | int unsigned need_timer; | |
171 | ||
172 | twdr = (struct inet_timewait_death_row *)data; | |
173 | spin_lock(&twdr->death_lock); | |
174 | ||
175 | if (twdr->tw_count == 0) | |
176 | goto out; | |
177 | ||
178 | need_timer = 0; | |
179 | if (inet_twdr_do_twkill_work(twdr, twdr->slot)) { | |
180 | twdr->thread_slots |= (1 << twdr->slot); | |
181 | mb(); | |
182 | schedule_work(&twdr->twkill_work); | |
183 | need_timer = 1; | |
184 | } else { | |
185 | /* We purged the entire slot, anything left? */ | |
186 | if (twdr->tw_count) | |
187 | need_timer = 1; | |
188 | } | |
189 | twdr->slot = ((twdr->slot + 1) & (INET_TWDR_TWKILL_SLOTS - 1)); | |
190 | if (need_timer) | |
191 | mod_timer(&twdr->tw_timer, jiffies + twdr->period); | |
192 | out: | |
193 | spin_unlock(&twdr->death_lock); | |
194 | } | |
195 | ||
196 | EXPORT_SYMBOL_GPL(inet_twdr_hangman); | |
197 | ||
198 | extern void twkill_slots_invalid(void); | |
199 | ||
65f27f38 | 200 | void inet_twdr_twkill_work(struct work_struct *work) |
696ab2d3 | 201 | { |
65f27f38 DH |
202 | struct inet_timewait_death_row *twdr = |
203 | container_of(work, struct inet_timewait_death_row, twkill_work); | |
696ab2d3 ACM |
204 | int i; |
205 | ||
206 | if ((INET_TWDR_TWKILL_SLOTS - 1) > (sizeof(twdr->thread_slots) * 8)) | |
207 | twkill_slots_invalid(); | |
208 | ||
209 | while (twdr->thread_slots) { | |
210 | spin_lock_bh(&twdr->death_lock); | |
211 | for (i = 0; i < INET_TWDR_TWKILL_SLOTS; i++) { | |
212 | if (!(twdr->thread_slots & (1 << i))) | |
213 | continue; | |
214 | ||
215 | while (inet_twdr_do_twkill_work(twdr, i) != 0) { | |
216 | if (need_resched()) { | |
217 | spin_unlock_bh(&twdr->death_lock); | |
218 | schedule(); | |
219 | spin_lock_bh(&twdr->death_lock); | |
220 | } | |
221 | } | |
222 | ||
223 | twdr->thread_slots &= ~(1 << i); | |
224 | } | |
225 | spin_unlock_bh(&twdr->death_lock); | |
226 | } | |
227 | } | |
228 | ||
229 | EXPORT_SYMBOL_GPL(inet_twdr_twkill_work); | |
230 | ||
231 | /* These are always called from BH context. See callers in | |
232 | * tcp_input.c to verify this. | |
233 | */ | |
234 | ||
235 | /* This is for handling early-kills of TIME_WAIT sockets. */ | |
236 | void inet_twsk_deschedule(struct inet_timewait_sock *tw, | |
237 | struct inet_timewait_death_row *twdr) | |
238 | { | |
239 | spin_lock(&twdr->death_lock); | |
240 | if (inet_twsk_del_dead_node(tw)) { | |
241 | inet_twsk_put(tw); | |
242 | if (--twdr->tw_count == 0) | |
243 | del_timer(&twdr->tw_timer); | |
244 | } | |
245 | spin_unlock(&twdr->death_lock); | |
246 | __inet_twsk_kill(tw, twdr->hashinfo); | |
247 | } | |
248 | ||
249 | EXPORT_SYMBOL(inet_twsk_deschedule); | |
250 | ||
251 | void inet_twsk_schedule(struct inet_timewait_sock *tw, | |
252 | struct inet_timewait_death_row *twdr, | |
253 | const int timeo, const int timewait_len) | |
254 | { | |
255 | struct hlist_head *list; | |
256 | int slot; | |
257 | ||
258 | /* timeout := RTO * 3.5 | |
259 | * | |
260 | * 3.5 = 1+2+0.5 to wait for two retransmits. | |
261 | * | |
262 | * RATIONALE: if FIN arrived and we entered TIME-WAIT state, | |
263 | * our ACK acking that FIN can be lost. If N subsequent retransmitted | |
264 | * FINs (or previous seqments) are lost (probability of such event | |
265 | * is p^(N+1), where p is probability to lose single packet and | |
266 | * time to detect the loss is about RTO*(2^N - 1) with exponential | |
267 | * backoff). Normal timewait length is calculated so, that we | |
268 | * waited at least for one retransmitted FIN (maximal RTO is 120sec). | |
269 | * [ BTW Linux. following BSD, violates this requirement waiting | |
270 | * only for 60sec, we should wait at least for 240 secs. | |
271 | * Well, 240 consumes too much of resources 8) | |
272 | * ] | |
273 | * This interval is not reduced to catch old duplicate and | |
274 | * responces to our wandering segments living for two MSLs. | |
275 | * However, if we use PAWS to detect | |
276 | * old duplicates, we can reduce the interval to bounds required | |
277 | * by RTO, rather than MSL. So, if peer understands PAWS, we | |
278 | * kill tw bucket after 3.5*RTO (it is important that this number | |
279 | * is greater than TS tick!) and detect old duplicates with help | |
280 | * of PAWS. | |
281 | */ | |
282 | slot = (timeo + (1 << INET_TWDR_RECYCLE_TICK) - 1) >> INET_TWDR_RECYCLE_TICK; | |
283 | ||
284 | spin_lock(&twdr->death_lock); | |
285 | ||
286 | /* Unlink it, if it was scheduled */ | |
287 | if (inet_twsk_del_dead_node(tw)) | |
288 | twdr->tw_count--; | |
289 | else | |
290 | atomic_inc(&tw->tw_refcnt); | |
291 | ||
292 | if (slot >= INET_TWDR_RECYCLE_SLOTS) { | |
293 | /* Schedule to slow timer */ | |
294 | if (timeo >= timewait_len) { | |
295 | slot = INET_TWDR_TWKILL_SLOTS - 1; | |
296 | } else { | |
297 | slot = (timeo + twdr->period - 1) / twdr->period; | |
298 | if (slot >= INET_TWDR_TWKILL_SLOTS) | |
299 | slot = INET_TWDR_TWKILL_SLOTS - 1; | |
300 | } | |
301 | tw->tw_ttd = jiffies + timeo; | |
302 | slot = (twdr->slot + slot) & (INET_TWDR_TWKILL_SLOTS - 1); | |
303 | list = &twdr->cells[slot]; | |
304 | } else { | |
305 | tw->tw_ttd = jiffies + (slot << INET_TWDR_RECYCLE_TICK); | |
306 | ||
307 | if (twdr->twcal_hand < 0) { | |
308 | twdr->twcal_hand = 0; | |
309 | twdr->twcal_jiffie = jiffies; | |
310 | twdr->twcal_timer.expires = twdr->twcal_jiffie + | |
311 | (slot << INET_TWDR_RECYCLE_TICK); | |
312 | add_timer(&twdr->twcal_timer); | |
313 | } else { | |
314 | if (time_after(twdr->twcal_timer.expires, | |
315 | jiffies + (slot << INET_TWDR_RECYCLE_TICK))) | |
316 | mod_timer(&twdr->twcal_timer, | |
317 | jiffies + (slot << INET_TWDR_RECYCLE_TICK)); | |
318 | slot = (twdr->twcal_hand + slot) & (INET_TWDR_RECYCLE_SLOTS - 1); | |
319 | } | |
320 | list = &twdr->twcal_row[slot]; | |
321 | } | |
322 | ||
323 | hlist_add_head(&tw->tw_death_node, list); | |
324 | ||
325 | if (twdr->tw_count++ == 0) | |
326 | mod_timer(&twdr->tw_timer, jiffies + twdr->period); | |
327 | spin_unlock(&twdr->death_lock); | |
328 | } | |
329 | ||
330 | EXPORT_SYMBOL_GPL(inet_twsk_schedule); | |
331 | ||
332 | void inet_twdr_twcal_tick(unsigned long data) | |
333 | { | |
334 | struct inet_timewait_death_row *twdr; | |
335 | int n, slot; | |
336 | unsigned long j; | |
337 | unsigned long now = jiffies; | |
338 | int killed = 0; | |
339 | int adv = 0; | |
340 | ||
341 | twdr = (struct inet_timewait_death_row *)data; | |
342 | ||
343 | spin_lock(&twdr->death_lock); | |
344 | if (twdr->twcal_hand < 0) | |
345 | goto out; | |
346 | ||
347 | slot = twdr->twcal_hand; | |
348 | j = twdr->twcal_jiffie; | |
349 | ||
350 | for (n = 0; n < INET_TWDR_RECYCLE_SLOTS; n++) { | |
351 | if (time_before_eq(j, now)) { | |
352 | struct hlist_node *node, *safe; | |
353 | struct inet_timewait_sock *tw; | |
354 | ||
355 | inet_twsk_for_each_inmate_safe(tw, node, safe, | |
356 | &twdr->twcal_row[slot]) { | |
357 | __inet_twsk_del_dead_node(tw); | |
358 | __inet_twsk_kill(tw, twdr->hashinfo); | |
359 | inet_twsk_put(tw); | |
360 | killed++; | |
361 | } | |
362 | } else { | |
363 | if (!adv) { | |
364 | adv = 1; | |
365 | twdr->twcal_jiffie = j; | |
366 | twdr->twcal_hand = slot; | |
367 | } | |
368 | ||
369 | if (!hlist_empty(&twdr->twcal_row[slot])) { | |
370 | mod_timer(&twdr->twcal_timer, j); | |
371 | goto out; | |
372 | } | |
373 | } | |
374 | j += 1 << INET_TWDR_RECYCLE_TICK; | |
375 | slot = (slot + 1) & (INET_TWDR_RECYCLE_SLOTS - 1); | |
376 | } | |
377 | twdr->twcal_hand = -1; | |
378 | ||
379 | out: | |
380 | if ((twdr->tw_count -= killed) == 0) | |
381 | del_timer(&twdr->tw_timer); | |
382 | NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITKILLED, killed); | |
383 | spin_unlock(&twdr->death_lock); | |
384 | } | |
385 | ||
386 | EXPORT_SYMBOL_GPL(inet_twdr_twcal_tick); |