net: convert TCP/DCCP ehash rwlocks to spinlocks
[linux-2.6.git] / net / ipv4 / inet_timewait_sock.c
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/kernel.h>
12 #include <net/inet_hashtables.h>
13 #include <net/inet_timewait_sock.h>
14 #include <net/ip.h>
15
16 /* Must be called with locally disabled BHs. */
17 static void __inet_twsk_kill(struct inet_timewait_sock *tw,
18                              struct inet_hashinfo *hashinfo)
19 {
20         struct inet_bind_hashbucket *bhead;
21         struct inet_bind_bucket *tb;
22         /* Unlink from established hashes. */
23         spinlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash);
24
25         spin_lock(lock);
26         if (hlist_nulls_unhashed(&tw->tw_node)) {
27                 spin_unlock(lock);
28                 return;
29         }
30         hlist_nulls_del_rcu(&tw->tw_node);
31         sk_nulls_node_init(&tw->tw_node);
32         spin_unlock(lock);
33
34         /* Disassociate with bind bucket. */
35         bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), tw->tw_num,
36                         hashinfo->bhash_size)];
37         spin_lock(&bhead->lock);
38         tb = tw->tw_tb;
39         __hlist_del(&tw->tw_bind_node);
40         tw->tw_tb = NULL;
41         inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
42         spin_unlock(&bhead->lock);
43 #ifdef SOCK_REFCNT_DEBUG
44         if (atomic_read(&tw->tw_refcnt) != 1) {
45                 printk(KERN_DEBUG "%s timewait_sock %p refcnt=%d\n",
46                        tw->tw_prot->name, tw, atomic_read(&tw->tw_refcnt));
47         }
48 #endif
49         inet_twsk_put(tw);
50 }
51
52 void inet_twsk_put(struct inet_timewait_sock *tw)
53 {
54         if (atomic_dec_and_test(&tw->tw_refcnt)) {
55                 struct module *owner = tw->tw_prot->owner;
56                 twsk_destructor((struct sock *)tw);
57 #ifdef SOCK_REFCNT_DEBUG
58                 printk(KERN_DEBUG "%s timewait_sock %p released\n",
59                        tw->tw_prot->name, tw);
60 #endif
61                 release_net(twsk_net(tw));
62                 kmem_cache_free(tw->tw_prot->twsk_prot->twsk_slab, tw);
63                 module_put(owner);
64         }
65 }
66 EXPORT_SYMBOL_GPL(inet_twsk_put);
67
68 /*
69  * Enter the time wait state. This is called with locally disabled BH.
70  * Essentially we whip up a timewait bucket, copy the relevant info into it
71  * from the SK, and mess with hash chains and list linkage.
72  */
73 void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
74                            struct inet_hashinfo *hashinfo)
75 {
76         const struct inet_sock *inet = inet_sk(sk);
77         const struct inet_connection_sock *icsk = inet_csk(sk);
78         struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, sk->sk_hash);
79         spinlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
80         struct inet_bind_hashbucket *bhead;
81         /* Step 1: Put TW into bind hash. Original socket stays there too.
82            Note, that any socket with inet->num != 0 MUST be bound in
83            binding cache, even if it is closed.
84          */
85         bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), inet->num,
86                         hashinfo->bhash_size)];
87         spin_lock(&bhead->lock);
88         tw->tw_tb = icsk->icsk_bind_hash;
89         WARN_ON(!icsk->icsk_bind_hash);
90         inet_twsk_add_bind_node(tw, &tw->tw_tb->owners);
91         spin_unlock(&bhead->lock);
92
93         spin_lock(lock);
94
95         /*
96          * Step 2: Hash TW into TIMEWAIT chain.
97          * Should be done before removing sk from established chain
98          * because readers are lockless and search established first.
99          */
100         atomic_inc(&tw->tw_refcnt);
101         inet_twsk_add_node_rcu(tw, &ehead->twchain);
102
103         /* Step 3: Remove SK from established hash. */
104         if (__sk_nulls_del_node_init_rcu(sk))
105                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
106
107         spin_unlock(lock);
108 }
109
110 EXPORT_SYMBOL_GPL(__inet_twsk_hashdance);
111
112 struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int state)
113 {
114         struct inet_timewait_sock *tw =
115                 kmem_cache_alloc(sk->sk_prot_creator->twsk_prot->twsk_slab,
116                                  GFP_ATOMIC);
117         if (tw != NULL) {
118                 const struct inet_sock *inet = inet_sk(sk);
119
120                 /* Give us an identity. */
121                 tw->tw_daddr        = inet->daddr;
122                 tw->tw_rcv_saddr    = inet->rcv_saddr;
123                 tw->tw_bound_dev_if = sk->sk_bound_dev_if;
124                 tw->tw_num          = inet->num;
125                 tw->tw_state        = TCP_TIME_WAIT;
126                 tw->tw_substate     = state;
127                 tw->tw_sport        = inet->sport;
128                 tw->tw_dport        = inet->dport;
129                 tw->tw_family       = sk->sk_family;
130                 tw->tw_reuse        = sk->sk_reuse;
131                 tw->tw_hash         = sk->sk_hash;
132                 tw->tw_ipv6only     = 0;
133                 tw->tw_transparent  = inet->transparent;
134                 tw->tw_prot         = sk->sk_prot_creator;
135                 twsk_net_set(tw, hold_net(sock_net(sk)));
136                 atomic_set(&tw->tw_refcnt, 1);
137                 inet_twsk_dead_node_init(tw);
138                 __module_get(tw->tw_prot->owner);
139         }
140
141         return tw;
142 }
143
144 EXPORT_SYMBOL_GPL(inet_twsk_alloc);
145
146 /* Returns non-zero if quota exceeded.  */
147 static int inet_twdr_do_twkill_work(struct inet_timewait_death_row *twdr,
148                                     const int slot)
149 {
150         struct inet_timewait_sock *tw;
151         struct hlist_node *node;
152         unsigned int killed;
153         int ret;
154
155         /* NOTE: compare this to previous version where lock
156          * was released after detaching chain. It was racy,
157          * because tw buckets are scheduled in not serialized context
158          * in 2.3 (with netfilter), and with softnet it is common, because
159          * soft irqs are not sequenced.
160          */
161         killed = 0;
162         ret = 0;
163 rescan:
164         inet_twsk_for_each_inmate(tw, node, &twdr->cells[slot]) {
165                 __inet_twsk_del_dead_node(tw);
166                 spin_unlock(&twdr->death_lock);
167                 __inet_twsk_kill(tw, twdr->hashinfo);
168 #ifdef CONFIG_NET_NS
169                 NET_INC_STATS_BH(twsk_net(tw), LINUX_MIB_TIMEWAITED);
170 #endif
171                 inet_twsk_put(tw);
172                 killed++;
173                 spin_lock(&twdr->death_lock);
174                 if (killed > INET_TWDR_TWKILL_QUOTA) {
175                         ret = 1;
176                         break;
177                 }
178
179                 /* While we dropped twdr->death_lock, another cpu may have
180                  * killed off the next TW bucket in the list, therefore
181                  * do a fresh re-read of the hlist head node with the
182                  * lock reacquired.  We still use the hlist traversal
183                  * macro in order to get the prefetches.
184                  */
185                 goto rescan;
186         }
187
188         twdr->tw_count -= killed;
189 #ifndef CONFIG_NET_NS
190         NET_ADD_STATS_BH(&init_net, LINUX_MIB_TIMEWAITED, killed);
191 #endif
192         return ret;
193 }
194
195 void inet_twdr_hangman(unsigned long data)
196 {
197         struct inet_timewait_death_row *twdr;
198         int unsigned need_timer;
199
200         twdr = (struct inet_timewait_death_row *)data;
201         spin_lock(&twdr->death_lock);
202
203         if (twdr->tw_count == 0)
204                 goto out;
205
206         need_timer = 0;
207         if (inet_twdr_do_twkill_work(twdr, twdr->slot)) {
208                 twdr->thread_slots |= (1 << twdr->slot);
209                 schedule_work(&twdr->twkill_work);
210                 need_timer = 1;
211         } else {
212                 /* We purged the entire slot, anything left?  */
213                 if (twdr->tw_count)
214                         need_timer = 1;
215         }
216         twdr->slot = ((twdr->slot + 1) & (INET_TWDR_TWKILL_SLOTS - 1));
217         if (need_timer)
218                 mod_timer(&twdr->tw_timer, jiffies + twdr->period);
219 out:
220         spin_unlock(&twdr->death_lock);
221 }
222
223 EXPORT_SYMBOL_GPL(inet_twdr_hangman);
224
225 void inet_twdr_twkill_work(struct work_struct *work)
226 {
227         struct inet_timewait_death_row *twdr =
228                 container_of(work, struct inet_timewait_death_row, twkill_work);
229         int i;
230
231         BUILD_BUG_ON((INET_TWDR_TWKILL_SLOTS - 1) >
232                         (sizeof(twdr->thread_slots) * 8));
233
234         while (twdr->thread_slots) {
235                 spin_lock_bh(&twdr->death_lock);
236                 for (i = 0; i < INET_TWDR_TWKILL_SLOTS; i++) {
237                         if (!(twdr->thread_slots & (1 << i)))
238                                 continue;
239
240                         while (inet_twdr_do_twkill_work(twdr, i) != 0) {
241                                 if (need_resched()) {
242                                         spin_unlock_bh(&twdr->death_lock);
243                                         schedule();
244                                         spin_lock_bh(&twdr->death_lock);
245                                 }
246                         }
247
248                         twdr->thread_slots &= ~(1 << i);
249                 }
250                 spin_unlock_bh(&twdr->death_lock);
251         }
252 }
253
254 EXPORT_SYMBOL_GPL(inet_twdr_twkill_work);
255
256 /* These are always called from BH context.  See callers in
257  * tcp_input.c to verify this.
258  */
259
260 /* This is for handling early-kills of TIME_WAIT sockets. */
261 void inet_twsk_deschedule(struct inet_timewait_sock *tw,
262                           struct inet_timewait_death_row *twdr)
263 {
264         spin_lock(&twdr->death_lock);
265         if (inet_twsk_del_dead_node(tw)) {
266                 inet_twsk_put(tw);
267                 if (--twdr->tw_count == 0)
268                         del_timer(&twdr->tw_timer);
269         }
270         spin_unlock(&twdr->death_lock);
271         __inet_twsk_kill(tw, twdr->hashinfo);
272 }
273
274 EXPORT_SYMBOL(inet_twsk_deschedule);
275
276 void inet_twsk_schedule(struct inet_timewait_sock *tw,
277                        struct inet_timewait_death_row *twdr,
278                        const int timeo, const int timewait_len)
279 {
280         struct hlist_head *list;
281         int slot;
282
283         /* timeout := RTO * 3.5
284          *
285          * 3.5 = 1+2+0.5 to wait for two retransmits.
286          *
287          * RATIONALE: if FIN arrived and we entered TIME-WAIT state,
288          * our ACK acking that FIN can be lost. If N subsequent retransmitted
289          * FINs (or previous seqments) are lost (probability of such event
290          * is p^(N+1), where p is probability to lose single packet and
291          * time to detect the loss is about RTO*(2^N - 1) with exponential
292          * backoff). Normal timewait length is calculated so, that we
293          * waited at least for one retransmitted FIN (maximal RTO is 120sec).
294          * [ BTW Linux. following BSD, violates this requirement waiting
295          *   only for 60sec, we should wait at least for 240 secs.
296          *   Well, 240 consumes too much of resources 8)
297          * ]
298          * This interval is not reduced to catch old duplicate and
299          * responces to our wandering segments living for two MSLs.
300          * However, if we use PAWS to detect
301          * old duplicates, we can reduce the interval to bounds required
302          * by RTO, rather than MSL. So, if peer understands PAWS, we
303          * kill tw bucket after 3.5*RTO (it is important that this number
304          * is greater than TS tick!) and detect old duplicates with help
305          * of PAWS.
306          */
307         slot = (timeo + (1 << INET_TWDR_RECYCLE_TICK) - 1) >> INET_TWDR_RECYCLE_TICK;
308
309         spin_lock(&twdr->death_lock);
310
311         /* Unlink it, if it was scheduled */
312         if (inet_twsk_del_dead_node(tw))
313                 twdr->tw_count--;
314         else
315                 atomic_inc(&tw->tw_refcnt);
316
317         if (slot >= INET_TWDR_RECYCLE_SLOTS) {
318                 /* Schedule to slow timer */
319                 if (timeo >= timewait_len) {
320                         slot = INET_TWDR_TWKILL_SLOTS - 1;
321                 } else {
322                         slot = DIV_ROUND_UP(timeo, twdr->period);
323                         if (slot >= INET_TWDR_TWKILL_SLOTS)
324                                 slot = INET_TWDR_TWKILL_SLOTS - 1;
325                 }
326                 tw->tw_ttd = jiffies + timeo;
327                 slot = (twdr->slot + slot) & (INET_TWDR_TWKILL_SLOTS - 1);
328                 list = &twdr->cells[slot];
329         } else {
330                 tw->tw_ttd = jiffies + (slot << INET_TWDR_RECYCLE_TICK);
331
332                 if (twdr->twcal_hand < 0) {
333                         twdr->twcal_hand = 0;
334                         twdr->twcal_jiffie = jiffies;
335                         twdr->twcal_timer.expires = twdr->twcal_jiffie +
336                                               (slot << INET_TWDR_RECYCLE_TICK);
337                         add_timer(&twdr->twcal_timer);
338                 } else {
339                         if (time_after(twdr->twcal_timer.expires,
340                                        jiffies + (slot << INET_TWDR_RECYCLE_TICK)))
341                                 mod_timer(&twdr->twcal_timer,
342                                           jiffies + (slot << INET_TWDR_RECYCLE_TICK));
343                         slot = (twdr->twcal_hand + slot) & (INET_TWDR_RECYCLE_SLOTS - 1);
344                 }
345                 list = &twdr->twcal_row[slot];
346         }
347
348         hlist_add_head(&tw->tw_death_node, list);
349
350         if (twdr->tw_count++ == 0)
351                 mod_timer(&twdr->tw_timer, jiffies + twdr->period);
352         spin_unlock(&twdr->death_lock);
353 }
354
355 EXPORT_SYMBOL_GPL(inet_twsk_schedule);
356
357 void inet_twdr_twcal_tick(unsigned long data)
358 {
359         struct inet_timewait_death_row *twdr;
360         int n, slot;
361         unsigned long j;
362         unsigned long now = jiffies;
363         int killed = 0;
364         int adv = 0;
365
366         twdr = (struct inet_timewait_death_row *)data;
367
368         spin_lock(&twdr->death_lock);
369         if (twdr->twcal_hand < 0)
370                 goto out;
371
372         slot = twdr->twcal_hand;
373         j = twdr->twcal_jiffie;
374
375         for (n = 0; n < INET_TWDR_RECYCLE_SLOTS; n++) {
376                 if (time_before_eq(j, now)) {
377                         struct hlist_node *node, *safe;
378                         struct inet_timewait_sock *tw;
379
380                         inet_twsk_for_each_inmate_safe(tw, node, safe,
381                                                        &twdr->twcal_row[slot]) {
382                                 __inet_twsk_del_dead_node(tw);
383                                 __inet_twsk_kill(tw, twdr->hashinfo);
384 #ifdef CONFIG_NET_NS
385                                 NET_INC_STATS_BH(twsk_net(tw), LINUX_MIB_TIMEWAITKILLED);
386 #endif
387                                 inet_twsk_put(tw);
388                                 killed++;
389                         }
390                 } else {
391                         if (!adv) {
392                                 adv = 1;
393                                 twdr->twcal_jiffie = j;
394                                 twdr->twcal_hand = slot;
395                         }
396
397                         if (!hlist_empty(&twdr->twcal_row[slot])) {
398                                 mod_timer(&twdr->twcal_timer, j);
399                                 goto out;
400                         }
401                 }
402                 j += 1 << INET_TWDR_RECYCLE_TICK;
403                 slot = (slot + 1) & (INET_TWDR_RECYCLE_SLOTS - 1);
404         }
405         twdr->twcal_hand = -1;
406
407 out:
408         if ((twdr->tw_count -= killed) == 0)
409                 del_timer(&twdr->tw_timer);
410 #ifndef CONFIG_NET_NS
411         NET_ADD_STATS_BH(&init_net, LINUX_MIB_TIMEWAITKILLED, killed);
412 #endif
413         spin_unlock(&twdr->death_lock);
414 }
415
416 EXPORT_SYMBOL_GPL(inet_twdr_twcal_tick);
417
418 void inet_twsk_purge(struct net *net, struct inet_hashinfo *hashinfo,
419                      struct inet_timewait_death_row *twdr, int family)
420 {
421         struct inet_timewait_sock *tw;
422         struct sock *sk;
423         struct hlist_nulls_node *node;
424         int h;
425
426         local_bh_disable();
427         for (h = 0; h < (hashinfo->ehash_size); h++) {
428                 struct inet_ehash_bucket *head =
429                         inet_ehash_bucket(hashinfo, h);
430                 spinlock_t *lock = inet_ehash_lockp(hashinfo, h);
431 restart:
432                 spin_lock(lock);
433                 sk_nulls_for_each(sk, node, &head->twchain) {
434
435                         tw = inet_twsk(sk);
436                         if (!net_eq(twsk_net(tw), net) ||
437                             tw->tw_family != family)
438                                 continue;
439
440                         atomic_inc(&tw->tw_refcnt);
441                         spin_unlock(lock);
442                         inet_twsk_deschedule(tw, twdr);
443                         inet_twsk_put(tw);
444
445                         goto restart;
446                 }
447                 spin_unlock(lock);
448         }
449         local_bh_enable();
450 }
451 EXPORT_SYMBOL_GPL(inet_twsk_purge);