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.
6 * Generic TIME_WAIT sockets functions
8 * From code orinally in TCP
11 #include <linux/kernel.h>
12 #include <linux/kmemcheck.h>
13 #include <net/inet_hashtables.h>
14 #include <net/inet_timewait_sock.h>
19 * unhash a timewait socket from established hash
20 * lock must be hold by caller
22 int inet_twsk_unhash(struct inet_timewait_sock
*tw
)
24 if (hlist_nulls_unhashed(&tw
->tw_node
))
27 hlist_nulls_del_rcu(&tw
->tw_node
);
28 sk_nulls_node_init(&tw
->tw_node
);
32 /* Must be called with locally disabled BHs. */
33 static void __inet_twsk_kill(struct inet_timewait_sock
*tw
,
34 struct inet_hashinfo
*hashinfo
)
36 struct inet_bind_hashbucket
*bhead
;
37 struct inet_bind_bucket
*tb
;
39 /* Unlink from established hashes. */
40 spinlock_t
*lock
= inet_ehash_lockp(hashinfo
, tw
->tw_hash
);
43 refcnt
= inet_twsk_unhash(tw
);
46 /* Disassociate with bind bucket. */
47 bhead
= &hashinfo
->bhash
[inet_bhashfn(twsk_net(tw
), tw
->tw_num
,
48 hashinfo
->bhash_size
)];
49 spin_lock(&bhead
->lock
);
52 __hlist_del(&tw
->tw_bind_node
);
54 inet_bind_bucket_destroy(hashinfo
->bind_bucket_cachep
, tb
);
57 spin_unlock(&bhead
->lock
);
58 #ifdef SOCK_REFCNT_DEBUG
59 if (atomic_read(&tw
->tw_refcnt
) != 1) {
60 printk(KERN_DEBUG
"%s timewait_sock %p refcnt=%d\n",
61 tw
->tw_prot
->name
, tw
, atomic_read(&tw
->tw_refcnt
));
70 static noinline
void inet_twsk_free(struct inet_timewait_sock
*tw
)
72 struct module
*owner
= tw
->tw_prot
->owner
;
73 twsk_destructor((struct sock
*)tw
);
74 #ifdef SOCK_REFCNT_DEBUG
75 pr_debug("%s timewait_sock %p released\n", tw
->tw_prot
->name
, tw
);
77 release_net(twsk_net(tw
));
78 kmem_cache_free(tw
->tw_prot
->twsk_prot
->twsk_slab
, tw
);
82 void inet_twsk_put(struct inet_timewait_sock
*tw
)
84 if (atomic_dec_and_test(&tw
->tw_refcnt
))
87 EXPORT_SYMBOL_GPL(inet_twsk_put
);
90 * Enter the time wait state. This is called with locally disabled BH.
91 * Essentially we whip up a timewait bucket, copy the relevant info into it
92 * from the SK, and mess with hash chains and list linkage.
94 void __inet_twsk_hashdance(struct inet_timewait_sock
*tw
, struct sock
*sk
,
95 struct inet_hashinfo
*hashinfo
)
97 const struct inet_sock
*inet
= inet_sk(sk
);
98 const struct inet_connection_sock
*icsk
= inet_csk(sk
);
99 struct inet_ehash_bucket
*ehead
= inet_ehash_bucket(hashinfo
, sk
->sk_hash
);
100 spinlock_t
*lock
= inet_ehash_lockp(hashinfo
, sk
->sk_hash
);
101 struct inet_bind_hashbucket
*bhead
;
102 /* Step 1: Put TW into bind hash. Original socket stays there too.
103 Note, that any socket with inet->num != 0 MUST be bound in
104 binding cache, even if it is closed.
106 bhead
= &hashinfo
->bhash
[inet_bhashfn(twsk_net(tw
), inet
->inet_num
,
107 hashinfo
->bhash_size
)];
108 spin_lock(&bhead
->lock
);
109 tw
->tw_tb
= icsk
->icsk_bind_hash
;
110 WARN_ON(!icsk
->icsk_bind_hash
);
111 inet_twsk_add_bind_node(tw
, &tw
->tw_tb
->owners
);
112 atomic_inc(&tw
->tw_refcnt
);
113 spin_unlock(&bhead
->lock
);
118 * Step 2: Hash TW into TIMEWAIT chain.
119 * Should be done before removing sk from established chain
120 * because readers are lockless and search established first.
122 atomic_inc(&tw
->tw_refcnt
);
123 inet_twsk_add_node_rcu(tw
, &ehead
->twchain
);
125 /* Step 3: Remove SK from established hash. */
126 if (__sk_nulls_del_node_init_rcu(sk
))
127 sock_prot_inuse_add(sock_net(sk
), sk
->sk_prot
, -1);
132 EXPORT_SYMBOL_GPL(__inet_twsk_hashdance
);
134 struct inet_timewait_sock
*inet_twsk_alloc(const struct sock
*sk
, const int state
)
136 struct inet_timewait_sock
*tw
=
137 kmem_cache_alloc(sk
->sk_prot_creator
->twsk_prot
->twsk_slab
,
140 const struct inet_sock
*inet
= inet_sk(sk
);
142 kmemcheck_annotate_bitfield(tw
, flags
);
144 /* Give us an identity. */
145 tw
->tw_daddr
= inet
->inet_daddr
;
146 tw
->tw_rcv_saddr
= inet
->inet_rcv_saddr
;
147 tw
->tw_bound_dev_if
= sk
->sk_bound_dev_if
;
148 tw
->tw_num
= inet
->inet_num
;
149 tw
->tw_state
= TCP_TIME_WAIT
;
150 tw
->tw_substate
= state
;
151 tw
->tw_sport
= inet
->inet_sport
;
152 tw
->tw_dport
= inet
->inet_dport
;
153 tw
->tw_family
= sk
->sk_family
;
154 tw
->tw_reuse
= sk
->sk_reuse
;
155 tw
->tw_hash
= sk
->sk_hash
;
157 tw
->tw_transparent
= inet
->transparent
;
158 tw
->tw_prot
= sk
->sk_prot_creator
;
159 twsk_net_set(tw
, hold_net(sock_net(sk
)));
160 atomic_set(&tw
->tw_refcnt
, 1);
161 inet_twsk_dead_node_init(tw
);
162 __module_get(tw
->tw_prot
->owner
);
168 EXPORT_SYMBOL_GPL(inet_twsk_alloc
);
170 /* Returns non-zero if quota exceeded. */
171 static int inet_twdr_do_twkill_work(struct inet_timewait_death_row
*twdr
,
174 struct inet_timewait_sock
*tw
;
175 struct hlist_node
*node
;
179 /* NOTE: compare this to previous version where lock
180 * was released after detaching chain. It was racy,
181 * because tw buckets are scheduled in not serialized context
182 * in 2.3 (with netfilter), and with softnet it is common, because
183 * soft irqs are not sequenced.
188 inet_twsk_for_each_inmate(tw
, node
, &twdr
->cells
[slot
]) {
189 __inet_twsk_del_dead_node(tw
);
190 spin_unlock(&twdr
->death_lock
);
191 __inet_twsk_kill(tw
, twdr
->hashinfo
);
193 NET_INC_STATS_BH(twsk_net(tw
), LINUX_MIB_TIMEWAITED
);
197 spin_lock(&twdr
->death_lock
);
198 if (killed
> INET_TWDR_TWKILL_QUOTA
) {
203 /* While we dropped twdr->death_lock, another cpu may have
204 * killed off the next TW bucket in the list, therefore
205 * do a fresh re-read of the hlist head node with the
206 * lock reacquired. We still use the hlist traversal
207 * macro in order to get the prefetches.
212 twdr
->tw_count
-= killed
;
213 #ifndef CONFIG_NET_NS
214 NET_ADD_STATS_BH(&init_net
, LINUX_MIB_TIMEWAITED
, killed
);
219 void inet_twdr_hangman(unsigned long data
)
221 struct inet_timewait_death_row
*twdr
;
222 int unsigned need_timer
;
224 twdr
= (struct inet_timewait_death_row
*)data
;
225 spin_lock(&twdr
->death_lock
);
227 if (twdr
->tw_count
== 0)
231 if (inet_twdr_do_twkill_work(twdr
, twdr
->slot
)) {
232 twdr
->thread_slots
|= (1 << twdr
->slot
);
233 schedule_work(&twdr
->twkill_work
);
236 /* We purged the entire slot, anything left? */
239 twdr
->slot
= ((twdr
->slot
+ 1) & (INET_TWDR_TWKILL_SLOTS
- 1));
242 mod_timer(&twdr
->tw_timer
, jiffies
+ twdr
->period
);
244 spin_unlock(&twdr
->death_lock
);
247 EXPORT_SYMBOL_GPL(inet_twdr_hangman
);
249 void inet_twdr_twkill_work(struct work_struct
*work
)
251 struct inet_timewait_death_row
*twdr
=
252 container_of(work
, struct inet_timewait_death_row
, twkill_work
);
255 BUILD_BUG_ON((INET_TWDR_TWKILL_SLOTS
- 1) >
256 (sizeof(twdr
->thread_slots
) * 8));
258 while (twdr
->thread_slots
) {
259 spin_lock_bh(&twdr
->death_lock
);
260 for (i
= 0; i
< INET_TWDR_TWKILL_SLOTS
; i
++) {
261 if (!(twdr
->thread_slots
& (1 << i
)))
264 while (inet_twdr_do_twkill_work(twdr
, i
) != 0) {
265 if (need_resched()) {
266 spin_unlock_bh(&twdr
->death_lock
);
268 spin_lock_bh(&twdr
->death_lock
);
272 twdr
->thread_slots
&= ~(1 << i
);
274 spin_unlock_bh(&twdr
->death_lock
);
278 EXPORT_SYMBOL_GPL(inet_twdr_twkill_work
);
280 /* These are always called from BH context. See callers in
281 * tcp_input.c to verify this.
284 /* This is for handling early-kills of TIME_WAIT sockets. */
285 void inet_twsk_deschedule(struct inet_timewait_sock
*tw
,
286 struct inet_timewait_death_row
*twdr
)
288 spin_lock(&twdr
->death_lock
);
289 if (inet_twsk_del_dead_node(tw
)) {
291 if (--twdr
->tw_count
== 0)
292 del_timer(&twdr
->tw_timer
);
294 spin_unlock(&twdr
->death_lock
);
295 __inet_twsk_kill(tw
, twdr
->hashinfo
);
298 EXPORT_SYMBOL(inet_twsk_deschedule
);
300 void inet_twsk_schedule(struct inet_timewait_sock
*tw
,
301 struct inet_timewait_death_row
*twdr
,
302 const int timeo
, const int timewait_len
)
304 struct hlist_head
*list
;
307 /* timeout := RTO * 3.5
309 * 3.5 = 1+2+0.5 to wait for two retransmits.
311 * RATIONALE: if FIN arrived and we entered TIME-WAIT state,
312 * our ACK acking that FIN can be lost. If N subsequent retransmitted
313 * FINs (or previous seqments) are lost (probability of such event
314 * is p^(N+1), where p is probability to lose single packet and
315 * time to detect the loss is about RTO*(2^N - 1) with exponential
316 * backoff). Normal timewait length is calculated so, that we
317 * waited at least for one retransmitted FIN (maximal RTO is 120sec).
318 * [ BTW Linux. following BSD, violates this requirement waiting
319 * only for 60sec, we should wait at least for 240 secs.
320 * Well, 240 consumes too much of resources 8)
322 * This interval is not reduced to catch old duplicate and
323 * responces to our wandering segments living for two MSLs.
324 * However, if we use PAWS to detect
325 * old duplicates, we can reduce the interval to bounds required
326 * by RTO, rather than MSL. So, if peer understands PAWS, we
327 * kill tw bucket after 3.5*RTO (it is important that this number
328 * is greater than TS tick!) and detect old duplicates with help
331 slot
= (timeo
+ (1 << INET_TWDR_RECYCLE_TICK
) - 1) >> INET_TWDR_RECYCLE_TICK
;
333 spin_lock(&twdr
->death_lock
);
335 /* Unlink it, if it was scheduled */
336 if (inet_twsk_del_dead_node(tw
))
339 atomic_inc(&tw
->tw_refcnt
);
341 if (slot
>= INET_TWDR_RECYCLE_SLOTS
) {
342 /* Schedule to slow timer */
343 if (timeo
>= timewait_len
) {
344 slot
= INET_TWDR_TWKILL_SLOTS
- 1;
346 slot
= DIV_ROUND_UP(timeo
, twdr
->period
);
347 if (slot
>= INET_TWDR_TWKILL_SLOTS
)
348 slot
= INET_TWDR_TWKILL_SLOTS
- 1;
350 tw
->tw_ttd
= jiffies
+ timeo
;
351 slot
= (twdr
->slot
+ slot
) & (INET_TWDR_TWKILL_SLOTS
- 1);
352 list
= &twdr
->cells
[slot
];
354 tw
->tw_ttd
= jiffies
+ (slot
<< INET_TWDR_RECYCLE_TICK
);
356 if (twdr
->twcal_hand
< 0) {
357 twdr
->twcal_hand
= 0;
358 twdr
->twcal_jiffie
= jiffies
;
359 twdr
->twcal_timer
.expires
= twdr
->twcal_jiffie
+
360 (slot
<< INET_TWDR_RECYCLE_TICK
);
361 add_timer(&twdr
->twcal_timer
);
363 if (time_after(twdr
->twcal_timer
.expires
,
364 jiffies
+ (slot
<< INET_TWDR_RECYCLE_TICK
)))
365 mod_timer(&twdr
->twcal_timer
,
366 jiffies
+ (slot
<< INET_TWDR_RECYCLE_TICK
));
367 slot
= (twdr
->twcal_hand
+ slot
) & (INET_TWDR_RECYCLE_SLOTS
- 1);
369 list
= &twdr
->twcal_row
[slot
];
372 hlist_add_head(&tw
->tw_death_node
, list
);
374 if (twdr
->tw_count
++ == 0)
375 mod_timer(&twdr
->tw_timer
, jiffies
+ twdr
->period
);
376 spin_unlock(&twdr
->death_lock
);
379 EXPORT_SYMBOL_GPL(inet_twsk_schedule
);
381 void inet_twdr_twcal_tick(unsigned long data
)
383 struct inet_timewait_death_row
*twdr
;
386 unsigned long now
= jiffies
;
390 twdr
= (struct inet_timewait_death_row
*)data
;
392 spin_lock(&twdr
->death_lock
);
393 if (twdr
->twcal_hand
< 0)
396 slot
= twdr
->twcal_hand
;
397 j
= twdr
->twcal_jiffie
;
399 for (n
= 0; n
< INET_TWDR_RECYCLE_SLOTS
; n
++) {
400 if (time_before_eq(j
, now
)) {
401 struct hlist_node
*node
, *safe
;
402 struct inet_timewait_sock
*tw
;
404 inet_twsk_for_each_inmate_safe(tw
, node
, safe
,
405 &twdr
->twcal_row
[slot
]) {
406 __inet_twsk_del_dead_node(tw
);
407 __inet_twsk_kill(tw
, twdr
->hashinfo
);
409 NET_INC_STATS_BH(twsk_net(tw
), LINUX_MIB_TIMEWAITKILLED
);
417 twdr
->twcal_jiffie
= j
;
418 twdr
->twcal_hand
= slot
;
421 if (!hlist_empty(&twdr
->twcal_row
[slot
])) {
422 mod_timer(&twdr
->twcal_timer
, j
);
426 j
+= 1 << INET_TWDR_RECYCLE_TICK
;
427 slot
= (slot
+ 1) & (INET_TWDR_RECYCLE_SLOTS
- 1);
429 twdr
->twcal_hand
= -1;
432 if ((twdr
->tw_count
-= killed
) == 0)
433 del_timer(&twdr
->tw_timer
);
434 #ifndef CONFIG_NET_NS
435 NET_ADD_STATS_BH(&init_net
, LINUX_MIB_TIMEWAITKILLED
, killed
);
437 spin_unlock(&twdr
->death_lock
);
440 EXPORT_SYMBOL_GPL(inet_twdr_twcal_tick
);
442 void inet_twsk_purge(struct inet_hashinfo
*hashinfo
,
443 struct inet_timewait_death_row
*twdr
, int family
)
445 struct inet_timewait_sock
*tw
;
447 struct hlist_nulls_node
*node
;
450 for (slot
= 0; slot
<= hashinfo
->ehash_mask
; slot
++) {
451 struct inet_ehash_bucket
*head
= &hashinfo
->ehash
[slot
];
455 sk_nulls_for_each_rcu(sk
, node
, &head
->twchain
) {
457 if ((tw
->tw_family
!= family
) ||
458 atomic_read(&twsk_net(tw
)->count
))
461 if (unlikely(!atomic_inc_not_zero(&tw
->tw_refcnt
)))
464 if (unlikely((tw
->tw_family
!= family
) ||
465 atomic_read(&twsk_net(tw
)->count
))) {
471 inet_twsk_deschedule(tw
, twdr
);
475 /* If the nulls value we got at the end of this lookup is
476 * not the expected one, we must restart lookup.
477 * We probably met an item that was moved to another chain.
479 if (get_nulls_value(node
) != slot
)
484 EXPORT_SYMBOL_GPL(inet_twsk_purge
);
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