ipvs: fix synchronization on connection close
[linux-2.6.git] / net / netfilter / ipvs / ip_vs_lblcr.c
1 /*
2  * IPVS:        Locality-Based Least-Connection with Replication scheduler
3  *
4  * Authors:     Wensong Zhang <wensong@gnuchina.org>
5  *
6  *              This program is free software; you can redistribute it and/or
7  *              modify it under the terms of the GNU General Public License
8  *              as published by the Free Software Foundation; either version
9  *              2 of the License, or (at your option) any later version.
10  *
11  * Changes:
12  *     Julian Anastasov        :    Added the missing (dest->weight>0)
13  *                                  condition in the ip_vs_dest_set_max.
14  *
15  */
16
17 /*
18  * The lblc/r algorithm is as follows (pseudo code):
19  *
20  *       if serverSet[dest_ip] is null then
21  *               n, serverSet[dest_ip] <- {weighted least-conn node};
22  *       else
23  *               n <- {least-conn (alive) node in serverSet[dest_ip]};
24  *               if (n is null) OR
25  *                  (n.conns>n.weight AND
26  *                   there is a node m with m.conns<m.weight/2) then
27  *                   n <- {weighted least-conn node};
28  *                   add n to serverSet[dest_ip];
29  *               if |serverSet[dest_ip]| > 1 AND
30  *                   now - serverSet[dest_ip].lastMod > T then
31  *                   m <- {most conn node in serverSet[dest_ip]};
32  *                   remove m from serverSet[dest_ip];
33  *       if serverSet[dest_ip] changed then
34  *               serverSet[dest_ip].lastMod <- now;
35  *
36  *       return n;
37  *
38  */
39
40 #define KMSG_COMPONENT "IPVS"
41 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
42
43 #include <linux/ip.h>
44 #include <linux/module.h>
45 #include <linux/kernel.h>
46 #include <linux/skbuff.h>
47 #include <linux/jiffies.h>
48
49 /* for sysctl */
50 #include <linux/fs.h>
51 #include <linux/sysctl.h>
52 #include <net/net_namespace.h>
53
54 #include <net/ip_vs.h>
55
56
57 /*
58  *    It is for garbage collection of stale IPVS lblcr entries,
59  *    when the table is full.
60  */
61 #define CHECK_EXPIRE_INTERVAL   (60*HZ)
62 #define ENTRY_TIMEOUT           (6*60*HZ)
63
64 /*
65  *    It is for full expiration check.
66  *    When there is no partial expiration check (garbage collection)
67  *    in a half hour, do a full expiration check to collect stale
68  *    entries that haven't been touched for a day.
69  */
70 #define COUNT_FOR_FULL_EXPIRATION   30
71 static int sysctl_ip_vs_lblcr_expiration = 24*60*60*HZ;
72
73
74 /*
75  *     for IPVS lblcr entry hash table
76  */
77 #ifndef CONFIG_IP_VS_LBLCR_TAB_BITS
78 #define CONFIG_IP_VS_LBLCR_TAB_BITS      10
79 #endif
80 #define IP_VS_LBLCR_TAB_BITS     CONFIG_IP_VS_LBLCR_TAB_BITS
81 #define IP_VS_LBLCR_TAB_SIZE     (1 << IP_VS_LBLCR_TAB_BITS)
82 #define IP_VS_LBLCR_TAB_MASK     (IP_VS_LBLCR_TAB_SIZE - 1)
83
84
85 /*
86  *      IPVS destination set structure and operations
87  */
88 struct ip_vs_dest_list {
89         struct ip_vs_dest_list  *next;          /* list link */
90         struct ip_vs_dest       *dest;          /* destination server */
91 };
92
93 struct ip_vs_dest_set {
94         atomic_t                size;           /* set size */
95         unsigned long           lastmod;        /* last modified time */
96         struct ip_vs_dest_list  *list;          /* destination list */
97         rwlock_t                lock;           /* lock for this list */
98 };
99
100
101 static struct ip_vs_dest_list *
102 ip_vs_dest_set_insert(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
103 {
104         struct ip_vs_dest_list *e;
105
106         for (e=set->list; e!=NULL; e=e->next) {
107                 if (e->dest == dest)
108                         /* already existed */
109                         return NULL;
110         }
111
112         e = kmalloc(sizeof(*e), GFP_ATOMIC);
113         if (e == NULL) {
114                 pr_err("%s(): no memory\n", __func__);
115                 return NULL;
116         }
117
118         atomic_inc(&dest->refcnt);
119         e->dest = dest;
120
121         /* link it to the list */
122         e->next = set->list;
123         set->list = e;
124         atomic_inc(&set->size);
125
126         set->lastmod = jiffies;
127         return e;
128 }
129
130 static void
131 ip_vs_dest_set_erase(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
132 {
133         struct ip_vs_dest_list *e, **ep;
134
135         for (ep=&set->list, e=*ep; e!=NULL; e=*ep) {
136                 if (e->dest == dest) {
137                         /* HIT */
138                         *ep = e->next;
139                         atomic_dec(&set->size);
140                         set->lastmod = jiffies;
141                         atomic_dec(&e->dest->refcnt);
142                         kfree(e);
143                         break;
144                 }
145                 ep = &e->next;
146         }
147 }
148
149 static void ip_vs_dest_set_eraseall(struct ip_vs_dest_set *set)
150 {
151         struct ip_vs_dest_list *e, **ep;
152
153         write_lock(&set->lock);
154         for (ep=&set->list, e=*ep; e!=NULL; e=*ep) {
155                 *ep = e->next;
156                 /*
157                  * We don't kfree dest because it is refered either
158                  * by its service or by the trash dest list.
159                  */
160                 atomic_dec(&e->dest->refcnt);
161                 kfree(e);
162         }
163         write_unlock(&set->lock);
164 }
165
166 /* get weighted least-connection node in the destination set */
167 static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
168 {
169         register struct ip_vs_dest_list *e;
170         struct ip_vs_dest *dest, *least;
171         int loh, doh;
172
173         if (set == NULL)
174                 return NULL;
175
176         /* select the first destination server, whose weight > 0 */
177         for (e=set->list; e!=NULL; e=e->next) {
178                 least = e->dest;
179                 if (least->flags & IP_VS_DEST_F_OVERLOAD)
180                         continue;
181
182                 if ((atomic_read(&least->weight) > 0)
183                     && (least->flags & IP_VS_DEST_F_AVAILABLE)) {
184                         loh = atomic_read(&least->activeconns) * 50
185                                 + atomic_read(&least->inactconns);
186                         goto nextstage;
187                 }
188         }
189         return NULL;
190
191         /* find the destination with the weighted least load */
192   nextstage:
193         for (e=e->next; e!=NULL; e=e->next) {
194                 dest = e->dest;
195                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
196                         continue;
197
198                 doh = atomic_read(&dest->activeconns) * 50
199                         + atomic_read(&dest->inactconns);
200                 if ((loh * atomic_read(&dest->weight) >
201                      doh * atomic_read(&least->weight))
202                     && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
203                         least = dest;
204                         loh = doh;
205                 }
206         }
207
208         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
209                       "activeconns %d refcnt %d weight %d overhead %d\n",
210                       __func__,
211                       IP_VS_DBG_ADDR(least->af, &least->addr),
212                       ntohs(least->port),
213                       atomic_read(&least->activeconns),
214                       atomic_read(&least->refcnt),
215                       atomic_read(&least->weight), loh);
216         return least;
217 }
218
219
220 /* get weighted most-connection node in the destination set */
221 static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
222 {
223         register struct ip_vs_dest_list *e;
224         struct ip_vs_dest *dest, *most;
225         int moh, doh;
226
227         if (set == NULL)
228                 return NULL;
229
230         /* select the first destination server, whose weight > 0 */
231         for (e=set->list; e!=NULL; e=e->next) {
232                 most = e->dest;
233                 if (atomic_read(&most->weight) > 0) {
234                         moh = atomic_read(&most->activeconns) * 50
235                                 + atomic_read(&most->inactconns);
236                         goto nextstage;
237                 }
238         }
239         return NULL;
240
241         /* find the destination with the weighted most load */
242   nextstage:
243         for (e=e->next; e!=NULL; e=e->next) {
244                 dest = e->dest;
245                 doh = atomic_read(&dest->activeconns) * 50
246                         + atomic_read(&dest->inactconns);
247                 /* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
248                 if ((moh * atomic_read(&dest->weight) <
249                      doh * atomic_read(&most->weight))
250                     && (atomic_read(&dest->weight) > 0)) {
251                         most = dest;
252                         moh = doh;
253                 }
254         }
255
256         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
257                       "activeconns %d refcnt %d weight %d overhead %d\n",
258                       __func__,
259                       IP_VS_DBG_ADDR(most->af, &most->addr), ntohs(most->port),
260                       atomic_read(&most->activeconns),
261                       atomic_read(&most->refcnt),
262                       atomic_read(&most->weight), moh);
263         return most;
264 }
265
266
267 /*
268  *      IPVS lblcr entry represents an association between destination
269  *      IP address and its destination server set
270  */
271 struct ip_vs_lblcr_entry {
272         struct list_head        list;
273         int                     af;             /* address family */
274         union nf_inet_addr      addr;           /* destination IP address */
275         struct ip_vs_dest_set   set;            /* destination server set */
276         unsigned long           lastuse;        /* last used time */
277 };
278
279
280 /*
281  *      IPVS lblcr hash table
282  */
283 struct ip_vs_lblcr_table {
284         struct list_head        bucket[IP_VS_LBLCR_TAB_SIZE];  /* hash bucket */
285         atomic_t                entries;        /* number of entries */
286         int                     max_size;       /* maximum size of entries */
287         struct timer_list       periodic_timer; /* collect stale entries */
288         int                     rover;          /* rover for expire check */
289         int                     counter;        /* counter for no expire */
290 };
291
292
293 /*
294  *      IPVS LBLCR sysctl table
295  */
296
297 static ctl_table vs_vars_table[] = {
298         {
299                 .procname       = "lblcr_expiration",
300                 .data           = &sysctl_ip_vs_lblcr_expiration,
301                 .maxlen         = sizeof(int),
302                 .mode           = 0644,
303                 .proc_handler   = proc_dointvec_jiffies,
304         },
305         { }
306 };
307
308 static struct ctl_table_header * sysctl_header;
309
310 static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
311 {
312         list_del(&en->list);
313         ip_vs_dest_set_eraseall(&en->set);
314         kfree(en);
315 }
316
317
318 /*
319  *      Returns hash value for IPVS LBLCR entry
320  */
321 static inline unsigned
322 ip_vs_lblcr_hashkey(int af, const union nf_inet_addr *addr)
323 {
324         __be32 addr_fold = addr->ip;
325
326 #ifdef CONFIG_IP_VS_IPV6
327         if (af == AF_INET6)
328                 addr_fold = addr->ip6[0]^addr->ip6[1]^
329                             addr->ip6[2]^addr->ip6[3];
330 #endif
331         return (ntohl(addr_fold)*2654435761UL) & IP_VS_LBLCR_TAB_MASK;
332 }
333
334
335 /*
336  *      Hash an entry in the ip_vs_lblcr_table.
337  *      returns bool success.
338  */
339 static void
340 ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
341 {
342         unsigned hash = ip_vs_lblcr_hashkey(en->af, &en->addr);
343
344         list_add(&en->list, &tbl->bucket[hash]);
345         atomic_inc(&tbl->entries);
346 }
347
348
349 /*
350  *  Get ip_vs_lblcr_entry associated with supplied parameters. Called under
351  *  read lock.
352  */
353 static inline struct ip_vs_lblcr_entry *
354 ip_vs_lblcr_get(int af, struct ip_vs_lblcr_table *tbl,
355                 const union nf_inet_addr *addr)
356 {
357         unsigned hash = ip_vs_lblcr_hashkey(af, addr);
358         struct ip_vs_lblcr_entry *en;
359
360         list_for_each_entry(en, &tbl->bucket[hash], list)
361                 if (ip_vs_addr_equal(af, &en->addr, addr))
362                         return en;
363
364         return NULL;
365 }
366
367
368 /*
369  * Create or update an ip_vs_lblcr_entry, which is a mapping of a destination
370  * IP address to a server. Called under write lock.
371  */
372 static inline struct ip_vs_lblcr_entry *
373 ip_vs_lblcr_new(struct ip_vs_lblcr_table *tbl, const union nf_inet_addr *daddr,
374                 struct ip_vs_dest *dest)
375 {
376         struct ip_vs_lblcr_entry *en;
377
378         en = ip_vs_lblcr_get(dest->af, tbl, daddr);
379         if (!en) {
380                 en = kmalloc(sizeof(*en), GFP_ATOMIC);
381                 if (!en) {
382                         pr_err("%s(): no memory\n", __func__);
383                         return NULL;
384                 }
385
386                 en->af = dest->af;
387                 ip_vs_addr_copy(dest->af, &en->addr, daddr);
388                 en->lastuse = jiffies;
389
390                 /* initilize its dest set */
391                 atomic_set(&(en->set.size), 0);
392                 en->set.list = NULL;
393                 rwlock_init(&en->set.lock);
394
395                 ip_vs_lblcr_hash(tbl, en);
396         }
397
398         write_lock(&en->set.lock);
399         ip_vs_dest_set_insert(&en->set, dest);
400         write_unlock(&en->set.lock);
401
402         return en;
403 }
404
405
406 /*
407  *      Flush all the entries of the specified table.
408  */
409 static void ip_vs_lblcr_flush(struct ip_vs_lblcr_table *tbl)
410 {
411         int i;
412         struct ip_vs_lblcr_entry *en, *nxt;
413
414         /* No locking required, only called during cleanup. */
415         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
416                 list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {
417                         ip_vs_lblcr_free(en);
418                 }
419         }
420 }
421
422
423 static inline void ip_vs_lblcr_full_check(struct ip_vs_service *svc)
424 {
425         struct ip_vs_lblcr_table *tbl = svc->sched_data;
426         unsigned long now = jiffies;
427         int i, j;
428         struct ip_vs_lblcr_entry *en, *nxt;
429
430         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
431                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
432
433                 write_lock(&svc->sched_lock);
434                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
435                         if (time_after(en->lastuse+sysctl_ip_vs_lblcr_expiration,
436                                        now))
437                                 continue;
438
439                         ip_vs_lblcr_free(en);
440                         atomic_dec(&tbl->entries);
441                 }
442                 write_unlock(&svc->sched_lock);
443         }
444         tbl->rover = j;
445 }
446
447
448 /*
449  *      Periodical timer handler for IPVS lblcr table
450  *      It is used to collect stale entries when the number of entries
451  *      exceeds the maximum size of the table.
452  *
453  *      Fixme: we probably need more complicated algorithm to collect
454  *             entries that have not been used for a long time even
455  *             if the number of entries doesn't exceed the maximum size
456  *             of the table.
457  *      The full expiration check is for this purpose now.
458  */
459 static void ip_vs_lblcr_check_expire(unsigned long data)
460 {
461         struct ip_vs_service *svc = (struct ip_vs_service *) data;
462         struct ip_vs_lblcr_table *tbl = svc->sched_data;
463         unsigned long now = jiffies;
464         int goal;
465         int i, j;
466         struct ip_vs_lblcr_entry *en, *nxt;
467
468         if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
469                 /* do full expiration check */
470                 ip_vs_lblcr_full_check(svc);
471                 tbl->counter = 1;
472                 goto out;
473         }
474
475         if (atomic_read(&tbl->entries) <= tbl->max_size) {
476                 tbl->counter++;
477                 goto out;
478         }
479
480         goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3;
481         if (goal > tbl->max_size/2)
482                 goal = tbl->max_size/2;
483
484         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
485                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
486
487                 write_lock(&svc->sched_lock);
488                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
489                         if (time_before(now, en->lastuse+ENTRY_TIMEOUT))
490                                 continue;
491
492                         ip_vs_lblcr_free(en);
493                         atomic_dec(&tbl->entries);
494                         goal--;
495                 }
496                 write_unlock(&svc->sched_lock);
497                 if (goal <= 0)
498                         break;
499         }
500         tbl->rover = j;
501
502   out:
503         mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
504 }
505
506 static int ip_vs_lblcr_init_svc(struct ip_vs_service *svc)
507 {
508         int i;
509         struct ip_vs_lblcr_table *tbl;
510
511         /*
512          *    Allocate the ip_vs_lblcr_table for this service
513          */
514         tbl = kmalloc(sizeof(*tbl), GFP_ATOMIC);
515         if (tbl == NULL) {
516                 pr_err("%s(): no memory\n", __func__);
517                 return -ENOMEM;
518         }
519         svc->sched_data = tbl;
520         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) allocated for "
521                   "current service\n", sizeof(*tbl));
522
523         /*
524          *    Initialize the hash buckets
525          */
526         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
527                 INIT_LIST_HEAD(&tbl->bucket[i]);
528         }
529         tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
530         tbl->rover = 0;
531         tbl->counter = 1;
532
533         /*
534          *    Hook periodic timer for garbage collection
535          */
536         setup_timer(&tbl->periodic_timer, ip_vs_lblcr_check_expire,
537                         (unsigned long)svc);
538         mod_timer(&tbl->periodic_timer, jiffies + CHECK_EXPIRE_INTERVAL);
539
540         return 0;
541 }
542
543
544 static int ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
545 {
546         struct ip_vs_lblcr_table *tbl = svc->sched_data;
547
548         /* remove periodic timer */
549         del_timer_sync(&tbl->periodic_timer);
550
551         /* got to clean up table entries here */
552         ip_vs_lblcr_flush(tbl);
553
554         /* release the table itself */
555         kfree(tbl);
556         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) released\n",
557                   sizeof(*tbl));
558
559         return 0;
560 }
561
562
563 static inline struct ip_vs_dest *
564 __ip_vs_lblcr_schedule(struct ip_vs_service *svc)
565 {
566         struct ip_vs_dest *dest, *least;
567         int loh, doh;
568
569         /*
570          * We think the overhead of processing active connections is fifty
571          * times higher than that of inactive connections in average. (This
572          * fifty times might not be accurate, we will change it later.) We
573          * use the following formula to estimate the overhead:
574          *                dest->activeconns*50 + dest->inactconns
575          * and the load:
576          *                (dest overhead) / dest->weight
577          *
578          * Remember -- no floats in kernel mode!!!
579          * The comparison of h1*w2 > h2*w1 is equivalent to that of
580          *                h1/w1 > h2/w2
581          * if every weight is larger than zero.
582          *
583          * The server with weight=0 is quiesced and will not receive any
584          * new connection.
585          */
586         list_for_each_entry(dest, &svc->destinations, n_list) {
587                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
588                         continue;
589
590                 if (atomic_read(&dest->weight) > 0) {
591                         least = dest;
592                         loh = atomic_read(&least->activeconns) * 50
593                                 + atomic_read(&least->inactconns);
594                         goto nextstage;
595                 }
596         }
597         return NULL;
598
599         /*
600          *    Find the destination with the least load.
601          */
602   nextstage:
603         list_for_each_entry_continue(dest, &svc->destinations, n_list) {
604                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
605                         continue;
606
607                 doh = atomic_read(&dest->activeconns) * 50
608                         + atomic_read(&dest->inactconns);
609                 if (loh * atomic_read(&dest->weight) >
610                     doh * atomic_read(&least->weight)) {
611                         least = dest;
612                         loh = doh;
613                 }
614         }
615
616         IP_VS_DBG_BUF(6, "LBLCR: server %s:%d "
617                       "activeconns %d refcnt %d weight %d overhead %d\n",
618                       IP_VS_DBG_ADDR(least->af, &least->addr),
619                       ntohs(least->port),
620                       atomic_read(&least->activeconns),
621                       atomic_read(&least->refcnt),
622                       atomic_read(&least->weight), loh);
623
624         return least;
625 }
626
627
628 /*
629  *   If this destination server is overloaded and there is a less loaded
630  *   server, then return true.
631  */
632 static inline int
633 is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
634 {
635         if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
636                 struct ip_vs_dest *d;
637
638                 list_for_each_entry(d, &svc->destinations, n_list) {
639                         if (atomic_read(&d->activeconns)*2
640                             < atomic_read(&d->weight)) {
641                                 return 1;
642                         }
643                 }
644         }
645         return 0;
646 }
647
648
649 /*
650  *    Locality-Based (weighted) Least-Connection scheduling
651  */
652 static struct ip_vs_dest *
653 ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
654 {
655         struct ip_vs_lblcr_table *tbl = svc->sched_data;
656         struct ip_vs_iphdr iph;
657         struct ip_vs_dest *dest = NULL;
658         struct ip_vs_lblcr_entry *en;
659
660         ip_vs_fill_iphdr(svc->af, skb_network_header(skb), &iph);
661
662         IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
663
664         /* First look in our cache */
665         read_lock(&svc->sched_lock);
666         en = ip_vs_lblcr_get(svc->af, tbl, &iph.daddr);
667         if (en) {
668                 /* We only hold a read lock, but this is atomic */
669                 en->lastuse = jiffies;
670
671                 /* Get the least loaded destination */
672                 read_lock(&en->set.lock);
673                 dest = ip_vs_dest_set_min(&en->set);
674                 read_unlock(&en->set.lock);
675
676                 /* More than one destination + enough time passed by, cleanup */
677                 if (atomic_read(&en->set.size) > 1 &&
678                                 time_after(jiffies, en->set.lastmod +
679                                 sysctl_ip_vs_lblcr_expiration)) {
680                         struct ip_vs_dest *m;
681
682                         write_lock(&en->set.lock);
683                         m = ip_vs_dest_set_max(&en->set);
684                         if (m)
685                                 ip_vs_dest_set_erase(&en->set, m);
686                         write_unlock(&en->set.lock);
687                 }
688
689                 /* If the destination is not overloaded, use it */
690                 if (dest && !is_overloaded(dest, svc)) {
691                         read_unlock(&svc->sched_lock);
692                         goto out;
693                 }
694
695                 /* The cache entry is invalid, time to schedule */
696                 dest = __ip_vs_lblcr_schedule(svc);
697                 if (!dest) {
698                         IP_VS_ERR_RL("LBLCR: no destination available\n");
699                         read_unlock(&svc->sched_lock);
700                         return NULL;
701                 }
702
703                 /* Update our cache entry */
704                 write_lock(&en->set.lock);
705                 ip_vs_dest_set_insert(&en->set, dest);
706                 write_unlock(&en->set.lock);
707         }
708         read_unlock(&svc->sched_lock);
709
710         if (dest)
711                 goto out;
712
713         /* No cache entry, time to schedule */
714         dest = __ip_vs_lblcr_schedule(svc);
715         if (!dest) {
716                 IP_VS_DBG(1, "no destination available\n");
717                 return NULL;
718         }
719
720         /* If we fail to create a cache entry, we'll just use the valid dest */
721         write_lock(&svc->sched_lock);
722         ip_vs_lblcr_new(tbl, &iph.daddr, dest);
723         write_unlock(&svc->sched_lock);
724
725 out:
726         IP_VS_DBG_BUF(6, "LBLCR: destination IP address %s --> server %s:%d\n",
727                       IP_VS_DBG_ADDR(svc->af, &iph.daddr),
728                       IP_VS_DBG_ADDR(svc->af, &dest->addr), ntohs(dest->port));
729
730         return dest;
731 }
732
733
734 /*
735  *      IPVS LBLCR Scheduler structure
736  */
737 static struct ip_vs_scheduler ip_vs_lblcr_scheduler =
738 {
739         .name =                 "lblcr",
740         .refcnt =               ATOMIC_INIT(0),
741         .module =               THIS_MODULE,
742         .n_list =               LIST_HEAD_INIT(ip_vs_lblcr_scheduler.n_list),
743         .init_service =         ip_vs_lblcr_init_svc,
744         .done_service =         ip_vs_lblcr_done_svc,
745         .schedule =             ip_vs_lblcr_schedule,
746 };
747
748
749 static int __init ip_vs_lblcr_init(void)
750 {
751         int ret;
752
753         sysctl_header = register_sysctl_paths(net_vs_ctl_path, vs_vars_table);
754         ret = register_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
755         if (ret)
756                 unregister_sysctl_table(sysctl_header);
757         return ret;
758 }
759
760
761 static void __exit ip_vs_lblcr_cleanup(void)
762 {
763         unregister_sysctl_table(sysctl_header);
764         unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
765 }
766
767
768 module_init(ip_vs_lblcr_init);
769 module_exit(ip_vs_lblcr_cleanup);
770 MODULE_LICENSE("GPL");