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Linux/net/netfilter/ipvs/ip_vs_lblcr.c

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  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 #include <linux/list.h>
 49 #include <linux/slab.h>
 50 
 51 /* for sysctl */
 52 #include <linux/fs.h>
 53 #include <linux/sysctl.h>
 54 #include <net/net_namespace.h>
 55 
 56 #include <net/ip_vs.h>
 57 
 58 
 59 /*
 60  *    It is for garbage collection of stale IPVS lblcr entries,
 61  *    when the table is full.
 62  */
 63 #define CHECK_EXPIRE_INTERVAL   (60*HZ)
 64 #define ENTRY_TIMEOUT           (6*60*HZ)
 65 
 66 #define DEFAULT_EXPIRATION      (24*60*60*HZ)
 67 
 68 /*
 69  *    It is for full expiration check.
 70  *    When there is no partial expiration check (garbage collection)
 71  *    in a half hour, do a full expiration check to collect stale
 72  *    entries that haven't been touched for a day.
 73  */
 74 #define COUNT_FOR_FULL_EXPIRATION   30
 75 
 76 /*
 77  *     for IPVS lblcr entry hash table
 78  */
 79 #ifndef CONFIG_IP_VS_LBLCR_TAB_BITS
 80 #define CONFIG_IP_VS_LBLCR_TAB_BITS      10
 81 #endif
 82 #define IP_VS_LBLCR_TAB_BITS     CONFIG_IP_VS_LBLCR_TAB_BITS
 83 #define IP_VS_LBLCR_TAB_SIZE     (1 << IP_VS_LBLCR_TAB_BITS)
 84 #define IP_VS_LBLCR_TAB_MASK     (IP_VS_LBLCR_TAB_SIZE - 1)
 85 
 86 
 87 /*
 88  *      IPVS destination set structure and operations
 89  */
 90 struct ip_vs_dest_set_elem {
 91         struct list_head        list;          /* list link */
 92         struct ip_vs_dest       *dest;          /* destination server */
 93         struct rcu_head         rcu_head;
 94 };
 95 
 96 struct ip_vs_dest_set {
 97         atomic_t                size;           /* set size */
 98         unsigned long           lastmod;        /* last modified time */
 99         struct list_head        list;           /* destination list */
100 };
101 
102 
103 static void ip_vs_dest_set_insert(struct ip_vs_dest_set *set,
104                                   struct ip_vs_dest *dest, bool check)
105 {
106         struct ip_vs_dest_set_elem *e;
107 
108         if (check) {
109                 list_for_each_entry(e, &set->list, list) {
110                         if (e->dest == dest)
111                                 return;
112                 }
113         }
114 
115         e = kmalloc(sizeof(*e), GFP_ATOMIC);
116         if (e == NULL)
117                 return;
118 
119         ip_vs_dest_hold(dest);
120         e->dest = dest;
121 
122         list_add_rcu(&e->list, &set->list);
123         atomic_inc(&set->size);
124 
125         set->lastmod = jiffies;
126 }
127 
128 static void ip_vs_lblcr_elem_rcu_free(struct rcu_head *head)
129 {
130         struct ip_vs_dest_set_elem *e;
131 
132         e = container_of(head, struct ip_vs_dest_set_elem, rcu_head);
133         ip_vs_dest_put_and_free(e->dest);
134         kfree(e);
135 }
136 
137 static void
138 ip_vs_dest_set_erase(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
139 {
140         struct ip_vs_dest_set_elem *e;
141 
142         list_for_each_entry(e, &set->list, list) {
143                 if (e->dest == dest) {
144                         /* HIT */
145                         atomic_dec(&set->size);
146                         set->lastmod = jiffies;
147                         list_del_rcu(&e->list);
148                         call_rcu(&e->rcu_head, ip_vs_lblcr_elem_rcu_free);
149                         break;
150                 }
151         }
152 }
153 
154 static void ip_vs_dest_set_eraseall(struct ip_vs_dest_set *set)
155 {
156         struct ip_vs_dest_set_elem *e, *ep;
157 
158         list_for_each_entry_safe(e, ep, &set->list, list) {
159                 list_del_rcu(&e->list);
160                 call_rcu(&e->rcu_head, ip_vs_lblcr_elem_rcu_free);
161         }
162 }
163 
164 /* get weighted least-connection node in the destination set */
165 static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
166 {
167         register struct ip_vs_dest_set_elem *e;
168         struct ip_vs_dest *dest, *least;
169         int loh, doh;
170 
171         /* select the first destination server, whose weight > 0 */
172         list_for_each_entry_rcu(e, &set->list, list) {
173                 least = e->dest;
174                 if (least->flags & IP_VS_DEST_F_OVERLOAD)
175                         continue;
176 
177                 if ((atomic_read(&least->weight) > 0)
178                     && (least->flags & IP_VS_DEST_F_AVAILABLE)) {
179                         loh = ip_vs_dest_conn_overhead(least);
180                         goto nextstage;
181                 }
182         }
183         return NULL;
184 
185         /* find the destination with the weighted least load */
186   nextstage:
187         list_for_each_entry_continue_rcu(e, &set->list, list) {
188                 dest = e->dest;
189                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
190                         continue;
191 
192                 doh = ip_vs_dest_conn_overhead(dest);
193                 if (((__s64)loh * atomic_read(&dest->weight) >
194                      (__s64)doh * atomic_read(&least->weight))
195                     && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
196                         least = dest;
197                         loh = doh;
198                 }
199         }
200 
201         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
202                       "activeconns %d refcnt %d weight %d overhead %d\n",
203                       __func__,
204                       IP_VS_DBG_ADDR(least->af, &least->addr),
205                       ntohs(least->port),
206                       atomic_read(&least->activeconns),
207                       atomic_read(&least->refcnt),
208                       atomic_read(&least->weight), loh);
209         return least;
210 }
211 
212 
213 /* get weighted most-connection node in the destination set */
214 static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
215 {
216         register struct ip_vs_dest_set_elem *e;
217         struct ip_vs_dest *dest, *most;
218         int moh, doh;
219 
220         if (set == NULL)
221                 return NULL;
222 
223         /* select the first destination server, whose weight > 0 */
224         list_for_each_entry(e, &set->list, list) {
225                 most = e->dest;
226                 if (atomic_read(&most->weight) > 0) {
227                         moh = ip_vs_dest_conn_overhead(most);
228                         goto nextstage;
229                 }
230         }
231         return NULL;
232 
233         /* find the destination with the weighted most load */
234   nextstage:
235         list_for_each_entry_continue(e, &set->list, list) {
236                 dest = e->dest;
237                 doh = ip_vs_dest_conn_overhead(dest);
238                 /* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
239                 if (((__s64)moh * atomic_read(&dest->weight) <
240                      (__s64)doh * atomic_read(&most->weight))
241                     && (atomic_read(&dest->weight) > 0)) {
242                         most = dest;
243                         moh = doh;
244                 }
245         }
246 
247         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
248                       "activeconns %d refcnt %d weight %d overhead %d\n",
249                       __func__,
250                       IP_VS_DBG_ADDR(most->af, &most->addr), ntohs(most->port),
251                       atomic_read(&most->activeconns),
252                       atomic_read(&most->refcnt),
253                       atomic_read(&most->weight), moh);
254         return most;
255 }
256 
257 
258 /*
259  *      IPVS lblcr entry represents an association between destination
260  *      IP address and its destination server set
261  */
262 struct ip_vs_lblcr_entry {
263         struct hlist_node       list;
264         int                     af;             /* address family */
265         union nf_inet_addr      addr;           /* destination IP address */
266         struct ip_vs_dest_set   set;            /* destination server set */
267         unsigned long           lastuse;        /* last used time */
268         struct rcu_head         rcu_head;
269 };
270 
271 
272 /*
273  *      IPVS lblcr hash table
274  */
275 struct ip_vs_lblcr_table {
276         struct rcu_head         rcu_head;
277         struct hlist_head       bucket[IP_VS_LBLCR_TAB_SIZE];  /* hash bucket */
278         atomic_t                entries;        /* number of entries */
279         int                     max_size;       /* maximum size of entries */
280         struct timer_list       periodic_timer; /* collect stale entries */
281         int                     rover;          /* rover for expire check */
282         int                     counter;        /* counter for no expire */
283         bool                    dead;
284 };
285 
286 
287 #ifdef CONFIG_SYSCTL
288 /*
289  *      IPVS LBLCR sysctl table
290  */
291 
292 static struct ctl_table vs_vars_table[] = {
293         {
294                 .procname       = "lblcr_expiration",
295                 .data           = NULL,
296                 .maxlen         = sizeof(int),
297                 .mode           = 0644,
298                 .proc_handler   = proc_dointvec_jiffies,
299         },
300         { }
301 };
302 #endif
303 
304 static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
305 {
306         hlist_del_rcu(&en->list);
307         ip_vs_dest_set_eraseall(&en->set);
308         kfree_rcu(en, rcu_head);
309 }
310 
311 
312 /*
313  *      Returns hash value for IPVS LBLCR entry
314  */
315 static inline unsigned int
316 ip_vs_lblcr_hashkey(int af, const union nf_inet_addr *addr)
317 {
318         __be32 addr_fold = addr->ip;
319 
320 #ifdef CONFIG_IP_VS_IPV6
321         if (af == AF_INET6)
322                 addr_fold = addr->ip6[0]^addr->ip6[1]^
323                             addr->ip6[2]^addr->ip6[3];
324 #endif
325         return (ntohl(addr_fold)*2654435761UL) & IP_VS_LBLCR_TAB_MASK;
326 }
327 
328 
329 /*
330  *      Hash an entry in the ip_vs_lblcr_table.
331  *      returns bool success.
332  */
333 static void
334 ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
335 {
336         unsigned int hash = ip_vs_lblcr_hashkey(en->af, &en->addr);
337 
338         hlist_add_head_rcu(&en->list, &tbl->bucket[hash]);
339         atomic_inc(&tbl->entries);
340 }
341 
342 
343 /* Get ip_vs_lblcr_entry associated with supplied parameters. */
344 static inline struct ip_vs_lblcr_entry *
345 ip_vs_lblcr_get(int af, struct ip_vs_lblcr_table *tbl,
346                 const union nf_inet_addr *addr)
347 {
348         unsigned int hash = ip_vs_lblcr_hashkey(af, addr);
349         struct ip_vs_lblcr_entry *en;
350 
351         hlist_for_each_entry_rcu(en, &tbl->bucket[hash], list)
352                 if (ip_vs_addr_equal(af, &en->addr, addr))
353                         return en;
354 
355         return NULL;
356 }
357 
358 
359 /*
360  * Create or update an ip_vs_lblcr_entry, which is a mapping of a destination
361  * IP address to a server. Called under spin lock.
362  */
363 static inline struct ip_vs_lblcr_entry *
364 ip_vs_lblcr_new(struct ip_vs_lblcr_table *tbl, const union nf_inet_addr *daddr,
365                 u16 af, struct ip_vs_dest *dest)
366 {
367         struct ip_vs_lblcr_entry *en;
368 
369         en = ip_vs_lblcr_get(af, tbl, daddr);
370         if (!en) {
371                 en = kmalloc(sizeof(*en), GFP_ATOMIC);
372                 if (!en)
373                         return NULL;
374 
375                 en->af = af;
376                 ip_vs_addr_copy(af, &en->addr, daddr);
377                 en->lastuse = jiffies;
378 
379                 /* initialize its dest set */
380                 atomic_set(&(en->set.size), 0);
381                 INIT_LIST_HEAD(&en->set.list);
382 
383                 ip_vs_dest_set_insert(&en->set, dest, false);
384 
385                 ip_vs_lblcr_hash(tbl, en);
386                 return en;
387         }
388 
389         ip_vs_dest_set_insert(&en->set, dest, true);
390 
391         return en;
392 }
393 
394 
395 /*
396  *      Flush all the entries of the specified table.
397  */
398 static void ip_vs_lblcr_flush(struct ip_vs_service *svc)
399 {
400         struct ip_vs_lblcr_table *tbl = svc->sched_data;
401         int i;
402         struct ip_vs_lblcr_entry *en;
403         struct hlist_node *next;
404 
405         spin_lock_bh(&svc->sched_lock);
406         tbl->dead = 1;
407         for (i = 0; i < IP_VS_LBLCR_TAB_SIZE; i++) {
408                 hlist_for_each_entry_safe(en, next, &tbl->bucket[i], list) {
409                         ip_vs_lblcr_free(en);
410                 }
411         }
412         spin_unlock_bh(&svc->sched_lock);
413 }
414 
415 static int sysctl_lblcr_expiration(struct ip_vs_service *svc)
416 {
417 #ifdef CONFIG_SYSCTL
418         struct netns_ipvs *ipvs = net_ipvs(svc->net);
419         return ipvs->sysctl_lblcr_expiration;
420 #else
421         return DEFAULT_EXPIRATION;
422 #endif
423 }
424 
425 static inline void ip_vs_lblcr_full_check(struct ip_vs_service *svc)
426 {
427         struct ip_vs_lblcr_table *tbl = svc->sched_data;
428         unsigned long now = jiffies;
429         int i, j;
430         struct ip_vs_lblcr_entry *en;
431         struct hlist_node *next;
432 
433         for (i = 0, j = tbl->rover; i < IP_VS_LBLCR_TAB_SIZE; i++) {
434                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
435 
436                 spin_lock(&svc->sched_lock);
437                 hlist_for_each_entry_safe(en, next, &tbl->bucket[j], list) {
438                         if (time_after(en->lastuse +
439                                        sysctl_lblcr_expiration(svc), now))
440                                 continue;
441 
442                         ip_vs_lblcr_free(en);
443                         atomic_dec(&tbl->entries);
444                 }
445                 spin_unlock(&svc->sched_lock);
446         }
447         tbl->rover = j;
448 }
449 
450 
451 /*
452  *      Periodical timer handler for IPVS lblcr table
453  *      It is used to collect stale entries when the number of entries
454  *      exceeds the maximum size of the table.
455  *
456  *      Fixme: we probably need more complicated algorithm to collect
457  *             entries that have not been used for a long time even
458  *             if the number of entries doesn't exceed the maximum size
459  *             of the table.
460  *      The full expiration check is for this purpose now.
461  */
462 static void ip_vs_lblcr_check_expire(unsigned long data)
463 {
464         struct ip_vs_service *svc = (struct ip_vs_service *) data;
465         struct ip_vs_lblcr_table *tbl = svc->sched_data;
466         unsigned long now = jiffies;
467         int goal;
468         int i, j;
469         struct ip_vs_lblcr_entry *en;
470         struct hlist_node *next;
471 
472         if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
473                 /* do full expiration check */
474                 ip_vs_lblcr_full_check(svc);
475                 tbl->counter = 1;
476                 goto out;
477         }
478 
479         if (atomic_read(&tbl->entries) <= tbl->max_size) {
480                 tbl->counter++;
481                 goto out;
482         }
483 
484         goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3;
485         if (goal > tbl->max_size/2)
486                 goal = tbl->max_size/2;
487 
488         for (i = 0, j = tbl->rover; i < IP_VS_LBLCR_TAB_SIZE; i++) {
489                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
490 
491                 spin_lock(&svc->sched_lock);
492                 hlist_for_each_entry_safe(en, next, &tbl->bucket[j], list) {
493                         if (time_before(now, en->lastuse+ENTRY_TIMEOUT))
494                                 continue;
495 
496                         ip_vs_lblcr_free(en);
497                         atomic_dec(&tbl->entries);
498                         goal--;
499                 }
500                 spin_unlock(&svc->sched_lock);
501                 if (goal <= 0)
502                         break;
503         }
504         tbl->rover = j;
505 
506   out:
507         mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
508 }
509 
510 static int ip_vs_lblcr_init_svc(struct ip_vs_service *svc)
511 {
512         int i;
513         struct ip_vs_lblcr_table *tbl;
514 
515         /*
516          *    Allocate the ip_vs_lblcr_table for this service
517          */
518         tbl = kmalloc(sizeof(*tbl), GFP_KERNEL);
519         if (tbl == NULL)
520                 return -ENOMEM;
521 
522         svc->sched_data = tbl;
523         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) allocated for "
524                   "current service\n", sizeof(*tbl));
525 
526         /*
527          *    Initialize the hash buckets
528          */
529         for (i = 0; i < IP_VS_LBLCR_TAB_SIZE; i++) {
530                 INIT_HLIST_HEAD(&tbl->bucket[i]);
531         }
532         tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
533         tbl->rover = 0;
534         tbl->counter = 1;
535         tbl->dead = 0;
536 
537         /*
538          *    Hook periodic timer for garbage collection
539          */
540         setup_timer(&tbl->periodic_timer, ip_vs_lblcr_check_expire,
541                         (unsigned long)svc);
542         mod_timer(&tbl->periodic_timer, jiffies + CHECK_EXPIRE_INTERVAL);
543 
544         return 0;
545 }
546 
547 
548 static void ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
549 {
550         struct ip_vs_lblcr_table *tbl = svc->sched_data;
551 
552         /* remove periodic timer */
553         del_timer_sync(&tbl->periodic_timer);
554 
555         /* got to clean up table entries here */
556         ip_vs_lblcr_flush(svc);
557 
558         /* release the table itself */
559         kfree_rcu(tbl, rcu_head);
560         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) released\n",
561                   sizeof(*tbl));
562 }
563 
564 
565 static inline struct ip_vs_dest *
566 __ip_vs_lblcr_schedule(struct ip_vs_service *svc)
567 {
568         struct ip_vs_dest *dest, *least;
569         int loh, doh;
570 
571         /*
572          * We use the following formula to estimate the load:
573          *                (dest overhead) / dest->weight
574          *
575          * Remember -- no floats in kernel mode!!!
576          * The comparison of h1*w2 > h2*w1 is equivalent to that of
577          *                h1/w1 > h2/w2
578          * if every weight is larger than zero.
579          *
580          * The server with weight=0 is quiesced and will not receive any
581          * new connection.
582          */
583         list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
584                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
585                         continue;
586 
587                 if (atomic_read(&dest->weight) > 0) {
588                         least = dest;
589                         loh = ip_vs_dest_conn_overhead(least);
590                         goto nextstage;
591                 }
592         }
593         return NULL;
594 
595         /*
596          *    Find the destination with the least load.
597          */
598   nextstage:
599         list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) {
600                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
601                         continue;
602 
603                 doh = ip_vs_dest_conn_overhead(dest);
604                 if ((__s64)loh * atomic_read(&dest->weight) >
605                     (__s64)doh * atomic_read(&least->weight)) {
606                         least = dest;
607                         loh = doh;
608                 }
609         }
610 
611         IP_VS_DBG_BUF(6, "LBLCR: server %s:%d "
612                       "activeconns %d refcnt %d weight %d overhead %d\n",
613                       IP_VS_DBG_ADDR(least->af, &least->addr),
614                       ntohs(least->port),
615                       atomic_read(&least->activeconns),
616                       atomic_read(&least->refcnt),
617                       atomic_read(&least->weight), loh);
618 
619         return least;
620 }
621 
622 
623 /*
624  *   If this destination server is overloaded and there is a less loaded
625  *   server, then return true.
626  */
627 static inline int
628 is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
629 {
630         if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
631                 struct ip_vs_dest *d;
632 
633                 list_for_each_entry_rcu(d, &svc->destinations, n_list) {
634                         if (atomic_read(&d->activeconns)*2
635                             < atomic_read(&d->weight)) {
636                                 return 1;
637                         }
638                 }
639         }
640         return 0;
641 }
642 
643 
644 /*
645  *    Locality-Based (weighted) Least-Connection scheduling
646  */
647 static struct ip_vs_dest *
648 ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
649                      struct ip_vs_iphdr *iph)
650 {
651         struct ip_vs_lblcr_table *tbl = svc->sched_data;
652         struct ip_vs_dest *dest;
653         struct ip_vs_lblcr_entry *en;
654 
655         IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
656 
657         /* First look in our cache */
658         en = ip_vs_lblcr_get(svc->af, tbl, &iph->daddr);
659         if (en) {
660                 en->lastuse = jiffies;
661 
662                 /* Get the least loaded destination */
663                 dest = ip_vs_dest_set_min(&en->set);
664 
665                 /* More than one destination + enough time passed by, cleanup */
666                 if (atomic_read(&en->set.size) > 1 &&
667                     time_after(jiffies, en->set.lastmod +
668                                 sysctl_lblcr_expiration(svc))) {
669                         spin_lock_bh(&svc->sched_lock);
670                         if (atomic_read(&en->set.size) > 1) {
671                                 struct ip_vs_dest *m;
672 
673                                 m = ip_vs_dest_set_max(&en->set);
674                                 if (m)
675                                         ip_vs_dest_set_erase(&en->set, m);
676                         }
677                         spin_unlock_bh(&svc->sched_lock);
678                 }
679 
680                 /* If the destination is not overloaded, use it */
681                 if (dest && !is_overloaded(dest, svc))
682                         goto out;
683 
684                 /* The cache entry is invalid, time to schedule */
685                 dest = __ip_vs_lblcr_schedule(svc);
686                 if (!dest) {
687                         ip_vs_scheduler_err(svc, "no destination available");
688                         return NULL;
689                 }
690 
691                 /* Update our cache entry */
692                 spin_lock_bh(&svc->sched_lock);
693                 if (!tbl->dead)
694                         ip_vs_dest_set_insert(&en->set, dest, true);
695                 spin_unlock_bh(&svc->sched_lock);
696                 goto out;
697         }
698 
699         /* No cache entry, time to schedule */
700         dest = __ip_vs_lblcr_schedule(svc);
701         if (!dest) {
702                 IP_VS_DBG(1, "no destination available\n");
703                 return NULL;
704         }
705 
706         /* If we fail to create a cache entry, we'll just use the valid dest */
707         spin_lock_bh(&svc->sched_lock);
708         if (!tbl->dead)
709                 ip_vs_lblcr_new(tbl, &iph->daddr, svc->af, dest);
710         spin_unlock_bh(&svc->sched_lock);
711 
712 out:
713         IP_VS_DBG_BUF(6, "LBLCR: destination IP address %s --> server %s:%d\n",
714                       IP_VS_DBG_ADDR(svc->af, &iph->daddr),
715                       IP_VS_DBG_ADDR(dest->af, &dest->addr), ntohs(dest->port));
716 
717         return dest;
718 }
719 
720 
721 /*
722  *      IPVS LBLCR Scheduler structure
723  */
724 static struct ip_vs_scheduler ip_vs_lblcr_scheduler =
725 {
726         .name =                 "lblcr",
727         .refcnt =               ATOMIC_INIT(0),
728         .module =               THIS_MODULE,
729         .n_list =               LIST_HEAD_INIT(ip_vs_lblcr_scheduler.n_list),
730         .init_service =         ip_vs_lblcr_init_svc,
731         .done_service =         ip_vs_lblcr_done_svc,
732         .schedule =             ip_vs_lblcr_schedule,
733 };
734 
735 /*
736  *  per netns init.
737  */
738 #ifdef CONFIG_SYSCTL
739 static int __net_init __ip_vs_lblcr_init(struct net *net)
740 {
741         struct netns_ipvs *ipvs = net_ipvs(net);
742 
743         if (!ipvs)
744                 return -ENOENT;
745 
746         if (!net_eq(net, &init_net)) {
747                 ipvs->lblcr_ctl_table = kmemdup(vs_vars_table,
748                                                 sizeof(vs_vars_table),
749                                                 GFP_KERNEL);
750                 if (ipvs->lblcr_ctl_table == NULL)
751                         return -ENOMEM;
752 
753                 /* Don't export sysctls to unprivileged users */
754                 if (net->user_ns != &init_user_ns)
755                         ipvs->lblcr_ctl_table[0].procname = NULL;
756         } else
757                 ipvs->lblcr_ctl_table = vs_vars_table;
758         ipvs->sysctl_lblcr_expiration = DEFAULT_EXPIRATION;
759         ipvs->lblcr_ctl_table[0].data = &ipvs->sysctl_lblcr_expiration;
760 
761         ipvs->lblcr_ctl_header =
762                 register_net_sysctl(net, "net/ipv4/vs", ipvs->lblcr_ctl_table);
763         if (!ipvs->lblcr_ctl_header) {
764                 if (!net_eq(net, &init_net))
765                         kfree(ipvs->lblcr_ctl_table);
766                 return -ENOMEM;
767         }
768 
769         return 0;
770 }
771 
772 static void __net_exit __ip_vs_lblcr_exit(struct net *net)
773 {
774         struct netns_ipvs *ipvs = net_ipvs(net);
775 
776         unregister_net_sysctl_table(ipvs->lblcr_ctl_header);
777 
778         if (!net_eq(net, &init_net))
779                 kfree(ipvs->lblcr_ctl_table);
780 }
781 
782 #else
783 
784 static int __net_init __ip_vs_lblcr_init(struct net *net) { return 0; }
785 static void __net_exit __ip_vs_lblcr_exit(struct net *net) { }
786 
787 #endif
788 
789 static struct pernet_operations ip_vs_lblcr_ops = {
790         .init = __ip_vs_lblcr_init,
791         .exit = __ip_vs_lblcr_exit,
792 };
793 
794 static int __init ip_vs_lblcr_init(void)
795 {
796         int ret;
797 
798         ret = register_pernet_subsys(&ip_vs_lblcr_ops);
799         if (ret)
800                 return ret;
801 
802         ret = register_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
803         if (ret)
804                 unregister_pernet_subsys(&ip_vs_lblcr_ops);
805         return ret;
806 }
807 
808 static void __exit ip_vs_lblcr_cleanup(void)
809 {
810         unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
811         unregister_pernet_subsys(&ip_vs_lblcr_ops);
812         rcu_barrier();
813 }
814 
815 
816 module_init(ip_vs_lblcr_init);
817 module_exit(ip_vs_lblcr_cleanup);
818 MODULE_LICENSE("GPL");
819 

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