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