net/ipv4/ipvs/ip_vs_lblcr.c

   1 /*
   2  * IPVS:        Locality-Based Least-Connection with Replication scheduler
   3  *
   4  * Version:     $Id: ip_vs_lblcr.c,v 1.11 2002/09/15 08:14:08 wensong Exp $
   5  *
   6  * Authors:     Wensong Zhang <wensong@gnuchina.org>
   7  *
   8  *              This program is free software; you can redistribute it and/or
   9  *              modify it under the terms of the GNU General Public License
  10  *              as published by the Free Software Foundation; either version
  11  *              2 of the License, or (at your option) any later version.
  12  *
  13  * Changes:
  14  *     Julian Anastasov        :    Added the missing (dest->weight>0)
  15  *                                  condition in the ip_vs_dest_set_max.
  16  *
  17  */
  18
  19 /*
  20  * The lblc/r algorithm is as follows (pseudo code):
  21  *
  22  *       if serverSet[dest_ip] is null then
  23  *               n, serverSet[dest_ip] <- {weighted least-conn node};
  24  *       else
  25  *               n <- {least-conn (alive) node in serverSet[dest_ip]};
  26  *               if (n is null) OR
  27  *                  (n.conns>n.weight AND
  28  *                   there is a node m with m.conns<m.weight/2) then
  29  *                   n <- {weighted least-conn node};
  30  *                   add n to serverSet[dest_ip];
  31  *               if |serverSet[dest_ip]| > 1 AND
  32  *                   now - serverSet[dest_ip].lastMod > T then
  33  *                   m <- {most conn node in serverSet[dest_ip]};
  34  *                   remove m from serverSet[dest_ip];
  35  *       if serverSet[dest_ip] changed then
  36  *               serverSet[dest_ip].lastMod <- now;
  37  *
  38  *       return n;
  39  *
  40  */
  41
  42 #include <linux/ip.h>
  43 #include <linux/module.h>
  44 #include <linux/kernel.h>
  45 #include <linux/skbuff.h>
  46 #include <linux/jiffies.h>
  47
  48 /* for sysctl */
  49 #include <linux/fs.h>
  50 #include <linux/sysctl.h>
  51 #include <net/net_namespace.h>
  52
  53 #include <net/ip_vs.h>
  54
  55
  56 /*
  57  *    It is for garbage collection of stale IPVS lblcr entries,
  58  *    when the table is full.
  59  */
  60 #define CHECK_EXPIRE_INTERVAL   (60*HZ)
  61 #define ENTRY_TIMEOUT           (6*60*HZ)
  62
  63 /*
  64  *    It is for full expiration check.
  65  *    When there is no partial expiration check (garbage collection)
  66  *    in a half hour, do a full expiration check to collect stale
  67  *    entries that haven't been touched for a day.
  68  */
  69 #define COUNT_FOR_FULL_EXPIRATION   30
  70 static int sysctl_ip_vs_lblcr_expiration = 24*60*60*HZ;
  71
  72
  73 /*
  74  *     for IPVS lblcr entry hash table
  75  */
  76 #ifndef CONFIG_IP_VS_LBLCR_TAB_BITS
  77 #define CONFIG_IP_VS_LBLCR_TAB_BITS      10
  78 #endif
  79 #define IP_VS_LBLCR_TAB_BITS     CONFIG_IP_VS_LBLCR_TAB_BITS
  80 #define IP_VS_LBLCR_TAB_SIZE     (1 << IP_VS_LBLCR_TAB_BITS)
  81 #define IP_VS_LBLCR_TAB_MASK     (IP_VS_LBLCR_TAB_SIZE - 1)
  82
  83
  84 /*
  85  *      IPVS destination set structure and operations
  86  */
  87 struct ip_vs_dest_list {
  88         struct ip_vs_dest_list  *next;          /* list link */
  89         struct ip_vs_dest       *dest;          /* destination server */
  90 };
  91
  92 struct ip_vs_dest_set {
  93         atomic_t                size;           /* set size */
  94         unsigned long           lastmod;        /* last modified time */
  95         struct ip_vs_dest_list  *list;          /* destination list */
  96         rwlock_t                lock;           /* lock for this list */
  97 };
  98
  99
 100 static struct ip_vs_dest_list *
 101 ip_vs_dest_set_insert(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
 102 {
 103         struct ip_vs_dest_list *e;
 104
 105         for (e=set->list; e!=NULL; e=e->next) {
 106                 if (e->dest == dest)
 107                         /* already existed */
 108                         return NULL;
 109         }
 110
 111         e = kmalloc(sizeof(struct ip_vs_dest_list), GFP_ATOMIC);
 112         if (e == NULL) {
 113                 IP_VS_ERR("ip_vs_dest_set_insert(): no memory\n");
 114                 return NULL;
 115         }
 116
 117         atomic_inc(&dest->refcnt);
 118         e->dest = dest;
 119
 120         /* link it to the list */
 121         write_lock(&set->lock);
 122         e->next = set->list;
 123         set->list = e;
 124         atomic_inc(&set->size);
 125         write_unlock(&set->lock);
 126
 127         set->lastmod = jiffies;
 128         return e;
 129 }
 130
 131 static void
 132 ip_vs_dest_set_erase(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
 133 {
 134         struct ip_vs_dest_list *e, **ep;
 135
 136         write_lock(&set->lock);
 137         for (ep=&set->list, e=*ep; e!=NULL; e=*ep) {
 138                 if (e->dest == dest) {
 139                         /* HIT */
 140                         *ep = e->next;
 141                         atomic_dec(&set->size);
 142                         set->lastmod = jiffies;
 143                         atomic_dec(&e->dest->refcnt);
 144                         kfree(e);
 145                         break;
 146                 }
 147                 ep = &e->next;
 148         }
 149         write_unlock(&set->lock);
 150 }
 151
 152 static void ip_vs_dest_set_eraseall(struct ip_vs_dest_set *set)
 153 {
 154         struct ip_vs_dest_list *e, **ep;
 155
 156         write_lock(&set->lock);
 157         for (ep=&set->list, e=*ep; e!=NULL; e=*ep) {
 158                 *ep = e->next;
 159                 /*
 160                  * We don't kfree dest because it is refered either
 161                  * by its service or by the trash dest list.
 162                  */
 163                 atomic_dec(&e->dest->refcnt);
 164                 kfree(e);
 165         }
 166         write_unlock(&set->lock);
 167 }
 168
 169 /* get weighted least-connection node in the destination set */
 170 static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
 171 {
 172         register struct ip_vs_dest_list *e;
 173         struct ip_vs_dest *dest, *least;
 174         int loh, doh;
 175
 176         if (set == NULL)
 177                 return NULL;
 178
 179         read_lock(&set->lock);
 180         /* select the first destination server, whose weight > 0 */
 181         for (e=set->list; e!=NULL; e=e->next) {
 182                 least = e->dest;
 183                 if (least->flags & IP_VS_DEST_F_OVERLOAD)
 184                         continue;
 185
 186                 if ((atomic_read(&least->weight) > 0)
 187                     && (least->flags & IP_VS_DEST_F_AVAILABLE)) {
 188                         loh = atomic_read(&least->activeconns) * 50
 189                                 + atomic_read(&least->inactconns);
 190                         goto nextstage;
 191                 }
 192         }
 193         read_unlock(&set->lock);
 194         return NULL;
 195
 196         /* find the destination with the weighted least load */
 197   nextstage:
 198         for (e=e->next; e!=NULL; e=e->next) {
 199                 dest = e->dest;
 200                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 201                         continue;
 202
 203                 doh = atomic_read(&dest->activeconns) * 50
 204                         + atomic_read(&dest->inactconns);
 205                 if ((loh * atomic_read(&dest->weight) >
 206                      doh * atomic_read(&least->weight))
 207                     && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
 208                         least = dest;
 209                         loh = doh;
 210                 }
 211         }
 212         read_unlock(&set->lock);
 213
 214         IP_VS_DBG(6, "ip_vs_dest_set_min: server %d.%d.%d.%d:%d "
 215                   "activeconns %d refcnt %d weight %d overhead %d\n",
 216                   NIPQUAD(least->addr), ntohs(least->port),
 217                   atomic_read(&least->activeconns),
 218                   atomic_read(&least->refcnt),
 219                   atomic_read(&least->weight), loh);
 220         return least;
 221 }
 222
 223
 224 /* get weighted most-connection node in the destination set */
 225 static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
 226 {
 227         register struct ip_vs_dest_list *e;
 228         struct ip_vs_dest *dest, *most;
 229         int moh, doh;
 230
 231         if (set == NULL)
 232                 return NULL;
 233
 234         read_lock(&set->lock);
 235         /* select the first destination server, whose weight > 0 */
 236         for (e=set->list; e!=NULL; e=e->next) {
 237                 most = e->dest;
 238                 if (atomic_read(&most->weight) > 0) {
 239                         moh = atomic_read(&most->activeconns) * 50
 240                                 + atomic_read(&most->inactconns);
 241                         goto nextstage;
 242                 }
 243         }
 244         read_unlock(&set->lock);
 245         return NULL;
 246
 247         /* find the destination with the weighted most load */
 248   nextstage:
 249         for (e=e->next; e!=NULL; e=e->next) {
 250                 dest = e->dest;
 251                 doh = atomic_read(&dest->activeconns) * 50
 252                         + atomic_read(&dest->inactconns);
 253                 /* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
 254                 if ((moh * atomic_read(&dest->weight) <
 255                      doh * atomic_read(&most->weight))
 256                     && (atomic_read(&dest->weight) > 0)) {
 257                         most = dest;
 258                         moh = doh;
 259                 }
 260         }
 261         read_unlock(&set->lock);
 262
 263         IP_VS_DBG(6, "ip_vs_dest_set_max: server %d.%d.%d.%d:%d "
 264                   "activeconns %d refcnt %d weight %d overhead %d\n",
 265                   NIPQUAD(most->addr), ntohs(most->port),
 266                   atomic_read(&most->activeconns),
 267                   atomic_read(&most->refcnt),
 268                   atomic_read(&most->weight), moh);
 269         return most;
 270 }
 271
 272
 273 /*
 274  *      IPVS lblcr entry represents an association between destination
 275  *      IP address and its destination server set
 276  */
 277 struct ip_vs_lblcr_entry {
 278         struct list_head        list;
 279         __be32                   addr;           /* destination IP address */
 280         struct ip_vs_dest_set   set;            /* destination server set */
 281         unsigned long           lastuse;        /* last used time */
 282 };
 283
 284
 285 /*
 286  *      IPVS lblcr hash table
 287  */
 288 struct ip_vs_lblcr_table {
 289         rwlock_t                lock;           /* lock for this table */
 290         struct list_head        bucket[IP_VS_LBLCR_TAB_SIZE];  /* hash bucket */
 291         atomic_t                entries;        /* number of entries */
 292         int                     max_size;       /* maximum size of entries */
 293         struct timer_list       periodic_timer; /* collect stale entries */
 294         int                     rover;          /* rover for expire check */
 295         int                     counter;        /* counter for no expire */
 296 };
 297
 298
 299 /*
 300  *      IPVS LBLCR sysctl table
 301  */
 302
 303 static ctl_table vs_vars_table[] = {
 304         {
 305                 .procname       = "lblcr_expiration",
 306                 .data           = &sysctl_ip_vs_lblcr_expiration,
 307                 .maxlen         = sizeof(int),
 308                 .mode           = 0644,
 309                 .proc_handler   = &proc_dointvec_jiffies,
 310         },
 311         { .ctl_name = 0 }
 312 };
 313
 314 static struct ctl_table_header * sysctl_header;
 315
 316 /*
 317  *      new/free a ip_vs_lblcr_entry, which is a mapping of a destination
 318  *      IP address to a server.
 319  */
 320 static inline struct ip_vs_lblcr_entry *ip_vs_lblcr_new(__be32 daddr)
 321 {
 322         struct ip_vs_lblcr_entry *en;
 323
 324         en = kmalloc(sizeof(struct ip_vs_lblcr_entry), GFP_ATOMIC);
 325         if (en == NULL) {
 326                 IP_VS_ERR("ip_vs_lblcr_new(): no memory\n");
 327                 return NULL;
 328         }
 329
 330         INIT_LIST_HEAD(&en->list);
 331         en->addr = daddr;
 332
 333         /* initilize its dest set */
 334         atomic_set(&(en->set.size), 0);
 335         en->set.list = NULL;
 336         rwlock_init(&en->set.lock);
 337
 338         return en;
 339 }
 340
 341
 342 static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
 343 {
 344         list_del(&en->list);
 345         ip_vs_dest_set_eraseall(&en->set);
 346         kfree(en);
 347 }
 348
 349
 350 /*
 351  *      Returns hash value for IPVS LBLCR entry
 352  */
 353 static inline unsigned ip_vs_lblcr_hashkey(__be32 addr)
 354 {
 355         return (ntohl(addr)*2654435761UL) & IP_VS_LBLCR_TAB_MASK;
 356 }
 357
 358
 359 /*
 360  *      Hash an entry in the ip_vs_lblcr_table.
 361  *      returns bool success.
 362  */
 363 static int
 364 ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
 365 {
 366         unsigned hash;
 367
 368         if (!list_empty(&en->list)) {
 369                 IP_VS_ERR("ip_vs_lblcr_hash(): request for already hashed, "
 370                           "called from %p\n", __builtin_return_address(0));
 371                 return 0;
 372         }
 373
 374         /*
 375          *      Hash by destination IP address
 376          */
 377         hash = ip_vs_lblcr_hashkey(en->addr);
 378
 379         write_lock(&tbl->lock);
 380         list_add(&en->list, &tbl->bucket[hash]);
 381         atomic_inc(&tbl->entries);
 382         write_unlock(&tbl->lock);
 383
 384         return 1;
 385 }
 386
 387
 388 /*
 389  *  Get ip_vs_lblcr_entry associated with supplied parameters.
 390  */
 391 static inline struct ip_vs_lblcr_entry *
 392 ip_vs_lblcr_get(struct ip_vs_lblcr_table *tbl, __be32 addr)
 393 {
 394         unsigned hash;
 395         struct ip_vs_lblcr_entry *en;
 396
 397         hash = ip_vs_lblcr_hashkey(addr);
 398
 399         read_lock(&tbl->lock);
 400
 401         list_for_each_entry(en, &tbl->bucket[hash], list) {
 402                 if (en->addr == addr) {
 403                         /* HIT */
 404                         read_unlock(&tbl->lock);
 405                         return en;
 406                 }
 407         }
 408
 409         read_unlock(&tbl->lock);
 410
 411         return NULL;
 412 }
 413
 414
 415 /*
 416  *      Flush all the entries of the specified table.
 417  */
 418 static void ip_vs_lblcr_flush(struct ip_vs_lblcr_table *tbl)
 419 {
 420         int i;
 421         struct ip_vs_lblcr_entry *en, *nxt;
 422
 423         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 424                 write_lock(&tbl->lock);
 425                 list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {
 426                         ip_vs_lblcr_free(en);
 427                         atomic_dec(&tbl->entries);
 428                 }
 429                 write_unlock(&tbl->lock);
 430         }
 431 }
 432
 433
 434 static inline void ip_vs_lblcr_full_check(struct ip_vs_lblcr_table *tbl)
 435 {
 436         unsigned long now = jiffies;
 437         int i, j;
 438         struct ip_vs_lblcr_entry *en, *nxt;
 439
 440         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 441                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 442
 443                 write_lock(&tbl->lock);
 444                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 445                         if (time_after(en->lastuse+sysctl_ip_vs_lblcr_expiration,
 446                                        now))
 447                                 continue;
 448
 449                         ip_vs_lblcr_free(en);
 450                         atomic_dec(&tbl->entries);
 451                 }
 452                 write_unlock(&tbl->lock);
 453         }
 454         tbl->rover = j;
 455 }
 456
 457
 458 /*
 459  *      Periodical timer handler for IPVS lblcr table
 460  *      It is used to collect stale entries when the number of entries
 461  *      exceeds the maximum size of the table.
 462  *
 463  *      Fixme: we probably need more complicated algorithm to collect
 464  *             entries that have not been used for a long time even
 465  *             if the number of entries doesn't exceed the maximum size
 466  *             of the table.
 467  *      The full expiration check is for this purpose now.
 468  */
 469 static void ip_vs_lblcr_check_expire(unsigned long data)
 470 {
 471         struct ip_vs_lblcr_table *tbl;
 472         unsigned long now = jiffies;
 473         int goal;
 474         int i, j;
 475         struct ip_vs_lblcr_entry *en, *nxt;
 476
 477         tbl = (struct ip_vs_lblcr_table *)data;
 478
 479         if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
 480                 /* do full expiration check */
 481                 ip_vs_lblcr_full_check(tbl);
 482                 tbl->counter = 1;
 483                 goto out;
 484         }
 485
 486         if (atomic_read(&tbl->entries) <= tbl->max_size) {
 487                 tbl->counter++;
 488                 goto out;
 489         }
 490
 491         goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3;
 492         if (goal > tbl->max_size/2)
 493                 goal = tbl->max_size/2;
 494
 495         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 496                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 497
 498                 write_lock(&tbl->lock);
 499                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 500                         if (time_before(now, en->lastuse+ENTRY_TIMEOUT))
 501                                 continue;
 502
 503                         ip_vs_lblcr_free(en);
 504                         atomic_dec(&tbl->entries);
 505                         goal--;
 506                 }
 507                 write_unlock(&tbl->lock);
 508                 if (goal <= 0)
 509                         break;
 510         }
 511         tbl->rover = j;
 512
 513   out:
 514         mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
 515 }
 516
 517 static int ip_vs_lblcr_init_svc(struct ip_vs_service *svc)
 518 {
 519         int i;
 520         struct ip_vs_lblcr_table *tbl;
 521
 522         /*
 523          *    Allocate the ip_vs_lblcr_table for this service
 524          */
 525         tbl = kmalloc(sizeof(struct ip_vs_lblcr_table), GFP_ATOMIC);
 526         if (tbl == NULL) {
 527                 IP_VS_ERR("ip_vs_lblcr_init_svc(): no memory\n");
 528                 return -ENOMEM;
 529         }
 530         svc->sched_data = tbl;
 531         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) allocated for "
 532                   "current service\n",
 533                   sizeof(struct ip_vs_lblcr_table));
 534
 535         /*
 536          *    Initialize the hash buckets
 537          */
 538         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 539                 INIT_LIST_HEAD(&tbl->bucket[i]);
 540         }
 541         rwlock_init(&tbl->lock);
 542         tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
 543         tbl->rover = 0;
 544         tbl->counter = 1;
 545
 546         /*
 547          *    Hook periodic timer for garbage collection
 548          */
 549         setup_timer(&tbl->periodic_timer, ip_vs_lblcr_check_expire,
 550                         (unsigned long)tbl);
 551         tbl->periodic_timer.expires = jiffies+CHECK_EXPIRE_INTERVAL;
 552         add_timer(&tbl->periodic_timer);
 553
 554         return 0;
 555 }
 556
 557
 558 static int ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
 559 {
 560         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 561
 562         /* remove periodic timer */
 563         del_timer_sync(&tbl->periodic_timer);
 564
 565         /* got to clean up table entries here */
 566         ip_vs_lblcr_flush(tbl);
 567
 568         /* release the table itself */
 569         kfree(svc->sched_data);
 570         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) released\n",
 571                   sizeof(struct ip_vs_lblcr_table));
 572
 573         return 0;
 574 }
 575
 576
 577 static int ip_vs_lblcr_update_svc(struct ip_vs_service *svc)
 578 {
 579         return 0;
 580 }
 581
 582
 583 static inline struct ip_vs_dest *
 584 __ip_vs_wlc_schedule(struct ip_vs_service *svc, struct iphdr *iph)
 585 {
 586         struct ip_vs_dest *dest, *least;
 587         int loh, doh;
 588
 589         /*
 590          * We think the overhead of processing active connections is fifty
 591          * times higher than that of inactive connections in average. (This
 592          * fifty times might not be accurate, we will change it later.) We
 593          * use the following formula to estimate the overhead:
 594          *                dest->activeconns*50 + dest->inactconns
 595          * and the load:
 596          *                (dest overhead) / dest->weight
 597          *
 598          * Remember -- no floats in kernel mode!!!
 599          * The comparison of h1*w2 > h2*w1 is equivalent to that of
 600          *                h1/w1 > h2/w2
 601          * if every weight is larger than zero.
 602          *
 603          * The server with weight=0 is quiesced and will not receive any
 604          * new connection.
 605          */
 606         list_for_each_entry(dest, &svc->destinations, n_list) {
 607                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 608                         continue;
 609
 610                 if (atomic_read(&dest->weight) > 0) {
 611                         least = dest;
 612                         loh = atomic_read(&least->activeconns) * 50
 613                                 + atomic_read(&least->inactconns);
 614                         goto nextstage;
 615                 }
 616         }
 617         return NULL;
 618
 619         /*
 620          *    Find the destination with the least load.
 621          */
 622   nextstage:
 623         list_for_each_entry_continue(dest, &svc->destinations, n_list) {
 624                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 625                         continue;
 626
 627                 doh = atomic_read(&dest->activeconns) * 50
 628                         + atomic_read(&dest->inactconns);
 629                 if (loh * atomic_read(&dest->weight) >
 630                     doh * atomic_read(&least->weight)) {
 631                         least = dest;
 632                         loh = doh;
 633                 }
 634         }
 635
 636         IP_VS_DBG(6, "LBLCR: server %d.%d.%d.%d:%d "
 637                   "activeconns %d refcnt %d weight %d overhead %d\n",
 638                   NIPQUAD(least->addr), ntohs(least->port),
 639                   atomic_read(&least->activeconns),
 640                   atomic_read(&least->refcnt),
 641                   atomic_read(&least->weight), loh);
 642
 643         return least;
 644 }
 645
 646
 647 /*
 648  *   If this destination server is overloaded and there is a less loaded
 649  *   server, then return true.
 650  */
 651 static inline int
 652 is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
 653 {
 654         if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
 655                 struct ip_vs_dest *d;
 656
 657                 list_for_each_entry(d, &svc->destinations, n_list) {
 658                         if (atomic_read(&d->activeconns)*2
 659                             < atomic_read(&d->weight)) {
 660                                 return 1;
 661                         }
 662                 }
 663         }
 664         return 0;
 665 }
 666
 667
 668 /*
 669  *    Locality-Based (weighted) Least-Connection scheduling
 670  */
 671 static struct ip_vs_dest *
 672 ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
 673 {
 674         struct ip_vs_dest *dest;
 675         struct ip_vs_lblcr_table *tbl;
 676         struct ip_vs_lblcr_entry *en;
 677         struct iphdr *iph = ip_hdr(skb);
 678
 679         IP_VS_DBG(6, "ip_vs_lblcr_schedule(): Scheduling...\n");
 680
 681         tbl = (struct ip_vs_lblcr_table *)svc->sched_data;
 682         en = ip_vs_lblcr_get(tbl, iph->daddr);
 683         if (en == NULL) {
 684                 dest = __ip_vs_wlc_schedule(svc, iph);
 685                 if (dest == NULL) {
 686                         IP_VS_DBG(1, "no destination available\n");
 687                         return NULL;
 688                 }
 689                 en = ip_vs_lblcr_new(iph->daddr);
 690                 if (en == NULL) {
 691                         return NULL;
 692                 }
 693                 ip_vs_dest_set_insert(&en->set, dest);
 694                 ip_vs_lblcr_hash(tbl, en);
 695         } else {
 696                 dest = ip_vs_dest_set_min(&en->set);
 697                 if (!dest || is_overloaded(dest, svc)) {
 698                         dest = __ip_vs_wlc_schedule(svc, iph);
 699                         if (dest == NULL) {
 700                                 IP_VS_DBG(1, "no destination available\n");
 701                                 return NULL;
 702                         }
 703                         ip_vs_dest_set_insert(&en->set, dest);
 704                 }
 705                 if (atomic_read(&en->set.size) > 1 &&
 706                     jiffies-en->set.lastmod > sysctl_ip_vs_lblcr_expiration) {
 707                         struct ip_vs_dest *m;
 708                         m = ip_vs_dest_set_max(&en->set);
 709                         if (m)
 710                                 ip_vs_dest_set_erase(&en->set, m);
 711                 }
 712         }
 713         en->lastuse = jiffies;
 714
 715         IP_VS_DBG(6, "LBLCR: destination IP address %u.%u.%u.%u "
 716                   "--> server %u.%u.%u.%u:%d\n",
 717                   NIPQUAD(en->addr),
 718                   NIPQUAD(dest->addr),
 719                   ntohs(dest->port));
 720
 721         return dest;
 722 }
 723
 724
 725 /*
 726  *      IPVS LBLCR Scheduler structure
 727  */
 728 static struct ip_vs_scheduler ip_vs_lblcr_scheduler =
 729 {
 730         .name =                 "lblcr",
 731         .refcnt =               ATOMIC_INIT(0),
 732         .module =               THIS_MODULE,
 733         .init_service =         ip_vs_lblcr_init_svc,
 734         .done_service =         ip_vs_lblcr_done_svc,
 735         .update_service =       ip_vs_lblcr_update_svc,
 736         .schedule =             ip_vs_lblcr_schedule,
 737 };
 738
 739
 740 static int __init ip_vs_lblcr_init(void)
 741 {
 742         int ret;
 743
 744         INIT_LIST_HEAD(&ip_vs_lblcr_scheduler.n_list);
 745         sysctl_header = register_sysctl_paths(net_vs_ctl_path, vs_vars_table);
 746         ret = register_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 747         if (ret)
 748                 unregister_sysctl_table(sysctl_header);
 749         return ret;
 750 }
 751
 752
 753 static void __exit ip_vs_lblcr_cleanup(void)
 754 {
 755         unregister_sysctl_table(sysctl_header);
 756         unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 757 }
 758
 759
 760 module_init(ip_vs_lblcr_init);
 761 module_exit(ip_vs_lblcr_cleanup);
 762 MODULE_LICENSE("GPL");