net/ipv4/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(struct ip_vs_dest_list), 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         write_lock(&set->lock);
 120         e->next = set->list;
 121         set->list = e;
 122         atomic_inc(&set->size);
 123         write_unlock(&set->lock);
 124
 125         set->lastmod = jiffies;
 126         return e;
 127 }
 128
 129 static void
 130 ip_vs_dest_set_erase(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
 131 {
 132         struct ip_vs_dest_list *e, **ep;
 133
 134         write_lock(&set->lock);
 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         write_unlock(&set->lock);
 148 }
 149
 150 static void ip_vs_dest_set_eraseall(struct ip_vs_dest_set *set)
 151 {
 152         struct ip_vs_dest_list *e, **ep;
 153
 154         write_lock(&set->lock);
 155         for (ep=&set->list, e=*ep; e!=NULL; e=*ep) {
 156                 *ep = e->next;
 157                 /*
 158                  * We don't kfree dest because it is refered either
 159                  * by its service or by the trash dest list.
 160                  */
 161                 atomic_dec(&e->dest->refcnt);
 162                 kfree(e);
 163         }
 164         write_unlock(&set->lock);
 165 }
 166
 167 /* get weighted least-connection node in the destination set */
 168 static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
 169 {
 170         register struct ip_vs_dest_list *e;
 171         struct ip_vs_dest *dest, *least;
 172         int loh, doh;
 173
 174         if (set == NULL)
 175                 return NULL;
 176
 177         read_lock(&set->lock);
 178         /* select the first destination server, whose weight > 0 */
 179         for (e=set->list; e!=NULL; e=e->next) {
 180                 least = e->dest;
 181                 if (least->flags & IP_VS_DEST_F_OVERLOAD)
 182                         continue;
 183
 184                 if ((atomic_read(&least->weight) > 0)
 185                     && (least->flags & IP_VS_DEST_F_AVAILABLE)) {
 186                         loh = atomic_read(&least->activeconns) * 50
 187                                 + atomic_read(&least->inactconns);
 188                         goto nextstage;
 189                 }
 190         }
 191         read_unlock(&set->lock);
 192         return NULL;
 193
 194         /* find the destination with the weighted least load */
 195   nextstage:
 196         for (e=e->next; e!=NULL; e=e->next) {
 197                 dest = e->dest;
 198                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 199                         continue;
 200
 201                 doh = atomic_read(&dest->activeconns) * 50
 202                         + atomic_read(&dest->inactconns);
 203                 if ((loh * atomic_read(&dest->weight) >
 204                      doh * atomic_read(&least->weight))
 205                     && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
 206                         least = dest;
 207                         loh = doh;
 208                 }
 209         }
 210         read_unlock(&set->lock);
 211
 212         IP_VS_DBG(6, "ip_vs_dest_set_min: server %d.%d.%d.%d:%d "
 213                   "activeconns %d refcnt %d weight %d overhead %d\n",
 214                   NIPQUAD(least->addr), ntohs(least->port),
 215                   atomic_read(&least->activeconns),
 216                   atomic_read(&least->refcnt),
 217                   atomic_read(&least->weight), loh);
 218         return least;
 219 }
 220
 221
 222 /* get weighted most-connection node in the destination set */
 223 static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
 224 {
 225         register struct ip_vs_dest_list *e;
 226         struct ip_vs_dest *dest, *most;
 227         int moh, doh;
 228
 229         if (set == NULL)
 230                 return NULL;
 231
 232         read_lock(&set->lock);
 233         /* select the first destination server, whose weight > 0 */
 234         for (e=set->list; e!=NULL; e=e->next) {
 235                 most = e->dest;
 236                 if (atomic_read(&most->weight) > 0) {
 237                         moh = atomic_read(&most->activeconns) * 50
 238                                 + atomic_read(&most->inactconns);
 239                         goto nextstage;
 240                 }
 241         }
 242         read_unlock(&set->lock);
 243         return NULL;
 244
 245         /* find the destination with the weighted most load */
 246   nextstage:
 247         for (e=e->next; e!=NULL; e=e->next) {
 248                 dest = e->dest;
 249                 doh = atomic_read(&dest->activeconns) * 50
 250                         + atomic_read(&dest->inactconns);
 251                 /* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
 252                 if ((moh * atomic_read(&dest->weight) <
 253                      doh * atomic_read(&most->weight))
 254                     && (atomic_read(&dest->weight) > 0)) {
 255                         most = dest;
 256                         moh = doh;
 257                 }
 258         }
 259         read_unlock(&set->lock);
 260
 261         IP_VS_DBG(6, "ip_vs_dest_set_max: server %d.%d.%d.%d:%d "
 262                   "activeconns %d refcnt %d weight %d overhead %d\n",
 263                   NIPQUAD(most->addr), ntohs(most->port),
 264                   atomic_read(&most->activeconns),
 265                   atomic_read(&most->refcnt),
 266                   atomic_read(&most->weight), moh);
 267         return most;
 268 }
 269
 270
 271 /*
 272  *      IPVS lblcr entry represents an association between destination
 273  *      IP address and its destination server set
 274  */
 275 struct ip_vs_lblcr_entry {
 276         struct list_head        list;
 277         __be32                   addr;           /* destination IP address */
 278         struct ip_vs_dest_set   set;            /* destination server set */
 279         unsigned long           lastuse;        /* last used time */
 280 };
 281
 282
 283 /*
 284  *      IPVS lblcr hash table
 285  */
 286 struct ip_vs_lblcr_table {
 287         rwlock_t                lock;           /* lock for this table */
 288         struct list_head        bucket[IP_VS_LBLCR_TAB_SIZE];  /* hash bucket */
 289         atomic_t                entries;        /* number of entries */
 290         int                     max_size;       /* maximum size of entries */
 291         struct timer_list       periodic_timer; /* collect stale entries */
 292         int                     rover;          /* rover for expire check */
 293         int                     counter;        /* counter for no expire */
 294 };
 295
 296
 297 /*
 298  *      IPVS LBLCR sysctl table
 299  */
 300
 301 static ctl_table vs_vars_table[] = {
 302         {
 303                 .procname       = "lblcr_expiration",
 304                 .data           = &sysctl_ip_vs_lblcr_expiration,
 305                 .maxlen         = sizeof(int),
 306                 .mode           = 0644,
 307                 .proc_handler   = &proc_dointvec_jiffies,
 308         },
 309         { .ctl_name = 0 }
 310 };
 311
 312 static struct ctl_table_header * sysctl_header;
 313
 314 /*
 315  *      new/free a ip_vs_lblcr_entry, which is a mapping of a destination
 316  *      IP address to a server.
 317  */
 318 static inline struct ip_vs_lblcr_entry *ip_vs_lblcr_new(__be32 daddr)
 319 {
 320         struct ip_vs_lblcr_entry *en;
 321
 322         en = kmalloc(sizeof(struct ip_vs_lblcr_entry), GFP_ATOMIC);
 323         if (en == NULL) {
 324                 IP_VS_ERR("ip_vs_lblcr_new(): no memory\n");
 325                 return NULL;
 326         }
 327
 328         INIT_LIST_HEAD(&en->list);
 329         en->addr = daddr;
 330
 331         /* initilize its dest set */
 332         atomic_set(&(en->set.size), 0);
 333         en->set.list = NULL;
 334         rwlock_init(&en->set.lock);
 335
 336         return en;
 337 }
 338
 339
 340 static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
 341 {
 342         list_del(&en->list);
 343         ip_vs_dest_set_eraseall(&en->set);
 344         kfree(en);
 345 }
 346
 347
 348 /*
 349  *      Returns hash value for IPVS LBLCR entry
 350  */
 351 static inline unsigned ip_vs_lblcr_hashkey(__be32 addr)
 352 {
 353         return (ntohl(addr)*2654435761UL) & IP_VS_LBLCR_TAB_MASK;
 354 }
 355
 356
 357 /*
 358  *      Hash an entry in the ip_vs_lblcr_table.
 359  *      returns bool success.
 360  */
 361 static int
 362 ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
 363 {
 364         unsigned hash;
 365
 366         if (!list_empty(&en->list)) {
 367                 IP_VS_ERR("ip_vs_lblcr_hash(): request for already hashed, "
 368                           "called from %p\n", __builtin_return_address(0));
 369                 return 0;
 370         }
 371
 372         /*
 373          *      Hash by destination IP address
 374          */
 375         hash = ip_vs_lblcr_hashkey(en->addr);
 376
 377         write_lock(&tbl->lock);
 378         list_add(&en->list, &tbl->bucket[hash]);
 379         atomic_inc(&tbl->entries);
 380         write_unlock(&tbl->lock);
 381
 382         return 1;
 383 }
 384
 385
 386 /*
 387  *  Get ip_vs_lblcr_entry associated with supplied parameters.
 388  */
 389 static inline struct ip_vs_lblcr_entry *
 390 ip_vs_lblcr_get(struct ip_vs_lblcr_table *tbl, __be32 addr)
 391 {
 392         unsigned hash;
 393         struct ip_vs_lblcr_entry *en;
 394
 395         hash = ip_vs_lblcr_hashkey(addr);
 396
 397         read_lock(&tbl->lock);
 398
 399         list_for_each_entry(en, &tbl->bucket[hash], list) {
 400                 if (en->addr == addr) {
 401                         /* HIT */
 402                         read_unlock(&tbl->lock);
 403                         return en;
 404                 }
 405         }
 406
 407         read_unlock(&tbl->lock);
 408
 409         return NULL;
 410 }
 411
 412
 413 /*
 414  *      Flush all the entries of the specified table.
 415  */
 416 static void ip_vs_lblcr_flush(struct ip_vs_lblcr_table *tbl)
 417 {
 418         int i;
 419         struct ip_vs_lblcr_entry *en, *nxt;
 420
 421         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 422                 write_lock(&tbl->lock);
 423                 list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {
 424                         ip_vs_lblcr_free(en);
 425                         atomic_dec(&tbl->entries);
 426                 }
 427                 write_unlock(&tbl->lock);
 428         }
 429 }
 430
 431
 432 static inline void ip_vs_lblcr_full_check(struct ip_vs_lblcr_table *tbl)
 433 {
 434         unsigned long now = jiffies;
 435         int i, j;
 436         struct ip_vs_lblcr_entry *en, *nxt;
 437
 438         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 439                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 440
 441                 write_lock(&tbl->lock);
 442                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 443                         if (time_after(en->lastuse+sysctl_ip_vs_lblcr_expiration,
 444                                        now))
 445                                 continue;
 446
 447                         ip_vs_lblcr_free(en);
 448                         atomic_dec(&tbl->entries);
 449                 }
 450                 write_unlock(&tbl->lock);
 451         }
 452         tbl->rover = j;
 453 }
 454
 455
 456 /*
 457  *      Periodical timer handler for IPVS lblcr table
 458  *      It is used to collect stale entries when the number of entries
 459  *      exceeds the maximum size of the table.
 460  *
 461  *      Fixme: we probably need more complicated algorithm to collect
 462  *             entries that have not been used for a long time even
 463  *             if the number of entries doesn't exceed the maximum size
 464  *             of the table.
 465  *      The full expiration check is for this purpose now.
 466  */
 467 static void ip_vs_lblcr_check_expire(unsigned long data)
 468 {
 469         struct ip_vs_lblcr_table *tbl;
 470         unsigned long now = jiffies;
 471         int goal;
 472         int i, j;
 473         struct ip_vs_lblcr_entry *en, *nxt;
 474
 475         tbl = (struct ip_vs_lblcr_table *)data;
 476
 477         if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
 478                 /* do full expiration check */
 479                 ip_vs_lblcr_full_check(tbl);
 480                 tbl->counter = 1;
 481                 goto out;
 482         }
 483
 484         if (atomic_read(&tbl->entries) <= tbl->max_size) {
 485                 tbl->counter++;
 486                 goto out;
 487         }
 488
 489         goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3;
 490         if (goal > tbl->max_size/2)
 491                 goal = tbl->max_size/2;
 492
 493         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 494                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 495
 496                 write_lock(&tbl->lock);
 497                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 498                         if (time_before(now, en->lastuse+ENTRY_TIMEOUT))
 499                                 continue;
 500
 501                         ip_vs_lblcr_free(en);
 502                         atomic_dec(&tbl->entries);
 503                         goal--;
 504                 }
 505                 write_unlock(&tbl->lock);
 506                 if (goal <= 0)
 507                         break;
 508         }
 509         tbl->rover = j;
 510
 511   out:
 512         mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
 513 }
 514
 515 static int ip_vs_lblcr_init_svc(struct ip_vs_service *svc)
 516 {
 517         int i;
 518         struct ip_vs_lblcr_table *tbl;
 519
 520         /*
 521          *    Allocate the ip_vs_lblcr_table for this service
 522          */
 523         tbl = kmalloc(sizeof(struct ip_vs_lblcr_table), GFP_ATOMIC);
 524         if (tbl == NULL) {
 525                 IP_VS_ERR("ip_vs_lblcr_init_svc(): no memory\n");
 526                 return -ENOMEM;
 527         }
 528         svc->sched_data = tbl;
 529         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) allocated for "
 530                   "current service\n",
 531                   sizeof(struct ip_vs_lblcr_table));
 532
 533         /*
 534          *    Initialize the hash buckets
 535          */
 536         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 537                 INIT_LIST_HEAD(&tbl->bucket[i]);
 538         }
 539         rwlock_init(&tbl->lock);
 540         tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
 541         tbl->rover = 0;
 542         tbl->counter = 1;
 543
 544         /*
 545          *    Hook periodic timer for garbage collection
 546          */
 547         setup_timer(&tbl->periodic_timer, ip_vs_lblcr_check_expire,
 548                         (unsigned long)tbl);
 549         tbl->periodic_timer.expires = jiffies+CHECK_EXPIRE_INTERVAL;
 550         add_timer(&tbl->periodic_timer);
 551
 552         return 0;
 553 }
 554
 555
 556 static int ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
 557 {
 558         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 559
 560         /* remove periodic timer */
 561         del_timer_sync(&tbl->periodic_timer);
 562
 563         /* got to clean up table entries here */
 564         ip_vs_lblcr_flush(tbl);
 565
 566         /* release the table itself */
 567         kfree(svc->sched_data);
 568         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) released\n",
 569                   sizeof(struct ip_vs_lblcr_table));
 570
 571         return 0;
 572 }
 573
 574
 575 static inline struct ip_vs_dest *
 576 __ip_vs_lblcr_schedule(struct ip_vs_service *svc, struct iphdr *iph)
 577 {
 578         struct ip_vs_dest *dest, *least;
 579         int loh, doh;
 580
 581         /*
 582          * We think the overhead of processing active connections is fifty
 583          * times higher than that of inactive connections in average. (This
 584          * fifty times might not be accurate, we will change it later.) We
 585          * use the following formula to estimate the overhead:
 586          *                dest->activeconns*50 + dest->inactconns
 587          * and the load:
 588          *                (dest overhead) / dest->weight
 589          *
 590          * Remember -- no floats in kernel mode!!!
 591          * The comparison of h1*w2 > h2*w1 is equivalent to that of
 592          *                h1/w1 > h2/w2
 593          * if every weight is larger than zero.
 594          *
 595          * The server with weight=0 is quiesced and will not receive any
 596          * new connection.
 597          */
 598         list_for_each_entry(dest, &svc->destinations, n_list) {
 599                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 600                         continue;
 601
 602                 if (atomic_read(&dest->weight) > 0) {
 603                         least = dest;
 604                         loh = atomic_read(&least->activeconns) * 50
 605                                 + atomic_read(&least->inactconns);
 606                         goto nextstage;
 607                 }
 608         }
 609         return NULL;
 610
 611         /*
 612          *    Find the destination with the least load.
 613          */
 614   nextstage:
 615         list_for_each_entry_continue(dest, &svc->destinations, n_list) {
 616                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 617                         continue;
 618
 619                 doh = atomic_read(&dest->activeconns) * 50
 620                         + atomic_read(&dest->inactconns);
 621                 if (loh * atomic_read(&dest->weight) >
 622                     doh * atomic_read(&least->weight)) {
 623                         least = dest;
 624                         loh = doh;
 625                 }
 626         }
 627
 628         IP_VS_DBG(6, "LBLCR: server %d.%d.%d.%d:%d "
 629                   "activeconns %d refcnt %d weight %d overhead %d\n",
 630                   NIPQUAD(least->addr), ntohs(least->port),
 631                   atomic_read(&least->activeconns),
 632                   atomic_read(&least->refcnt),
 633                   atomic_read(&least->weight), loh);
 634
 635         return least;
 636 }
 637
 638
 639 /*
 640  *   If this destination server is overloaded and there is a less loaded
 641  *   server, then return true.
 642  */
 643 static inline int
 644 is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
 645 {
 646         if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
 647                 struct ip_vs_dest *d;
 648
 649                 list_for_each_entry(d, &svc->destinations, n_list) {
 650                         if (atomic_read(&d->activeconns)*2
 651                             < atomic_read(&d->weight)) {
 652                                 return 1;
 653                         }
 654                 }
 655         }
 656         return 0;
 657 }
 658
 659
 660 /*
 661  *    Locality-Based (weighted) Least-Connection scheduling
 662  */
 663 static struct ip_vs_dest *
 664 ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
 665 {
 666         struct ip_vs_dest *dest;
 667         struct ip_vs_lblcr_table *tbl;
 668         struct ip_vs_lblcr_entry *en;
 669         struct iphdr *iph = ip_hdr(skb);
 670
 671         IP_VS_DBG(6, "ip_vs_lblcr_schedule(): Scheduling...\n");
 672
 673         tbl = (struct ip_vs_lblcr_table *)svc->sched_data;
 674         en = ip_vs_lblcr_get(tbl, iph->daddr);
 675         if (en == NULL) {
 676                 dest = __ip_vs_lblcr_schedule(svc, iph);
 677                 if (dest == NULL) {
 678                         IP_VS_DBG(1, "no destination available\n");
 679                         return NULL;
 680                 }
 681                 en = ip_vs_lblcr_new(iph->daddr);
 682                 if (en == NULL) {
 683                         return NULL;
 684                 }
 685                 ip_vs_dest_set_insert(&en->set, dest);
 686                 ip_vs_lblcr_hash(tbl, en);
 687         } else {
 688                 dest = ip_vs_dest_set_min(&en->set);
 689                 if (!dest || is_overloaded(dest, svc)) {
 690                         dest = __ip_vs_lblcr_schedule(svc, iph);
 691                         if (dest == NULL) {
 692                                 IP_VS_DBG(1, "no destination available\n");
 693                                 return NULL;
 694                         }
 695                         ip_vs_dest_set_insert(&en->set, dest);
 696                 }
 697                 if (atomic_read(&en->set.size) > 1 &&
 698                     jiffies-en->set.lastmod > sysctl_ip_vs_lblcr_expiration) {
 699                         struct ip_vs_dest *m;
 700                         m = ip_vs_dest_set_max(&en->set);
 701                         if (m)
 702                                 ip_vs_dest_set_erase(&en->set, m);
 703                 }
 704         }
 705         en->lastuse = jiffies;
 706
 707         IP_VS_DBG(6, "LBLCR: destination IP address %u.%u.%u.%u "
 708                   "--> server %u.%u.%u.%u:%d\n",
 709                   NIPQUAD(en->addr),
 710                   NIPQUAD(dest->addr),
 711                   ntohs(dest->port));
 712
 713         return dest;
 714 }
 715
 716
 717 /*
 718  *      IPVS LBLCR Scheduler structure
 719  */
 720 static struct ip_vs_scheduler ip_vs_lblcr_scheduler =
 721 {
 722         .name =                 "lblcr",
 723         .refcnt =               ATOMIC_INIT(0),
 724         .module =               THIS_MODULE,
 725         .n_list =               LIST_HEAD_INIT(ip_vs_lblcr_scheduler.n_list),
 726         .init_service =         ip_vs_lblcr_init_svc,
 727         .done_service =         ip_vs_lblcr_done_svc,
 728         .schedule =             ip_vs_lblcr_schedule,
 729 };
 730
 731
 732 static int __init ip_vs_lblcr_init(void)
 733 {
 734         int ret;
 735
 736         sysctl_header = register_sysctl_paths(net_vs_ctl_path, vs_vars_table);
 737         ret = register_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 738         if (ret)
 739                 unregister_sysctl_table(sysctl_header);
 740         return ret;
 741 }
 742
 743
 744 static void __exit ip_vs_lblcr_cleanup(void)
 745 {
 746         unregister_sysctl_table(sysctl_header);
 747         unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 748 }
 749
 750
 751 module_init(ip_vs_lblcr_init);
 752 module_exit(ip_vs_lblcr_cleanup);
 753 MODULE_LICENSE("GPL");