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 ctl_table vs_table[] = {
 315         {
 316                 .ctl_name       = NET_IPV4_VS,
 317                 .procname       = "vs",
 318                 .mode           = 0555,
 319                 .child          = vs_vars_table
 320         },
 321         { .ctl_name = 0 }
 322 };
 323
 324 static ctl_table ipvs_ipv4_table[] = {
 325         {
 326                 .ctl_name       = NET_IPV4,
 327                 .procname       = "ipv4",
 328                 .mode           = 0555,
 329                 .child          = vs_table
 330         },
 331         { .ctl_name = 0 }
 332 };
 333
 334 static ctl_table lblcr_root_table[] = {
 335         {
 336                 .ctl_name       = CTL_NET,
 337                 .procname       = "net",
 338                 .mode           = 0555,
 339                 .child          = ipvs_ipv4_table
 340         },
 341         { .ctl_name = 0 }
 342 };
 343
 344 static struct ctl_table_header * sysctl_header;
 345
 346 /*
 347  *      new/free a ip_vs_lblcr_entry, which is a mapping of a destination
 348  *      IP address to a server.
 349  */
 350 static inline struct ip_vs_lblcr_entry *ip_vs_lblcr_new(__be32 daddr)
 351 {
 352         struct ip_vs_lblcr_entry *en;
 353
 354         en = kmalloc(sizeof(struct ip_vs_lblcr_entry), GFP_ATOMIC);
 355         if (en == NULL) {
 356                 IP_VS_ERR("ip_vs_lblcr_new(): no memory\n");
 357                 return NULL;
 358         }
 359
 360         INIT_LIST_HEAD(&en->list);
 361         en->addr = daddr;
 362
 363         /* initilize its dest set */
 364         atomic_set(&(en->set.size), 0);
 365         en->set.list = NULL;
 366         rwlock_init(&en->set.lock);
 367
 368         return en;
 369 }
 370
 371
 372 static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
 373 {
 374         list_del(&en->list);
 375         ip_vs_dest_set_eraseall(&en->set);
 376         kfree(en);
 377 }
 378
 379
 380 /*
 381  *      Returns hash value for IPVS LBLCR entry
 382  */
 383 static inline unsigned ip_vs_lblcr_hashkey(__be32 addr)
 384 {
 385         return (ntohl(addr)*2654435761UL) & IP_VS_LBLCR_TAB_MASK;
 386 }
 387
 388
 389 /*
 390  *      Hash an entry in the ip_vs_lblcr_table.
 391  *      returns bool success.
 392  */
 393 static int
 394 ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
 395 {
 396         unsigned hash;
 397
 398         if (!list_empty(&en->list)) {
 399                 IP_VS_ERR("ip_vs_lblcr_hash(): request for already hashed, "
 400                           "called from %p\n", __builtin_return_address(0));
 401                 return 0;
 402         }
 403
 404         /*
 405          *      Hash by destination IP address
 406          */
 407         hash = ip_vs_lblcr_hashkey(en->addr);
 408
 409         write_lock(&tbl->lock);
 410         list_add(&en->list, &tbl->bucket[hash]);
 411         atomic_inc(&tbl->entries);
 412         write_unlock(&tbl->lock);
 413
 414         return 1;
 415 }
 416
 417
 418 /*
 419  *  Get ip_vs_lblcr_entry associated with supplied parameters.
 420  */
 421 static inline struct ip_vs_lblcr_entry *
 422 ip_vs_lblcr_get(struct ip_vs_lblcr_table *tbl, __be32 addr)
 423 {
 424         unsigned hash;
 425         struct ip_vs_lblcr_entry *en;
 426
 427         hash = ip_vs_lblcr_hashkey(addr);
 428
 429         read_lock(&tbl->lock);
 430
 431         list_for_each_entry(en, &tbl->bucket[hash], list) {
 432                 if (en->addr == addr) {
 433                         /* HIT */
 434                         read_unlock(&tbl->lock);
 435                         return en;
 436                 }
 437         }
 438
 439         read_unlock(&tbl->lock);
 440
 441         return NULL;
 442 }
 443
 444
 445 /*
 446  *      Flush all the entries of the specified table.
 447  */
 448 static void ip_vs_lblcr_flush(struct ip_vs_lblcr_table *tbl)
 449 {
 450         int i;
 451         struct ip_vs_lblcr_entry *en, *nxt;
 452
 453         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 454                 write_lock(&tbl->lock);
 455                 list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {
 456                         ip_vs_lblcr_free(en);
 457                         atomic_dec(&tbl->entries);
 458                 }
 459                 write_unlock(&tbl->lock);
 460         }
 461 }
 462
 463
 464 static inline void ip_vs_lblcr_full_check(struct ip_vs_lblcr_table *tbl)
 465 {
 466         unsigned long now = jiffies;
 467         int i, j;
 468         struct ip_vs_lblcr_entry *en, *nxt;
 469
 470         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 471                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 472
 473                 write_lock(&tbl->lock);
 474                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 475                         if (time_after(en->lastuse+sysctl_ip_vs_lblcr_expiration,
 476                                        now))
 477                                 continue;
 478
 479                         ip_vs_lblcr_free(en);
 480                         atomic_dec(&tbl->entries);
 481                 }
 482                 write_unlock(&tbl->lock);
 483         }
 484         tbl->rover = j;
 485 }
 486
 487
 488 /*
 489  *      Periodical timer handler for IPVS lblcr table
 490  *      It is used to collect stale entries when the number of entries
 491  *      exceeds the maximum size of the table.
 492  *
 493  *      Fixme: we probably need more complicated algorithm to collect
 494  *             entries that have not been used for a long time even
 495  *             if the number of entries doesn't exceed the maximum size
 496  *             of the table.
 497  *      The full expiration check is for this purpose now.
 498  */
 499 static void ip_vs_lblcr_check_expire(unsigned long data)
 500 {
 501         struct ip_vs_lblcr_table *tbl;
 502         unsigned long now = jiffies;
 503         int goal;
 504         int i, j;
 505         struct ip_vs_lblcr_entry *en, *nxt;
 506
 507         tbl = (struct ip_vs_lblcr_table *)data;
 508
 509         if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
 510                 /* do full expiration check */
 511                 ip_vs_lblcr_full_check(tbl);
 512                 tbl->counter = 1;
 513                 goto out;
 514         }
 515
 516         if (atomic_read(&tbl->entries) <= tbl->max_size) {
 517                 tbl->counter++;
 518                 goto out;
 519         }
 520
 521         goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3;
 522         if (goal > tbl->max_size/2)
 523                 goal = tbl->max_size/2;
 524
 525         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 526                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 527
 528                 write_lock(&tbl->lock);
 529                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 530                         if (time_before(now, en->lastuse+ENTRY_TIMEOUT))
 531                                 continue;
 532
 533                         ip_vs_lblcr_free(en);
 534                         atomic_dec(&tbl->entries);
 535                         goal--;
 536                 }
 537                 write_unlock(&tbl->lock);
 538                 if (goal <= 0)
 539                         break;
 540         }
 541         tbl->rover = j;
 542
 543   out:
 544         mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
 545 }
 546
 547 static int ip_vs_lblcr_init_svc(struct ip_vs_service *svc)
 548 {
 549         int i;
 550         struct ip_vs_lblcr_table *tbl;
 551
 552         /*
 553          *    Allocate the ip_vs_lblcr_table for this service
 554          */
 555         tbl = kmalloc(sizeof(struct ip_vs_lblcr_table), GFP_ATOMIC);
 556         if (tbl == NULL) {
 557                 IP_VS_ERR("ip_vs_lblcr_init_svc(): no memory\n");
 558                 return -ENOMEM;
 559         }
 560         svc->sched_data = tbl;
 561         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) allocated for "
 562                   "current service\n",
 563                   sizeof(struct ip_vs_lblcr_table));
 564
 565         /*
 566          *    Initialize the hash buckets
 567          */
 568         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 569                 INIT_LIST_HEAD(&tbl->bucket[i]);
 570         }
 571         rwlock_init(&tbl->lock);
 572         tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
 573         tbl->rover = 0;
 574         tbl->counter = 1;
 575
 576         /*
 577          *    Hook periodic timer for garbage collection
 578          */
 579         init_timer(&tbl->periodic_timer);
 580         tbl->periodic_timer.data = (unsigned long)tbl;
 581         tbl->periodic_timer.function = ip_vs_lblcr_check_expire;
 582         tbl->periodic_timer.expires = jiffies+CHECK_EXPIRE_INTERVAL;
 583         add_timer(&tbl->periodic_timer);
 584
 585         return 0;
 586 }
 587
 588
 589 static int ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
 590 {
 591         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 592
 593         /* remove periodic timer */
 594         del_timer_sync(&tbl->periodic_timer);
 595
 596         /* got to clean up table entries here */
 597         ip_vs_lblcr_flush(tbl);
 598
 599         /* release the table itself */
 600         kfree(svc->sched_data);
 601         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) released\n",
 602                   sizeof(struct ip_vs_lblcr_table));
 603
 604         return 0;
 605 }
 606
 607
 608 static int ip_vs_lblcr_update_svc(struct ip_vs_service *svc)
 609 {
 610         return 0;
 611 }
 612
 613
 614 static inline struct ip_vs_dest *
 615 __ip_vs_wlc_schedule(struct ip_vs_service *svc, struct iphdr *iph)
 616 {
 617         struct ip_vs_dest *dest, *least;
 618         int loh, doh;
 619
 620         /*
 621          * We think the overhead of processing active connections is fifty
 622          * times higher than that of inactive connections in average. (This
 623          * fifty times might not be accurate, we will change it later.) We
 624          * use the following formula to estimate the overhead:
 625          *                dest->activeconns*50 + dest->inactconns
 626          * and the load:
 627          *                (dest overhead) / dest->weight
 628          *
 629          * Remember -- no floats in kernel mode!!!
 630          * The comparison of h1*w2 > h2*w1 is equivalent to that of
 631          *                h1/w1 > h2/w2
 632          * if every weight is larger than zero.
 633          *
 634          * The server with weight=0 is quiesced and will not receive any
 635          * new connection.
 636          */
 637         list_for_each_entry(dest, &svc->destinations, n_list) {
 638                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 639                         continue;
 640
 641                 if (atomic_read(&dest->weight) > 0) {
 642                         least = dest;
 643                         loh = atomic_read(&least->activeconns) * 50
 644                                 + atomic_read(&least->inactconns);
 645                         goto nextstage;
 646                 }
 647         }
 648         return NULL;
 649
 650         /*
 651          *    Find the destination with the least load.
 652          */
 653   nextstage:
 654         list_for_each_entry_continue(dest, &svc->destinations, n_list) {
 655                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 656                         continue;
 657
 658                 doh = atomic_read(&dest->activeconns) * 50
 659                         + atomic_read(&dest->inactconns);
 660                 if (loh * atomic_read(&dest->weight) >
 661                     doh * atomic_read(&least->weight)) {
 662                         least = dest;
 663                         loh = doh;
 664                 }
 665         }
 666
 667         IP_VS_DBG(6, "LBLCR: server %d.%d.%d.%d:%d "
 668                   "activeconns %d refcnt %d weight %d overhead %d\n",
 669                   NIPQUAD(least->addr), ntohs(least->port),
 670                   atomic_read(&least->activeconns),
 671                   atomic_read(&least->refcnt),
 672                   atomic_read(&least->weight), loh);
 673
 674         return least;
 675 }
 676
 677
 678 /*
 679  *   If this destination server is overloaded and there is a less loaded
 680  *   server, then return true.
 681  */
 682 static inline int
 683 is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
 684 {
 685         if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
 686                 struct ip_vs_dest *d;
 687
 688                 list_for_each_entry(d, &svc->destinations, n_list) {
 689                         if (atomic_read(&d->activeconns)*2
 690                             < atomic_read(&d->weight)) {
 691                                 return 1;
 692                         }
 693                 }
 694         }
 695         return 0;
 696 }
 697
 698
 699 /*
 700  *    Locality-Based (weighted) Least-Connection scheduling
 701  */
 702 static struct ip_vs_dest *
 703 ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
 704 {
 705         struct ip_vs_dest *dest;
 706         struct ip_vs_lblcr_table *tbl;
 707         struct ip_vs_lblcr_entry *en;
 708         struct iphdr *iph = ip_hdr(skb);
 709
 710         IP_VS_DBG(6, "ip_vs_lblcr_schedule(): Scheduling...\n");
 711
 712         tbl = (struct ip_vs_lblcr_table *)svc->sched_data;
 713         en = ip_vs_lblcr_get(tbl, iph->daddr);
 714         if (en == NULL) {
 715                 dest = __ip_vs_wlc_schedule(svc, iph);
 716                 if (dest == NULL) {
 717                         IP_VS_DBG(1, "no destination available\n");
 718                         return NULL;
 719                 }
 720                 en = ip_vs_lblcr_new(iph->daddr);
 721                 if (en == NULL) {
 722                         return NULL;
 723                 }
 724                 ip_vs_dest_set_insert(&en->set, dest);
 725                 ip_vs_lblcr_hash(tbl, en);
 726         } else {
 727                 dest = ip_vs_dest_set_min(&en->set);
 728                 if (!dest || is_overloaded(dest, svc)) {
 729                         dest = __ip_vs_wlc_schedule(svc, iph);
 730                         if (dest == NULL) {
 731                                 IP_VS_DBG(1, "no destination available\n");
 732                                 return NULL;
 733                         }
 734                         ip_vs_dest_set_insert(&en->set, dest);
 735                 }
 736                 if (atomic_read(&en->set.size) > 1 &&
 737                     jiffies-en->set.lastmod > sysctl_ip_vs_lblcr_expiration) {
 738                         struct ip_vs_dest *m;
 739                         m = ip_vs_dest_set_max(&en->set);
 740                         if (m)
 741                                 ip_vs_dest_set_erase(&en->set, m);
 742                 }
 743         }
 744         en->lastuse = jiffies;
 745
 746         IP_VS_DBG(6, "LBLCR: destination IP address %u.%u.%u.%u "
 747                   "--> server %u.%u.%u.%u:%d\n",
 748                   NIPQUAD(en->addr),
 749                   NIPQUAD(dest->addr),
 750                   ntohs(dest->port));
 751
 752         return dest;
 753 }
 754
 755
 756 /*
 757  *      IPVS LBLCR Scheduler structure
 758  */
 759 static struct ip_vs_scheduler ip_vs_lblcr_scheduler =
 760 {
 761         .name =                 "lblcr",
 762         .refcnt =               ATOMIC_INIT(0),
 763         .module =               THIS_MODULE,
 764         .init_service =         ip_vs_lblcr_init_svc,
 765         .done_service =         ip_vs_lblcr_done_svc,
 766         .update_service =       ip_vs_lblcr_update_svc,
 767         .schedule =             ip_vs_lblcr_schedule,
 768 };
 769
 770
 771 static int __init ip_vs_lblcr_init(void)
 772 {
 773         INIT_LIST_HEAD(&ip_vs_lblcr_scheduler.n_list);
 774         sysctl_header = register_sysctl_table(lblcr_root_table);
 775         return register_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 776 }
 777
 778
 779 static void __exit ip_vs_lblcr_cleanup(void)
 780 {
 781         unregister_sysctl_table(sysctl_header);
 782         unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 783 }
 784
 785
 786 module_init(ip_vs_lblcr_init);
 787 module_exit(ip_vs_lblcr_cleanup);
 788 MODULE_LICENSE("GPL");