SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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 #define KMSG_COMPONENT "IPVS"
  41 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  42
  43 #include <linux/ip.h>
  44 #include <linux/module.h>
  45 #include <linux/kernel.h>
  46 #include <linux/skbuff.h>
  47 #include <linux/jiffies.h>
  48
  49 /* for sysctl */
  50 #include <linux/fs.h>
  51 #include <linux/sysctl.h>
  52 #include <net/net_namespace.h>
  53
  54 #include <net/ip_vs.h>
  55
  56
  57 /*
  58  *    It is for garbage collection of stale IPVS lblcr entries,
  59  *    when the table is full.
  60  */
  61 #define CHECK_EXPIRE_INTERVAL   (60*HZ)
  62 #define ENTRY_TIMEOUT           (6*60*HZ)
  63
  64 /*
  65  *    It is for full expiration check.
  66  *    When there is no partial expiration check (garbage collection)
  67  *    in a half hour, do a full expiration check to collect stale
  68  *    entries that haven't been touched for a day.
  69  */
  70 #define COUNT_FOR_FULL_EXPIRATION   30
  71 static int sysctl_ip_vs_lblcr_expiration = 24*60*60*HZ;
  72
  73
  74 /*
  75  *     for IPVS lblcr entry hash table
  76  */
  77 #ifndef CONFIG_IP_VS_LBLCR_TAB_BITS
  78 #define CONFIG_IP_VS_LBLCR_TAB_BITS      10
  79 #endif
  80 #define IP_VS_LBLCR_TAB_BITS     CONFIG_IP_VS_LBLCR_TAB_BITS
  81 #define IP_VS_LBLCR_TAB_SIZE     (1 << IP_VS_LBLCR_TAB_BITS)
  82 #define IP_VS_LBLCR_TAB_MASK     (IP_VS_LBLCR_TAB_SIZE - 1)
  83
  84
  85 /*
  86  *      IPVS destination set structure and operations
  87  */
  88 struct ip_vs_dest_list {
  89         struct ip_vs_dest_list  *next;          /* list link */
  90         struct ip_vs_dest       *dest;          /* destination server */
  91 };
  92
  93 struct ip_vs_dest_set {
  94         atomic_t                size;           /* set size */
  95         unsigned long           lastmod;        /* last modified time */
  96         struct ip_vs_dest_list  *list;          /* destination list */
  97         rwlock_t                lock;           /* lock for this list */
  98 };
  99
 100
 101 static struct ip_vs_dest_list *
 102 ip_vs_dest_set_insert(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
 103 {
 104         struct ip_vs_dest_list *e;
 105
 106         for (e=set->list; e!=NULL; e=e->next) {
 107                 if (e->dest == dest)
 108                         /* already existed */
 109                         return NULL;
 110         }
 111
 112         e = kmalloc(sizeof(*e), GFP_ATOMIC);
 113         if (e == NULL) {
 114                 pr_err("%s(): no memory\n", __func__);
 115                 return NULL;
 116         }
 117
 118         atomic_inc(&dest->refcnt);
 119         e->dest = dest;
 120
 121         /* link it to the list */
 122         e->next = set->list;
 123         set->list = e;
 124         atomic_inc(&set->size);
 125
 126         set->lastmod = jiffies;
 127         return e;
 128 }
 129
 130 static void
 131 ip_vs_dest_set_erase(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
 132 {
 133         struct ip_vs_dest_list *e, **ep;
 134
 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 }
 148
 149 static void ip_vs_dest_set_eraseall(struct ip_vs_dest_set *set)
 150 {
 151         struct ip_vs_dest_list *e, **ep;
 152
 153         write_lock(&set->lock);
 154         for (ep=&set->list, e=*ep; e!=NULL; e=*ep) {
 155                 *ep = e->next;
 156                 /*
 157                  * We don't kfree dest because it is refered either
 158                  * by its service or by the trash dest list.
 159                  */
 160                 atomic_dec(&e->dest->refcnt);
 161                 kfree(e);
 162         }
 163         write_unlock(&set->lock);
 164 }
 165
 166 /* get weighted least-connection node in the destination set */
 167 static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
 168 {
 169         register struct ip_vs_dest_list *e;
 170         struct ip_vs_dest *dest, *least;
 171         int loh, doh;
 172
 173         if (set == NULL)
 174                 return NULL;
 175
 176         /* select the first destination server, whose weight > 0 */
 177         for (e=set->list; e!=NULL; e=e->next) {
 178                 least = e->dest;
 179                 if (least->flags & IP_VS_DEST_F_OVERLOAD)
 180                         continue;
 181
 182                 if ((atomic_read(&least->weight) > 0)
 183                     && (least->flags & IP_VS_DEST_F_AVAILABLE)) {
 184                         loh = atomic_read(&least->activeconns) * 50
 185                                 + atomic_read(&least->inactconns);
 186                         goto nextstage;
 187                 }
 188         }
 189         return NULL;
 190
 191         /* find the destination with the weighted least load */
 192   nextstage:
 193         for (e=e->next; e!=NULL; e=e->next) {
 194                 dest = e->dest;
 195                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 196                         continue;
 197
 198                 doh = atomic_read(&dest->activeconns) * 50
 199                         + atomic_read(&dest->inactconns);
 200                 if ((loh * atomic_read(&dest->weight) >
 201                      doh * atomic_read(&least->weight))
 202                     && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
 203                         least = dest;
 204                         loh = doh;
 205                 }
 206         }
 207
 208         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
 209                       "activeconns %d refcnt %d weight %d overhead %d\n",
 210                       __func__,
 211                       IP_VS_DBG_ADDR(least->af, &least->addr),
 212                       ntohs(least->port),
 213                       atomic_read(&least->activeconns),
 214                       atomic_read(&least->refcnt),
 215                       atomic_read(&least->weight), loh);
 216         return least;
 217 }
 218
 219
 220 /* get weighted most-connection node in the destination set */
 221 static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
 222 {
 223         register struct ip_vs_dest_list *e;
 224         struct ip_vs_dest *dest, *most;
 225         int moh, doh;
 226
 227         if (set == NULL)
 228                 return NULL;
 229
 230         /* select the first destination server, whose weight > 0 */
 231         for (e=set->list; e!=NULL; e=e->next) {
 232                 most = e->dest;
 233                 if (atomic_read(&most->weight) > 0) {
 234                         moh = atomic_read(&most->activeconns) * 50
 235                                 + atomic_read(&most->inactconns);
 236                         goto nextstage;
 237                 }
 238         }
 239         return NULL;
 240
 241         /* find the destination with the weighted most load */
 242   nextstage:
 243         for (e=e->next; e!=NULL; e=e->next) {
 244                 dest = e->dest;
 245                 doh = atomic_read(&dest->activeconns) * 50
 246                         + atomic_read(&dest->inactconns);
 247                 /* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
 248                 if ((moh * atomic_read(&dest->weight) <
 249                      doh * atomic_read(&most->weight))
 250                     && (atomic_read(&dest->weight) > 0)) {
 251                         most = dest;
 252                         moh = doh;
 253                 }
 254         }
 255
 256         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
 257                       "activeconns %d refcnt %d weight %d overhead %d\n",
 258                       __func__,
 259                       IP_VS_DBG_ADDR(most->af, &most->addr), ntohs(most->port),
 260                       atomic_read(&most->activeconns),
 261                       atomic_read(&most->refcnt),
 262                       atomic_read(&most->weight), moh);
 263         return most;
 264 }
 265
 266
 267 /*
 268  *      IPVS lblcr entry represents an association between destination
 269  *      IP address and its destination server set
 270  */
 271 struct ip_vs_lblcr_entry {
 272         struct list_head        list;
 273         int                     af;             /* address family */
 274         union nf_inet_addr      addr;           /* destination IP address */
 275         struct ip_vs_dest_set   set;            /* destination server set */
 276         unsigned long           lastuse;        /* last used time */
 277 };
 278
 279
 280 /*
 281  *      IPVS lblcr hash table
 282  */
 283 struct ip_vs_lblcr_table {
 284         struct list_head        bucket[IP_VS_LBLCR_TAB_SIZE];  /* hash bucket */
 285         atomic_t                entries;        /* number of entries */
 286         int                     max_size;       /* maximum size of entries */
 287         struct timer_list       periodic_timer; /* collect stale entries */
 288         int                     rover;          /* rover for expire check */
 289         int                     counter;        /* counter for no expire */
 290 };
 291
 292
 293 /*
 294  *      IPVS LBLCR sysctl table
 295  */
 296
 297 static ctl_table vs_vars_table[] = {
 298         {
 299                 .procname       = "lblcr_expiration",
 300                 .data           = &sysctl_ip_vs_lblcr_expiration,
 301                 .maxlen         = sizeof(int),
 302                 .mode           = 0644,
 303                 .proc_handler   = proc_dointvec_jiffies,
 304         },
 305         { }
 306 };
 307
 308 static struct ctl_table_header * sysctl_header;
 309
 310 static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
 311 {
 312         list_del(&en->list);
 313         ip_vs_dest_set_eraseall(&en->set);
 314         kfree(en);
 315 }
 316
 317
 318 /*
 319  *      Returns hash value for IPVS LBLCR entry
 320  */
 321 static inline unsigned
 322 ip_vs_lblcr_hashkey(int af, const union nf_inet_addr *addr)
 323 {
 324         __be32 addr_fold = addr->ip;
 325
 326 #ifdef CONFIG_IP_VS_IPV6
 327         if (af == AF_INET6)
 328                 addr_fold = addr->ip6[0]^addr->ip6[1]^
 329                             addr->ip6[2]^addr->ip6[3];
 330 #endif
 331         return (ntohl(addr_fold)*2654435761UL) & IP_VS_LBLCR_TAB_MASK;
 332 }
 333
 334
 335 /*
 336  *      Hash an entry in the ip_vs_lblcr_table.
 337  *      returns bool success.
 338  */
 339 static void
 340 ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
 341 {
 342         unsigned hash = ip_vs_lblcr_hashkey(en->af, &en->addr);
 343
 344         list_add(&en->list, &tbl->bucket[hash]);
 345         atomic_inc(&tbl->entries);
 346 }
 347
 348
 349 /*
 350  *  Get ip_vs_lblcr_entry associated with supplied parameters. Called under
 351  *  read lock.
 352  */
 353 static inline struct ip_vs_lblcr_entry *
 354 ip_vs_lblcr_get(int af, struct ip_vs_lblcr_table *tbl,
 355                 const union nf_inet_addr *addr)
 356 {
 357         unsigned hash = ip_vs_lblcr_hashkey(af, addr);
 358         struct ip_vs_lblcr_entry *en;
 359
 360         list_for_each_entry(en, &tbl->bucket[hash], list)
 361                 if (ip_vs_addr_equal(af, &en->addr, addr))
 362                         return en;
 363
 364         return NULL;
 365 }
 366
 367
 368 /*
 369  * Create or update an ip_vs_lblcr_entry, which is a mapping of a destination
 370  * IP address to a server. Called under write lock.
 371  */
 372 static inline struct ip_vs_lblcr_entry *
 373 ip_vs_lblcr_new(struct ip_vs_lblcr_table *tbl, const union nf_inet_addr *daddr,
 374                 struct ip_vs_dest *dest)
 375 {
 376         struct ip_vs_lblcr_entry *en;
 377
 378         en = ip_vs_lblcr_get(dest->af, tbl, daddr);
 379         if (!en) {
 380                 en = kmalloc(sizeof(*en), GFP_ATOMIC);
 381                 if (!en) {
 382                         pr_err("%s(): no memory\n", __func__);
 383                         return NULL;
 384                 }
 385
 386                 en->af = dest->af;
 387                 ip_vs_addr_copy(dest->af, &en->addr, daddr);
 388                 en->lastuse = jiffies;
 389
 390                 /* initilize its dest set */
 391                 atomic_set(&(en->set.size), 0);
 392                 en->set.list = NULL;
 393                 rwlock_init(&en->set.lock);
 394
 395                 ip_vs_lblcr_hash(tbl, en);
 396         }
 397
 398         write_lock(&en->set.lock);
 399         ip_vs_dest_set_insert(&en->set, dest);
 400         write_unlock(&en->set.lock);
 401
 402         return en;
 403 }
 404
 405
 406 /*
 407  *      Flush all the entries of the specified table.
 408  */
 409 static void ip_vs_lblcr_flush(struct ip_vs_lblcr_table *tbl)
 410 {
 411         int i;
 412         struct ip_vs_lblcr_entry *en, *nxt;
 413
 414         /* No locking required, only called during cleanup. */
 415         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 416                 list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {
 417                         ip_vs_lblcr_free(en);
 418                 }
 419         }
 420 }
 421
 422
 423 static inline void ip_vs_lblcr_full_check(struct ip_vs_service *svc)
 424 {
 425         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 426         unsigned long now = jiffies;
 427         int i, j;
 428         struct ip_vs_lblcr_entry *en, *nxt;
 429
 430         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 431                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 432
 433                 write_lock(&svc->sched_lock);
 434                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 435                         if (time_after(en->lastuse+sysctl_ip_vs_lblcr_expiration,
 436                                        now))
 437                                 continue;
 438
 439                         ip_vs_lblcr_free(en);
 440                         atomic_dec(&tbl->entries);
 441                 }
 442                 write_unlock(&svc->sched_lock);
 443         }
 444         tbl->rover = j;
 445 }
 446
 447
 448 /*
 449  *      Periodical timer handler for IPVS lblcr table
 450  *      It is used to collect stale entries when the number of entries
 451  *      exceeds the maximum size of the table.
 452  *
 453  *      Fixme: we probably need more complicated algorithm to collect
 454  *             entries that have not been used for a long time even
 455  *             if the number of entries doesn't exceed the maximum size
 456  *             of the table.
 457  *      The full expiration check is for this purpose now.
 458  */
 459 static void ip_vs_lblcr_check_expire(unsigned long data)
 460 {
 461         struct ip_vs_service *svc = (struct ip_vs_service *) data;
 462         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 463         unsigned long now = jiffies;
 464         int goal;
 465         int i, j;
 466         struct ip_vs_lblcr_entry *en, *nxt;
 467
 468         if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
 469                 /* do full expiration check */
 470                 ip_vs_lblcr_full_check(svc);
 471                 tbl->counter = 1;
 472                 goto out;
 473         }
 474
 475         if (atomic_read(&tbl->entries) <= tbl->max_size) {
 476                 tbl->counter++;
 477                 goto out;
 478         }
 479
 480         goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3;
 481         if (goal > tbl->max_size/2)
 482                 goal = tbl->max_size/2;
 483
 484         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 485                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 486
 487                 write_lock(&svc->sched_lock);
 488                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 489                         if (time_before(now, en->lastuse+ENTRY_TIMEOUT))
 490                                 continue;
 491
 492                         ip_vs_lblcr_free(en);
 493                         atomic_dec(&tbl->entries);
 494                         goal--;
 495                 }
 496                 write_unlock(&svc->sched_lock);
 497                 if (goal <= 0)
 498                         break;
 499         }
 500         tbl->rover = j;
 501
 502   out:
 503         mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
 504 }
 505
 506 static int ip_vs_lblcr_init_svc(struct ip_vs_service *svc)
 507 {
 508         int i;
 509         struct ip_vs_lblcr_table *tbl;
 510
 511         /*
 512          *    Allocate the ip_vs_lblcr_table for this service
 513          */
 514         tbl = kmalloc(sizeof(*tbl), GFP_ATOMIC);
 515         if (tbl == NULL) {
 516                 pr_err("%s(): no memory\n", __func__);
 517                 return -ENOMEM;
 518         }
 519         svc->sched_data = tbl;
 520         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) allocated for "
 521                   "current service\n", sizeof(*tbl));
 522
 523         /*
 524          *    Initialize the hash buckets
 525          */
 526         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 527                 INIT_LIST_HEAD(&tbl->bucket[i]);
 528         }
 529         tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
 530         tbl->rover = 0;
 531         tbl->counter = 1;
 532
 533         /*
 534          *    Hook periodic timer for garbage collection
 535          */
 536         setup_timer(&tbl->periodic_timer, ip_vs_lblcr_check_expire,
 537                         (unsigned long)svc);
 538         mod_timer(&tbl->periodic_timer, jiffies + CHECK_EXPIRE_INTERVAL);
 539
 540         return 0;
 541 }
 542
 543
 544 static int ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
 545 {
 546         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 547
 548         /* remove periodic timer */
 549         del_timer_sync(&tbl->periodic_timer);
 550
 551         /* got to clean up table entries here */
 552         ip_vs_lblcr_flush(tbl);
 553
 554         /* release the table itself */
 555         kfree(tbl);
 556         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) released\n",
 557                   sizeof(*tbl));
 558
 559         return 0;
 560 }
 561
 562
 563 static inline struct ip_vs_dest *
 564 __ip_vs_lblcr_schedule(struct ip_vs_service *svc)
 565 {
 566         struct ip_vs_dest *dest, *least;
 567         int loh, doh;
 568
 569         /*
 570          * We think the overhead of processing active connections is fifty
 571          * times higher than that of inactive connections in average. (This
 572          * fifty times might not be accurate, we will change it later.) We
 573          * use the following formula to estimate the overhead:
 574          *                dest->activeconns*50 + dest->inactconns
 575          * and the load:
 576          *                (dest overhead) / dest->weight
 577          *
 578          * Remember -- no floats in kernel mode!!!
 579          * The comparison of h1*w2 > h2*w1 is equivalent to that of
 580          *                h1/w1 > h2/w2
 581          * if every weight is larger than zero.
 582          *
 583          * The server with weight=0 is quiesced and will not receive any
 584          * new connection.
 585          */
 586         list_for_each_entry(dest, &svc->destinations, n_list) {
 587                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 588                         continue;
 589
 590                 if (atomic_read(&dest->weight) > 0) {
 591                         least = dest;
 592                         loh = atomic_read(&least->activeconns) * 50
 593                                 + atomic_read(&least->inactconns);
 594                         goto nextstage;
 595                 }
 596         }
 597         return NULL;
 598
 599         /*
 600          *    Find the destination with the least load.
 601          */
 602   nextstage:
 603         list_for_each_entry_continue(dest, &svc->destinations, n_list) {
 604                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 605                         continue;
 606
 607                 doh = atomic_read(&dest->activeconns) * 50
 608                         + atomic_read(&dest->inactconns);
 609                 if (loh * atomic_read(&dest->weight) >
 610                     doh * atomic_read(&least->weight)) {
 611                         least = dest;
 612                         loh = doh;
 613                 }
 614         }
 615
 616         IP_VS_DBG_BUF(6, "LBLCR: server %s:%d "
 617                       "activeconns %d refcnt %d weight %d overhead %d\n",
 618                       IP_VS_DBG_ADDR(least->af, &least->addr),
 619                       ntohs(least->port),
 620                       atomic_read(&least->activeconns),
 621                       atomic_read(&least->refcnt),
 622                       atomic_read(&least->weight), loh);
 623
 624         return least;
 625 }
 626
 627
 628 /*
 629  *   If this destination server is overloaded and there is a less loaded
 630  *   server, then return true.
 631  */
 632 static inline int
 633 is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
 634 {
 635         if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
 636                 struct ip_vs_dest *d;
 637
 638                 list_for_each_entry(d, &svc->destinations, n_list) {
 639                         if (atomic_read(&d->activeconns)*2
 640                             < atomic_read(&d->weight)) {
 641                                 return 1;
 642                         }
 643                 }
 644         }
 645         return 0;
 646 }
 647
 648
 649 /*
 650  *    Locality-Based (weighted) Least-Connection scheduling
 651  */
 652 static struct ip_vs_dest *
 653 ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
 654 {
 655         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 656         struct ip_vs_iphdr iph;
 657         struct ip_vs_dest *dest = NULL;
 658         struct ip_vs_lblcr_entry *en;
 659
 660         ip_vs_fill_iphdr(svc->af, skb_network_header(skb), &iph);
 661
 662         IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
 663
 664         /* First look in our cache */
 665         read_lock(&svc->sched_lock);
 666         en = ip_vs_lblcr_get(svc->af, tbl, &iph.daddr);
 667         if (en) {
 668                 /* We only hold a read lock, but this is atomic */
 669                 en->lastuse = jiffies;
 670
 671                 /* Get the least loaded destination */
 672                 read_lock(&en->set.lock);
 673                 dest = ip_vs_dest_set_min(&en->set);
 674                 read_unlock(&en->set.lock);
 675
 676                 /* More than one destination + enough time passed by, cleanup */
 677                 if (atomic_read(&en->set.size) > 1 &&
 678                                 time_after(jiffies, en->set.lastmod +
 679                                 sysctl_ip_vs_lblcr_expiration)) {
 680                         struct ip_vs_dest *m;
 681
 682                         write_lock(&en->set.lock);
 683                         m = ip_vs_dest_set_max(&en->set);
 684                         if (m)
 685                                 ip_vs_dest_set_erase(&en->set, m);
 686                         write_unlock(&en->set.lock);
 687                 }
 688
 689                 /* If the destination is not overloaded, use it */
 690                 if (dest && !is_overloaded(dest, svc)) {
 691                         read_unlock(&svc->sched_lock);
 692                         goto out;
 693                 }
 694
 695                 /* The cache entry is invalid, time to schedule */
 696                 dest = __ip_vs_lblcr_schedule(svc);
 697                 if (!dest) {
 698                         IP_VS_ERR_RL("LBLCR: no destination available\n");
 699                         read_unlock(&svc->sched_lock);
 700                         return NULL;
 701                 }
 702
 703                 /* Update our cache entry */
 704                 write_lock(&en->set.lock);
 705                 ip_vs_dest_set_insert(&en->set, dest);
 706                 write_unlock(&en->set.lock);
 707         }
 708         read_unlock(&svc->sched_lock);
 709
 710         if (dest)
 711                 goto out;
 712
 713         /* No cache entry, time to schedule */
 714         dest = __ip_vs_lblcr_schedule(svc);
 715         if (!dest) {
 716                 IP_VS_DBG(1, "no destination available\n");
 717                 return NULL;
 718         }
 719
 720         /* If we fail to create a cache entry, we'll just use the valid dest */
 721         write_lock(&svc->sched_lock);
 722         ip_vs_lblcr_new(tbl, &iph.daddr, dest);
 723         write_unlock(&svc->sched_lock);
 724
 725 out:
 726         IP_VS_DBG_BUF(6, "LBLCR: destination IP address %s --> server %s:%d\n",
 727                       IP_VS_DBG_ADDR(svc->af, &iph.daddr),
 728                       IP_VS_DBG_ADDR(svc->af, &dest->addr), ntohs(dest->port));
 729
 730         return dest;
 731 }
 732
 733
 734 /*
 735  *      IPVS LBLCR Scheduler structure
 736  */
 737 static struct ip_vs_scheduler ip_vs_lblcr_scheduler =
 738 {
 739         .name =                 "lblcr",
 740         .refcnt =               ATOMIC_INIT(0),
 741         .module =               THIS_MODULE,
 742         .n_list =               LIST_HEAD_INIT(ip_vs_lblcr_scheduler.n_list),
 743         .init_service =         ip_vs_lblcr_init_svc,
 744         .done_service =         ip_vs_lblcr_done_svc,
 745         .schedule =             ip_vs_lblcr_schedule,
 746 };
 747
 748
 749 static int __init ip_vs_lblcr_init(void)
 750 {
 751         int ret;
 752
 753         sysctl_header = register_sysctl_paths(net_vs_ctl_path, vs_vars_table);
 754         ret = register_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 755         if (ret)
 756                 unregister_sysctl_table(sysctl_header);
 757         return ret;
 758 }
 759
 760
 761 static void __exit ip_vs_lblcr_cleanup(void)
 762 {
 763         unregister_sysctl_table(sysctl_header);
 764         unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 765 }
 766
 767
 768 module_init(ip_vs_lblcr_init);
 769 module_exit(ip_vs_lblcr_cleanup);
 770 MODULE_LICENSE("GPL");