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 #include <linux/list.h>
  49 #include <linux/slab.h>
  50
  51 /* for sysctl */
  52 #include <linux/fs.h>
  53 #include <linux/sysctl.h>
  54 #include <net/net_namespace.h>
  55
  56 #include <net/ip_vs.h>
  57
  58
  59 /*
  60  *    It is for garbage collection of stale IPVS lblcr entries,
  61  *    when the table is full.
  62  */
  63 #define CHECK_EXPIRE_INTERVAL   (60*HZ)
  64 #define ENTRY_TIMEOUT           (6*60*HZ)
  65
  66 /*
  67  *    It is for full expiration check.
  68  *    When there is no partial expiration check (garbage collection)
  69  *    in a half hour, do a full expiration check to collect stale
  70  *    entries that haven't been touched for a day.
  71  */
  72 #define COUNT_FOR_FULL_EXPIRATION   30
  73 static int sysctl_ip_vs_lblcr_expiration = 24*60*60*HZ;
  74
  75
  76 /*
  77  *     for IPVS lblcr entry hash table
  78  */
  79 #ifndef CONFIG_IP_VS_LBLCR_TAB_BITS
  80 #define CONFIG_IP_VS_LBLCR_TAB_BITS      10
  81 #endif
  82 #define IP_VS_LBLCR_TAB_BITS     CONFIG_IP_VS_LBLCR_TAB_BITS
  83 #define IP_VS_LBLCR_TAB_SIZE     (1 << IP_VS_LBLCR_TAB_BITS)
  84 #define IP_VS_LBLCR_TAB_MASK     (IP_VS_LBLCR_TAB_SIZE - 1)
  85
  86
  87 /*
  88  *      IPVS destination set structure and operations
  89  */
  90 struct ip_vs_dest_set_elem {
  91         struct list_head        list;          /* list link */
  92         struct ip_vs_dest       *dest;          /* destination server */
  93 };
  94
  95 struct ip_vs_dest_set {
  96         atomic_t                size;           /* set size */
  97         unsigned long           lastmod;        /* last modified time */
  98         struct list_head        list;           /* destination list */
  99         rwlock_t                lock;           /* lock for this list */
 100 };
 101
 102
 103 static struct ip_vs_dest_set_elem *
 104 ip_vs_dest_set_insert(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
 105 {
 106         struct ip_vs_dest_set_elem *e;
 107
 108         list_for_each_entry(e, &set->list, list) {
 109                 if (e->dest == dest)
 110                         /* already existed */
 111                         return NULL;
 112         }
 113
 114         e = kmalloc(sizeof(*e), GFP_ATOMIC);
 115         if (e == NULL) {
 116                 pr_err("%s(): no memory\n", __func__);
 117                 return NULL;
 118         }
 119
 120         atomic_inc(&dest->refcnt);
 121         e->dest = dest;
 122
 123         list_add(&e->list, &set->list);
 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_set_elem *e;
 134
 135         list_for_each_entry(e, &set->list, list) {
 136                 if (e->dest == dest) {
 137                         /* HIT */
 138                         atomic_dec(&set->size);
 139                         set->lastmod = jiffies;
 140                         atomic_dec(&e->dest->refcnt);
 141                         list_del(&e->list);
 142                         kfree(e);
 143                         break;
 144                 }
 145         }
 146 }
 147
 148 static void ip_vs_dest_set_eraseall(struct ip_vs_dest_set *set)
 149 {
 150         struct ip_vs_dest_set_elem *e, *ep;
 151
 152         write_lock(&set->lock);
 153         list_for_each_entry_safe(e, ep, &set->list, list) {
 154                 /*
 155                  * We don't kfree dest because it is refered either
 156                  * by its service or by the trash dest list.
 157                  */
 158                 atomic_dec(&e->dest->refcnt);
 159                 list_del(&e->list);
 160                 kfree(e);
 161         }
 162         write_unlock(&set->lock);
 163 }
 164
 165 /* get weighted least-connection node in the destination set */
 166 static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
 167 {
 168         register struct ip_vs_dest_set_elem *e;
 169         struct ip_vs_dest *dest, *least;
 170         int loh, doh;
 171
 172         if (set == NULL)
 173                 return NULL;
 174
 175         /* select the first destination server, whose weight > 0 */
 176         list_for_each_entry(e, &set->list, list) {
 177                 least = e->dest;
 178                 if (least->flags & IP_VS_DEST_F_OVERLOAD)
 179                         continue;
 180
 181                 if ((atomic_read(&least->weight) > 0)
 182                     && (least->flags & IP_VS_DEST_F_AVAILABLE)) {
 183                         loh = atomic_read(&least->activeconns) * 50
 184                                 + atomic_read(&least->inactconns);
 185                         goto nextstage;
 186                 }
 187         }
 188         return NULL;
 189
 190         /* find the destination with the weighted least load */
 191   nextstage:
 192         list_for_each_entry(e, &set->list, list) {
 193                 dest = e->dest;
 194                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 195                         continue;
 196
 197                 doh = atomic_read(&dest->activeconns) * 50
 198                         + atomic_read(&dest->inactconns);
 199                 if ((loh * atomic_read(&dest->weight) >
 200                      doh * atomic_read(&least->weight))
 201                     && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
 202                         least = dest;
 203                         loh = doh;
 204                 }
 205         }
 206
 207         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
 208                       "activeconns %d refcnt %d weight %d overhead %d\n",
 209                       __func__,
 210                       IP_VS_DBG_ADDR(least->af, &least->addr),
 211                       ntohs(least->port),
 212                       atomic_read(&least->activeconns),
 213                       atomic_read(&least->refcnt),
 214                       atomic_read(&least->weight), loh);
 215         return least;
 216 }
 217
 218
 219 /* get weighted most-connection node in the destination set */
 220 static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
 221 {
 222         register struct ip_vs_dest_set_elem *e;
 223         struct ip_vs_dest *dest, *most;
 224         int moh, doh;
 225
 226         if (set == NULL)
 227                 return NULL;
 228
 229         /* select the first destination server, whose weight > 0 */
 230         list_for_each_entry(e, &set->list, list) {
 231                 most = e->dest;
 232                 if (atomic_read(&most->weight) > 0) {
 233                         moh = atomic_read(&most->activeconns) * 50
 234                                 + atomic_read(&most->inactconns);
 235                         goto nextstage;
 236                 }
 237         }
 238         return NULL;
 239
 240         /* find the destination with the weighted most load */
 241   nextstage:
 242         list_for_each_entry(e, &set->list, list) {
 243                 dest = e->dest;
 244                 doh = atomic_read(&dest->activeconns) * 50
 245                         + atomic_read(&dest->inactconns);
 246                 /* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
 247                 if ((moh * atomic_read(&dest->weight) <
 248                      doh * atomic_read(&most->weight))
 249                     && (atomic_read(&dest->weight) > 0)) {
 250                         most = dest;
 251                         moh = doh;
 252                 }
 253         }
 254
 255         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
 256                       "activeconns %d refcnt %d weight %d overhead %d\n",
 257                       __func__,
 258                       IP_VS_DBG_ADDR(most->af, &most->addr), ntohs(most->port),
 259                       atomic_read(&most->activeconns),
 260                       atomic_read(&most->refcnt),
 261                       atomic_read(&most->weight), moh);
 262         return most;
 263 }
 264
 265
 266 /*
 267  *      IPVS lblcr entry represents an association between destination
 268  *      IP address and its destination server set
 269  */
 270 struct ip_vs_lblcr_entry {
 271         struct list_head        list;
 272         int                     af;             /* address family */
 273         union nf_inet_addr      addr;           /* destination IP address */
 274         struct ip_vs_dest_set   set;            /* destination server set */
 275         unsigned long           lastuse;        /* last used time */
 276 };
 277
 278
 279 /*
 280  *      IPVS lblcr hash table
 281  */
 282 struct ip_vs_lblcr_table {
 283         struct list_head        bucket[IP_VS_LBLCR_TAB_SIZE];  /* hash bucket */
 284         atomic_t                entries;        /* number of entries */
 285         int                     max_size;       /* maximum size of entries */
 286         struct timer_list       periodic_timer; /* collect stale entries */
 287         int                     rover;          /* rover for expire check */
 288         int                     counter;        /* counter for no expire */
 289 };
 290
 291
 292 /*
 293  *      IPVS LBLCR sysctl table
 294  */
 295
 296 static ctl_table vs_vars_table[] = {
 297         {
 298                 .procname       = "lblcr_expiration",
 299                 .data           = &sysctl_ip_vs_lblcr_expiration,
 300                 .maxlen         = sizeof(int),
 301                 .mode           = 0644,
 302                 .proc_handler   = proc_dointvec_jiffies,
 303         },
 304         { }
 305 };
 306
 307 static struct ctl_table_header * sysctl_header;
 308
 309 static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
 310 {
 311         list_del(&en->list);
 312         ip_vs_dest_set_eraseall(&en->set);
 313         kfree(en);
 314 }
 315
 316
 317 /*
 318  *      Returns hash value for IPVS LBLCR entry
 319  */
 320 static inline unsigned
 321 ip_vs_lblcr_hashkey(int af, const union nf_inet_addr *addr)
 322 {
 323         __be32 addr_fold = addr->ip;
 324
 325 #ifdef CONFIG_IP_VS_IPV6
 326         if (af == AF_INET6)
 327                 addr_fold = addr->ip6[0]^addr->ip6[1]^
 328                             addr->ip6[2]^addr->ip6[3];
 329 #endif
 330         return (ntohl(addr_fold)*2654435761UL) & IP_VS_LBLCR_TAB_MASK;
 331 }
 332
 333
 334 /*
 335  *      Hash an entry in the ip_vs_lblcr_table.
 336  *      returns bool success.
 337  */
 338 static void
 339 ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
 340 {
 341         unsigned hash = ip_vs_lblcr_hashkey(en->af, &en->addr);
 342
 343         list_add(&en->list, &tbl->bucket[hash]);
 344         atomic_inc(&tbl->entries);
 345 }
 346
 347
 348 /*
 349  *  Get ip_vs_lblcr_entry associated with supplied parameters. Called under
 350  *  read lock.
 351  */
 352 static inline struct ip_vs_lblcr_entry *
 353 ip_vs_lblcr_get(int af, struct ip_vs_lblcr_table *tbl,
 354                 const union nf_inet_addr *addr)
 355 {
 356         unsigned hash = ip_vs_lblcr_hashkey(af, addr);
 357         struct ip_vs_lblcr_entry *en;
 358
 359         list_for_each_entry(en, &tbl->bucket[hash], list)
 360                 if (ip_vs_addr_equal(af, &en->addr, addr))
 361                         return en;
 362
 363         return NULL;
 364 }
 365
 366
 367 /*
 368  * Create or update an ip_vs_lblcr_entry, which is a mapping of a destination
 369  * IP address to a server. Called under write lock.
 370  */
 371 static inline struct ip_vs_lblcr_entry *
 372 ip_vs_lblcr_new(struct ip_vs_lblcr_table *tbl, const union nf_inet_addr *daddr,
 373                 struct ip_vs_dest *dest)
 374 {
 375         struct ip_vs_lblcr_entry *en;
 376
 377         en = ip_vs_lblcr_get(dest->af, tbl, daddr);
 378         if (!en) {
 379                 en = kmalloc(sizeof(*en), GFP_ATOMIC);
 380                 if (!en) {
 381                         pr_err("%s(): no memory\n", __func__);
 382                         return NULL;
 383                 }
 384
 385                 en->af = dest->af;
 386                 ip_vs_addr_copy(dest->af, &en->addr, daddr);
 387                 en->lastuse = jiffies;
 388
 389                 /* initialize its dest set */
 390                 atomic_set(&(en->set.size), 0);
 391                 INIT_LIST_HEAD(&en->set.list);
 392                 rwlock_init(&en->set.lock);
 393
 394                 ip_vs_lblcr_hash(tbl, en);
 395         }
 396
 397         write_lock(&en->set.lock);
 398         ip_vs_dest_set_insert(&en->set, dest);
 399         write_unlock(&en->set.lock);
 400
 401         return en;
 402 }
 403
 404
 405 /*
 406  *      Flush all the entries of the specified table.
 407  */
 408 static void ip_vs_lblcr_flush(struct ip_vs_lblcr_table *tbl)
 409 {
 410         int i;
 411         struct ip_vs_lblcr_entry *en, *nxt;
 412
 413         /* No locking required, only called during cleanup. */
 414         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 415                 list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {
 416                         ip_vs_lblcr_free(en);
 417                 }
 418         }
 419 }
 420
 421
 422 static inline void ip_vs_lblcr_full_check(struct ip_vs_service *svc)
 423 {
 424         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 425         unsigned long now = jiffies;
 426         int i, j;
 427         struct ip_vs_lblcr_entry *en, *nxt;
 428
 429         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 430                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 431
 432                 write_lock(&svc->sched_lock);
 433                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 434                         if (time_after(en->lastuse+sysctl_ip_vs_lblcr_expiration,
 435                                        now))
 436                                 continue;
 437
 438                         ip_vs_lblcr_free(en);
 439                         atomic_dec(&tbl->entries);
 440                 }
 441                 write_unlock(&svc->sched_lock);
 442         }
 443         tbl->rover = j;
 444 }
 445
 446
 447 /*
 448  *      Periodical timer handler for IPVS lblcr table
 449  *      It is used to collect stale entries when the number of entries
 450  *      exceeds the maximum size of the table.
 451  *
 452  *      Fixme: we probably need more complicated algorithm to collect
 453  *             entries that have not been used for a long time even
 454  *             if the number of entries doesn't exceed the maximum size
 455  *             of the table.
 456  *      The full expiration check is for this purpose now.
 457  */
 458 static void ip_vs_lblcr_check_expire(unsigned long data)
 459 {
 460         struct ip_vs_service *svc = (struct ip_vs_service *) data;
 461         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 462         unsigned long now = jiffies;
 463         int goal;
 464         int i, j;
 465         struct ip_vs_lblcr_entry *en, *nxt;
 466
 467         if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
 468                 /* do full expiration check */
 469                 ip_vs_lblcr_full_check(svc);
 470                 tbl->counter = 1;
 471                 goto out;
 472         }
 473
 474         if (atomic_read(&tbl->entries) <= tbl->max_size) {
 475                 tbl->counter++;
 476                 goto out;
 477         }
 478
 479         goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3;
 480         if (goal > tbl->max_size/2)
 481                 goal = tbl->max_size/2;
 482
 483         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 484                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 485
 486                 write_lock(&svc->sched_lock);
 487                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 488                         if (time_before(now, en->lastuse+ENTRY_TIMEOUT))
 489                                 continue;
 490
 491                         ip_vs_lblcr_free(en);
 492                         atomic_dec(&tbl->entries);
 493                         goal--;
 494                 }
 495                 write_unlock(&svc->sched_lock);
 496                 if (goal <= 0)
 497                         break;
 498         }
 499         tbl->rover = j;
 500
 501   out:
 502         mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
 503 }
 504
 505 static int ip_vs_lblcr_init_svc(struct ip_vs_service *svc)
 506 {
 507         int i;
 508         struct ip_vs_lblcr_table *tbl;
 509
 510         /*
 511          *    Allocate the ip_vs_lblcr_table for this service
 512          */
 513         tbl = kmalloc(sizeof(*tbl), GFP_ATOMIC);
 514         if (tbl == NULL) {
 515                 pr_err("%s(): no memory\n", __func__);
 516                 return -ENOMEM;
 517         }
 518         svc->sched_data = tbl;
 519         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) allocated for "
 520                   "current service\n", sizeof(*tbl));
 521
 522         /*
 523          *    Initialize the hash buckets
 524          */
 525         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 526                 INIT_LIST_HEAD(&tbl->bucket[i]);
 527         }
 528         tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
 529         tbl->rover = 0;
 530         tbl->counter = 1;
 531
 532         /*
 533          *    Hook periodic timer for garbage collection
 534          */
 535         setup_timer(&tbl->periodic_timer, ip_vs_lblcr_check_expire,
 536                         (unsigned long)svc);
 537         mod_timer(&tbl->periodic_timer, jiffies + CHECK_EXPIRE_INTERVAL);
 538
 539         return 0;
 540 }
 541
 542
 543 static int ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
 544 {
 545         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 546
 547         /* remove periodic timer */
 548         del_timer_sync(&tbl->periodic_timer);
 549
 550         /* got to clean up table entries here */
 551         ip_vs_lblcr_flush(tbl);
 552
 553         /* release the table itself */
 554         kfree(tbl);
 555         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) released\n",
 556                   sizeof(*tbl));
 557
 558         return 0;
 559 }
 560
 561
 562 static inline struct ip_vs_dest *
 563 __ip_vs_lblcr_schedule(struct ip_vs_service *svc)
 564 {
 565         struct ip_vs_dest *dest, *least;
 566         int loh, doh;
 567
 568         /*
 569          * We think the overhead of processing active connections is fifty
 570          * times higher than that of inactive connections in average. (This
 571          * fifty times might not be accurate, we will change it later.) We
 572          * use the following formula to estimate the overhead:
 573          *                dest->activeconns*50 + dest->inactconns
 574          * and the load:
 575          *                (dest overhead) / dest->weight
 576          *
 577          * Remember -- no floats in kernel mode!!!
 578          * The comparison of h1*w2 > h2*w1 is equivalent to that of
 579          *                h1/w1 > h2/w2
 580          * if every weight is larger than zero.
 581          *
 582          * The server with weight=0 is quiesced and will not receive any
 583          * new connection.
 584          */
 585         list_for_each_entry(dest, &svc->destinations, n_list) {
 586                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 587                         continue;
 588
 589                 if (atomic_read(&dest->weight) > 0) {
 590                         least = dest;
 591                         loh = atomic_read(&least->activeconns) * 50
 592                                 + atomic_read(&least->inactconns);
 593                         goto nextstage;
 594                 }
 595         }
 596         return NULL;
 597
 598         /*
 599          *    Find the destination with the least load.
 600          */
 601   nextstage:
 602         list_for_each_entry_continue(dest, &svc->destinations, n_list) {
 603                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 604                         continue;
 605
 606                 doh = atomic_read(&dest->activeconns) * 50
 607                         + atomic_read(&dest->inactconns);
 608                 if (loh * atomic_read(&dest->weight) >
 609                     doh * atomic_read(&least->weight)) {
 610                         least = dest;
 611                         loh = doh;
 612                 }
 613         }
 614
 615         IP_VS_DBG_BUF(6, "LBLCR: server %s:%d "
 616                       "activeconns %d refcnt %d weight %d overhead %d\n",
 617                       IP_VS_DBG_ADDR(least->af, &least->addr),
 618                       ntohs(least->port),
 619                       atomic_read(&least->activeconns),
 620                       atomic_read(&least->refcnt),
 621                       atomic_read(&least->weight), loh);
 622
 623         return least;
 624 }
 625
 626
 627 /*
 628  *   If this destination server is overloaded and there is a less loaded
 629  *   server, then return true.
 630  */
 631 static inline int
 632 is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
 633 {
 634         if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
 635                 struct ip_vs_dest *d;
 636
 637                 list_for_each_entry(d, &svc->destinations, n_list) {
 638                         if (atomic_read(&d->activeconns)*2
 639                             < atomic_read(&d->weight)) {
 640                                 return 1;
 641                         }
 642                 }
 643         }
 644         return 0;
 645 }
 646
 647
 648 /*
 649  *    Locality-Based (weighted) Least-Connection scheduling
 650  */
 651 static struct ip_vs_dest *
 652 ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
 653 {
 654         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 655         struct ip_vs_iphdr iph;
 656         struct ip_vs_dest *dest = NULL;
 657         struct ip_vs_lblcr_entry *en;
 658
 659         ip_vs_fill_iphdr(svc->af, skb_network_header(skb), &iph);
 660
 661         IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
 662
 663         /* First look in our cache */
 664         read_lock(&svc->sched_lock);
 665         en = ip_vs_lblcr_get(svc->af, tbl, &iph.daddr);
 666         if (en) {
 667                 /* We only hold a read lock, but this is atomic */
 668                 en->lastuse = jiffies;
 669
 670                 /* Get the least loaded destination */
 671                 read_lock(&en->set.lock);
 672                 dest = ip_vs_dest_set_min(&en->set);
 673                 read_unlock(&en->set.lock);
 674
 675                 /* More than one destination + enough time passed by, cleanup */
 676                 if (atomic_read(&en->set.size) > 1 &&
 677                                 time_after(jiffies, en->set.lastmod +
 678                                 sysctl_ip_vs_lblcr_expiration)) {
 679                         struct ip_vs_dest *m;
 680
 681                         write_lock(&en->set.lock);
 682                         m = ip_vs_dest_set_max(&en->set);
 683                         if (m)
 684                                 ip_vs_dest_set_erase(&en->set, m);
 685                         write_unlock(&en->set.lock);
 686                 }
 687
 688                 /* If the destination is not overloaded, use it */
 689                 if (dest && !is_overloaded(dest, svc)) {
 690                         read_unlock(&svc->sched_lock);
 691                         goto out;
 692                 }
 693
 694                 /* The cache entry is invalid, time to schedule */
 695                 dest = __ip_vs_lblcr_schedule(svc);
 696                 if (!dest) {
 697                         IP_VS_ERR_RL("LBLCR: no destination available\n");
 698                         read_unlock(&svc->sched_lock);
 699                         return NULL;
 700                 }
 701
 702                 /* Update our cache entry */
 703                 write_lock(&en->set.lock);
 704                 ip_vs_dest_set_insert(&en->set, dest);
 705                 write_unlock(&en->set.lock);
 706         }
 707         read_unlock(&svc->sched_lock);
 708
 709         if (dest)
 710                 goto out;
 711
 712         /* No cache entry, time to schedule */
 713         dest = __ip_vs_lblcr_schedule(svc);
 714         if (!dest) {
 715                 IP_VS_DBG(1, "no destination available\n");
 716                 return NULL;
 717         }
 718
 719         /* If we fail to create a cache entry, we'll just use the valid dest */
 720         write_lock(&svc->sched_lock);
 721         ip_vs_lblcr_new(tbl, &iph.daddr, dest);
 722         write_unlock(&svc->sched_lock);
 723
 724 out:
 725         IP_VS_DBG_BUF(6, "LBLCR: destination IP address %s --> server %s:%d\n",
 726                       IP_VS_DBG_ADDR(svc->af, &iph.daddr),
 727                       IP_VS_DBG_ADDR(svc->af, &dest->addr), ntohs(dest->port));
 728
 729         return dest;
 730 }
 731
 732
 733 /*
 734  *      IPVS LBLCR Scheduler structure
 735  */
 736 static struct ip_vs_scheduler ip_vs_lblcr_scheduler =
 737 {
 738         .name =                 "lblcr",
 739         .refcnt =               ATOMIC_INIT(0),
 740         .module =               THIS_MODULE,
 741         .n_list =               LIST_HEAD_INIT(ip_vs_lblcr_scheduler.n_list),
 742         .init_service =         ip_vs_lblcr_init_svc,
 743         .done_service =         ip_vs_lblcr_done_svc,
 744         .schedule =             ip_vs_lblcr_schedule,
 745 };
 746
 747 /*
 748  *  per netns init.
 749  */
 750 static int __net_init __ip_vs_lblcr_init(struct net *net)
 751 {
 752         if (!net_eq(net, &init_net))    /* netns not enabled yet */
 753                 return -EPERM;
 754
 755         sysctl_header = register_net_sysctl_table(net, net_vs_ctl_path,
 756                                                   vs_vars_table);
 757         if (!sysctl_header)
 758                 return -ENOMEM;
 759
 760         return 0;
 761 }
 762
 763 static void __net_exit __ip_vs_lblcr_exit(struct net *net)
 764 {
 765         if (!net_eq(net, &init_net))    /* netns not enabled yet */
 766                 return;
 767
 768         unregister_net_sysctl_table(sysctl_header);
 769 }
 770
 771 static struct pernet_operations ip_vs_lblcr_ops = {
 772         .init = __ip_vs_lblcr_init,
 773         .exit = __ip_vs_lblcr_exit,
 774 };
 775
 776 static int __init ip_vs_lblcr_init(void)
 777 {
 778         int ret;
 779
 780         ret = register_pernet_subsys(&ip_vs_lblcr_ops);
 781         if (ret)
 782                 return ret;
 783
 784         ret = register_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 785         if (ret)
 786                 unregister_pernet_subsys(&ip_vs_lblcr_ops);
 787         return ret;
 788 }
 789
 790 static void __exit ip_vs_lblcr_cleanup(void)
 791 {
 792         unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 793         unregister_pernet_subsys(&ip_vs_lblcr_ops);
 794 }
 795
 796
 797 module_init(ip_vs_lblcr_init);
 798 module_exit(ip_vs_lblcr_cleanup);
 799 MODULE_LICENSE("GPL");