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 #define DEFAULT_EXPIRATION      (24*60*60*HZ)
  67
  68 /*
  69  *    It is for full expiration check.
  70  *    When there is no partial expiration check (garbage collection)
  71  *    in a half hour, do a full expiration check to collect stale
  72  *    entries that haven't been touched for a day.
  73  */
  74 #define COUNT_FOR_FULL_EXPIRATION   30
  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 = ip_vs_dest_conn_overhead(least);
 184                         goto nextstage;
 185                 }
 186         }
 187         return NULL;
 188
 189         /* find the destination with the weighted least load */
 190   nextstage:
 191         list_for_each_entry(e, &set->list, list) {
 192                 dest = e->dest;
 193                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 194                         continue;
 195
 196                 doh = ip_vs_dest_conn_overhead(dest);
 197                 if ((loh * atomic_read(&dest->weight) >
 198                      doh * atomic_read(&least->weight))
 199                     && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
 200                         least = dest;
 201                         loh = doh;
 202                 }
 203         }
 204
 205         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
 206                       "activeconns %d refcnt %d weight %d overhead %d\n",
 207                       __func__,
 208                       IP_VS_DBG_ADDR(least->af, &least->addr),
 209                       ntohs(least->port),
 210                       atomic_read(&least->activeconns),
 211                       atomic_read(&least->refcnt),
 212                       atomic_read(&least->weight), loh);
 213         return least;
 214 }
 215
 216
 217 /* get weighted most-connection node in the destination set */
 218 static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
 219 {
 220         register struct ip_vs_dest_set_elem *e;
 221         struct ip_vs_dest *dest, *most;
 222         int moh, doh;
 223
 224         if (set == NULL)
 225                 return NULL;
 226
 227         /* select the first destination server, whose weight > 0 */
 228         list_for_each_entry(e, &set->list, list) {
 229                 most = e->dest;
 230                 if (atomic_read(&most->weight) > 0) {
 231                         moh = ip_vs_dest_conn_overhead(most);
 232                         goto nextstage;
 233                 }
 234         }
 235         return NULL;
 236
 237         /* find the destination with the weighted most load */
 238   nextstage:
 239         list_for_each_entry(e, &set->list, list) {
 240                 dest = e->dest;
 241                 doh = ip_vs_dest_conn_overhead(dest);
 242                 /* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
 243                 if ((moh * atomic_read(&dest->weight) <
 244                      doh * atomic_read(&most->weight))
 245                     && (atomic_read(&dest->weight) > 0)) {
 246                         most = dest;
 247                         moh = doh;
 248                 }
 249         }
 250
 251         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
 252                       "activeconns %d refcnt %d weight %d overhead %d\n",
 253                       __func__,
 254                       IP_VS_DBG_ADDR(most->af, &most->addr), ntohs(most->port),
 255                       atomic_read(&most->activeconns),
 256                       atomic_read(&most->refcnt),
 257                       atomic_read(&most->weight), moh);
 258         return most;
 259 }
 260
 261
 262 /*
 263  *      IPVS lblcr entry represents an association between destination
 264  *      IP address and its destination server set
 265  */
 266 struct ip_vs_lblcr_entry {
 267         struct list_head        list;
 268         int                     af;             /* address family */
 269         union nf_inet_addr      addr;           /* destination IP address */
 270         struct ip_vs_dest_set   set;            /* destination server set */
 271         unsigned long           lastuse;        /* last used time */
 272 };
 273
 274
 275 /*
 276  *      IPVS lblcr hash table
 277  */
 278 struct ip_vs_lblcr_table {
 279         struct list_head        bucket[IP_VS_LBLCR_TAB_SIZE];  /* hash bucket */
 280         atomic_t                entries;        /* number of entries */
 281         int                     max_size;       /* maximum size of entries */
 282         struct timer_list       periodic_timer; /* collect stale entries */
 283         int                     rover;          /* rover for expire check */
 284         int                     counter;        /* counter for no expire */
 285 };
 286
 287
 288 #ifdef CONFIG_SYSCTL
 289 /*
 290  *      IPVS LBLCR sysctl table
 291  */
 292
 293 static ctl_table vs_vars_table[] = {
 294         {
 295                 .procname       = "lblcr_expiration",
 296                 .data           = NULL,
 297                 .maxlen         = sizeof(int),
 298                 .mode           = 0644,
 299                 .proc_handler   = proc_dointvec_jiffies,
 300         },
 301         { }
 302 };
 303 #endif
 304
 305 static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
 306 {
 307         list_del(&en->list);
 308         ip_vs_dest_set_eraseall(&en->set);
 309         kfree(en);
 310 }
 311
 312
 313 /*
 314  *      Returns hash value for IPVS LBLCR entry
 315  */
 316 static inline unsigned
 317 ip_vs_lblcr_hashkey(int af, const union nf_inet_addr *addr)
 318 {
 319         __be32 addr_fold = addr->ip;
 320
 321 #ifdef CONFIG_IP_VS_IPV6
 322         if (af == AF_INET6)
 323                 addr_fold = addr->ip6[0]^addr->ip6[1]^
 324                             addr->ip6[2]^addr->ip6[3];
 325 #endif
 326         return (ntohl(addr_fold)*2654435761UL) & IP_VS_LBLCR_TAB_MASK;
 327 }
 328
 329
 330 /*
 331  *      Hash an entry in the ip_vs_lblcr_table.
 332  *      returns bool success.
 333  */
 334 static void
 335 ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
 336 {
 337         unsigned hash = ip_vs_lblcr_hashkey(en->af, &en->addr);
 338
 339         list_add(&en->list, &tbl->bucket[hash]);
 340         atomic_inc(&tbl->entries);
 341 }
 342
 343
 344 /*
 345  *  Get ip_vs_lblcr_entry associated with supplied parameters. Called under
 346  *  read lock.
 347  */
 348 static inline struct ip_vs_lblcr_entry *
 349 ip_vs_lblcr_get(int af, struct ip_vs_lblcr_table *tbl,
 350                 const union nf_inet_addr *addr)
 351 {
 352         unsigned hash = ip_vs_lblcr_hashkey(af, addr);
 353         struct ip_vs_lblcr_entry *en;
 354
 355         list_for_each_entry(en, &tbl->bucket[hash], list)
 356                 if (ip_vs_addr_equal(af, &en->addr, addr))
 357                         return en;
 358
 359         return NULL;
 360 }
 361
 362
 363 /*
 364  * Create or update an ip_vs_lblcr_entry, which is a mapping of a destination
 365  * IP address to a server. Called under write lock.
 366  */
 367 static inline struct ip_vs_lblcr_entry *
 368 ip_vs_lblcr_new(struct ip_vs_lblcr_table *tbl, const union nf_inet_addr *daddr,
 369                 struct ip_vs_dest *dest)
 370 {
 371         struct ip_vs_lblcr_entry *en;
 372
 373         en = ip_vs_lblcr_get(dest->af, tbl, daddr);
 374         if (!en) {
 375                 en = kmalloc(sizeof(*en), GFP_ATOMIC);
 376                 if (!en) {
 377                         pr_err("%s(): no memory\n", __func__);
 378                         return NULL;
 379                 }
 380
 381                 en->af = dest->af;
 382                 ip_vs_addr_copy(dest->af, &en->addr, daddr);
 383                 en->lastuse = jiffies;
 384
 385                 /* initialize its dest set */
 386                 atomic_set(&(en->set.size), 0);
 387                 INIT_LIST_HEAD(&en->set.list);
 388                 rwlock_init(&en->set.lock);
 389
 390                 ip_vs_lblcr_hash(tbl, en);
 391         }
 392
 393         write_lock(&en->set.lock);
 394         ip_vs_dest_set_insert(&en->set, dest);
 395         write_unlock(&en->set.lock);
 396
 397         return en;
 398 }
 399
 400
 401 /*
 402  *      Flush all the entries of the specified table.
 403  */
 404 static void ip_vs_lblcr_flush(struct ip_vs_lblcr_table *tbl)
 405 {
 406         int i;
 407         struct ip_vs_lblcr_entry *en, *nxt;
 408
 409         /* No locking required, only called during cleanup. */
 410         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 411                 list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {
 412                         ip_vs_lblcr_free(en);
 413                 }
 414         }
 415 }
 416
 417 static int sysctl_lblcr_expiration(struct ip_vs_service *svc)
 418 {
 419 #ifdef CONFIG_SYSCTL
 420         struct netns_ipvs *ipvs = net_ipvs(svc->net);
 421         return ipvs->sysctl_lblcr_expiration;
 422 #else
 423         return DEFAULT_EXPIRATION;
 424 #endif
 425 }
 426
 427 static inline void ip_vs_lblcr_full_check(struct ip_vs_service *svc)
 428 {
 429         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 430         unsigned long now = jiffies;
 431         int i, j;
 432         struct ip_vs_lblcr_entry *en, *nxt;
 433
 434         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 435                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 436
 437                 write_lock(&svc->sched_lock);
 438                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 439                         if (time_after(en->lastuse +
 440                                        sysctl_lblcr_expiration(svc), now))
 441                                 continue;
 442
 443                         ip_vs_lblcr_free(en);
 444                         atomic_dec(&tbl->entries);
 445                 }
 446                 write_unlock(&svc->sched_lock);
 447         }
 448         tbl->rover = j;
 449 }
 450
 451
 452 /*
 453  *      Periodical timer handler for IPVS lblcr table
 454  *      It is used to collect stale entries when the number of entries
 455  *      exceeds the maximum size of the table.
 456  *
 457  *      Fixme: we probably need more complicated algorithm to collect
 458  *             entries that have not been used for a long time even
 459  *             if the number of entries doesn't exceed the maximum size
 460  *             of the table.
 461  *      The full expiration check is for this purpose now.
 462  */
 463 static void ip_vs_lblcr_check_expire(unsigned long data)
 464 {
 465         struct ip_vs_service *svc = (struct ip_vs_service *) data;
 466         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 467         unsigned long now = jiffies;
 468         int goal;
 469         int i, j;
 470         struct ip_vs_lblcr_entry *en, *nxt;
 471
 472         if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
 473                 /* do full expiration check */
 474                 ip_vs_lblcr_full_check(svc);
 475                 tbl->counter = 1;
 476                 goto out;
 477         }
 478
 479         if (atomic_read(&tbl->entries) <= tbl->max_size) {
 480                 tbl->counter++;
 481                 goto out;
 482         }
 483
 484         goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3;
 485         if (goal > tbl->max_size/2)
 486                 goal = tbl->max_size/2;
 487
 488         for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 489                 j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
 490
 491                 write_lock(&svc->sched_lock);
 492                 list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
 493                         if (time_before(now, en->lastuse+ENTRY_TIMEOUT))
 494                                 continue;
 495
 496                         ip_vs_lblcr_free(en);
 497                         atomic_dec(&tbl->entries);
 498                         goal--;
 499                 }
 500                 write_unlock(&svc->sched_lock);
 501                 if (goal <= 0)
 502                         break;
 503         }
 504         tbl->rover = j;
 505
 506   out:
 507         mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
 508 }
 509
 510 static int ip_vs_lblcr_init_svc(struct ip_vs_service *svc)
 511 {
 512         int i;
 513         struct ip_vs_lblcr_table *tbl;
 514
 515         /*
 516          *    Allocate the ip_vs_lblcr_table for this service
 517          */
 518         tbl = kmalloc(sizeof(*tbl), GFP_ATOMIC);
 519         if (tbl == NULL) {
 520                 pr_err("%s(): no memory\n", __func__);
 521                 return -ENOMEM;
 522         }
 523         svc->sched_data = tbl;
 524         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) allocated for "
 525                   "current service\n", sizeof(*tbl));
 526
 527         /*
 528          *    Initialize the hash buckets
 529          */
 530         for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
 531                 INIT_LIST_HEAD(&tbl->bucket[i]);
 532         }
 533         tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
 534         tbl->rover = 0;
 535         tbl->counter = 1;
 536
 537         /*
 538          *    Hook periodic timer for garbage collection
 539          */
 540         setup_timer(&tbl->periodic_timer, ip_vs_lblcr_check_expire,
 541                         (unsigned long)svc);
 542         mod_timer(&tbl->periodic_timer, jiffies + CHECK_EXPIRE_INTERVAL);
 543
 544         return 0;
 545 }
 546
 547
 548 static int ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
 549 {
 550         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 551
 552         /* remove periodic timer */
 553         del_timer_sync(&tbl->periodic_timer);
 554
 555         /* got to clean up table entries here */
 556         ip_vs_lblcr_flush(tbl);
 557
 558         /* release the table itself */
 559         kfree(tbl);
 560         IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) released\n",
 561                   sizeof(*tbl));
 562
 563         return 0;
 564 }
 565
 566
 567 static inline struct ip_vs_dest *
 568 __ip_vs_lblcr_schedule(struct ip_vs_service *svc)
 569 {
 570         struct ip_vs_dest *dest, *least;
 571         int loh, doh;
 572
 573         /*
 574          * We use the following formula to estimate 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 = ip_vs_dest_conn_overhead(least);
 592                         goto nextstage;
 593                 }
 594         }
 595         return NULL;
 596
 597         /*
 598          *    Find the destination with the least load.
 599          */
 600   nextstage:
 601         list_for_each_entry_continue(dest, &svc->destinations, n_list) {
 602                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 603                         continue;
 604
 605                 doh = ip_vs_dest_conn_overhead(dest);
 606                 if (loh * atomic_read(&dest->weight) >
 607                     doh * atomic_read(&least->weight)) {
 608                         least = dest;
 609                         loh = doh;
 610                 }
 611         }
 612
 613         IP_VS_DBG_BUF(6, "LBLCR: server %s:%d "
 614                       "activeconns %d refcnt %d weight %d overhead %d\n",
 615                       IP_VS_DBG_ADDR(least->af, &least->addr),
 616                       ntohs(least->port),
 617                       atomic_read(&least->activeconns),
 618                       atomic_read(&least->refcnt),
 619                       atomic_read(&least->weight), loh);
 620
 621         return least;
 622 }
 623
 624
 625 /*
 626  *   If this destination server is overloaded and there is a less loaded
 627  *   server, then return true.
 628  */
 629 static inline int
 630 is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
 631 {
 632         if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
 633                 struct ip_vs_dest *d;
 634
 635                 list_for_each_entry(d, &svc->destinations, n_list) {
 636                         if (atomic_read(&d->activeconns)*2
 637                             < atomic_read(&d->weight)) {
 638                                 return 1;
 639                         }
 640                 }
 641         }
 642         return 0;
 643 }
 644
 645
 646 /*
 647  *    Locality-Based (weighted) Least-Connection scheduling
 648  */
 649 static struct ip_vs_dest *
 650 ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
 651 {
 652         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 653         struct ip_vs_iphdr iph;
 654         struct ip_vs_dest *dest = NULL;
 655         struct ip_vs_lblcr_entry *en;
 656
 657         ip_vs_fill_iphdr(svc->af, skb_network_header(skb), &iph);
 658
 659         IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
 660
 661         /* First look in our cache */
 662         read_lock(&svc->sched_lock);
 663         en = ip_vs_lblcr_get(svc->af, tbl, &iph.daddr);
 664         if (en) {
 665                 /* We only hold a read lock, but this is atomic */
 666                 en->lastuse = jiffies;
 667
 668                 /* Get the least loaded destination */
 669                 read_lock(&en->set.lock);
 670                 dest = ip_vs_dest_set_min(&en->set);
 671                 read_unlock(&en->set.lock);
 672
 673                 /* More than one destination + enough time passed by, cleanup */
 674                 if (atomic_read(&en->set.size) > 1 &&
 675                                 time_after(jiffies, en->set.lastmod +
 676                                 sysctl_lblcr_expiration(svc))) {
 677                         struct ip_vs_dest *m;
 678
 679                         write_lock(&en->set.lock);
 680                         m = ip_vs_dest_set_max(&en->set);
 681                         if (m)
 682                                 ip_vs_dest_set_erase(&en->set, m);
 683                         write_unlock(&en->set.lock);
 684                 }
 685
 686                 /* If the destination is not overloaded, use it */
 687                 if (dest && !is_overloaded(dest, svc)) {
 688                         read_unlock(&svc->sched_lock);
 689                         goto out;
 690                 }
 691
 692                 /* The cache entry is invalid, time to schedule */
 693                 dest = __ip_vs_lblcr_schedule(svc);
 694                 if (!dest) {
 695                         ip_vs_scheduler_err(svc, "no destination available");
 696                         read_unlock(&svc->sched_lock);
 697                         return NULL;
 698                 }
 699
 700                 /* Update our cache entry */
 701                 write_lock(&en->set.lock);
 702                 ip_vs_dest_set_insert(&en->set, dest);
 703                 write_unlock(&en->set.lock);
 704         }
 705         read_unlock(&svc->sched_lock);
 706
 707         if (dest)
 708                 goto out;
 709
 710         /* No cache entry, time to schedule */
 711         dest = __ip_vs_lblcr_schedule(svc);
 712         if (!dest) {
 713                 IP_VS_DBG(1, "no destination available\n");
 714                 return NULL;
 715         }
 716
 717         /* If we fail to create a cache entry, we'll just use the valid dest */
 718         write_lock(&svc->sched_lock);
 719         ip_vs_lblcr_new(tbl, &iph.daddr, dest);
 720         write_unlock(&svc->sched_lock);
 721
 722 out:
 723         IP_VS_DBG_BUF(6, "LBLCR: destination IP address %s --> server %s:%d\n",
 724                       IP_VS_DBG_ADDR(svc->af, &iph.daddr),
 725                       IP_VS_DBG_ADDR(svc->af, &dest->addr), ntohs(dest->port));
 726
 727         return dest;
 728 }
 729
 730
 731 /*
 732  *      IPVS LBLCR Scheduler structure
 733  */
 734 static struct ip_vs_scheduler ip_vs_lblcr_scheduler =
 735 {
 736         .name =                 "lblcr",
 737         .refcnt =               ATOMIC_INIT(0),
 738         .module =               THIS_MODULE,
 739         .n_list =               LIST_HEAD_INIT(ip_vs_lblcr_scheduler.n_list),
 740         .init_service =         ip_vs_lblcr_init_svc,
 741         .done_service =         ip_vs_lblcr_done_svc,
 742         .schedule =             ip_vs_lblcr_schedule,
 743 };
 744
 745 /*
 746  *  per netns init.
 747  */
 748 #ifdef CONFIG_SYSCTL
 749 static int __net_init __ip_vs_lblcr_init(struct net *net)
 750 {
 751         struct netns_ipvs *ipvs = net_ipvs(net);
 752
 753         if (!net_eq(net, &init_net)) {
 754                 ipvs->lblcr_ctl_table = kmemdup(vs_vars_table,
 755                                                 sizeof(vs_vars_table),
 756                                                 GFP_KERNEL);
 757                 if (ipvs->lblcr_ctl_table == NULL)
 758                         return -ENOMEM;
 759         } else
 760                 ipvs->lblcr_ctl_table = vs_vars_table;
 761         ipvs->sysctl_lblcr_expiration = DEFAULT_EXPIRATION;
 762         ipvs->lblcr_ctl_table[0].data = &ipvs->sysctl_lblcr_expiration;
 763
 764         ipvs->lblcr_ctl_header =
 765                 register_net_sysctl_table(net, net_vs_ctl_path,
 766                                           ipvs->lblcr_ctl_table);
 767         if (!ipvs->lblcr_ctl_header) {
 768                 if (!net_eq(net, &init_net))
 769                         kfree(ipvs->lblcr_ctl_table);
 770                 return -ENOMEM;
 771         }
 772
 773         return 0;
 774 }
 775
 776 static void __net_exit __ip_vs_lblcr_exit(struct net *net)
 777 {
 778         struct netns_ipvs *ipvs = net_ipvs(net);
 779
 780         unregister_net_sysctl_table(ipvs->lblcr_ctl_header);
 781
 782         if (!net_eq(net, &init_net))
 783                 kfree(ipvs->lblcr_ctl_table);
 784 }
 785
 786 #else
 787
 788 static int __net_init __ip_vs_lblcr_init(struct net *net) { return 0; }
 789 static void __net_exit __ip_vs_lblcr_exit(struct net *net) { }
 790
 791 #endif
 792
 793 static struct pernet_operations ip_vs_lblcr_ops = {
 794         .init = __ip_vs_lblcr_init,
 795         .exit = __ip_vs_lblcr_exit,
 796 };
 797
 798 static int __init ip_vs_lblcr_init(void)
 799 {
 800         int ret;
 801
 802         ret = register_pernet_subsys(&ip_vs_lblcr_ops);
 803         if (ret)
 804                 return ret;
 805
 806         ret = register_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 807         if (ret)
 808                 unregister_pernet_subsys(&ip_vs_lblcr_ops);
 809         return ret;
 810 }
 811
 812 static void __exit ip_vs_lblcr_cleanup(void)
 813 {
 814         unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 815         unregister_pernet_subsys(&ip_vs_lblcr_ops);
 816 }
 817
 818
 819 module_init(ip_vs_lblcr_init);
 820 module_exit(ip_vs_lblcr_cleanup);
 821 MODULE_LICENSE("GPL");