root/net/netfilter/ipvs/ip_vs_lblcr.c

DEFINITIONS

1. ip_vs_dest_set_insert
2. ip_vs_lblcr_elem_rcu_free
3. ip_vs_dest_set_erase
4. ip_vs_dest_set_eraseall
5. ip_vs_dest_set_min
6. ip_vs_dest_set_max
7. ip_vs_lblcr_free
8. ip_vs_lblcr_hashkey
9. ip_vs_lblcr_hash
10. ip_vs_lblcr_get
11. ip_vs_lblcr_new
12. ip_vs_lblcr_flush
13. sysctl_lblcr_expiration
14. ip_vs_lblcr_full_check
15. ip_vs_lblcr_check_expire
16. ip_vs_lblcr_init_svc
17. ip_vs_lblcr_done_svc
18. __ip_vs_lblcr_schedule
19. is_overloaded
20. ip_vs_lblcr_schedule
21. __ip_vs_lblcr_init
22. __ip_vs_lblcr_exit
23. __ip_vs_lblcr_init
24. __ip_vs_lblcr_exit
25. ip_vs_lblcr_init
26. ip_vs_lblcr_cleanup

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * IPVS:        Locality-Based Least-Connection with Replication scheduler
   4  *
   5  * Authors:     Wensong Zhang <wensong@gnuchina.org>
   6  *
   7  * Changes:
   8  *     Julian Anastasov        :    Added the missing (dest->weight>0)
   9  *                                  condition in the ip_vs_dest_set_max.
  10  */
  11 
  12 /*
  13  * The lblc/r algorithm is as follows (pseudo code):
  14  *
  15  *       if serverSet[dest_ip] is null then
  16  *               n, serverSet[dest_ip] <- {weighted least-conn node};
  17  *       else
  18  *               n <- {least-conn (alive) node in serverSet[dest_ip]};
  19  *               if (n is null) OR
  20  *                  (n.conns>n.weight AND
  21  *                   there is a node m with m.conns<m.weight/2) then
  22  *                   n <- {weighted least-conn node};
  23  *                   add n to serverSet[dest_ip];
  24  *               if |serverSet[dest_ip]| > 1 AND
  25  *                   now - serverSet[dest_ip].lastMod > T then
  26  *                   m <- {most conn node in serverSet[dest_ip]};
  27  *                   remove m from serverSet[dest_ip];
  28  *       if serverSet[dest_ip] changed then
  29  *               serverSet[dest_ip].lastMod <- now;
  30  *
  31  *       return n;
  32  *
  33  */
  34 
  35 #define KMSG_COMPONENT "IPVS"
  36 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  37 
  38 #include <linux/ip.h>
  39 #include <linux/module.h>
  40 #include <linux/kernel.h>
  41 #include <linux/skbuff.h>
  42 #include <linux/jiffies.h>
  43 #include <linux/list.h>
  44 #include <linux/slab.h>
  45 #include <linux/hash.h>
  46 
  47 /* for sysctl */
  48 #include <linux/fs.h>
  49 #include <linux/sysctl.h>
  50 #include <net/net_namespace.h>
  51 
  52 #include <net/ip_vs.h>
  53 
  54 
  55 /*
  56  *    It is for garbage collection of stale IPVS lblcr entries,
  57  *    when the table is full.
  58  */
  59 #define CHECK_EXPIRE_INTERVAL   (60*HZ)
  60 #define ENTRY_TIMEOUT           (6*60*HZ)
  61 
  62 #define DEFAULT_EXPIRATION      (24*60*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 
  72 /*
  73  *     for IPVS lblcr entry hash table
  74  */
  75 #ifndef CONFIG_IP_VS_LBLCR_TAB_BITS
  76 #define CONFIG_IP_VS_LBLCR_TAB_BITS      10
  77 #endif
  78 #define IP_VS_LBLCR_TAB_BITS     CONFIG_IP_VS_LBLCR_TAB_BITS
  79 #define IP_VS_LBLCR_TAB_SIZE     (1 << IP_VS_LBLCR_TAB_BITS)
  80 #define IP_VS_LBLCR_TAB_MASK     (IP_VS_LBLCR_TAB_SIZE - 1)
  81 
  82 
  83 /*
  84  *      IPVS destination set structure and operations
  85  */
  86 struct ip_vs_dest_set_elem {
  87         struct list_head        list;          /* list link */
  88         struct ip_vs_dest       *dest;          /* destination server */
  89         struct rcu_head         rcu_head;
  90 };
  91 
  92 struct ip_vs_dest_set {
  93         atomic_t                size;           /* set size */
  94         unsigned long           lastmod;        /* last modified time */
  95         struct list_head        list;           /* destination list */
  96 };
  97 
  98 
  99 static void ip_vs_dest_set_insert(struct ip_vs_dest_set *set,
 100                                   struct ip_vs_dest *dest, bool check)
 101 {
 102         struct ip_vs_dest_set_elem *e;
 103 
 104         if (check) {
 105                 list_for_each_entry(e, &set->list, list) {
 106                         if (e->dest == dest)
 107                                 return;
 108                 }
 109         }
 110 
 111         e = kmalloc(sizeof(*e), GFP_ATOMIC);
 112         if (e == NULL)
 113                 return;
 114 
 115         ip_vs_dest_hold(dest);
 116         e->dest = dest;
 117 
 118         list_add_rcu(&e->list, &set->list);
 119         atomic_inc(&set->size);
 120 
 121         set->lastmod = jiffies;
 122 }
 123 
 124 static void ip_vs_lblcr_elem_rcu_free(struct rcu_head *head)
 125 {
 126         struct ip_vs_dest_set_elem *e;
 127 
 128         e = container_of(head, struct ip_vs_dest_set_elem, rcu_head);
 129         ip_vs_dest_put_and_free(e->dest);
 130         kfree(e);
 131 }
 132 
 133 static void
 134 ip_vs_dest_set_erase(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
 135 {
 136         struct ip_vs_dest_set_elem *e;
 137 
 138         list_for_each_entry(e, &set->list, list) {
 139                 if (e->dest == dest) {
 140                         /* HIT */
 141                         atomic_dec(&set->size);
 142                         set->lastmod = jiffies;
 143                         list_del_rcu(&e->list);
 144                         call_rcu(&e->rcu_head, ip_vs_lblcr_elem_rcu_free);
 145                         break;
 146                 }
 147         }
 148 }
 149 
 150 static void ip_vs_dest_set_eraseall(struct ip_vs_dest_set *set)
 151 {
 152         struct ip_vs_dest_set_elem *e, *ep;
 153 
 154         list_for_each_entry_safe(e, ep, &set->list, list) {
 155                 list_del_rcu(&e->list);
 156                 call_rcu(&e->rcu_head, ip_vs_lblcr_elem_rcu_free);
 157         }
 158 }
 159 
 160 /* get weighted least-connection node in the destination set */
 161 static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
 162 {
 163         struct ip_vs_dest_set_elem *e;
 164         struct ip_vs_dest *dest, *least;
 165         int loh, doh;
 166 
 167         /* select the first destination server, whose weight > 0 */
 168         list_for_each_entry_rcu(e, &set->list, list) {
 169                 least = e->dest;
 170                 if (least->flags & IP_VS_DEST_F_OVERLOAD)
 171                         continue;
 172 
 173                 if ((atomic_read(&least->weight) > 0)
 174                     && (least->flags & IP_VS_DEST_F_AVAILABLE)) {
 175                         loh = ip_vs_dest_conn_overhead(least);
 176                         goto nextstage;
 177                 }
 178         }
 179         return NULL;
 180 
 181         /* find the destination with the weighted least load */
 182   nextstage:
 183         list_for_each_entry_continue_rcu(e, &set->list, list) {
 184                 dest = e->dest;
 185                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 186                         continue;
 187 
 188                 doh = ip_vs_dest_conn_overhead(dest);
 189                 if (((__s64)loh * atomic_read(&dest->weight) >
 190                      (__s64)doh * atomic_read(&least->weight))
 191                     && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
 192                         least = dest;
 193                         loh = doh;
 194                 }
 195         }
 196 
 197         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
 198                       "activeconns %d refcnt %d weight %d overhead %d\n",
 199                       __func__,
 200                       IP_VS_DBG_ADDR(least->af, &least->addr),
 201                       ntohs(least->port),
 202                       atomic_read(&least->activeconns),
 203                       refcount_read(&least->refcnt),
 204                       atomic_read(&least->weight), loh);
 205         return least;
 206 }
 207 
 208 
 209 /* get weighted most-connection node in the destination set */
 210 static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
 211 {
 212         struct ip_vs_dest_set_elem *e;
 213         struct ip_vs_dest *dest, *most;
 214         int moh, doh;
 215 
 216         if (set == NULL)
 217                 return NULL;
 218 
 219         /* select the first destination server, whose weight > 0 */
 220         list_for_each_entry(e, &set->list, list) {
 221                 most = e->dest;
 222                 if (atomic_read(&most->weight) > 0) {
 223                         moh = ip_vs_dest_conn_overhead(most);
 224                         goto nextstage;
 225                 }
 226         }
 227         return NULL;
 228 
 229         /* find the destination with the weighted most load */
 230   nextstage:
 231         list_for_each_entry_continue(e, &set->list, list) {
 232                 dest = e->dest;
 233                 doh = ip_vs_dest_conn_overhead(dest);
 234                 /* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
 235                 if (((__s64)moh * atomic_read(&dest->weight) <
 236                      (__s64)doh * atomic_read(&most->weight))
 237                     && (atomic_read(&dest->weight) > 0)) {
 238                         most = dest;
 239                         moh = doh;
 240                 }
 241         }
 242 
 243         IP_VS_DBG_BUF(6, "%s(): server %s:%d "
 244                       "activeconns %d refcnt %d weight %d overhead %d\n",
 245                       __func__,
 246                       IP_VS_DBG_ADDR(most->af, &most->addr), ntohs(most->port),
 247                       atomic_read(&most->activeconns),
 248                       refcount_read(&most->refcnt),
 249                       atomic_read(&most->weight), moh);
 250         return most;
 251 }
 252 
 253 
 254 /*
 255  *      IPVS lblcr entry represents an association between destination
 256  *      IP address and its destination server set
 257  */
 258 struct ip_vs_lblcr_entry {
 259         struct hlist_node       list;
 260         int                     af;             /* address family */
 261         union nf_inet_addr      addr;           /* destination IP address */
 262         struct ip_vs_dest_set   set;            /* destination server set */
 263         unsigned long           lastuse;        /* last used time */
 264         struct rcu_head         rcu_head;
 265 };
 266 
 267 
 268 /*
 269  *      IPVS lblcr hash table
 270  */
 271 struct ip_vs_lblcr_table {
 272         struct rcu_head         rcu_head;
 273         struct hlist_head       bucket[IP_VS_LBLCR_TAB_SIZE];  /* hash bucket */
 274         atomic_t                entries;        /* number of entries */
 275         int                     max_size;       /* maximum size of entries */
 276         struct timer_list       periodic_timer; /* collect stale entries */
 277         struct ip_vs_service    *svc;           /* pointer back to service */
 278         int                     rover;          /* rover for expire check */
 279         int                     counter;        /* counter for no expire */
 280         bool                    dead;
 281 };
 282 
 283 
 284 #ifdef CONFIG_SYSCTL
 285 /*
 286  *      IPVS LBLCR sysctl table
 287  */
 288 
 289 static struct ctl_table vs_vars_table[] = {
 290         {
 291                 .procname       = "lblcr_expiration",
 292                 .data           = NULL,
 293                 .maxlen         = sizeof(int),
 294                 .mode           = 0644,
 295                 .proc_handler   = proc_dointvec_jiffies,
 296         },
 297         { }
 298 };
 299 #endif
 300 
 301 static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
 302 {
 303         hlist_del_rcu(&en->list);
 304         ip_vs_dest_set_eraseall(&en->set);
 305         kfree_rcu(en, rcu_head);
 306 }
 307 
 308 
 309 /*
 310  *      Returns hash value for IPVS LBLCR entry
 311  */
 312 static inline unsigned int
 313 ip_vs_lblcr_hashkey(int af, const union nf_inet_addr *addr)
 314 {
 315         __be32 addr_fold = addr->ip;
 316 
 317 #ifdef CONFIG_IP_VS_IPV6
 318         if (af == AF_INET6)
 319                 addr_fold = addr->ip6[0]^addr->ip6[1]^
 320                             addr->ip6[2]^addr->ip6[3];
 321 #endif
 322         return hash_32(ntohl(addr_fold), IP_VS_LBLCR_TAB_BITS);
 323 }
 324 
 325 
 326 /*
 327  *      Hash an entry in the ip_vs_lblcr_table.
 328  *      returns bool success.
 329  */
 330 static void
 331 ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
 332 {
 333         unsigned int hash = ip_vs_lblcr_hashkey(en->af, &en->addr);
 334 
 335         hlist_add_head_rcu(&en->list, &tbl->bucket[hash]);
 336         atomic_inc(&tbl->entries);
 337 }
 338 
 339 
 340 /* Get ip_vs_lblcr_entry associated with supplied parameters. */
 341 static inline struct ip_vs_lblcr_entry *
 342 ip_vs_lblcr_get(int af, struct ip_vs_lblcr_table *tbl,
 343                 const union nf_inet_addr *addr)
 344 {
 345         unsigned int hash = ip_vs_lblcr_hashkey(af, addr);
 346         struct ip_vs_lblcr_entry *en;
 347 
 348         hlist_for_each_entry_rcu(en, &tbl->bucket[hash], list)
 349                 if (ip_vs_addr_equal(af, &en->addr, addr))
 350                         return en;
 351 
 352         return NULL;
 353 }
 354 
 355 
 356 /*
 357  * Create or update an ip_vs_lblcr_entry, which is a mapping of a destination
 358  * IP address to a server. Called under spin lock.
 359  */
 360 static inline struct ip_vs_lblcr_entry *
 361 ip_vs_lblcr_new(struct ip_vs_lblcr_table *tbl, const union nf_inet_addr *daddr,
 362                 u16 af, struct ip_vs_dest *dest)
 363 {
 364         struct ip_vs_lblcr_entry *en;
 365 
 366         en = ip_vs_lblcr_get(af, tbl, daddr);
 367         if (!en) {
 368                 en = kmalloc(sizeof(*en), GFP_ATOMIC);
 369                 if (!en)
 370                         return NULL;
 371 
 372                 en->af = af;
 373                 ip_vs_addr_copy(af, &en->addr, daddr);
 374                 en->lastuse = jiffies;
 375 
 376                 /* initialize its dest set */
 377                 atomic_set(&(en->set.size), 0);
 378                 INIT_LIST_HEAD(&en->set.list);
 379 
 380                 ip_vs_dest_set_insert(&en->set, dest, false);
 381 
 382                 ip_vs_lblcr_hash(tbl, en);
 383                 return en;
 384         }
 385 
 386         ip_vs_dest_set_insert(&en->set, dest, true);
 387 
 388         return en;
 389 }
 390 
 391 
 392 /*
 393  *      Flush all the entries of the specified table.
 394  */
 395 static void ip_vs_lblcr_flush(struct ip_vs_service *svc)
 396 {
 397         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 398         int i;
 399         struct ip_vs_lblcr_entry *en;
 400         struct hlist_node *next;
 401 
 402         spin_lock_bh(&svc->sched_lock);
 403         tbl->dead = true;
 404         for (i = 0; i < IP_VS_LBLCR_TAB_SIZE; i++) {
 405                 hlist_for_each_entry_safe(en, next, &tbl->bucket[i], list) {
 406                         ip_vs_lblcr_free(en);
 407                 }
 408         }
 409         spin_unlock_bh(&svc->sched_lock);
 410 }
 411 
 412 static int sysctl_lblcr_expiration(struct ip_vs_service *svc)
 413 {
 414 #ifdef CONFIG_SYSCTL
 415         return svc->ipvs->sysctl_lblcr_expiration;
 416 #else
 417         return DEFAULT_EXPIRATION;
 418 #endif
 419 }
 420 
 421 static inline void ip_vs_lblcr_full_check(struct ip_vs_service *svc)
 422 {
 423         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 424         unsigned long now = jiffies;
 425         int i, j;
 426         struct ip_vs_lblcr_entry *en;
 427         struct hlist_node *next;
 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                 spin_lock(&svc->sched_lock);
 433                 hlist_for_each_entry_safe(en, next, &tbl->bucket[j], list) {
 434                         if (time_after(en->lastuse +
 435                                        sysctl_lblcr_expiration(svc), now))
 436                                 continue;
 437 
 438                         ip_vs_lblcr_free(en);
 439                         atomic_dec(&tbl->entries);
 440                 }
 441                 spin_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(struct timer_list *t)
 459 {
 460         struct ip_vs_lblcr_table *tbl = from_timer(tbl, t, periodic_timer);
 461         struct ip_vs_service *svc = tbl->svc;
 462         unsigned long now = jiffies;
 463         int goal;
 464         int i, j;
 465         struct ip_vs_lblcr_entry *en;
 466         struct hlist_node *next;
 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                 spin_lock(&svc->sched_lock);
 488                 hlist_for_each_entry_safe(en, next, &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                 spin_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_KERNEL);
 515         if (tbl == NULL)
 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_HLIST_HEAD(&tbl->bucket[i]);
 527         }
 528         tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
 529         tbl->rover = 0;
 530         tbl->counter = 1;
 531         tbl->dead = false;
 532         tbl->svc = svc;
 533         atomic_set(&tbl->entries, 0);
 534 
 535         /*
 536          *    Hook periodic timer for garbage collection
 537          */
 538         timer_setup(&tbl->periodic_timer, ip_vs_lblcr_check_expire, 0);
 539         mod_timer(&tbl->periodic_timer, jiffies + CHECK_EXPIRE_INTERVAL);
 540 
 541         return 0;
 542 }
 543 
 544 
 545 static void ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
 546 {
 547         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 548 
 549         /* remove periodic timer */
 550         del_timer_sync(&tbl->periodic_timer);
 551 
 552         /* got to clean up table entries here */
 553         ip_vs_lblcr_flush(svc);
 554 
 555         /* release the table itself */
 556         kfree_rcu(tbl, rcu_head);
 557         IP_VS_DBG(6, "LBLCR hash table (memory=%zdbytes) released\n",
 558                   sizeof(*tbl));
 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 use the following formula to estimate the load:
 570          *                (dest overhead) / dest->weight
 571          *
 572          * Remember -- no floats in kernel mode!!!
 573          * The comparison of h1*w2 > h2*w1 is equivalent to that of
 574          *                h1/w1 > h2/w2
 575          * if every weight is larger than zero.
 576          *
 577          * The server with weight=0 is quiesced and will not receive any
 578          * new connection.
 579          */
 580         list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
 581                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 582                         continue;
 583 
 584                 if (atomic_read(&dest->weight) > 0) {
 585                         least = dest;
 586                         loh = ip_vs_dest_conn_overhead(least);
 587                         goto nextstage;
 588                 }
 589         }
 590         return NULL;
 591 
 592         /*
 593          *    Find the destination with the least load.
 594          */
 595   nextstage:
 596         list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) {
 597                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 598                         continue;
 599 
 600                 doh = ip_vs_dest_conn_overhead(dest);
 601                 if ((__s64)loh * atomic_read(&dest->weight) >
 602                     (__s64)doh * atomic_read(&least->weight)) {
 603                         least = dest;
 604                         loh = doh;
 605                 }
 606         }
 607 
 608         IP_VS_DBG_BUF(6, "LBLCR: server %s:%d "
 609                       "activeconns %d refcnt %d weight %d overhead %d\n",
 610                       IP_VS_DBG_ADDR(least->af, &least->addr),
 611                       ntohs(least->port),
 612                       atomic_read(&least->activeconns),
 613                       refcount_read(&least->refcnt),
 614                       atomic_read(&least->weight), loh);
 615 
 616         return least;
 617 }
 618 
 619 
 620 /*
 621  *   If this destination server is overloaded and there is a less loaded
 622  *   server, then return true.
 623  */
 624 static inline int
 625 is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
 626 {
 627         if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
 628                 struct ip_vs_dest *d;
 629 
 630                 list_for_each_entry_rcu(d, &svc->destinations, n_list) {
 631                         if (atomic_read(&d->activeconns)*2
 632                             < atomic_read(&d->weight)) {
 633                                 return 1;
 634                         }
 635                 }
 636         }
 637         return 0;
 638 }
 639 
 640 
 641 /*
 642  *    Locality-Based (weighted) Least-Connection scheduling
 643  */
 644 static struct ip_vs_dest *
 645 ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
 646                      struct ip_vs_iphdr *iph)
 647 {
 648         struct ip_vs_lblcr_table *tbl = svc->sched_data;
 649         struct ip_vs_dest *dest;
 650         struct ip_vs_lblcr_entry *en;
 651 
 652         IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
 653 
 654         /* First look in our cache */
 655         en = ip_vs_lblcr_get(svc->af, tbl, &iph->daddr);
 656         if (en) {
 657                 en->lastuse = jiffies;
 658 
 659                 /* Get the least loaded destination */
 660                 dest = ip_vs_dest_set_min(&en->set);
 661 
 662                 /* More than one destination + enough time passed by, cleanup */
 663                 if (atomic_read(&en->set.size) > 1 &&
 664                     time_after(jiffies, en->set.lastmod +
 665                                 sysctl_lblcr_expiration(svc))) {
 666                         spin_lock_bh(&svc->sched_lock);
 667                         if (atomic_read(&en->set.size) > 1) {
 668                                 struct ip_vs_dest *m;
 669 
 670                                 m = ip_vs_dest_set_max(&en->set);
 671                                 if (m)
 672                                         ip_vs_dest_set_erase(&en->set, m);
 673                         }
 674                         spin_unlock_bh(&svc->sched_lock);
 675                 }
 676 
 677                 /* If the destination is not overloaded, use it */
 678                 if (dest && !is_overloaded(dest, svc))
 679                         goto out;
 680 
 681                 /* The cache entry is invalid, time to schedule */
 682                 dest = __ip_vs_lblcr_schedule(svc);
 683                 if (!dest) {
 684                         ip_vs_scheduler_err(svc, "no destination available");
 685                         return NULL;
 686                 }
 687 
 688                 /* Update our cache entry */
 689                 spin_lock_bh(&svc->sched_lock);
 690                 if (!tbl->dead)
 691                         ip_vs_dest_set_insert(&en->set, dest, true);
 692                 spin_unlock_bh(&svc->sched_lock);
 693                 goto out;
 694         }
 695 
 696         /* No cache entry, time to schedule */
 697         dest = __ip_vs_lblcr_schedule(svc);
 698         if (!dest) {
 699                 IP_VS_DBG(1, "no destination available\n");
 700                 return NULL;
 701         }
 702 
 703         /* If we fail to create a cache entry, we'll just use the valid dest */
 704         spin_lock_bh(&svc->sched_lock);
 705         if (!tbl->dead)
 706                 ip_vs_lblcr_new(tbl, &iph->daddr, svc->af, dest);
 707         spin_unlock_bh(&svc->sched_lock);
 708 
 709 out:
 710         IP_VS_DBG_BUF(6, "LBLCR: destination IP address %s --> server %s:%d\n",
 711                       IP_VS_DBG_ADDR(svc->af, &iph->daddr),
 712                       IP_VS_DBG_ADDR(dest->af, &dest->addr), ntohs(dest->port));
 713 
 714         return dest;
 715 }
 716 
 717 
 718 /*
 719  *      IPVS LBLCR Scheduler structure
 720  */
 721 static struct ip_vs_scheduler ip_vs_lblcr_scheduler =
 722 {
 723         .name =                 "lblcr",
 724         .refcnt =               ATOMIC_INIT(0),
 725         .module =               THIS_MODULE,
 726         .n_list =               LIST_HEAD_INIT(ip_vs_lblcr_scheduler.n_list),
 727         .init_service =         ip_vs_lblcr_init_svc,
 728         .done_service =         ip_vs_lblcr_done_svc,
 729         .schedule =             ip_vs_lblcr_schedule,
 730 };
 731 
 732 /*
 733  *  per netns init.
 734  */
 735 #ifdef CONFIG_SYSCTL
 736 static int __net_init __ip_vs_lblcr_init(struct net *net)
 737 {
 738         struct netns_ipvs *ipvs = net_ipvs(net);
 739 
 740         if (!ipvs)
 741                 return -ENOENT;
 742 
 743         if (!net_eq(net, &init_net)) {
 744                 ipvs->lblcr_ctl_table = kmemdup(vs_vars_table,
 745                                                 sizeof(vs_vars_table),
 746                                                 GFP_KERNEL);
 747                 if (ipvs->lblcr_ctl_table == NULL)
 748                         return -ENOMEM;
 749 
 750                 /* Don't export sysctls to unprivileged users */
 751                 if (net->user_ns != &init_user_ns)
 752                         ipvs->lblcr_ctl_table[0].procname = NULL;
 753         } else
 754                 ipvs->lblcr_ctl_table = vs_vars_table;
 755         ipvs->sysctl_lblcr_expiration = DEFAULT_EXPIRATION;
 756         ipvs->lblcr_ctl_table[0].data = &ipvs->sysctl_lblcr_expiration;
 757 
 758         ipvs->lblcr_ctl_header =
 759                 register_net_sysctl(net, "net/ipv4/vs", ipvs->lblcr_ctl_table);
 760         if (!ipvs->lblcr_ctl_header) {
 761                 if (!net_eq(net, &init_net))
 762                         kfree(ipvs->lblcr_ctl_table);
 763                 return -ENOMEM;
 764         }
 765 
 766         return 0;
 767 }
 768 
 769 static void __net_exit __ip_vs_lblcr_exit(struct net *net)
 770 {
 771         struct netns_ipvs *ipvs = net_ipvs(net);
 772 
 773         unregister_net_sysctl_table(ipvs->lblcr_ctl_header);
 774 
 775         if (!net_eq(net, &init_net))
 776                 kfree(ipvs->lblcr_ctl_table);
 777 }
 778 
 779 #else
 780 
 781 static int __net_init __ip_vs_lblcr_init(struct net *net) { return 0; }
 782 static void __net_exit __ip_vs_lblcr_exit(struct net *net) { }
 783 
 784 #endif
 785 
 786 static struct pernet_operations ip_vs_lblcr_ops = {
 787         .init = __ip_vs_lblcr_init,
 788         .exit = __ip_vs_lblcr_exit,
 789 };
 790 
 791 static int __init ip_vs_lblcr_init(void)
 792 {
 793         int ret;
 794 
 795         ret = register_pernet_subsys(&ip_vs_lblcr_ops);
 796         if (ret)
 797                 return ret;
 798 
 799         ret = register_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 800         if (ret)
 801                 unregister_pernet_subsys(&ip_vs_lblcr_ops);
 802         return ret;
 803 }
 804 
 805 static void __exit ip_vs_lblcr_cleanup(void)
 806 {
 807         unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
 808         unregister_pernet_subsys(&ip_vs_lblcr_ops);
 809         rcu_barrier();
 810 }
 811 
 812 
 813 module_init(ip_vs_lblcr_init);
 814 module_exit(ip_vs_lblcr_cleanup);
 815 MODULE_LICENSE("GPL");