net/ipv4/ipvs/ip_vs_conn.c

   1 /*
   2  * IPVS         An implementation of the IP virtual server support for the
   3  *              LINUX operating system.  IPVS is now implemented as a module
   4  *              over the Netfilter framework. IPVS can be used to build a
   5  *              high-performance and highly available server based on a
   6  *              cluster of servers.
   7  *
   8  * Version:     $Id: ip_vs_conn.c,v 1.31 2003/04/18 09:03:16 wensong Exp $
   9  *
  10  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
  11  *              Peter Kese <peter.kese@ijs.si>
  12  *              Julian Anastasov <ja@ssi.bg>
  13  *
  14  *              This program is free software; you can redistribute it and/or
  15  *              modify it under the terms of the GNU General Public License
  16  *              as published by the Free Software Foundation; either version
  17  *              2 of the License, or (at your option) any later version.
  18  *
  19  * The IPVS code for kernel 2.2 was done by Wensong Zhang and Peter Kese,
  20  * with changes/fixes from Julian Anastasov, Lars Marowsky-Bree, Horms
  21  * and others. Many code here is taken from IP MASQ code of kernel 2.2.
  22  *
  23  * Changes:
  24  *
  25  */
  26
  27 #include <linux/kernel.h>
  28 #include <linux/vmalloc.h>
  29 #include <linux/proc_fs.h>              /* for proc_net_* */
  30 #include <linux/seq_file.h>
  31 #include <linux/jhash.h>
  32 #include <linux/random.h>
  33
  34 #include <net/ip_vs.h>
  35
  36
  37 /*
  38  *  Connection hash table: for input and output packets lookups of IPVS
  39  */
  40 static struct list_head *ip_vs_conn_tab;
  41
  42 /*  SLAB cache for IPVS connections */
  43 static kmem_cache_t *ip_vs_conn_cachep;
  44
  45 /*  counter for current IPVS connections */
  46 static atomic_t ip_vs_conn_count = ATOMIC_INIT(0);
  47
  48 /*  counter for no client port connections */
  49 static atomic_t ip_vs_conn_no_cport_cnt = ATOMIC_INIT(0);
  50
  51 /* random value for IPVS connection hash */
  52 static unsigned int ip_vs_conn_rnd;
  53
  54 /*
  55  *  Fine locking granularity for big connection hash table
  56  */
  57 #define CT_LOCKARRAY_BITS  4
  58 #define CT_LOCKARRAY_SIZE  (1<<CT_LOCKARRAY_BITS)
  59 #define CT_LOCKARRAY_MASK  (CT_LOCKARRAY_SIZE-1)
  60
  61 struct ip_vs_aligned_lock
  62 {
  63         rwlock_t        l;
  64 } __attribute__((__aligned__(SMP_CACHE_BYTES)));
  65
  66 /* lock array for conn table */
  67 struct ip_vs_aligned_lock
  68 __ip_vs_conntbl_lock_array[CT_LOCKARRAY_SIZE] __cacheline_aligned;
  69
  70 static inline void ct_read_lock(unsigned key)
  71 {
  72         read_lock(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
  73 }
  74
  75 static inline void ct_read_unlock(unsigned key)
  76 {
  77         read_unlock(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
  78 }
  79
  80 static inline void ct_write_lock(unsigned key)
  81 {
  82         write_lock(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
  83 }
  84
  85 static inline void ct_write_unlock(unsigned key)
  86 {
  87         write_unlock(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
  88 }
  89
  90 static inline void ct_read_lock_bh(unsigned key)
  91 {
  92         read_lock_bh(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
  93 }
  94
  95 static inline void ct_read_unlock_bh(unsigned key)
  96 {
  97         read_unlock_bh(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
  98 }
  99
 100 static inline void ct_write_lock_bh(unsigned key)
 101 {
 102         write_lock_bh(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
 103 }
 104
 105 static inline void ct_write_unlock_bh(unsigned key)
 106 {
 107         write_unlock_bh(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
 108 }
 109
 110
 111 /*
 112  *      Returns hash value for IPVS connection entry
 113  */
 114 static unsigned int ip_vs_conn_hashkey(unsigned proto, __u32 addr, __u16 port)
 115 {
 116         return jhash_3words(addr, port, proto, ip_vs_conn_rnd)
 117                 & IP_VS_CONN_TAB_MASK;
 118 }
 119
 120
 121 /*
 122  *      Hashes ip_vs_conn in ip_vs_conn_tab by proto,addr,port.
 123  *      returns bool success.
 124  */
 125 static inline int ip_vs_conn_hash(struct ip_vs_conn *cp)
 126 {
 127         unsigned hash;
 128         int ret;
 129
 130         /* Hash by protocol, client address and port */
 131         hash = ip_vs_conn_hashkey(cp->protocol, cp->caddr, cp->cport);
 132
 133         ct_write_lock(hash);
 134
 135         if (!(cp->flags & IP_VS_CONN_F_HASHED)) {
 136                 list_add(&cp->c_list, &ip_vs_conn_tab[hash]);
 137                 cp->flags |= IP_VS_CONN_F_HASHED;
 138                 atomic_inc(&cp->refcnt);
 139                 ret = 1;
 140         } else {
 141                 IP_VS_ERR("ip_vs_conn_hash(): request for already hashed, "
 142                           "called from %p\n", __builtin_return_address(0));
 143                 ret = 0;
 144         }
 145
 146         ct_write_unlock(hash);
 147
 148         return ret;
 149 }
 150
 151
 152 /*
 153  *      UNhashes ip_vs_conn from ip_vs_conn_tab.
 154  *      returns bool success.
 155  */
 156 static inline int ip_vs_conn_unhash(struct ip_vs_conn *cp)
 157 {
 158         unsigned hash;
 159         int ret;
 160
 161         /* unhash it and decrease its reference counter */
 162         hash = ip_vs_conn_hashkey(cp->protocol, cp->caddr, cp->cport);
 163
 164         ct_write_lock(hash);
 165
 166         if (cp->flags & IP_VS_CONN_F_HASHED) {
 167                 list_del(&cp->c_list);
 168                 cp->flags &= ~IP_VS_CONN_F_HASHED;
 169                 atomic_dec(&cp->refcnt);
 170                 ret = 1;
 171         } else
 172                 ret = 0;
 173
 174         ct_write_unlock(hash);
 175
 176         return ret;
 177 }
 178
 179
 180 /*
 181  *  Gets ip_vs_conn associated with supplied parameters in the ip_vs_conn_tab.
 182  *  Called for pkts coming from OUTside-to-INside.
 183  *      s_addr, s_port: pkt source address (foreign host)
 184  *      d_addr, d_port: pkt dest address (load balancer)
 185  */
 186 static inline struct ip_vs_conn *__ip_vs_conn_in_get
 187 (int protocol, __u32 s_addr, __u16 s_port, __u32 d_addr, __u16 d_port)
 188 {
 189         unsigned hash;
 190         struct ip_vs_conn *cp;
 191
 192         hash = ip_vs_conn_hashkey(protocol, s_addr, s_port);
 193
 194         ct_read_lock(hash);
 195
 196         list_for_each_entry(cp, &ip_vs_conn_tab[hash], c_list) {
 197                 if (s_addr==cp->caddr && s_port==cp->cport &&
 198                     d_port==cp->vport && d_addr==cp->vaddr &&
 199                     protocol==cp->protocol) {
 200                         /* HIT */
 201                         atomic_inc(&cp->refcnt);
 202                         ct_read_unlock(hash);
 203                         return cp;
 204                 }
 205         }
 206
 207         ct_read_unlock(hash);
 208
 209         return NULL;
 210 }
 211
 212 struct ip_vs_conn *ip_vs_conn_in_get
 213 (int protocol, __u32 s_addr, __u16 s_port, __u32 d_addr, __u16 d_port)
 214 {
 215         struct ip_vs_conn *cp;
 216
 217         cp = __ip_vs_conn_in_get(protocol, s_addr, s_port, d_addr, d_port);
 218         if (!cp && atomic_read(&ip_vs_conn_no_cport_cnt))
 219                 cp = __ip_vs_conn_in_get(protocol, s_addr, 0, d_addr, d_port);
 220
 221         IP_VS_DBG(7, "lookup/in %s %u.%u.%u.%u:%d->%u.%u.%u.%u:%d %s\n",
 222                   ip_vs_proto_name(protocol),
 223                   NIPQUAD(s_addr), ntohs(s_port),
 224                   NIPQUAD(d_addr), ntohs(d_port),
 225                   cp?"hit":"not hit");
 226
 227         return cp;
 228 }
 229
 230
 231 /*
 232  *  Gets ip_vs_conn associated with supplied parameters in the ip_vs_conn_tab.
 233  *  Called for pkts coming from inside-to-OUTside.
 234  *      s_addr, s_port: pkt source address (inside host)
 235  *      d_addr, d_port: pkt dest address (foreign host)
 236  */
 237 struct ip_vs_conn *ip_vs_conn_out_get
 238 (int protocol, __u32 s_addr, __u16 s_port, __u32 d_addr, __u16 d_port)
 239 {
 240         unsigned hash;
 241         struct ip_vs_conn *cp, *ret=NULL;
 242
 243         /*
 244          *      Check for "full" addressed entries
 245          */
 246         hash = ip_vs_conn_hashkey(protocol, d_addr, d_port);
 247
 248         ct_read_lock(hash);
 249
 250         list_for_each_entry(cp, &ip_vs_conn_tab[hash], c_list) {
 251                 if (d_addr == cp->caddr && d_port == cp->cport &&
 252                     s_port == cp->dport && s_addr == cp->daddr &&
 253                     protocol == cp->protocol) {
 254                         /* HIT */
 255                         atomic_inc(&cp->refcnt);
 256                         ret = cp;
 257                         break;
 258                 }
 259         }
 260
 261         ct_read_unlock(hash);
 262
 263         IP_VS_DBG(7, "lookup/out %s %u.%u.%u.%u:%d->%u.%u.%u.%u:%d %s\n",
 264                   ip_vs_proto_name(protocol),
 265                   NIPQUAD(s_addr), ntohs(s_port),
 266                   NIPQUAD(d_addr), ntohs(d_port),
 267                   ret?"hit":"not hit");
 268
 269         return ret;
 270 }
 271
 272
 273 /*
 274  *      Put back the conn and restart its timer with its timeout
 275  */
 276 void ip_vs_conn_put(struct ip_vs_conn *cp)
 277 {
 278         /* reset it expire in its timeout */
 279         mod_timer(&cp->timer, jiffies+cp->timeout);
 280
 281         __ip_vs_conn_put(cp);
 282 }
 283
 284
 285 /*
 286  *      Fill a no_client_port connection with a client port number
 287  */
 288 void ip_vs_conn_fill_cport(struct ip_vs_conn *cp, __u16 cport)
 289 {
 290         if (ip_vs_conn_unhash(cp)) {
 291                 spin_lock(&cp->lock);
 292                 if (cp->flags & IP_VS_CONN_F_NO_CPORT) {
 293                         atomic_dec(&ip_vs_conn_no_cport_cnt);
 294                         cp->flags &= ~IP_VS_CONN_F_NO_CPORT;
 295                         cp->cport = cport;
 296                 }
 297                 spin_unlock(&cp->lock);
 298
 299                 /* hash on new dport */
 300                 ip_vs_conn_hash(cp);
 301         }
 302 }
 303
 304
 305 /*
 306  *      Bind a connection entry with the corresponding packet_xmit.
 307  *      Called by ip_vs_conn_new.
 308  */
 309 static inline void ip_vs_bind_xmit(struct ip_vs_conn *cp)
 310 {
 311         switch (IP_VS_FWD_METHOD(cp)) {
 312         case IP_VS_CONN_F_MASQ:
 313                 cp->packet_xmit = ip_vs_nat_xmit;
 314                 break;
 315
 316         case IP_VS_CONN_F_TUNNEL:
 317                 cp->packet_xmit = ip_vs_tunnel_xmit;
 318                 break;
 319
 320         case IP_VS_CONN_F_DROUTE:
 321                 cp->packet_xmit = ip_vs_dr_xmit;
 322                 break;
 323
 324         case IP_VS_CONN_F_LOCALNODE:
 325                 cp->packet_xmit = ip_vs_null_xmit;
 326                 break;
 327
 328         case IP_VS_CONN_F_BYPASS:
 329                 cp->packet_xmit = ip_vs_bypass_xmit;
 330                 break;
 331         }
 332 }
 333
 334
 335 static inline int ip_vs_dest_totalconns(struct ip_vs_dest *dest)
 336 {
 337         return atomic_read(&dest->activeconns)
 338                 + atomic_read(&dest->inactconns);
 339 }
 340
 341 /*
 342  *      Bind a connection entry with a virtual service destination
 343  *      Called just after a new connection entry is created.
 344  */
 345 static inline void
 346 ip_vs_bind_dest(struct ip_vs_conn *cp, struct ip_vs_dest *dest)
 347 {
 348         /* if dest is NULL, then return directly */
 349         if (!dest)
 350                 return;
 351
 352         /* Increase the refcnt counter of the dest */
 353         atomic_inc(&dest->refcnt);
 354
 355         /* Bind with the destination and its corresponding transmitter */
 356         cp->flags |= atomic_read(&dest->conn_flags);
 357         cp->dest = dest;
 358
 359         IP_VS_DBG(9, "Bind-dest %s c:%u.%u.%u.%u:%d v:%u.%u.%u.%u:%d "
 360                   "d:%u.%u.%u.%u:%d fwd:%c s:%u flg:%X cnt:%d destcnt:%d\n",
 361                   ip_vs_proto_name(cp->protocol),
 362                   NIPQUAD(cp->caddr), ntohs(cp->cport),
 363                   NIPQUAD(cp->vaddr), ntohs(cp->vport),
 364                   NIPQUAD(cp->daddr), ntohs(cp->dport),
 365                   ip_vs_fwd_tag(cp), cp->state,
 366                   cp->flags, atomic_read(&cp->refcnt),
 367                   atomic_read(&dest->refcnt));
 368
 369         /* Update the connection counters */
 370         if (cp->cport || (cp->flags & IP_VS_CONN_F_NO_CPORT)) {
 371                 /* It is a normal connection, so increase the inactive
 372                    connection counter because it is in TCP SYNRECV
 373                    state (inactive) or other protocol inacive state */
 374                 atomic_inc(&dest->inactconns);
 375         } else {
 376                 /* It is a persistent connection/template, so increase
 377                    the peristent connection counter */
 378                 atomic_inc(&dest->persistconns);
 379         }
 380
 381         if (dest->u_threshold != 0 &&
 382             ip_vs_dest_totalconns(dest) >= dest->u_threshold)
 383                 dest->flags |= IP_VS_DEST_F_OVERLOAD;
 384 }
 385
 386
 387 /*
 388  *      Unbind a connection entry with its VS destination
 389  *      Called by the ip_vs_conn_expire function.
 390  */
 391 static inline void ip_vs_unbind_dest(struct ip_vs_conn *cp)
 392 {
 393         struct ip_vs_dest *dest = cp->dest;
 394
 395         if (!dest)
 396                 return;
 397
 398         IP_VS_DBG(9, "Unbind-dest %s c:%u.%u.%u.%u:%d v:%u.%u.%u.%u:%d "
 399                   "d:%u.%u.%u.%u:%d fwd:%c s:%u flg:%X cnt:%d destcnt:%d\n",
 400                   ip_vs_proto_name(cp->protocol),
 401                   NIPQUAD(cp->caddr), ntohs(cp->cport),
 402                   NIPQUAD(cp->vaddr), ntohs(cp->vport),
 403                   NIPQUAD(cp->daddr), ntohs(cp->dport),
 404                   ip_vs_fwd_tag(cp), cp->state,
 405                   cp->flags, atomic_read(&cp->refcnt),
 406                   atomic_read(&dest->refcnt));
 407
 408         /* Update the connection counters */
 409         if (cp->cport || (cp->flags & IP_VS_CONN_F_NO_CPORT)) {
 410                 /* It is a normal connection, so decrease the inactconns
 411                    or activeconns counter */
 412                 if (cp->flags & IP_VS_CONN_F_INACTIVE) {
 413                         atomic_dec(&dest->inactconns);
 414                 } else {
 415                         atomic_dec(&dest->activeconns);
 416                 }
 417         } else {
 418                 /* It is a persistent connection/template, so decrease
 419                    the peristent connection counter */
 420                 atomic_dec(&dest->persistconns);
 421         }
 422
 423         if (dest->l_threshold != 0) {
 424                 if (ip_vs_dest_totalconns(dest) < dest->l_threshold)
 425                         dest->flags &= ~IP_VS_DEST_F_OVERLOAD;
 426         } else if (dest->u_threshold != 0) {
 427                 if (ip_vs_dest_totalconns(dest) * 4 < dest->u_threshold * 3)
 428                         dest->flags &= ~IP_VS_DEST_F_OVERLOAD;
 429         } else {
 430                 if (dest->flags & IP_VS_DEST_F_OVERLOAD)
 431                         dest->flags &= ~IP_VS_DEST_F_OVERLOAD;
 432         }
 433
 434         /*
 435          * Simply decrease the refcnt of the dest, because the
 436          * dest will be either in service's destination list
 437          * or in the trash.
 438          */
 439         atomic_dec(&dest->refcnt);
 440 }
 441
 442
 443 /*
 444  *      Checking if the destination of a connection template is available.
 445  *      If available, return 1, otherwise invalidate this connection
 446  *      template and return 0.
 447  */
 448 int ip_vs_check_template(struct ip_vs_conn *ct)
 449 {
 450         struct ip_vs_dest *dest = ct->dest;
 451
 452         /*
 453          * Checking the dest server status.
 454          */
 455         if ((dest == NULL) ||
 456             !(dest->flags & IP_VS_DEST_F_AVAILABLE)) {
 457                 IP_VS_DBG(9, "check_template: dest not available for "
 458                           "protocol %s s:%u.%u.%u.%u:%d v:%u.%u.%u.%u:%d "
 459                           "-> d:%u.%u.%u.%u:%d\n",
 460                           ip_vs_proto_name(ct->protocol),
 461                           NIPQUAD(ct->caddr), ntohs(ct->cport),
 462                           NIPQUAD(ct->vaddr), ntohs(ct->vport),
 463                           NIPQUAD(ct->daddr), ntohs(ct->dport));
 464
 465                 /*
 466                  * Invalidate the connection template
 467                  */
 468                 if (ct->cport) {
 469                         if (ip_vs_conn_unhash(ct)) {
 470                                 ct->dport = 65535;
 471                                 ct->vport = 65535;
 472                                 ct->cport = 0;
 473                                 ip_vs_conn_hash(ct);
 474                         }
 475                 }
 476
 477                 /*
 478                  * Simply decrease the refcnt of the template,
 479                  * don't restart its timer.
 480                  */
 481                 atomic_dec(&ct->refcnt);
 482                 return 0;
 483         }
 484         return 1;
 485 }
 486
 487 static void ip_vs_conn_expire(unsigned long data)
 488 {
 489         struct ip_vs_conn *cp = (struct ip_vs_conn *)data;
 490
 491         cp->timeout = 60*HZ;
 492
 493         /*
 494          *      hey, I'm using it
 495          */
 496         atomic_inc(&cp->refcnt);
 497
 498         /*
 499          *      do I control anybody?
 500          */
 501         if (atomic_read(&cp->n_control))
 502                 goto expire_later;
 503
 504         /*
 505          *      unhash it if it is hashed in the conn table
 506          */
 507         if (!ip_vs_conn_unhash(cp))
 508                 goto expire_later;
 509
 510         /*
 511          *      refcnt==1 implies I'm the only one referrer
 512          */
 513         if (likely(atomic_read(&cp->refcnt) == 1)) {
 514                 /* delete the timer if it is activated by other users */
 515                 if (timer_pending(&cp->timer))
 516                         del_timer(&cp->timer);
 517
 518                 /* does anybody control me? */
 519                 if (cp->control)
 520                         ip_vs_control_del(cp);
 521
 522                 if (unlikely(cp->app != NULL))
 523                         ip_vs_unbind_app(cp);
 524                 ip_vs_unbind_dest(cp);
 525                 if (cp->flags & IP_VS_CONN_F_NO_CPORT)
 526                         atomic_dec(&ip_vs_conn_no_cport_cnt);
 527                 atomic_dec(&ip_vs_conn_count);
 528
 529                 kmem_cache_free(ip_vs_conn_cachep, cp);
 530                 return;
 531         }
 532
 533         /* hash it back to the table */
 534         ip_vs_conn_hash(cp);
 535
 536   expire_later:
 537         IP_VS_DBG(7, "delayed: refcnt-1=%d conn.n_control=%d\n",
 538                   atomic_read(&cp->refcnt)-1,
 539                   atomic_read(&cp->n_control));
 540
 541         ip_vs_conn_put(cp);
 542 }
 543
 544
 545 void ip_vs_conn_expire_now(struct ip_vs_conn *cp)
 546 {
 547         if (del_timer(&cp->timer))
 548                 mod_timer(&cp->timer, jiffies);
 549         __ip_vs_conn_put(cp);
 550 }
 551
 552
 553 /*
 554  *      Create a new connection entry and hash it into the ip_vs_conn_tab
 555  */
 556 struct ip_vs_conn *
 557 ip_vs_conn_new(int proto, __u32 caddr, __u16 cport, __u32 vaddr, __u16 vport,
 558                __u32 daddr, __u16 dport, unsigned flags,
 559                struct ip_vs_dest *dest)
 560 {
 561         struct ip_vs_conn *cp;
 562         struct ip_vs_protocol *pp = ip_vs_proto_get(proto);
 563
 564         cp = kmem_cache_alloc(ip_vs_conn_cachep, GFP_ATOMIC);
 565         if (cp == NULL) {
 566                 IP_VS_ERR_RL("ip_vs_conn_new: no memory available.\n");
 567                 return NULL;
 568         }
 569
 570         memset(cp, 0, sizeof(*cp));
 571         INIT_LIST_HEAD(&cp->c_list);
 572         init_timer(&cp->timer);
 573         cp->timer.data     = (unsigned long)cp;
 574         cp->timer.function = ip_vs_conn_expire;
 575         cp->protocol       = proto;
 576         cp->caddr          = caddr;
 577         cp->cport          = cport;
 578         cp->vaddr          = vaddr;
 579         cp->vport          = vport;
 580         cp->daddr          = daddr;
 581         cp->dport          = dport;
 582         cp->flags          = flags;
 583         cp->lock           = SPIN_LOCK_UNLOCKED;
 584
 585         /*
 586          * Set the entry is referenced by the current thread before hashing
 587          * it in the table, so that other thread run ip_vs_random_dropentry
 588          * but cannot drop this entry.
 589          */
 590         atomic_set(&cp->refcnt, 1);
 591
 592         atomic_set(&cp->n_control, 0);
 593         atomic_set(&cp->in_pkts, 0);
 594
 595         atomic_inc(&ip_vs_conn_count);
 596         if (flags & IP_VS_CONN_F_NO_CPORT)
 597                 atomic_inc(&ip_vs_conn_no_cport_cnt);
 598
 599         /* Bind the connection with a destination server */
 600         ip_vs_bind_dest(cp, dest);
 601
 602         /* Set its state and timeout */
 603         cp->state = 0;
 604         cp->timeout = 3*HZ;
 605
 606         /* Bind its packet transmitter */
 607         ip_vs_bind_xmit(cp);
 608
 609         if (unlikely(pp && atomic_read(&pp->appcnt)))
 610                 ip_vs_bind_app(cp, pp);
 611
 612         /* Hash it in the ip_vs_conn_tab finally */
 613         ip_vs_conn_hash(cp);
 614
 615         return cp;
 616 }
 617
 618
 619 /*
 620  *      /proc/net/ip_vs_conn entries
 621  */
 622 #ifdef CONFIG_PROC_FS
 623
 624 static void *ip_vs_conn_array(struct seq_file *seq, loff_t pos)
 625 {
 626         int idx;
 627         struct ip_vs_conn *cp;
 628
 629         for(idx = 0; idx < IP_VS_CONN_TAB_SIZE; idx++) {
 630                 ct_read_lock_bh(idx);
 631                 list_for_each_entry(cp, &ip_vs_conn_tab[idx], c_list) {
 632                         if (pos-- == 0) {
 633                                 seq->private = &ip_vs_conn_tab[idx];
 634                                 return cp;
 635                         }
 636                 }
 637                 ct_read_unlock_bh(idx);
 638         }
 639
 640         return NULL;
 641 }
 642
 643 static void *ip_vs_conn_seq_start(struct seq_file *seq, loff_t *pos)
 644 {
 645         seq->private = NULL;
 646         return *pos ? ip_vs_conn_array(seq, *pos - 1) :SEQ_START_TOKEN;
 647 }
 648
 649 static void *ip_vs_conn_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 650 {
 651         struct ip_vs_conn *cp = v;
 652         struct list_head *e, *l = seq->private;
 653         int idx;
 654
 655         ++*pos;
 656         if (v == SEQ_START_TOKEN)
 657                 return ip_vs_conn_array(seq, 0);
 658
 659         /* more on same hash chain? */
 660         if ((e = cp->c_list.next) != l)
 661                 return list_entry(e, struct ip_vs_conn, c_list);
 662
 663         idx = l - ip_vs_conn_tab;
 664         ct_read_unlock_bh(idx);
 665
 666         while (++idx < IP_VS_CONN_TAB_SIZE) {
 667                 ct_read_lock_bh(idx);
 668                 list_for_each_entry(cp, &ip_vs_conn_tab[idx], c_list) {
 669                         seq->private = &ip_vs_conn_tab[idx];
 670                         return cp;
 671                 }
 672                 ct_read_unlock_bh(idx);
 673         }
 674         seq->private = NULL;
 675         return NULL;
 676 }
 677
 678 static void ip_vs_conn_seq_stop(struct seq_file *seq, void *v)
 679 {
 680         struct list_head *l = seq->private;
 681
 682         if (l)
 683                 ct_read_unlock_bh(l - ip_vs_conn_tab);
 684 }
 685
 686 static int ip_vs_conn_seq_show(struct seq_file *seq, void *v)
 687 {
 688
 689         if (v == SEQ_START_TOKEN)
 690                 seq_puts(seq,
 691    "Pro FromIP   FPrt ToIP     TPrt DestIP   DPrt State       Expires\n");
 692         else {
 693                 const struct ip_vs_conn *cp = v;
 694
 695                 seq_printf(seq,
 696                         "%-3s %08X %04X %08X %04X %08X %04X %-11s %7lu\n",
 697                                 ip_vs_proto_name(cp->protocol),
 698                                 ntohl(cp->caddr), ntohs(cp->cport),
 699                                 ntohl(cp->vaddr), ntohs(cp->vport),
 700                                 ntohl(cp->daddr), ntohs(cp->dport),
 701                                 ip_vs_state_name(cp->protocol, cp->state),
 702                                 (cp->timer.expires-jiffies)/HZ);
 703         }
 704         return 0;
 705 }
 706
 707 static struct seq_operations ip_vs_conn_seq_ops = {
 708         .start = ip_vs_conn_seq_start,
 709         .next  = ip_vs_conn_seq_next,
 710         .stop  = ip_vs_conn_seq_stop,
 711         .show  = ip_vs_conn_seq_show,
 712 };
 713
 714 static int ip_vs_conn_open(struct inode *inode, struct file *file)
 715 {
 716         return seq_open(file, &ip_vs_conn_seq_ops);
 717 }
 718
 719 static struct file_operations ip_vs_conn_fops = {
 720         .owner   = THIS_MODULE,
 721         .open    = ip_vs_conn_open,
 722         .read    = seq_read,
 723         .llseek  = seq_lseek,
 724         .release = seq_release,
 725 };
 726 #endif
 727
 728
 729 /*
 730  *      Randomly drop connection entries before running out of memory
 731  */
 732 static inline int todrop_entry(struct ip_vs_conn *cp)
 733 {
 734         /*
 735          * The drop rate array needs tuning for real environments.
 736          * Called from timer bh only => no locking
 737          */
 738         static char todrop_rate[9] = {0, 1, 2, 3, 4, 5, 6, 7, 8};
 739         static char todrop_counter[9] = {0};
 740         int i;
 741
 742         /* if the conn entry hasn't lasted for 60 seconds, don't drop it.
 743            This will leave enough time for normal connection to get
 744            through. */
 745         if (time_before(cp->timeout + jiffies, cp->timer.expires + 60*HZ))
 746                 return 0;
 747
 748         /* Don't drop the entry if its number of incoming packets is not
 749            located in [0, 8] */
 750         i = atomic_read(&cp->in_pkts);
 751         if (i > 8 || i < 0) return 0;
 752
 753         if (!todrop_rate[i]) return 0;
 754         if (--todrop_counter[i] > 0) return 0;
 755
 756         todrop_counter[i] = todrop_rate[i];
 757         return 1;
 758 }
 759
 760
 761 void ip_vs_random_dropentry(void)
 762 {
 763         int idx;
 764         struct ip_vs_conn *cp;
 765         struct ip_vs_conn *ct;
 766
 767         /*
 768          * Randomly scan 1/32 of the whole table every second
 769          */
 770         for (idx = 0; idx < (IP_VS_CONN_TAB_SIZE>>5); idx++) {
 771                 unsigned hash = net_random() & IP_VS_CONN_TAB_MASK;
 772
 773                 /*
 774                  *  Lock is actually needed in this loop.
 775                  */
 776                 ct_write_lock(hash);
 777
 778                 list_for_each_entry(cp, &ip_vs_conn_tab[hash], c_list) {
 779                         if (!cp->cport && !(cp->flags & IP_VS_CONN_F_NO_CPORT))
 780                                 /* connection template */
 781                                 continue;
 782
 783                         if (cp->protocol == IPPROTO_TCP) {
 784                                 switch(cp->state) {
 785                                 case IP_VS_TCP_S_SYN_RECV:
 786                                 case IP_VS_TCP_S_SYNACK:
 787                                         break;
 788
 789                                 case IP_VS_TCP_S_ESTABLISHED:
 790                                         if (todrop_entry(cp))
 791                                                 break;
 792                                         continue;
 793
 794                                 default:
 795                                         continue;
 796                                 }
 797                         } else {
 798                                 if (!todrop_entry(cp))
 799                                         continue;
 800                         }
 801
 802                         /*
 803                          * Drop the entry, and drop its ct if not referenced
 804                          */
 805                         atomic_inc(&cp->refcnt);
 806                         ct_write_unlock(hash);
 807
 808                         if ((ct = cp->control))
 809                                 atomic_inc(&ct->refcnt);
 810                         IP_VS_DBG(4, "del connection\n");
 811                         ip_vs_conn_expire_now(cp);
 812                         if (ct) {
 813                                 IP_VS_DBG(4, "del conn template\n");
 814                                 ip_vs_conn_expire_now(ct);
 815                         }
 816                         ct_write_lock(hash);
 817                 }
 818                 ct_write_unlock(hash);
 819         }
 820 }
 821
 822
 823 /*
 824  *      Flush all the connection entries in the ip_vs_conn_tab
 825  */
 826 static void ip_vs_conn_flush(void)
 827 {
 828         int idx;
 829         struct ip_vs_conn *cp;
 830         struct ip_vs_conn *ct;
 831
 832   flush_again:
 833         for (idx=0; idx<IP_VS_CONN_TAB_SIZE; idx++) {
 834                 /*
 835                  *  Lock is actually needed in this loop.
 836                  */
 837                 ct_write_lock_bh(idx);
 838
 839                 list_for_each_entry(cp, &ip_vs_conn_tab[idx], c_list) {
 840                         atomic_inc(&cp->refcnt);
 841                         ct_write_unlock(idx);
 842
 843                         if ((ct = cp->control))
 844                                 atomic_inc(&ct->refcnt);
 845                         IP_VS_DBG(4, "del connection\n");
 846                         ip_vs_conn_expire_now(cp);
 847                         if (ct) {
 848                                 IP_VS_DBG(4, "del conn template\n");
 849                                 ip_vs_conn_expire_now(ct);
 850                         }
 851                         ct_write_lock(idx);
 852                 }
 853                 ct_write_unlock_bh(idx);
 854         }
 855
 856         /* the counter may be not NULL, because maybe some conn entries
 857            are run by slow timer handler or unhashed but still referred */
 858         if (atomic_read(&ip_vs_conn_count) != 0) {
 859                 schedule();
 860                 goto flush_again;
 861         }
 862 }
 863
 864
 865 int ip_vs_conn_init(void)
 866 {
 867         int idx;
 868
 869         /*
 870          * Allocate the connection hash table and initialize its list heads
 871          */
 872         ip_vs_conn_tab = vmalloc(IP_VS_CONN_TAB_SIZE*sizeof(struct list_head));
 873         if (!ip_vs_conn_tab)
 874                 return -ENOMEM;
 875
 876         /* Allocate ip_vs_conn slab cache */
 877         ip_vs_conn_cachep = kmem_cache_create("ip_vs_conn",
 878                                               sizeof(struct ip_vs_conn), 0,
 879                                               SLAB_HWCACHE_ALIGN, NULL, NULL);
 880         if (!ip_vs_conn_cachep) {
 881                 vfree(ip_vs_conn_tab);
 882                 return -ENOMEM;
 883         }
 884
 885         IP_VS_INFO("Connection hash table configured "
 886                    "(size=%d, memory=%ldKbytes)\n",
 887                    IP_VS_CONN_TAB_SIZE,
 888                    (long)(IP_VS_CONN_TAB_SIZE*sizeof(struct list_head))/1024);
 889         IP_VS_DBG(0, "Each connection entry needs %Zd bytes at least\n",
 890                   sizeof(struct ip_vs_conn));
 891
 892         for (idx = 0; idx < IP_VS_CONN_TAB_SIZE; idx++) {
 893                 INIT_LIST_HEAD(&ip_vs_conn_tab[idx]);
 894         }
 895
 896         for (idx = 0; idx < CT_LOCKARRAY_SIZE; idx++)  {
 897                 __ip_vs_conntbl_lock_array[idx].l = RW_LOCK_UNLOCKED;
 898         }
 899
 900         proc_net_fops_create("ip_vs_conn", 0, &ip_vs_conn_fops);
 901
 902         /* calculate the random value for connection hash */
 903         get_random_bytes(&ip_vs_conn_rnd, sizeof(ip_vs_conn_rnd));
 904
 905         return 0;
 906 }
 907
 908
 909 void ip_vs_conn_cleanup(void)
 910 {
 911         /* flush all the connection entries first */
 912         ip_vs_conn_flush();
 913
 914         /* Release the empty cache */
 915         kmem_cache_destroy(ip_vs_conn_cachep);
 916         proc_net_remove("ip_vs_conn");
 917         vfree(ip_vs_conn_tab);
 918 }