net/ipv4/ipvs/ip_vs_sync.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_sync.c,v 1.13 2003/06/08 09:31:19 wensong Exp $
   9  *
  10  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
  11  *
  12  * ip_vs_sync:  sync connection info from master load balancer to backups
  13  *              through multicast
  14  *
  15  * Changes:
  16  *      Alexandre Cassen        :       Added master & backup support at a time.
  17  *      Alexandre Cassen        :       Added SyncID support for incoming sync
  18  *                                      messages filtering.
  19  *      Justin Ossevoort        :       Fix endian problem on sync message size.
  20  */
  21
  22 #include <linux/module.h>
  23 #include <linux/slab.h>
  24 #include <linux/inetdevice.h>
  25 #include <linux/net.h>
  26 #include <linux/completion.h>
  27 #include <linux/delay.h>
  28 #include <linux/skbuff.h>
  29 #include <linux/in.h>
  30 #include <linux/igmp.h>                 /* for ip_mc_join_group */
  31 #include <linux/udp.h>
  32
  33 #include <net/ip.h>
  34 #include <net/sock.h>
  35 #include <asm/uaccess.h>                /* for get_fs and set_fs */
  36
  37 #include <net/ip_vs.h>
  38
  39 #define IP_VS_SYNC_GROUP 0xe0000051    /* multicast addr - 224.0.0.81 */
  40 #define IP_VS_SYNC_PORT  8848          /* multicast port */
  41
  42
  43 /*
  44  *      IPVS sync connection entry
  45  */
  46 struct ip_vs_sync_conn {
  47         __u8                    reserved;
  48
  49         /* Protocol, addresses and port numbers */
  50         __u8                    protocol;       /* Which protocol (TCP/UDP) */
  51         __u16                   cport;
  52         __u16                   vport;
  53         __u16                   dport;
  54         __u32                   caddr;          /* client address */
  55         __u32                   vaddr;          /* virtual address */
  56         __u32                   daddr;          /* destination address */
  57
  58         /* Flags and state transition */
  59         __u16                   flags;          /* status flags */
  60         __u16                   state;          /* state info */
  61
  62         /* The sequence options start here */
  63 };
  64
  65 struct ip_vs_sync_conn_options {
  66         struct ip_vs_seq        in_seq;         /* incoming seq. struct */
  67         struct ip_vs_seq        out_seq;        /* outgoing seq. struct */
  68 };
  69
  70 #define IP_VS_SYNC_CONN_TIMEOUT (3*60*HZ)
  71 #define SIMPLE_CONN_SIZE  (sizeof(struct ip_vs_sync_conn))
  72 #define FULL_CONN_SIZE  \
  73 (sizeof(struct ip_vs_sync_conn) + sizeof(struct ip_vs_sync_conn_options))
  74
  75
  76 /*
  77   The master mulitcasts messages to the backup load balancers in the
  78   following format.
  79
  80        0                   1                   2                   3
  81        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  82       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  83       |  Count Conns  |    SyncID     |            Size               |
  84       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  85       |                                                               |
  86       |                    IPVS Sync Connection (1)                   |
  87       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  88       |                            .                                  |
  89       |                            .                                  |
  90       |                            .                                  |
  91       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  92       |                                                               |
  93       |                    IPVS Sync Connection (n)                   |
  94       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  95 */
  96
  97 #define SYNC_MESG_HEADER_LEN    4
  98
  99 struct ip_vs_sync_mesg {
 100         __u8                    nr_conns;
 101         __u8                    syncid;
 102         __u16                   size;
 103
 104         /* ip_vs_sync_conn entries start here */
 105 };
 106
 107 /* the maximum length of sync (sending/receiving) message */
 108 static int sync_send_mesg_maxlen;
 109 static int sync_recv_mesg_maxlen;
 110
 111 struct ip_vs_sync_buff {
 112         struct list_head        list;
 113         unsigned long           firstuse;
 114
 115         /* pointers for the message data */
 116         struct ip_vs_sync_mesg  *mesg;
 117         unsigned char           *head;
 118         unsigned char           *end;
 119 };
 120
 121
 122 /* the sync_buff list head and the lock */
 123 static LIST_HEAD(ip_vs_sync_queue);
 124 static DEFINE_SPINLOCK(ip_vs_sync_lock);
 125
 126 /* current sync_buff for accepting new conn entries */
 127 static struct ip_vs_sync_buff   *curr_sb = NULL;
 128 static DEFINE_SPINLOCK(curr_sb_lock);
 129
 130 /* ipvs sync daemon state */
 131 volatile int ip_vs_sync_state = IP_VS_STATE_NONE;
 132 volatile int ip_vs_master_syncid = 0;
 133 volatile int ip_vs_backup_syncid = 0;
 134
 135 /* multicast interface name */
 136 char ip_vs_master_mcast_ifn[IP_VS_IFNAME_MAXLEN];
 137 char ip_vs_backup_mcast_ifn[IP_VS_IFNAME_MAXLEN];
 138
 139 /* multicast addr */
 140 static struct sockaddr_in mcast_addr;
 141
 142
 143 static inline void sb_queue_tail(struct ip_vs_sync_buff *sb)
 144 {
 145         spin_lock(&ip_vs_sync_lock);
 146         list_add_tail(&sb->list, &ip_vs_sync_queue);
 147         spin_unlock(&ip_vs_sync_lock);
 148 }
 149
 150 static inline struct ip_vs_sync_buff * sb_dequeue(void)
 151 {
 152         struct ip_vs_sync_buff *sb;
 153
 154         spin_lock_bh(&ip_vs_sync_lock);
 155         if (list_empty(&ip_vs_sync_queue)) {
 156                 sb = NULL;
 157         } else {
 158                 sb = list_entry(ip_vs_sync_queue.next,
 159                                 struct ip_vs_sync_buff,
 160                                 list);
 161                 list_del(&sb->list);
 162         }
 163         spin_unlock_bh(&ip_vs_sync_lock);
 164
 165         return sb;
 166 }
 167
 168 static inline struct ip_vs_sync_buff * ip_vs_sync_buff_create(void)
 169 {
 170         struct ip_vs_sync_buff *sb;
 171
 172         if (!(sb=kmalloc(sizeof(struct ip_vs_sync_buff), GFP_ATOMIC)))
 173                 return NULL;
 174
 175         if (!(sb->mesg=kmalloc(sync_send_mesg_maxlen, GFP_ATOMIC))) {
 176                 kfree(sb);
 177                 return NULL;
 178         }
 179         sb->mesg->nr_conns = 0;
 180         sb->mesg->syncid = ip_vs_master_syncid;
 181         sb->mesg->size = 4;
 182         sb->head = (unsigned char *)sb->mesg + 4;
 183         sb->end = (unsigned char *)sb->mesg + sync_send_mesg_maxlen;
 184         sb->firstuse = jiffies;
 185         return sb;
 186 }
 187
 188 static inline void ip_vs_sync_buff_release(struct ip_vs_sync_buff *sb)
 189 {
 190         kfree(sb->mesg);
 191         kfree(sb);
 192 }
 193
 194 /*
 195  *      Get the current sync buffer if it has been created for more
 196  *      than the specified time or the specified time is zero.
 197  */
 198 static inline struct ip_vs_sync_buff *
 199 get_curr_sync_buff(unsigned long time)
 200 {
 201         struct ip_vs_sync_buff *sb;
 202
 203         spin_lock_bh(&curr_sb_lock);
 204         if (curr_sb && (time == 0 ||
 205                         time_before(jiffies - curr_sb->firstuse, time))) {
 206                 sb = curr_sb;
 207                 curr_sb = NULL;
 208         } else
 209                 sb = NULL;
 210         spin_unlock_bh(&curr_sb_lock);
 211         return sb;
 212 }
 213
 214
 215 /*
 216  *      Add an ip_vs_conn information into the current sync_buff.
 217  *      Called by ip_vs_in.
 218  */
 219 void ip_vs_sync_conn(struct ip_vs_conn *cp)
 220 {
 221         struct ip_vs_sync_mesg *m;
 222         struct ip_vs_sync_conn *s;
 223         int len;
 224
 225         spin_lock(&curr_sb_lock);
 226         if (!curr_sb) {
 227                 if (!(curr_sb=ip_vs_sync_buff_create())) {
 228                         spin_unlock(&curr_sb_lock);
 229                         IP_VS_ERR("ip_vs_sync_buff_create failed.\n");
 230                         return;
 231                 }
 232         }
 233
 234         len = (cp->flags & IP_VS_CONN_F_SEQ_MASK) ? FULL_CONN_SIZE :
 235                 SIMPLE_CONN_SIZE;
 236         m = curr_sb->mesg;
 237         s = (struct ip_vs_sync_conn *)curr_sb->head;
 238
 239         /* copy members */
 240         s->protocol = cp->protocol;
 241         s->cport = cp->cport;
 242         s->vport = cp->vport;
 243         s->dport = cp->dport;
 244         s->caddr = cp->caddr;
 245         s->vaddr = cp->vaddr;
 246         s->daddr = cp->daddr;
 247         s->flags = htons(cp->flags & ~IP_VS_CONN_F_HASHED);
 248         s->state = htons(cp->state);
 249         if (cp->flags & IP_VS_CONN_F_SEQ_MASK) {
 250                 struct ip_vs_sync_conn_options *opt =
 251                         (struct ip_vs_sync_conn_options *)&s[1];
 252                 memcpy(opt, &cp->in_seq, sizeof(*opt));
 253         }
 254
 255         m->nr_conns++;
 256         m->size += len;
 257         curr_sb->head += len;
 258
 259         /* check if there is a space for next one */
 260         if (curr_sb->head+FULL_CONN_SIZE > curr_sb->end) {
 261                 sb_queue_tail(curr_sb);
 262                 curr_sb = NULL;
 263         }
 264         spin_unlock(&curr_sb_lock);
 265
 266         /* synchronize its controller if it has */
 267         if (cp->control)
 268                 ip_vs_sync_conn(cp->control);
 269 }
 270
 271
 272 /*
 273  *      Process received multicast message and create the corresponding
 274  *      ip_vs_conn entries.
 275  */
 276 static void ip_vs_process_message(const char *buffer, const size_t buflen)
 277 {
 278         struct ip_vs_sync_mesg *m = (struct ip_vs_sync_mesg *)buffer;
 279         struct ip_vs_sync_conn *s;
 280         struct ip_vs_sync_conn_options *opt;
 281         struct ip_vs_conn *cp;
 282         char *p;
 283         int i;
 284
 285         /* Convert size back to host byte order */
 286         m->size = ntohs(m->size);
 287
 288         if (buflen != m->size) {
 289                 IP_VS_ERR("bogus message\n");
 290                 return;
 291         }
 292
 293         /* SyncID sanity check */
 294         if (ip_vs_backup_syncid != 0 && m->syncid != ip_vs_backup_syncid) {
 295                 IP_VS_DBG(7, "Ignoring incoming msg with syncid = %d\n",
 296                           m->syncid);
 297                 return;
 298         }
 299
 300         p = (char *)buffer + sizeof(struct ip_vs_sync_mesg);
 301         for (i=0; i<m->nr_conns; i++) {
 302                 unsigned flags;
 303
 304                 s = (struct ip_vs_sync_conn *)p;
 305                 flags = ntohs(s->flags);
 306                 if (!(flags & IP_VS_CONN_F_TEMPLATE))
 307                         cp = ip_vs_conn_in_get(s->protocol,
 308                                                s->caddr, s->cport,
 309                                                s->vaddr, s->vport);
 310                 else
 311                         cp = ip_vs_ct_in_get(s->protocol,
 312                                                s->caddr, s->cport,
 313                                                s->vaddr, s->vport);
 314                 if (!cp) {
 315                         cp = ip_vs_conn_new(s->protocol,
 316                                             s->caddr, s->cport,
 317                                             s->vaddr, s->vport,
 318                                             s->daddr, s->dport,
 319                                             flags, NULL);
 320                         if (!cp) {
 321                                 IP_VS_ERR("ip_vs_conn_new failed\n");
 322                                 return;
 323                         }
 324                         cp->state = ntohs(s->state);
 325                 } else if (!cp->dest) {
 326                         /* it is an entry created by the synchronization */
 327                         cp->state = ntohs(s->state);
 328                         cp->flags = flags | IP_VS_CONN_F_HASHED;
 329                 }       /* Note that we don't touch its state and flags
 330                            if it is a normal entry. */
 331
 332                 if (flags & IP_VS_CONN_F_SEQ_MASK) {
 333                         opt = (struct ip_vs_sync_conn_options *)&s[1];
 334                         memcpy(&cp->in_seq, opt, sizeof(*opt));
 335                         p += FULL_CONN_SIZE;
 336                 } else
 337                         p += SIMPLE_CONN_SIZE;
 338
 339                 atomic_set(&cp->in_pkts, sysctl_ip_vs_sync_threshold[0]);
 340                 cp->timeout = IP_VS_SYNC_CONN_TIMEOUT;
 341                 ip_vs_conn_put(cp);
 342
 343                 if (p > buffer+buflen) {
 344                         IP_VS_ERR("bogus message\n");
 345                         return;
 346                 }
 347         }
 348 }
 349
 350
 351 /*
 352  *      Setup loopback of outgoing multicasts on a sending socket
 353  */
 354 static void set_mcast_loop(struct sock *sk, u_char loop)
 355 {
 356         struct inet_sock *inet = inet_sk(sk);
 357
 358         /* setsockopt(sock, SOL_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)); */
 359         lock_sock(sk);
 360         inet->mc_loop = loop ? 1 : 0;
 361         release_sock(sk);
 362 }
 363
 364 /*
 365  *      Specify TTL for outgoing multicasts on a sending socket
 366  */
 367 static void set_mcast_ttl(struct sock *sk, u_char ttl)
 368 {
 369         struct inet_sock *inet = inet_sk(sk);
 370
 371         /* setsockopt(sock, SOL_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); */
 372         lock_sock(sk);
 373         inet->mc_ttl = ttl;
 374         release_sock(sk);
 375 }
 376
 377 /*
 378  *      Specifiy default interface for outgoing multicasts
 379  */
 380 static int set_mcast_if(struct sock *sk, char *ifname)
 381 {
 382         struct net_device *dev;
 383         struct inet_sock *inet = inet_sk(sk);
 384
 385         if ((dev = __dev_get_by_name(ifname)) == NULL)
 386                 return -ENODEV;
 387
 388         if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
 389                 return -EINVAL;
 390
 391         lock_sock(sk);
 392         inet->mc_index = dev->ifindex;
 393         /*  inet->mc_addr  = 0; */
 394         release_sock(sk);
 395
 396         return 0;
 397 }
 398
 399
 400 /*
 401  *      Set the maximum length of sync message according to the
 402  *      specified interface's MTU.
 403  */
 404 static int set_sync_mesg_maxlen(int sync_state)
 405 {
 406         struct net_device *dev;
 407         int num;
 408
 409         if (sync_state == IP_VS_STATE_MASTER) {
 410                 if ((dev = __dev_get_by_name(ip_vs_master_mcast_ifn)) == NULL)
 411                         return -ENODEV;
 412
 413                 num = (dev->mtu - sizeof(struct iphdr) -
 414                        sizeof(struct udphdr) -
 415                        SYNC_MESG_HEADER_LEN - 20) / SIMPLE_CONN_SIZE;
 416                 sync_send_mesg_maxlen =
 417                         SYNC_MESG_HEADER_LEN + SIMPLE_CONN_SIZE * num;
 418                 IP_VS_DBG(7, "setting the maximum length of sync sending "
 419                           "message %d.\n", sync_send_mesg_maxlen);
 420         } else if (sync_state == IP_VS_STATE_BACKUP) {
 421                 if ((dev = __dev_get_by_name(ip_vs_backup_mcast_ifn)) == NULL)
 422                         return -ENODEV;
 423
 424                 sync_recv_mesg_maxlen = dev->mtu -
 425                         sizeof(struct iphdr) - sizeof(struct udphdr);
 426                 IP_VS_DBG(7, "setting the maximum length of sync receiving "
 427                           "message %d.\n", sync_recv_mesg_maxlen);
 428         }
 429
 430         return 0;
 431 }
 432
 433
 434 /*
 435  *      Join a multicast group.
 436  *      the group is specified by a class D multicast address 224.0.0.0/8
 437  *      in the in_addr structure passed in as a parameter.
 438  */
 439 static int
 440 join_mcast_group(struct sock *sk, struct in_addr *addr, char *ifname)
 441 {
 442         struct ip_mreqn mreq;
 443         struct net_device *dev;
 444         int ret;
 445
 446         memset(&mreq, 0, sizeof(mreq));
 447         memcpy(&mreq.imr_multiaddr, addr, sizeof(struct in_addr));
 448
 449         if ((dev = __dev_get_by_name(ifname)) == NULL)
 450                 return -ENODEV;
 451         if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
 452                 return -EINVAL;
 453
 454         mreq.imr_ifindex = dev->ifindex;
 455
 456         lock_sock(sk);
 457         ret = ip_mc_join_group(sk, &mreq);
 458         release_sock(sk);
 459
 460         return ret;
 461 }
 462
 463
 464 static int bind_mcastif_addr(struct socket *sock, char *ifname)
 465 {
 466         struct net_device *dev;
 467         u32 addr;
 468         struct sockaddr_in sin;
 469
 470         if ((dev = __dev_get_by_name(ifname)) == NULL)
 471                 return -ENODEV;
 472
 473         addr = inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE);
 474         if (!addr)
 475                 IP_VS_ERR("You probably need to specify IP address on "
 476                           "multicast interface.\n");
 477
 478         IP_VS_DBG(7, "binding socket with (%s) %u.%u.%u.%u\n",
 479                   ifname, NIPQUAD(addr));
 480
 481         /* Now bind the socket with the address of multicast interface */
 482         sin.sin_family       = AF_INET;
 483         sin.sin_addr.s_addr  = addr;
 484         sin.sin_port         = 0;
 485
 486         return sock->ops->bind(sock, (struct sockaddr*)&sin, sizeof(sin));
 487 }
 488
 489 /*
 490  *      Set up sending multicast socket over UDP
 491  */
 492 static struct socket * make_send_sock(void)
 493 {
 494         struct socket *sock;
 495
 496         /* First create a socket */
 497         if (sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock) < 0) {
 498                 IP_VS_ERR("Error during creation of socket; terminating\n");
 499                 return NULL;
 500         }
 501
 502         if (set_mcast_if(sock->sk, ip_vs_master_mcast_ifn) < 0) {
 503                 IP_VS_ERR("Error setting outbound mcast interface\n");
 504                 goto error;
 505         }
 506
 507         set_mcast_loop(sock->sk, 0);
 508         set_mcast_ttl(sock->sk, 1);
 509
 510         if (bind_mcastif_addr(sock, ip_vs_master_mcast_ifn) < 0) {
 511                 IP_VS_ERR("Error binding address of the mcast interface\n");
 512                 goto error;
 513         }
 514
 515         if (sock->ops->connect(sock,
 516                                (struct sockaddr*)&mcast_addr,
 517                                sizeof(struct sockaddr), 0) < 0) {
 518                 IP_VS_ERR("Error connecting to the multicast addr\n");
 519                 goto error;
 520         }
 521
 522         return sock;
 523
 524   error:
 525         sock_release(sock);
 526         return NULL;
 527 }
 528
 529
 530 /*
 531  *      Set up receiving multicast socket over UDP
 532  */
 533 static struct socket * make_receive_sock(void)
 534 {
 535         struct socket *sock;
 536
 537         /* First create a socket */
 538         if (sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock) < 0) {
 539                 IP_VS_ERR("Error during creation of socket; terminating\n");
 540                 return NULL;
 541         }
 542
 543         /* it is equivalent to the REUSEADDR option in user-space */
 544         sock->sk->sk_reuse = 1;
 545
 546         if (sock->ops->bind(sock,
 547                             (struct sockaddr*)&mcast_addr,
 548                             sizeof(struct sockaddr)) < 0) {
 549                 IP_VS_ERR("Error binding to the multicast addr\n");
 550                 goto error;
 551         }
 552
 553         /* join the multicast group */
 554         if (join_mcast_group(sock->sk,
 555                              (struct in_addr*)&mcast_addr.sin_addr,
 556                              ip_vs_backup_mcast_ifn) < 0) {
 557                 IP_VS_ERR("Error joining to the multicast group\n");
 558                 goto error;
 559         }
 560
 561         return sock;
 562
 563   error:
 564         sock_release(sock);
 565         return NULL;
 566 }
 567
 568
 569 static int
 570 ip_vs_send_async(struct socket *sock, const char *buffer, const size_t length)
 571 {
 572         struct msghdr   msg = {.msg_flags = MSG_DONTWAIT|MSG_NOSIGNAL};
 573         struct kvec     iov;
 574         int             len;
 575
 576         EnterFunction(7);
 577         iov.iov_base     = (void *)buffer;
 578         iov.iov_len      = length;
 579
 580         len = kernel_sendmsg(sock, &msg, &iov, 1, (size_t)(length));
 581
 582         LeaveFunction(7);
 583         return len;
 584 }
 585
 586 static void
 587 ip_vs_send_sync_msg(struct socket *sock, struct ip_vs_sync_mesg *msg)
 588 {
 589         int msize;
 590
 591         msize = msg->size;
 592
 593         /* Put size in network byte order */
 594         msg->size = htons(msg->size);
 595
 596         if (ip_vs_send_async(sock, (char *)msg, msize) != msize)
 597                 IP_VS_ERR("ip_vs_send_async error\n");
 598 }
 599
 600 static int
 601 ip_vs_receive(struct socket *sock, char *buffer, const size_t buflen)
 602 {
 603         struct msghdr           msg = {NULL,};
 604         struct kvec             iov;
 605         int                     len;
 606
 607         EnterFunction(7);
 608
 609         /* Receive a packet */
 610         iov.iov_base     = buffer;
 611         iov.iov_len      = (size_t)buflen;
 612
 613         len = kernel_recvmsg(sock, &msg, &iov, 1, buflen, 0);
 614
 615         if (len < 0)
 616                 return -1;
 617
 618         LeaveFunction(7);
 619         return len;
 620 }
 621
 622
 623 static DECLARE_WAIT_QUEUE_HEAD(sync_wait);
 624 static pid_t sync_master_pid = 0;
 625 static pid_t sync_backup_pid = 0;
 626
 627 static DECLARE_WAIT_QUEUE_HEAD(stop_sync_wait);
 628 static int stop_master_sync = 0;
 629 static int stop_backup_sync = 0;
 630
 631 static void sync_master_loop(void)
 632 {
 633         struct socket *sock;
 634         struct ip_vs_sync_buff *sb;
 635
 636         /* create the sending multicast socket */
 637         sock = make_send_sock();
 638         if (!sock)
 639                 return;
 640
 641         IP_VS_INFO("sync thread started: state = MASTER, mcast_ifn = %s, "
 642                    "syncid = %d\n",
 643                    ip_vs_master_mcast_ifn, ip_vs_master_syncid);
 644
 645         for (;;) {
 646                 while ((sb=sb_dequeue())) {
 647                         ip_vs_send_sync_msg(sock, sb->mesg);
 648                         ip_vs_sync_buff_release(sb);
 649                 }
 650
 651                 /* check if entries stay in curr_sb for 2 seconds */
 652                 if ((sb = get_curr_sync_buff(2*HZ))) {
 653                         ip_vs_send_sync_msg(sock, sb->mesg);
 654                         ip_vs_sync_buff_release(sb);
 655                 }
 656
 657                 if (stop_master_sync)
 658                         break;
 659
 660                 ssleep(1);
 661         }
 662
 663         /* clean up the sync_buff queue */
 664         while ((sb=sb_dequeue())) {
 665                 ip_vs_sync_buff_release(sb);
 666         }
 667
 668         /* clean up the current sync_buff */
 669         if ((sb = get_curr_sync_buff(0))) {
 670                 ip_vs_sync_buff_release(sb);
 671         }
 672
 673         /* release the sending multicast socket */
 674         sock_release(sock);
 675 }
 676
 677
 678 static void sync_backup_loop(void)
 679 {
 680         struct socket *sock;
 681         char *buf;
 682         int len;
 683
 684         if (!(buf = kmalloc(sync_recv_mesg_maxlen, GFP_ATOMIC))) {
 685                 IP_VS_ERR("sync_backup_loop: kmalloc error\n");
 686                 return;
 687         }
 688
 689         /* create the receiving multicast socket */
 690         sock = make_receive_sock();
 691         if (!sock)
 692                 goto out;
 693
 694         IP_VS_INFO("sync thread started: state = BACKUP, mcast_ifn = %s, "
 695                    "syncid = %d\n",
 696                    ip_vs_backup_mcast_ifn, ip_vs_backup_syncid);
 697
 698         for (;;) {
 699                 /* do you have data now? */
 700                 while (!skb_queue_empty(&(sock->sk->sk_receive_queue))) {
 701                         if ((len =
 702                              ip_vs_receive(sock, buf,
 703                                            sync_recv_mesg_maxlen)) <= 0) {
 704                                 IP_VS_ERR("receiving message error\n");
 705                                 break;
 706                         }
 707                         /* disable bottom half, because it accessed the data
 708                            shared by softirq while getting/creating conns */
 709                         local_bh_disable();
 710                         ip_vs_process_message(buf, len);
 711                         local_bh_enable();
 712                 }
 713
 714                 if (stop_backup_sync)
 715                         break;
 716
 717                 ssleep(1);
 718         }
 719
 720         /* release the sending multicast socket */
 721         sock_release(sock);
 722
 723   out:
 724         kfree(buf);
 725 }
 726
 727
 728 static void set_sync_pid(int sync_state, pid_t sync_pid)
 729 {
 730         if (sync_state == IP_VS_STATE_MASTER)
 731                 sync_master_pid = sync_pid;
 732         else if (sync_state == IP_VS_STATE_BACKUP)
 733                 sync_backup_pid = sync_pid;
 734 }
 735
 736 static void set_stop_sync(int sync_state, int set)
 737 {
 738         if (sync_state == IP_VS_STATE_MASTER)
 739                 stop_master_sync = set;
 740         else if (sync_state == IP_VS_STATE_BACKUP)
 741                 stop_backup_sync = set;
 742         else {
 743                 stop_master_sync = set;
 744                 stop_backup_sync = set;
 745         }
 746 }
 747
 748 static int sync_thread(void *startup)
 749 {
 750         DECLARE_WAITQUEUE(wait, current);
 751         mm_segment_t oldmm;
 752         int state;
 753         const char *name;
 754
 755         /* increase the module use count */
 756         ip_vs_use_count_inc();
 757
 758         if (ip_vs_sync_state & IP_VS_STATE_MASTER && !sync_master_pid) {
 759                 state = IP_VS_STATE_MASTER;
 760                 name = "ipvs_syncmaster";
 761         } else if (ip_vs_sync_state & IP_VS_STATE_BACKUP && !sync_backup_pid) {
 762                 state = IP_VS_STATE_BACKUP;
 763                 name = "ipvs_syncbackup";
 764         } else {
 765                 IP_VS_BUG();
 766                 ip_vs_use_count_dec();
 767                 return -EINVAL;
 768         }
 769
 770         daemonize(name);
 771
 772         oldmm = get_fs();
 773         set_fs(KERNEL_DS);
 774
 775         /* Block all signals */
 776         spin_lock_irq(&current->sighand->siglock);
 777         siginitsetinv(&current->blocked, 0);
 778         recalc_sigpending();
 779         spin_unlock_irq(&current->sighand->siglock);
 780
 781         /* set the maximum length of sync message */
 782         set_sync_mesg_maxlen(state);
 783
 784         /* set up multicast address */
 785         mcast_addr.sin_family = AF_INET;
 786         mcast_addr.sin_port = htons(IP_VS_SYNC_PORT);
 787         mcast_addr.sin_addr.s_addr = htonl(IP_VS_SYNC_GROUP);
 788
 789         add_wait_queue(&sync_wait, &wait);
 790
 791         set_sync_pid(state, current->pid);
 792         complete((struct completion *)startup);
 793
 794         /* processing master/backup loop here */
 795         if (state == IP_VS_STATE_MASTER)
 796                 sync_master_loop();
 797         else if (state == IP_VS_STATE_BACKUP)
 798                 sync_backup_loop();
 799         else IP_VS_BUG();
 800
 801         remove_wait_queue(&sync_wait, &wait);
 802
 803         /* thread exits */
 804         set_sync_pid(state, 0);
 805         IP_VS_INFO("sync thread stopped!\n");
 806
 807         set_fs(oldmm);
 808
 809         /* decrease the module use count */
 810         ip_vs_use_count_dec();
 811
 812         set_stop_sync(state, 0);
 813         wake_up(&stop_sync_wait);
 814
 815         return 0;
 816 }
 817
 818
 819 static int fork_sync_thread(void *startup)
 820 {
 821         pid_t pid;
 822
 823         /* fork the sync thread here, then the parent process of the
 824            sync thread is the init process after this thread exits. */
 825   repeat:
 826         if ((pid = kernel_thread(sync_thread, startup, 0)) < 0) {
 827                 IP_VS_ERR("could not create sync_thread due to %d... "
 828                           "retrying.\n", pid);
 829                 ssleep(1);
 830                 goto repeat;
 831         }
 832
 833         return 0;
 834 }
 835
 836
 837 int start_sync_thread(int state, char *mcast_ifn, __u8 syncid)
 838 {
 839         DECLARE_COMPLETION(startup);
 840         pid_t pid;
 841
 842         if ((state == IP_VS_STATE_MASTER && sync_master_pid) ||
 843             (state == IP_VS_STATE_BACKUP && sync_backup_pid))
 844                 return -EEXIST;
 845
 846         IP_VS_DBG(7, "%s: pid %d\n", __FUNCTION__, current->pid);
 847         IP_VS_DBG(7, "Each ip_vs_sync_conn entry need %Zd bytes\n",
 848                   sizeof(struct ip_vs_sync_conn));
 849
 850         ip_vs_sync_state |= state;
 851         if (state == IP_VS_STATE_MASTER) {
 852                 strlcpy(ip_vs_master_mcast_ifn, mcast_ifn, sizeof(ip_vs_master_mcast_ifn));
 853                 ip_vs_master_syncid = syncid;
 854         } else {
 855                 strlcpy(ip_vs_backup_mcast_ifn, mcast_ifn, sizeof(ip_vs_backup_mcast_ifn));
 856                 ip_vs_backup_syncid = syncid;
 857         }
 858
 859   repeat:
 860         if ((pid = kernel_thread(fork_sync_thread, &startup, 0)) < 0) {
 861                 IP_VS_ERR("could not create fork_sync_thread due to %d... "
 862                           "retrying.\n", pid);
 863                 ssleep(1);
 864                 goto repeat;
 865         }
 866
 867         wait_for_completion(&startup);
 868
 869         return 0;
 870 }
 871
 872
 873 int stop_sync_thread(int state)
 874 {
 875         DECLARE_WAITQUEUE(wait, current);
 876
 877         if ((state == IP_VS_STATE_MASTER && !sync_master_pid) ||
 878             (state == IP_VS_STATE_BACKUP && !sync_backup_pid))
 879                 return -ESRCH;
 880
 881         IP_VS_DBG(7, "%s: pid %d\n", __FUNCTION__, current->pid);
 882         IP_VS_INFO("stopping sync thread %d ...\n",
 883                    (state == IP_VS_STATE_MASTER) ? sync_master_pid : sync_backup_pid);
 884
 885         __set_current_state(TASK_UNINTERRUPTIBLE);
 886         add_wait_queue(&stop_sync_wait, &wait);
 887         set_stop_sync(state, 1);
 888         ip_vs_sync_state -= state;
 889         wake_up(&sync_wait);
 890         schedule();
 891         __set_current_state(TASK_RUNNING);
 892         remove_wait_queue(&stop_sync_wait, &wait);
 893
 894         /* Note: no need to reap the sync thread, because its parent
 895            process is the init process */
 896
 897         if ((state == IP_VS_STATE_MASTER && stop_master_sync) ||
 898             (state == IP_VS_STATE_BACKUP && stop_backup_sync))
 899                 IP_VS_BUG();
 900
 901         return 0;
 902 }