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