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                 unsigned flags;
 301
 302                 s = (struct ip_vs_sync_conn *)p;
 303                 flags = ntohs(s->flags);
 304                 if (!(flags & IP_VS_CONN_F_TEMPLATE))
 305                         cp = ip_vs_conn_in_get(s->protocol,
 306                                                s->caddr, s->cport,
 307                                                s->vaddr, s->vport);
 308                 else
 309                         cp = ip_vs_ct_in_get(s->protocol,
 310                                                s->caddr, s->cport,
 311                                                s->vaddr, s->vport);
 312                 if (!cp) {
 313                         cp = ip_vs_conn_new(s->protocol,
 314                                             s->caddr, s->cport,
 315                                             s->vaddr, s->vport,
 316                                             s->daddr, s->dport,
 317                                             flags, NULL);
 318                         if (!cp) {
 319                                 IP_VS_ERR("ip_vs_conn_new failed\n");
 320                                 return;
 321                         }
 322                         cp->state = ntohs(s->state);
 323                 } else if (!cp->dest) {
 324                         /* it is an entry created by the synchronization */
 325                         cp->state = ntohs(s->state);
 326                         cp->flags = flags | IP_VS_CONN_F_HASHED;
 327                 }       /* Note that we don't touch its state and flags
 328                            if it is a normal entry. */
 329
 330                 if (flags & IP_VS_CONN_F_SEQ_MASK) {
 331                         opt = (struct ip_vs_sync_conn_options *)&s[1];
 332                         memcpy(&cp->in_seq, opt, sizeof(*opt));
 333                         p += FULL_CONN_SIZE;
 334                 } else
 335                         p += SIMPLE_CONN_SIZE;
 336
 337                 atomic_set(&cp->in_pkts, sysctl_ip_vs_sync_threshold[0]);
 338                 cp->timeout = IP_VS_SYNC_CONN_TIMEOUT;
 339                 ip_vs_conn_put(cp);
 340
 341                 if (p > buffer+buflen) {
 342                         IP_VS_ERR("bogus message\n");
 343                         return;
 344                 }
 345         }
 346 }
 347
 348
 349 /*
 350  *      Setup loopback of outgoing multicasts on a sending socket
 351  */
 352 static void set_mcast_loop(struct sock *sk, u_char loop)
 353 {
 354         struct inet_sock *inet = inet_sk(sk);
 355
 356         /* setsockopt(sock, SOL_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)); */
 357         lock_sock(sk);
 358         inet->mc_loop = loop ? 1 : 0;
 359         release_sock(sk);
 360 }
 361
 362 /*
 363  *      Specify TTL for outgoing multicasts on a sending socket
 364  */
 365 static void set_mcast_ttl(struct sock *sk, u_char ttl)
 366 {
 367         struct inet_sock *inet = inet_sk(sk);
 368
 369         /* setsockopt(sock, SOL_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); */
 370         lock_sock(sk);
 371         inet->mc_ttl = ttl;
 372         release_sock(sk);
 373 }
 374
 375 /*
 376  *      Specifiy default interface for outgoing multicasts
 377  */
 378 static int set_mcast_if(struct sock *sk, char *ifname)
 379 {
 380         struct net_device *dev;
 381         struct inet_sock *inet = inet_sk(sk);
 382
 383         if ((dev = __dev_get_by_name(ifname)) == NULL)
 384                 return -ENODEV;
 385
 386         if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
 387                 return -EINVAL;
 388
 389         lock_sock(sk);
 390         inet->mc_index = dev->ifindex;
 391         /*  inet->mc_addr  = 0; */
 392         release_sock(sk);
 393
 394         return 0;
 395 }
 396
 397
 398 /*
 399  *      Set the maximum length of sync message according to the
 400  *      specified interface's MTU.
 401  */
 402 static int set_sync_mesg_maxlen(int sync_state)
 403 {
 404         struct net_device *dev;
 405         int num;
 406
 407         if (sync_state == IP_VS_STATE_MASTER) {
 408                 if ((dev = __dev_get_by_name(ip_vs_master_mcast_ifn)) == NULL)
 409                         return -ENODEV;
 410
 411                 num = (dev->mtu - sizeof(struct iphdr) -
 412                        sizeof(struct udphdr) -
 413                        SYNC_MESG_HEADER_LEN - 20) / SIMPLE_CONN_SIZE;
 414                 sync_send_mesg_maxlen =
 415                         SYNC_MESG_HEADER_LEN + SIMPLE_CONN_SIZE * num;
 416                 IP_VS_DBG(7, "setting the maximum length of sync sending "
 417                           "message %d.\n", sync_send_mesg_maxlen);
 418         } else if (sync_state == IP_VS_STATE_BACKUP) {
 419                 if ((dev = __dev_get_by_name(ip_vs_backup_mcast_ifn)) == NULL)
 420                         return -ENODEV;
 421
 422                 sync_recv_mesg_maxlen = dev->mtu -
 423                         sizeof(struct iphdr) - sizeof(struct udphdr);
 424                 IP_VS_DBG(7, "setting the maximum length of sync receiving "
 425                           "message %d.\n", sync_recv_mesg_maxlen);
 426         }
 427
 428         return 0;
 429 }
 430
 431
 432 /*
 433  *      Join a multicast group.
 434  *      the group is specified by a class D multicast address 224.0.0.0/8
 435  *      in the in_addr structure passed in as a parameter.
 436  */
 437 static int
 438 join_mcast_group(struct sock *sk, struct in_addr *addr, char *ifname)
 439 {
 440         struct ip_mreqn mreq;
 441         struct net_device *dev;
 442         int ret;
 443
 444         memset(&mreq, 0, sizeof(mreq));
 445         memcpy(&mreq.imr_multiaddr, addr, sizeof(struct in_addr));
 446
 447         if ((dev = __dev_get_by_name(ifname)) == NULL)
 448                 return -ENODEV;
 449         if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
 450                 return -EINVAL;
 451
 452         mreq.imr_ifindex = dev->ifindex;
 453
 454         lock_sock(sk);
 455         ret = ip_mc_join_group(sk, &mreq);
 456         release_sock(sk);
 457
 458         return ret;
 459 }
 460
 461
 462 static int bind_mcastif_addr(struct socket *sock, char *ifname)
 463 {
 464         struct net_device *dev;
 465         u32 addr;
 466         struct sockaddr_in sin;
 467
 468         if ((dev = __dev_get_by_name(ifname)) == NULL)
 469                 return -ENODEV;
 470
 471         addr = inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE);
 472         if (!addr)
 473                 IP_VS_ERR("You probably need to specify IP address on "
 474                           "multicast interface.\n");
 475
 476         IP_VS_DBG(7, "binding socket with (%s) %u.%u.%u.%u\n",
 477                   ifname, NIPQUAD(addr));
 478
 479         /* Now bind the socket with the address of multicast interface */
 480         sin.sin_family       = AF_INET;
 481         sin.sin_addr.s_addr  = addr;
 482         sin.sin_port         = 0;
 483
 484         return sock->ops->bind(sock, (struct sockaddr*)&sin, sizeof(sin));
 485 }
 486
 487 /*
 488  *      Set up sending multicast socket over UDP
 489  */
 490 static struct socket * make_send_sock(void)
 491 {
 492         struct socket *sock;
 493
 494         /* First create a socket */
 495         if (sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock) < 0) {
 496                 IP_VS_ERR("Error during creation of socket; terminating\n");
 497                 return NULL;
 498         }
 499
 500         if (set_mcast_if(sock->sk, ip_vs_master_mcast_ifn) < 0) {
 501                 IP_VS_ERR("Error setting outbound mcast interface\n");
 502                 goto error;
 503         }
 504
 505         set_mcast_loop(sock->sk, 0);
 506         set_mcast_ttl(sock->sk, 1);
 507
 508         if (bind_mcastif_addr(sock, ip_vs_master_mcast_ifn) < 0) {
 509                 IP_VS_ERR("Error binding address of the mcast interface\n");
 510                 goto error;
 511         }
 512
 513         if (sock->ops->connect(sock,
 514                                (struct sockaddr*)&mcast_addr,
 515                                sizeof(struct sockaddr), 0) < 0) {
 516                 IP_VS_ERR("Error connecting to the multicast addr\n");
 517                 goto error;
 518         }
 519
 520         return sock;
 521
 522   error:
 523         sock_release(sock);
 524         return NULL;
 525 }
 526
 527
 528 /*
 529  *      Set up receiving multicast socket over UDP
 530  */
 531 static struct socket * make_receive_sock(void)
 532 {
 533         struct socket *sock;
 534
 535         /* First create a socket */
 536         if (sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock) < 0) {
 537                 IP_VS_ERR("Error during creation of socket; terminating\n");
 538                 return NULL;
 539         }
 540
 541         /* it is equivalent to the REUSEADDR option in user-space */
 542         sock->sk->sk_reuse = 1;
 543
 544         if (sock->ops->bind(sock,
 545                             (struct sockaddr*)&mcast_addr,
 546                             sizeof(struct sockaddr)) < 0) {
 547                 IP_VS_ERR("Error binding to the multicast addr\n");
 548                 goto error;
 549         }
 550
 551         /* join the multicast group */
 552         if (join_mcast_group(sock->sk,
 553                              (struct in_addr*)&mcast_addr.sin_addr,
 554                              ip_vs_backup_mcast_ifn) < 0) {
 555                 IP_VS_ERR("Error joining to the multicast group\n");
 556                 goto error;
 557         }
 558
 559         return sock;
 560
 561   error:
 562         sock_release(sock);
 563         return NULL;
 564 }
 565
 566
 567 static int
 568 ip_vs_send_async(struct socket *sock, const char *buffer, const size_t length)
 569 {
 570         struct msghdr   msg = {.msg_flags = MSG_DONTWAIT|MSG_NOSIGNAL};
 571         struct kvec     iov;
 572         int             len;
 573
 574         EnterFunction(7);
 575         iov.iov_base     = (void *)buffer;
 576         iov.iov_len      = length;
 577
 578         len = kernel_sendmsg(sock, &msg, &iov, 1, (size_t)(length));
 579
 580         LeaveFunction(7);
 581         return len;
 582 }
 583
 584 static void
 585 ip_vs_send_sync_msg(struct socket *sock, struct ip_vs_sync_mesg *msg)
 586 {
 587         int msize;
 588
 589         msize = msg->size;
 590
 591         /* Put size in network byte order */
 592         msg->size = htons(msg->size);
 593
 594         if (ip_vs_send_async(sock, (char *)msg, msize) != msize)
 595                 IP_VS_ERR("ip_vs_send_async error\n");
 596 }
 597
 598 static int
 599 ip_vs_receive(struct socket *sock, char *buffer, const size_t buflen)
 600 {
 601         struct msghdr           msg = {NULL,};
 602         struct kvec             iov;
 603         int                     len;
 604
 605         EnterFunction(7);
 606
 607         /* Receive a packet */
 608         iov.iov_base     = buffer;
 609         iov.iov_len      = (size_t)buflen;
 610
 611         len = kernel_recvmsg(sock, &msg, &iov, 1, buflen, 0);
 612
 613         if (len < 0)
 614                 return -1;
 615
 616         LeaveFunction(7);
 617         return len;
 618 }
 619
 620
 621 static DECLARE_WAIT_QUEUE_HEAD(sync_wait);
 622 static pid_t sync_master_pid = 0;
 623 static pid_t sync_backup_pid = 0;
 624
 625 static DECLARE_WAIT_QUEUE_HEAD(stop_sync_wait);
 626 static int stop_master_sync = 0;
 627 static int stop_backup_sync = 0;
 628
 629 static void sync_master_loop(void)
 630 {
 631         struct socket *sock;
 632         struct ip_vs_sync_buff *sb;
 633
 634         /* create the sending multicast socket */
 635         sock = make_send_sock();
 636         if (!sock)
 637                 return;
 638
 639         IP_VS_INFO("sync thread started: state = MASTER, mcast_ifn = %s, "
 640                    "syncid = %d\n",
 641                    ip_vs_master_mcast_ifn, ip_vs_master_syncid);
 642
 643         for (;;) {
 644                 while ((sb=sb_dequeue())) {
 645                         ip_vs_send_sync_msg(sock, sb->mesg);
 646                         ip_vs_sync_buff_release(sb);
 647                 }
 648
 649                 /* check if entries stay in curr_sb for 2 seconds */
 650                 if ((sb = get_curr_sync_buff(2*HZ))) {
 651                         ip_vs_send_sync_msg(sock, sb->mesg);
 652                         ip_vs_sync_buff_release(sb);
 653                 }
 654
 655                 if (stop_master_sync)
 656                         break;
 657
 658                 ssleep(1);
 659         }
 660
 661         /* clean up the sync_buff queue */
 662         while ((sb=sb_dequeue())) {
 663                 ip_vs_sync_buff_release(sb);
 664         }
 665
 666         /* clean up the current sync_buff */
 667         if ((sb = get_curr_sync_buff(0))) {
 668                 ip_vs_sync_buff_release(sb);
 669         }
 670
 671         /* release the sending multicast socket */
 672         sock_release(sock);
 673 }
 674
 675
 676 static void sync_backup_loop(void)
 677 {
 678         struct socket *sock;
 679         char *buf;
 680         int len;
 681
 682         if (!(buf = kmalloc(sync_recv_mesg_maxlen, GFP_ATOMIC))) {
 683                 IP_VS_ERR("sync_backup_loop: kmalloc error\n");
 684                 return;
 685         }
 686
 687         /* create the receiving multicast socket */
 688         sock = make_receive_sock();
 689         if (!sock)
 690                 goto out;
 691
 692         IP_VS_INFO("sync thread started: state = BACKUP, mcast_ifn = %s, "
 693                    "syncid = %d\n",
 694                    ip_vs_backup_mcast_ifn, ip_vs_backup_syncid);
 695
 696         for (;;) {
 697                 /* do you have data now? */
 698                 while (!skb_queue_empty(&(sock->sk->sk_receive_queue))) {
 699                         if ((len =
 700                              ip_vs_receive(sock, buf,
 701                                            sync_recv_mesg_maxlen)) <= 0) {
 702                                 IP_VS_ERR("receiving message error\n");
 703                                 break;
 704                         }
 705                         /* disable bottom half, because it accessed the data
 706                            shared by softirq while getting/creating conns */
 707                         local_bh_disable();
 708                         ip_vs_process_message(buf, len);
 709                         local_bh_enable();
 710                 }
 711
 712                 if (stop_backup_sync)
 713                         break;
 714
 715                 ssleep(1);
 716         }
 717
 718         /* release the sending multicast socket */
 719         sock_release(sock);
 720
 721   out:
 722         kfree(buf);
 723 }
 724
 725
 726 static void set_sync_pid(int sync_state, pid_t sync_pid)
 727 {
 728         if (sync_state == IP_VS_STATE_MASTER)
 729                 sync_master_pid = sync_pid;
 730         else if (sync_state == IP_VS_STATE_BACKUP)
 731                 sync_backup_pid = sync_pid;
 732 }
 733
 734 static void set_stop_sync(int sync_state, int set)
 735 {
 736         if (sync_state == IP_VS_STATE_MASTER)
 737                 stop_master_sync = set;
 738         else if (sync_state == IP_VS_STATE_BACKUP)
 739                 stop_backup_sync = set;
 740         else {
 741                 stop_master_sync = set;
 742                 stop_backup_sync = set;
 743         }
 744 }
 745
 746 static int sync_thread(void *startup)
 747 {
 748         DECLARE_WAITQUEUE(wait, current);
 749         mm_segment_t oldmm;
 750         int state;
 751         const char *name;
 752
 753         /* increase the module use count */
 754         ip_vs_use_count_inc();
 755
 756         if (ip_vs_sync_state & IP_VS_STATE_MASTER && !sync_master_pid) {
 757                 state = IP_VS_STATE_MASTER;
 758                 name = "ipvs_syncmaster";
 759         } else if (ip_vs_sync_state & IP_VS_STATE_BACKUP && !sync_backup_pid) {
 760                 state = IP_VS_STATE_BACKUP;
 761                 name = "ipvs_syncbackup";
 762         } else {
 763                 IP_VS_BUG();
 764                 ip_vs_use_count_dec();
 765                 return -EINVAL;
 766         }
 767
 768         daemonize(name);
 769
 770         oldmm = get_fs();
 771         set_fs(KERNEL_DS);
 772
 773         /* Block all signals */
 774         spin_lock_irq(&current->sighand->siglock);
 775         siginitsetinv(&current->blocked, 0);
 776         recalc_sigpending();
 777         spin_unlock_irq(&current->sighand->siglock);
 778
 779         /* set the maximum length of sync message */
 780         set_sync_mesg_maxlen(state);
 781
 782         /* set up multicast address */
 783         mcast_addr.sin_family = AF_INET;
 784         mcast_addr.sin_port = htons(IP_VS_SYNC_PORT);
 785         mcast_addr.sin_addr.s_addr = htonl(IP_VS_SYNC_GROUP);
 786
 787         add_wait_queue(&sync_wait, &wait);
 788
 789         set_sync_pid(state, current->pid);
 790         complete((struct completion *)startup);
 791
 792         /* processing master/backup loop here */
 793         if (state == IP_VS_STATE_MASTER)
 794                 sync_master_loop();
 795         else if (state == IP_VS_STATE_BACKUP)
 796                 sync_backup_loop();
 797         else IP_VS_BUG();
 798
 799         remove_wait_queue(&sync_wait, &wait);
 800
 801         /* thread exits */
 802         set_sync_pid(state, 0);
 803         IP_VS_INFO("sync thread stopped!\n");
 804
 805         set_fs(oldmm);
 806
 807         /* decrease the module use count */
 808         ip_vs_use_count_dec();
 809
 810         set_stop_sync(state, 0);
 811         wake_up(&stop_sync_wait);
 812
 813         return 0;
 814 }
 815
 816
 817 static int fork_sync_thread(void *startup)
 818 {
 819         pid_t pid;
 820
 821         /* fork the sync thread here, then the parent process of the
 822            sync thread is the init process after this thread exits. */
 823   repeat:
 824         if ((pid = kernel_thread(sync_thread, startup, 0)) < 0) {
 825                 IP_VS_ERR("could not create sync_thread due to %d... "
 826                           "retrying.\n", pid);
 827                 ssleep(1);
 828                 goto repeat;
 829         }
 830
 831         return 0;
 832 }
 833
 834
 835 int start_sync_thread(int state, char *mcast_ifn, __u8 syncid)
 836 {
 837         DECLARE_COMPLETION(startup);
 838         pid_t pid;
 839
 840         if ((state == IP_VS_STATE_MASTER && sync_master_pid) ||
 841             (state == IP_VS_STATE_BACKUP && sync_backup_pid))
 842                 return -EEXIST;
 843
 844         IP_VS_DBG(7, "%s: pid %d\n", __FUNCTION__, current->pid);
 845         IP_VS_DBG(7, "Each ip_vs_sync_conn entry need %Zd bytes\n",
 846                   sizeof(struct ip_vs_sync_conn));
 847
 848         ip_vs_sync_state |= state;
 849         if (state == IP_VS_STATE_MASTER) {
 850                 strlcpy(ip_vs_master_mcast_ifn, mcast_ifn, sizeof(ip_vs_master_mcast_ifn));
 851                 ip_vs_master_syncid = syncid;
 852         } else {
 853                 strlcpy(ip_vs_backup_mcast_ifn, mcast_ifn, sizeof(ip_vs_backup_mcast_ifn));
 854                 ip_vs_backup_syncid = syncid;
 855         }
 856
 857   repeat:
 858         if ((pid = kernel_thread(fork_sync_thread, &startup, 0)) < 0) {
 859                 IP_VS_ERR("could not create fork_sync_thread due to %d... "
 860                           "retrying.\n", pid);
 861                 ssleep(1);
 862                 goto repeat;
 863         }
 864
 865         wait_for_completion(&startup);
 866
 867         return 0;
 868 }
 869
 870
 871 int stop_sync_thread(int state)
 872 {
 873         DECLARE_WAITQUEUE(wait, current);
 874
 875         if ((state == IP_VS_STATE_MASTER && !sync_master_pid) ||
 876             (state == IP_VS_STATE_BACKUP && !sync_backup_pid))
 877                 return -ESRCH;
 878
 879         IP_VS_DBG(7, "%s: pid %d\n", __FUNCTION__, current->pid);
 880         IP_VS_INFO("stopping sync thread %d ...\n",
 881                    (state == IP_VS_STATE_MASTER) ? sync_master_pid : sync_backup_pid);
 882
 883         __set_current_state(TASK_UNINTERRUPTIBLE);
 884         add_wait_queue(&stop_sync_wait, &wait);
 885         set_stop_sync(state, 1);
 886         ip_vs_sync_state -= state;
 887         wake_up(&sync_wait);
 888         schedule();
 889         __set_current_state(TASK_RUNNING);
 890         remove_wait_queue(&stop_sync_wait, &wait);
 891
 892         /* Note: no need to reap the sync thread, because its parent
 893            process is the init process */
 894
 895         if ((state == IP_VS_STATE_MASTER && stop_master_sync) ||
 896             (state == IP_VS_STATE_BACKUP && stop_backup_sync))
 897                 IP_VS_BUG();
 898
 899         return 0;
 900 }