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         __be16                  cport;
  52         __be16                  vport;
  53         __be16                  dport;
  54         __be32                  caddr;          /* client address */
  55         __be32                  vaddr;          /* virtual address */
  56         __be32                  daddr;          /* destination address */
  57
  58         /* Flags and state transition */
  59         __be16                  flags;          /* status flags */
  60         __be16                  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 struct ip_vs_sync_thread_data {
  71         struct completion *startup;
  72         int state;
  73 };
  74
  75 #define IP_VS_SYNC_CONN_TIMEOUT (3*60*HZ)
  76 #define SIMPLE_CONN_SIZE  (sizeof(struct ip_vs_sync_conn))
  77 #define FULL_CONN_SIZE  \
  78 (sizeof(struct ip_vs_sync_conn) + sizeof(struct ip_vs_sync_conn_options))
  79
  80
  81 /*
  82   The master mulitcasts messages to the backup load balancers in the
  83   following format.
  84
  85        0                   1                   2                   3
  86        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
  87       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  88       |  Count Conns  |    SyncID     |            Size               |
  89       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  90       |                                                               |
  91       |                    IPVS Sync Connection (1)                   |
  92       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  93       |                            .                                  |
  94       |                            .                                  |
  95       |                            .                                  |
  96       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  97       |                                                               |
  98       |                    IPVS Sync Connection (n)                   |
  99       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 100 */
 101
 102 #define SYNC_MESG_HEADER_LEN    4
 103
 104 struct ip_vs_sync_mesg {
 105         __u8                    nr_conns;
 106         __u8                    syncid;
 107         __u16                   size;
 108
 109         /* ip_vs_sync_conn entries start here */
 110 };
 111
 112 /* the maximum length of sync (sending/receiving) message */
 113 static int sync_send_mesg_maxlen;
 114 static int sync_recv_mesg_maxlen;
 115
 116 struct ip_vs_sync_buff {
 117         struct list_head        list;
 118         unsigned long           firstuse;
 119
 120         /* pointers for the message data */
 121         struct ip_vs_sync_mesg  *mesg;
 122         unsigned char           *head;
 123         unsigned char           *end;
 124 };
 125
 126
 127 /* the sync_buff list head and the lock */
 128 static LIST_HEAD(ip_vs_sync_queue);
 129 static DEFINE_SPINLOCK(ip_vs_sync_lock);
 130
 131 /* current sync_buff for accepting new conn entries */
 132 static struct ip_vs_sync_buff   *curr_sb = NULL;
 133 static DEFINE_SPINLOCK(curr_sb_lock);
 134
 135 /* ipvs sync daemon state */
 136 volatile int ip_vs_sync_state = IP_VS_STATE_NONE;
 137 volatile int ip_vs_master_syncid = 0;
 138 volatile int ip_vs_backup_syncid = 0;
 139
 140 /* multicast interface name */
 141 char ip_vs_master_mcast_ifn[IP_VS_IFNAME_MAXLEN];
 142 char ip_vs_backup_mcast_ifn[IP_VS_IFNAME_MAXLEN];
 143
 144 /* multicast addr */
 145 static struct sockaddr_in mcast_addr;
 146
 147
 148 static inline void sb_queue_tail(struct ip_vs_sync_buff *sb)
 149 {
 150         spin_lock(&ip_vs_sync_lock);
 151         list_add_tail(&sb->list, &ip_vs_sync_queue);
 152         spin_unlock(&ip_vs_sync_lock);
 153 }
 154
 155 static inline struct ip_vs_sync_buff * sb_dequeue(void)
 156 {
 157         struct ip_vs_sync_buff *sb;
 158
 159         spin_lock_bh(&ip_vs_sync_lock);
 160         if (list_empty(&ip_vs_sync_queue)) {
 161                 sb = NULL;
 162         } else {
 163                 sb = list_entry(ip_vs_sync_queue.next,
 164                                 struct ip_vs_sync_buff,
 165                                 list);
 166                 list_del(&sb->list);
 167         }
 168         spin_unlock_bh(&ip_vs_sync_lock);
 169
 170         return sb;
 171 }
 172
 173 static inline struct ip_vs_sync_buff * ip_vs_sync_buff_create(void)
 174 {
 175         struct ip_vs_sync_buff *sb;
 176
 177         if (!(sb=kmalloc(sizeof(struct ip_vs_sync_buff), GFP_ATOMIC)))
 178                 return NULL;
 179
 180         if (!(sb->mesg=kmalloc(sync_send_mesg_maxlen, GFP_ATOMIC))) {
 181                 kfree(sb);
 182                 return NULL;
 183         }
 184         sb->mesg->nr_conns = 0;
 185         sb->mesg->syncid = ip_vs_master_syncid;
 186         sb->mesg->size = 4;
 187         sb->head = (unsigned char *)sb->mesg + 4;
 188         sb->end = (unsigned char *)sb->mesg + sync_send_mesg_maxlen;
 189         sb->firstuse = jiffies;
 190         return sb;
 191 }
 192
 193 static inline void ip_vs_sync_buff_release(struct ip_vs_sync_buff *sb)
 194 {
 195         kfree(sb->mesg);
 196         kfree(sb);
 197 }
 198
 199 /*
 200  *      Get the current sync buffer if it has been created for more
 201  *      than the specified time or the specified time is zero.
 202  */
 203 static inline struct ip_vs_sync_buff *
 204 get_curr_sync_buff(unsigned long time)
 205 {
 206         struct ip_vs_sync_buff *sb;
 207
 208         spin_lock_bh(&curr_sb_lock);
 209         if (curr_sb && (time == 0 ||
 210                         time_before(jiffies - curr_sb->firstuse, time))) {
 211                 sb = curr_sb;
 212                 curr_sb = NULL;
 213         } else
 214                 sb = NULL;
 215         spin_unlock_bh(&curr_sb_lock);
 216         return sb;
 217 }
 218
 219
 220 /*
 221  *      Add an ip_vs_conn information into the current sync_buff.
 222  *      Called by ip_vs_in.
 223  */
 224 void ip_vs_sync_conn(struct ip_vs_conn *cp)
 225 {
 226         struct ip_vs_sync_mesg *m;
 227         struct ip_vs_sync_conn *s;
 228         int len;
 229
 230         spin_lock(&curr_sb_lock);
 231         if (!curr_sb) {
 232                 if (!(curr_sb=ip_vs_sync_buff_create())) {
 233                         spin_unlock(&curr_sb_lock);
 234                         IP_VS_ERR("ip_vs_sync_buff_create failed.\n");
 235                         return;
 236                 }
 237         }
 238
 239         len = (cp->flags & IP_VS_CONN_F_SEQ_MASK) ? FULL_CONN_SIZE :
 240                 SIMPLE_CONN_SIZE;
 241         m = curr_sb->mesg;
 242         s = (struct ip_vs_sync_conn *)curr_sb->head;
 243
 244         /* copy members */
 245         s->protocol = cp->protocol;
 246         s->cport = cp->cport;
 247         s->vport = cp->vport;
 248         s->dport = cp->dport;
 249         s->caddr = cp->caddr;
 250         s->vaddr = cp->vaddr;
 251         s->daddr = cp->daddr;
 252         s->flags = htons(cp->flags & ~IP_VS_CONN_F_HASHED);
 253         s->state = htons(cp->state);
 254         if (cp->flags & IP_VS_CONN_F_SEQ_MASK) {
 255                 struct ip_vs_sync_conn_options *opt =
 256                         (struct ip_vs_sync_conn_options *)&s[1];
 257                 memcpy(opt, &cp->in_seq, sizeof(*opt));
 258         }
 259
 260         m->nr_conns++;
 261         m->size += len;
 262         curr_sb->head += len;
 263
 264         /* check if there is a space for next one */
 265         if (curr_sb->head+FULL_CONN_SIZE > curr_sb->end) {
 266                 sb_queue_tail(curr_sb);
 267                 curr_sb = NULL;
 268         }
 269         spin_unlock(&curr_sb_lock);
 270
 271         /* synchronize its controller if it has */
 272         if (cp->control)
 273                 ip_vs_sync_conn(cp->control);
 274 }
 275
 276
 277 /*
 278  *      Process received multicast message and create the corresponding
 279  *      ip_vs_conn entries.
 280  */
 281 static void ip_vs_process_message(const char *buffer, const size_t buflen)
 282 {
 283         struct ip_vs_sync_mesg *m = (struct ip_vs_sync_mesg *)buffer;
 284         struct ip_vs_sync_conn *s;
 285         struct ip_vs_sync_conn_options *opt;
 286         struct ip_vs_conn *cp;
 287         char *p;
 288         int i;
 289
 290         /* Convert size back to host byte order */
 291         m->size = ntohs(m->size);
 292
 293         if (buflen != m->size) {
 294                 IP_VS_ERR("bogus message\n");
 295                 return;
 296         }
 297
 298         /* SyncID sanity check */
 299         if (ip_vs_backup_syncid != 0 && m->syncid != ip_vs_backup_syncid) {
 300                 IP_VS_DBG(7, "Ignoring incoming msg with syncid = %d\n",
 301                           m->syncid);
 302                 return;
 303         }
 304
 305         p = (char *)buffer + sizeof(struct ip_vs_sync_mesg);
 306         for (i=0; i<m->nr_conns; i++) {
 307                 unsigned flags;
 308
 309                 s = (struct ip_vs_sync_conn *)p;
 310                 flags = ntohs(s->flags);
 311                 if (!(flags & IP_VS_CONN_F_TEMPLATE))
 312                         cp = ip_vs_conn_in_get(s->protocol,
 313                                                s->caddr, s->cport,
 314                                                s->vaddr, s->vport);
 315                 else
 316                         cp = ip_vs_ct_in_get(s->protocol,
 317                                                s->caddr, s->cport,
 318                                                s->vaddr, s->vport);
 319                 if (!cp) {
 320                         cp = ip_vs_conn_new(s->protocol,
 321                                             s->caddr, s->cport,
 322                                             s->vaddr, s->vport,
 323                                             s->daddr, s->dport,
 324                                             flags, NULL);
 325                         if (!cp) {
 326                                 IP_VS_ERR("ip_vs_conn_new failed\n");
 327                                 return;
 328                         }
 329                         cp->state = ntohs(s->state);
 330                 } else if (!cp->dest) {
 331                         /* it is an entry created by the synchronization */
 332                         cp->state = ntohs(s->state);
 333                         cp->flags = flags | IP_VS_CONN_F_HASHED;
 334                 }       /* Note that we don't touch its state and flags
 335                            if it is a normal entry. */
 336
 337                 if (flags & IP_VS_CONN_F_SEQ_MASK) {
 338                         opt = (struct ip_vs_sync_conn_options *)&s[1];
 339                         memcpy(&cp->in_seq, opt, sizeof(*opt));
 340                         p += FULL_CONN_SIZE;
 341                 } else
 342                         p += SIMPLE_CONN_SIZE;
 343
 344                 atomic_set(&cp->in_pkts, sysctl_ip_vs_sync_threshold[0]);
 345                 cp->timeout = IP_VS_SYNC_CONN_TIMEOUT;
 346                 ip_vs_conn_put(cp);
 347
 348                 if (p > buffer+buflen) {
 349                         IP_VS_ERR("bogus message\n");
 350                         return;
 351                 }
 352         }
 353 }
 354
 355
 356 /*
 357  *      Setup loopback of outgoing multicasts on a sending socket
 358  */
 359 static void set_mcast_loop(struct sock *sk, u_char loop)
 360 {
 361         struct inet_sock *inet = inet_sk(sk);
 362
 363         /* setsockopt(sock, SOL_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)); */
 364         lock_sock(sk);
 365         inet->mc_loop = loop ? 1 : 0;
 366         release_sock(sk);
 367 }
 368
 369 /*
 370  *      Specify TTL for outgoing multicasts on a sending socket
 371  */
 372 static void set_mcast_ttl(struct sock *sk, u_char ttl)
 373 {
 374         struct inet_sock *inet = inet_sk(sk);
 375
 376         /* setsockopt(sock, SOL_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); */
 377         lock_sock(sk);
 378         inet->mc_ttl = ttl;
 379         release_sock(sk);
 380 }
 381
 382 /*
 383  *      Specifiy default interface for outgoing multicasts
 384  */
 385 static int set_mcast_if(struct sock *sk, char *ifname)
 386 {
 387         struct net_device *dev;
 388         struct inet_sock *inet = inet_sk(sk);
 389
 390         if ((dev = __dev_get_by_name(&init_net, ifname)) == NULL)
 391                 return -ENODEV;
 392
 393         if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
 394                 return -EINVAL;
 395
 396         lock_sock(sk);
 397         inet->mc_index = dev->ifindex;
 398         /*  inet->mc_addr  = 0; */
 399         release_sock(sk);
 400
 401         return 0;
 402 }
 403
 404
 405 /*
 406  *      Set the maximum length of sync message according to the
 407  *      specified interface's MTU.
 408  */
 409 static int set_sync_mesg_maxlen(int sync_state)
 410 {
 411         struct net_device *dev;
 412         int num;
 413
 414         if (sync_state == IP_VS_STATE_MASTER) {
 415                 if ((dev = __dev_get_by_name(&init_net, ip_vs_master_mcast_ifn)) == NULL)
 416                         return -ENODEV;
 417
 418                 num = (dev->mtu - sizeof(struct iphdr) -
 419                        sizeof(struct udphdr) -
 420                        SYNC_MESG_HEADER_LEN - 20) / SIMPLE_CONN_SIZE;
 421                 sync_send_mesg_maxlen =
 422                         SYNC_MESG_HEADER_LEN + SIMPLE_CONN_SIZE * num;
 423                 IP_VS_DBG(7, "setting the maximum length of sync sending "
 424                           "message %d.\n", sync_send_mesg_maxlen);
 425         } else if (sync_state == IP_VS_STATE_BACKUP) {
 426                 if ((dev = __dev_get_by_name(&init_net, ip_vs_backup_mcast_ifn)) == NULL)
 427                         return -ENODEV;
 428
 429                 sync_recv_mesg_maxlen = dev->mtu -
 430                         sizeof(struct iphdr) - sizeof(struct udphdr);
 431                 IP_VS_DBG(7, "setting the maximum length of sync receiving "
 432                           "message %d.\n", sync_recv_mesg_maxlen);
 433         }
 434
 435         return 0;
 436 }
 437
 438
 439 /*
 440  *      Join a multicast group.
 441  *      the group is specified by a class D multicast address 224.0.0.0/8
 442  *      in the in_addr structure passed in as a parameter.
 443  */
 444 static int
 445 join_mcast_group(struct sock *sk, struct in_addr *addr, char *ifname)
 446 {
 447         struct ip_mreqn mreq;
 448         struct net_device *dev;
 449         int ret;
 450
 451         memset(&mreq, 0, sizeof(mreq));
 452         memcpy(&mreq.imr_multiaddr, addr, sizeof(struct in_addr));
 453
 454         if ((dev = __dev_get_by_name(&init_net, ifname)) == NULL)
 455                 return -ENODEV;
 456         if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
 457                 return -EINVAL;
 458
 459         mreq.imr_ifindex = dev->ifindex;
 460
 461         lock_sock(sk);
 462         ret = ip_mc_join_group(sk, &mreq);
 463         release_sock(sk);
 464
 465         return ret;
 466 }
 467
 468
 469 static int bind_mcastif_addr(struct socket *sock, char *ifname)
 470 {
 471         struct net_device *dev;
 472         __be32 addr;
 473         struct sockaddr_in sin;
 474
 475         if ((dev = __dev_get_by_name(&init_net, ifname)) == NULL)
 476                 return -ENODEV;
 477
 478         addr = inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE);
 479         if (!addr)
 480                 IP_VS_ERR("You probably need to specify IP address on "
 481                           "multicast interface.\n");
 482
 483         IP_VS_DBG(7, "binding socket with (%s) %u.%u.%u.%u\n",
 484                   ifname, NIPQUAD(addr));
 485
 486         /* Now bind the socket with the address of multicast interface */
 487         sin.sin_family       = AF_INET;
 488         sin.sin_addr.s_addr  = addr;
 489         sin.sin_port         = 0;
 490
 491         return sock->ops->bind(sock, (struct sockaddr*)&sin, sizeof(sin));
 492 }
 493
 494 /*
 495  *      Set up sending multicast socket over UDP
 496  */
 497 static struct socket * make_send_sock(void)
 498 {
 499         struct socket *sock;
 500
 501         /* First create a socket */
 502         if (sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock) < 0) {
 503                 IP_VS_ERR("Error during creation of socket; terminating\n");
 504                 return NULL;
 505         }
 506
 507         if (set_mcast_if(sock->sk, ip_vs_master_mcast_ifn) < 0) {
 508                 IP_VS_ERR("Error setting outbound mcast interface\n");
 509                 goto error;
 510         }
 511
 512         set_mcast_loop(sock->sk, 0);
 513         set_mcast_ttl(sock->sk, 1);
 514
 515         if (bind_mcastif_addr(sock, ip_vs_master_mcast_ifn) < 0) {
 516                 IP_VS_ERR("Error binding address of the mcast interface\n");
 517                 goto error;
 518         }
 519
 520         if (sock->ops->connect(sock,
 521                                (struct sockaddr*)&mcast_addr,
 522                                sizeof(struct sockaddr), 0) < 0) {
 523                 IP_VS_ERR("Error connecting to the multicast addr\n");
 524                 goto error;
 525         }
 526
 527         return sock;
 528
 529   error:
 530         sock_release(sock);
 531         return NULL;
 532 }
 533
 534
 535 /*
 536  *      Set up receiving multicast socket over UDP
 537  */
 538 static struct socket * make_receive_sock(void)
 539 {
 540         struct socket *sock;
 541
 542         /* First create a socket */
 543         if (sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock) < 0) {
 544                 IP_VS_ERR("Error during creation of socket; terminating\n");
 545                 return NULL;
 546         }
 547
 548         /* it is equivalent to the REUSEADDR option in user-space */
 549         sock->sk->sk_reuse = 1;
 550
 551         if (sock->ops->bind(sock,
 552                             (struct sockaddr*)&mcast_addr,
 553                             sizeof(struct sockaddr)) < 0) {
 554                 IP_VS_ERR("Error binding to the multicast addr\n");
 555                 goto error;
 556         }
 557
 558         /* join the multicast group */
 559         if (join_mcast_group(sock->sk,
 560                              (struct in_addr*)&mcast_addr.sin_addr,
 561                              ip_vs_backup_mcast_ifn) < 0) {
 562                 IP_VS_ERR("Error joining to the multicast group\n");
 563                 goto error;
 564         }
 565
 566         return sock;
 567
 568   error:
 569         sock_release(sock);
 570         return NULL;
 571 }
 572
 573
 574 static int
 575 ip_vs_send_async(struct socket *sock, const char *buffer, const size_t length)
 576 {
 577         struct msghdr   msg = {.msg_flags = MSG_DONTWAIT|MSG_NOSIGNAL};
 578         struct kvec     iov;
 579         int             len;
 580
 581         EnterFunction(7);
 582         iov.iov_base     = (void *)buffer;
 583         iov.iov_len      = length;
 584
 585         len = kernel_sendmsg(sock, &msg, &iov, 1, (size_t)(length));
 586
 587         LeaveFunction(7);
 588         return len;
 589 }
 590
 591 static void
 592 ip_vs_send_sync_msg(struct socket *sock, struct ip_vs_sync_mesg *msg)
 593 {
 594         int msize;
 595
 596         msize = msg->size;
 597
 598         /* Put size in network byte order */
 599         msg->size = htons(msg->size);
 600
 601         if (ip_vs_send_async(sock, (char *)msg, msize) != msize)
 602                 IP_VS_ERR("ip_vs_send_async error\n");
 603 }
 604
 605 static int
 606 ip_vs_receive(struct socket *sock, char *buffer, const size_t buflen)
 607 {
 608         struct msghdr           msg = {NULL,};
 609         struct kvec             iov;
 610         int                     len;
 611
 612         EnterFunction(7);
 613
 614         /* Receive a packet */
 615         iov.iov_base     = buffer;
 616         iov.iov_len      = (size_t)buflen;
 617
 618         len = kernel_recvmsg(sock, &msg, &iov, 1, buflen, 0);
 619
 620         if (len < 0)
 621                 return -1;
 622
 623         LeaveFunction(7);
 624         return len;
 625 }
 626
 627
 628 static DECLARE_WAIT_QUEUE_HEAD(sync_wait);
 629 static pid_t sync_master_pid = 0;
 630 static pid_t sync_backup_pid = 0;
 631
 632 static DECLARE_WAIT_QUEUE_HEAD(stop_sync_wait);
 633 static int stop_master_sync = 0;
 634 static int stop_backup_sync = 0;
 635
 636 static void sync_master_loop(void)
 637 {
 638         struct socket *sock;
 639         struct ip_vs_sync_buff *sb;
 640
 641         /* create the sending multicast socket */
 642         sock = make_send_sock();
 643         if (!sock)
 644                 return;
 645
 646         IP_VS_INFO("sync thread started: state = MASTER, mcast_ifn = %s, "
 647                    "syncid = %d\n",
 648                    ip_vs_master_mcast_ifn, ip_vs_master_syncid);
 649
 650         for (;;) {
 651                 while ((sb=sb_dequeue())) {
 652                         ip_vs_send_sync_msg(sock, sb->mesg);
 653                         ip_vs_sync_buff_release(sb);
 654                 }
 655
 656                 /* check if entries stay in curr_sb for 2 seconds */
 657                 if ((sb = get_curr_sync_buff(2*HZ))) {
 658                         ip_vs_send_sync_msg(sock, sb->mesg);
 659                         ip_vs_sync_buff_release(sb);
 660                 }
 661
 662                 if (stop_master_sync)
 663                         break;
 664
 665                 msleep_interruptible(1000);
 666         }
 667
 668         /* clean up the sync_buff queue */
 669         while ((sb=sb_dequeue())) {
 670                 ip_vs_sync_buff_release(sb);
 671         }
 672
 673         /* clean up the current sync_buff */
 674         if ((sb = get_curr_sync_buff(0))) {
 675                 ip_vs_sync_buff_release(sb);
 676         }
 677
 678         /* release the sending multicast socket */
 679         sock_release(sock);
 680 }
 681
 682
 683 static void sync_backup_loop(void)
 684 {
 685         struct socket *sock;
 686         char *buf;
 687         int len;
 688
 689         if (!(buf = kmalloc(sync_recv_mesg_maxlen, GFP_ATOMIC))) {
 690                 IP_VS_ERR("sync_backup_loop: kmalloc error\n");
 691                 return;
 692         }
 693
 694         /* create the receiving multicast socket */
 695         sock = make_receive_sock();
 696         if (!sock)
 697                 goto out;
 698
 699         IP_VS_INFO("sync thread started: state = BACKUP, mcast_ifn = %s, "
 700                    "syncid = %d\n",
 701                    ip_vs_backup_mcast_ifn, ip_vs_backup_syncid);
 702
 703         for (;;) {
 704                 /* do you have data now? */
 705                 while (!skb_queue_empty(&(sock->sk->sk_receive_queue))) {
 706                         if ((len =
 707                              ip_vs_receive(sock, buf,
 708                                            sync_recv_mesg_maxlen)) <= 0) {
 709                                 IP_VS_ERR("receiving message error\n");
 710                                 break;
 711                         }
 712                         /* disable bottom half, because it accessed the data
 713                            shared by softirq while getting/creating conns */
 714                         local_bh_disable();
 715                         ip_vs_process_message(buf, len);
 716                         local_bh_enable();
 717                 }
 718
 719                 if (stop_backup_sync)
 720                         break;
 721
 722                 msleep_interruptible(1000);
 723         }
 724
 725         /* release the sending multicast socket */
 726         sock_release(sock);
 727
 728   out:
 729         kfree(buf);
 730 }
 731
 732
 733 static void set_sync_pid(int sync_state, pid_t sync_pid)
 734 {
 735         if (sync_state == IP_VS_STATE_MASTER)
 736                 sync_master_pid = sync_pid;
 737         else if (sync_state == IP_VS_STATE_BACKUP)
 738                 sync_backup_pid = sync_pid;
 739 }
 740
 741 static void set_stop_sync(int sync_state, int set)
 742 {
 743         if (sync_state == IP_VS_STATE_MASTER)
 744                 stop_master_sync = set;
 745         else if (sync_state == IP_VS_STATE_BACKUP)
 746                 stop_backup_sync = set;
 747         else {
 748                 stop_master_sync = set;
 749                 stop_backup_sync = set;
 750         }
 751 }
 752
 753 static int sync_thread(void *startup)
 754 {
 755         DECLARE_WAITQUEUE(wait, current);
 756         mm_segment_t oldmm;
 757         int state;
 758         const char *name;
 759         struct ip_vs_sync_thread_data *tinfo = startup;
 760
 761         /* increase the module use count */
 762         ip_vs_use_count_inc();
 763
 764         if (ip_vs_sync_state & IP_VS_STATE_MASTER && !sync_master_pid) {
 765                 state = IP_VS_STATE_MASTER;
 766                 name = "ipvs_syncmaster";
 767         } else if (ip_vs_sync_state & IP_VS_STATE_BACKUP && !sync_backup_pid) {
 768                 state = IP_VS_STATE_BACKUP;
 769                 name = "ipvs_syncbackup";
 770         } else {
 771                 IP_VS_BUG();
 772                 ip_vs_use_count_dec();
 773                 return -EINVAL;
 774         }
 775
 776         daemonize(name);
 777
 778         oldmm = get_fs();
 779         set_fs(KERNEL_DS);
 780
 781         /* Block all signals */
 782         spin_lock_irq(&current->sighand->siglock);
 783         siginitsetinv(&current->blocked, 0);
 784         recalc_sigpending();
 785         spin_unlock_irq(&current->sighand->siglock);
 786
 787         /* set the maximum length of sync message */
 788         set_sync_mesg_maxlen(state);
 789
 790         /* set up multicast address */
 791         mcast_addr.sin_family = AF_INET;
 792         mcast_addr.sin_port = htons(IP_VS_SYNC_PORT);
 793         mcast_addr.sin_addr.s_addr = htonl(IP_VS_SYNC_GROUP);
 794
 795         add_wait_queue(&sync_wait, &wait);
 796
 797         set_sync_pid(state, current->pid);
 798         complete(tinfo->startup);
 799
 800         /*
 801          * once we call the completion queue above, we should
 802          * null out that reference, since its allocated on the
 803          * stack of the creating kernel thread
 804          */
 805         tinfo->startup = NULL;
 806
 807         /* processing master/backup loop here */
 808         if (state == IP_VS_STATE_MASTER)
 809                 sync_master_loop();
 810         else if (state == IP_VS_STATE_BACKUP)
 811                 sync_backup_loop();
 812         else IP_VS_BUG();
 813
 814         remove_wait_queue(&sync_wait, &wait);
 815
 816         /* thread exits */
 817
 818         /*
 819          * If we weren't explicitly stopped, then we
 820          * exited in error, and should undo our state
 821          */
 822         if ((!stop_master_sync) && (!stop_backup_sync))
 823                 ip_vs_sync_state -= tinfo->state;
 824
 825         set_sync_pid(state, 0);
 826         IP_VS_INFO("sync thread stopped!\n");
 827
 828         set_fs(oldmm);
 829
 830         /* decrease the module use count */
 831         ip_vs_use_count_dec();
 832
 833         set_stop_sync(state, 0);
 834         wake_up(&stop_sync_wait);
 835
 836         /*
 837          * we need to free the structure that was allocated
 838          * for us in start_sync_thread
 839          */
 840         kfree(tinfo);
 841         return 0;
 842 }
 843
 844
 845 static int fork_sync_thread(void *startup)
 846 {
 847         pid_t pid;
 848
 849         /* fork the sync thread here, then the parent process of the
 850            sync thread is the init process after this thread exits. */
 851   repeat:
 852         if ((pid = kernel_thread(sync_thread, startup, 0)) < 0) {
 853                 IP_VS_ERR("could not create sync_thread due to %d... "
 854                           "retrying.\n", pid);
 855                 msleep_interruptible(1000);
 856                 goto repeat;
 857         }
 858
 859         return 0;
 860 }
 861
 862
 863 int start_sync_thread(int state, char *mcast_ifn, __u8 syncid)
 864 {
 865         DECLARE_COMPLETION_ONSTACK(startup);
 866         pid_t pid;
 867         struct ip_vs_sync_thread_data *tinfo;
 868
 869         if ((state == IP_VS_STATE_MASTER && sync_master_pid) ||
 870             (state == IP_VS_STATE_BACKUP && sync_backup_pid))
 871                 return -EEXIST;
 872
 873         /*
 874          * Note that tinfo will be freed in sync_thread on exit
 875          */
 876         tinfo = kmalloc(sizeof(struct ip_vs_sync_thread_data), GFP_KERNEL);
 877         if (!tinfo)
 878                 return -ENOMEM;
 879
 880         IP_VS_DBG(7, "%s: pid %d\n", __FUNCTION__, current->pid);
 881         IP_VS_DBG(7, "Each ip_vs_sync_conn entry need %Zd bytes\n",
 882                   sizeof(struct ip_vs_sync_conn));
 883
 884         ip_vs_sync_state |= state;
 885         if (state == IP_VS_STATE_MASTER) {
 886                 strlcpy(ip_vs_master_mcast_ifn, mcast_ifn,
 887                         sizeof(ip_vs_master_mcast_ifn));
 888                 ip_vs_master_syncid = syncid;
 889         } else {
 890                 strlcpy(ip_vs_backup_mcast_ifn, mcast_ifn,
 891                         sizeof(ip_vs_backup_mcast_ifn));
 892                 ip_vs_backup_syncid = syncid;
 893         }
 894
 895         tinfo->state = state;
 896         tinfo->startup = &startup;
 897
 898   repeat:
 899         if ((pid = kernel_thread(fork_sync_thread, tinfo, 0)) < 0) {
 900                 IP_VS_ERR("could not create fork_sync_thread due to %d... "
 901                           "retrying.\n", pid);
 902                 msleep_interruptible(1000);
 903                 goto repeat;
 904         }
 905
 906         wait_for_completion(&startup);
 907
 908         return 0;
 909 }
 910
 911
 912 int stop_sync_thread(int state)
 913 {
 914         DECLARE_WAITQUEUE(wait, current);
 915
 916         if ((state == IP_VS_STATE_MASTER && !sync_master_pid) ||
 917             (state == IP_VS_STATE_BACKUP && !sync_backup_pid))
 918                 return -ESRCH;
 919
 920         IP_VS_DBG(7, "%s: pid %d\n", __FUNCTION__, current->pid);
 921         IP_VS_INFO("stopping sync thread %d ...\n",
 922                    (state == IP_VS_STATE_MASTER) ?
 923                    sync_master_pid : sync_backup_pid);
 924
 925         __set_current_state(TASK_UNINTERRUPTIBLE);
 926         add_wait_queue(&stop_sync_wait, &wait);
 927         set_stop_sync(state, 1);
 928         ip_vs_sync_state -= state;
 929         wake_up(&sync_wait);
 930         schedule();
 931         __set_current_state(TASK_RUNNING);
 932         remove_wait_queue(&stop_sync_wait, &wait);
 933
 934         /* Note: no need to reap the sync thread, because its parent
 935            process is the init process */
 936
 937         if ((state == IP_VS_STATE_MASTER && stop_master_sync) ||
 938             (state == IP_VS_STATE_BACKUP && stop_backup_sync))
 939                 IP_VS_BUG();
 940
 941         return 0;
 942 }