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 SIMPLE_CONN_SIZE  (sizeof(struct ip_vs_sync_conn))
  76 #define FULL_CONN_SIZE  \
  77 (sizeof(struct ip_vs_sync_conn) + sizeof(struct ip_vs_sync_conn_options))
  78
  79
  80 /*
  81   The master mulitcasts messages to the backup load balancers in the
  82   following format.
  83
  84        0                   1                   2                   3
  85        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
  86       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  87       |  Count Conns  |    SyncID     |            Size               |
  88       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  89       |                                                               |
  90       |                    IPVS Sync Connection (1)                   |
  91       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  92       |                            .                                  |
  93       |                            .                                  |
  94       |                            .                                  |
  95       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  96       |                                                               |
  97       |                    IPVS Sync Connection (n)                   |
  98       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  99 */
 100
 101 #define SYNC_MESG_HEADER_LEN    4
 102
 103 struct ip_vs_sync_mesg {
 104         __u8                    nr_conns;
 105         __u8                    syncid;
 106         __u16                   size;
 107
 108         /* ip_vs_sync_conn entries start here */
 109 };
 110
 111 /* the maximum length of sync (sending/receiving) message */
 112 static int sync_send_mesg_maxlen;
 113 static int sync_recv_mesg_maxlen;
 114
 115 struct ip_vs_sync_buff {
 116         struct list_head        list;
 117         unsigned long           firstuse;
 118
 119         /* pointers for the message data */
 120         struct ip_vs_sync_mesg  *mesg;
 121         unsigned char           *head;
 122         unsigned char           *end;
 123 };
 124
 125
 126 /* the sync_buff list head and the lock */
 127 static LIST_HEAD(ip_vs_sync_queue);
 128 static DEFINE_SPINLOCK(ip_vs_sync_lock);
 129
 130 /* current sync_buff for accepting new conn entries */
 131 static struct ip_vs_sync_buff   *curr_sb = NULL;
 132 static DEFINE_SPINLOCK(curr_sb_lock);
 133
 134 /* ipvs sync daemon state */
 135 volatile int ip_vs_sync_state = IP_VS_STATE_NONE;
 136 volatile int ip_vs_master_syncid = 0;
 137 volatile int ip_vs_backup_syncid = 0;
 138
 139 /* multicast interface name */
 140 char ip_vs_master_mcast_ifn[IP_VS_IFNAME_MAXLEN];
 141 char ip_vs_backup_mcast_ifn[IP_VS_IFNAME_MAXLEN];
 142
 143 /* multicast addr */
 144 static struct sockaddr_in mcast_addr;
 145
 146
 147 static inline void sb_queue_tail(struct ip_vs_sync_buff *sb)
 148 {
 149         spin_lock(&ip_vs_sync_lock);
 150         list_add_tail(&sb->list, &ip_vs_sync_queue);
 151         spin_unlock(&ip_vs_sync_lock);
 152 }
 153
 154 static inline struct ip_vs_sync_buff * sb_dequeue(void)
 155 {
 156         struct ip_vs_sync_buff *sb;
 157
 158         spin_lock_bh(&ip_vs_sync_lock);
 159         if (list_empty(&ip_vs_sync_queue)) {
 160                 sb = NULL;
 161         } else {
 162                 sb = list_entry(ip_vs_sync_queue.next,
 163                                 struct ip_vs_sync_buff,
 164                                 list);
 165                 list_del(&sb->list);
 166         }
 167         spin_unlock_bh(&ip_vs_sync_lock);
 168
 169         return sb;
 170 }
 171
 172 static inline struct ip_vs_sync_buff * ip_vs_sync_buff_create(void)
 173 {
 174         struct ip_vs_sync_buff *sb;
 175
 176         if (!(sb=kmalloc(sizeof(struct ip_vs_sync_buff), GFP_ATOMIC)))
 177                 return NULL;
 178
 179         if (!(sb->mesg=kmalloc(sync_send_mesg_maxlen, GFP_ATOMIC))) {
 180                 kfree(sb);
 181                 return NULL;
 182         }
 183         sb->mesg->nr_conns = 0;
 184         sb->mesg->syncid = ip_vs_master_syncid;
 185         sb->mesg->size = 4;
 186         sb->head = (unsigned char *)sb->mesg + 4;
 187         sb->end = (unsigned char *)sb->mesg + sync_send_mesg_maxlen;
 188         sb->firstuse = jiffies;
 189         return sb;
 190 }
 191
 192 static inline void ip_vs_sync_buff_release(struct ip_vs_sync_buff *sb)
 193 {
 194         kfree(sb->mesg);
 195         kfree(sb);
 196 }
 197
 198 /*
 199  *      Get the current sync buffer if it has been created for more
 200  *      than the specified time or the specified time is zero.
 201  */
 202 static inline struct ip_vs_sync_buff *
 203 get_curr_sync_buff(unsigned long time)
 204 {
 205         struct ip_vs_sync_buff *sb;
 206
 207         spin_lock_bh(&curr_sb_lock);
 208         if (curr_sb && (time == 0 ||
 209                         time_before(jiffies - curr_sb->firstuse, time))) {
 210                 sb = curr_sb;
 211                 curr_sb = NULL;
 212         } else
 213                 sb = NULL;
 214         spin_unlock_bh(&curr_sb_lock);
 215         return sb;
 216 }
 217
 218
 219 /*
 220  *      Add an ip_vs_conn information into the current sync_buff.
 221  *      Called by ip_vs_in.
 222  */
 223 void ip_vs_sync_conn(struct ip_vs_conn *cp)
 224 {
 225         struct ip_vs_sync_mesg *m;
 226         struct ip_vs_sync_conn *s;
 227         int len;
 228
 229         spin_lock(&curr_sb_lock);
 230         if (!curr_sb) {
 231                 if (!(curr_sb=ip_vs_sync_buff_create())) {
 232                         spin_unlock(&curr_sb_lock);
 233                         IP_VS_ERR("ip_vs_sync_buff_create failed.\n");
 234                         return;
 235                 }
 236         }
 237
 238         len = (cp->flags & IP_VS_CONN_F_SEQ_MASK) ? FULL_CONN_SIZE :
 239                 SIMPLE_CONN_SIZE;
 240         m = curr_sb->mesg;
 241         s = (struct ip_vs_sync_conn *)curr_sb->head;
 242
 243         /* copy members */
 244         s->protocol = cp->protocol;
 245         s->cport = cp->cport;
 246         s->vport = cp->vport;
 247         s->dport = cp->dport;
 248         s->caddr = cp->caddr;
 249         s->vaddr = cp->vaddr;
 250         s->daddr = cp->daddr;
 251         s->flags = htons(cp->flags & ~IP_VS_CONN_F_HASHED);
 252         s->state = htons(cp->state);
 253         if (cp->flags & IP_VS_CONN_F_SEQ_MASK) {
 254                 struct ip_vs_sync_conn_options *opt =
 255                         (struct ip_vs_sync_conn_options *)&s[1];
 256                 memcpy(opt, &cp->in_seq, sizeof(*opt));
 257         }
 258
 259         m->nr_conns++;
 260         m->size += len;
 261         curr_sb->head += len;
 262
 263         /* check if there is a space for next one */
 264         if (curr_sb->head+FULL_CONN_SIZE > curr_sb->end) {
 265                 sb_queue_tail(curr_sb);
 266                 curr_sb = NULL;
 267         }
 268         spin_unlock(&curr_sb_lock);
 269
 270         /* synchronize its controller if it has */
 271         if (cp->control)
 272                 ip_vs_sync_conn(cp->control);
 273 }
 274
 275
 276 /*
 277  *      Process received multicast message and create the corresponding
 278  *      ip_vs_conn entries.
 279  */
 280 static void ip_vs_process_message(const char *buffer, const size_t buflen)
 281 {
 282         struct ip_vs_sync_mesg *m = (struct ip_vs_sync_mesg *)buffer;
 283         struct ip_vs_sync_conn *s;
 284         struct ip_vs_sync_conn_options *opt;
 285         struct ip_vs_conn *cp;
 286         struct ip_vs_protocol *pp;
 287         struct ip_vs_dest *dest;
 288         char *p;
 289         int i;
 290
 291         /* Convert size back to host byte order */
 292         m->size = ntohs(m->size);
 293
 294         if (buflen != m->size) {
 295                 IP_VS_ERR("bogus message\n");
 296                 return;
 297         }
 298
 299         /* SyncID sanity check */
 300         if (ip_vs_backup_syncid != 0 && m->syncid != ip_vs_backup_syncid) {
 301                 IP_VS_DBG(7, "Ignoring incoming msg with syncid = %d\n",
 302                           m->syncid);
 303                 return;
 304         }
 305
 306         p = (char *)buffer + sizeof(struct ip_vs_sync_mesg);
 307         for (i=0; i<m->nr_conns; i++) {
 308                 unsigned flags;
 309
 310                 s = (struct ip_vs_sync_conn *)p;
 311                 flags = ntohs(s->flags);
 312                 if (!(flags & IP_VS_CONN_F_TEMPLATE))
 313                         cp = ip_vs_conn_in_get(s->protocol,
 314                                                s->caddr, s->cport,
 315                                                s->vaddr, s->vport);
 316                 else
 317                         cp = ip_vs_ct_in_get(s->protocol,
 318                                                s->caddr, s->cport,
 319                                                s->vaddr, s->vport);
 320                 if (!cp) {
 321                         /*
 322                          * Find the appropriate destination for the connection.
 323                          * If it is not found the connection will remain unbound
 324                          * but still handled.
 325                          */
 326                         dest = ip_vs_find_dest(s->daddr, s->dport,
 327                                                s->vaddr, s->vport,
 328                                                s->protocol);
 329                         cp = ip_vs_conn_new(s->protocol,
 330                                             s->caddr, s->cport,
 331                                             s->vaddr, s->vport,
 332                                             s->daddr, s->dport,
 333                                             flags, dest);
 334                         if (dest)
 335                                 atomic_dec(&dest->refcnt);
 336                         if (!cp) {
 337                                 IP_VS_ERR("ip_vs_conn_new failed\n");
 338                                 return;
 339                         }
 340                         cp->state = ntohs(s->state);
 341                 } else if (!cp->dest) {
 342                         dest = ip_vs_try_bind_dest(cp);
 343                         if (!dest) {
 344                                 /* it is an unbound entry created by
 345                                  * synchronization */
 346                                 cp->flags = flags | IP_VS_CONN_F_HASHED;
 347                         } else
 348                                 atomic_dec(&dest->refcnt);
 349                 }       /* Note that we don't touch its state and flags
 350                            if it is a normal entry. */
 351
 352                 if (flags & IP_VS_CONN_F_SEQ_MASK) {
 353                         opt = (struct ip_vs_sync_conn_options *)&s[1];
 354                         memcpy(&cp->in_seq, opt, sizeof(*opt));
 355                         p += FULL_CONN_SIZE;
 356                 } else
 357                         p += SIMPLE_CONN_SIZE;
 358
 359                 atomic_set(&cp->in_pkts, sysctl_ip_vs_sync_threshold[0]);
 360                 cp->state = ntohs(s->state);
 361                 pp = ip_vs_proto_get(s->protocol);
 362                 cp->timeout = pp->timeout_table[cp->state];
 363                 ip_vs_conn_put(cp);
 364
 365                 if (p > buffer+buflen) {
 366                         IP_VS_ERR("bogus message\n");
 367                         return;
 368                 }
 369         }
 370 }
 371
 372
 373 /*
 374  *      Setup loopback of outgoing multicasts on a sending socket
 375  */
 376 static void set_mcast_loop(struct sock *sk, u_char loop)
 377 {
 378         struct inet_sock *inet = inet_sk(sk);
 379
 380         /* setsockopt(sock, SOL_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)); */
 381         lock_sock(sk);
 382         inet->mc_loop = loop ? 1 : 0;
 383         release_sock(sk);
 384 }
 385
 386 /*
 387  *      Specify TTL for outgoing multicasts on a sending socket
 388  */
 389 static void set_mcast_ttl(struct sock *sk, u_char ttl)
 390 {
 391         struct inet_sock *inet = inet_sk(sk);
 392
 393         /* setsockopt(sock, SOL_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); */
 394         lock_sock(sk);
 395         inet->mc_ttl = ttl;
 396         release_sock(sk);
 397 }
 398
 399 /*
 400  *      Specifiy default interface for outgoing multicasts
 401  */
 402 static int set_mcast_if(struct sock *sk, char *ifname)
 403 {
 404         struct net_device *dev;
 405         struct inet_sock *inet = inet_sk(sk);
 406
 407         if ((dev = __dev_get_by_name(&init_net, ifname)) == NULL)
 408                 return -ENODEV;
 409
 410         if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
 411                 return -EINVAL;
 412
 413         lock_sock(sk);
 414         inet->mc_index = dev->ifindex;
 415         /*  inet->mc_addr  = 0; */
 416         release_sock(sk);
 417
 418         return 0;
 419 }
 420
 421
 422 /*
 423  *      Set the maximum length of sync message according to the
 424  *      specified interface's MTU.
 425  */
 426 static int set_sync_mesg_maxlen(int sync_state)
 427 {
 428         struct net_device *dev;
 429         int num;
 430
 431         if (sync_state == IP_VS_STATE_MASTER) {
 432                 if ((dev = __dev_get_by_name(&init_net, ip_vs_master_mcast_ifn)) == NULL)
 433                         return -ENODEV;
 434
 435                 num = (dev->mtu - sizeof(struct iphdr) -
 436                        sizeof(struct udphdr) -
 437                        SYNC_MESG_HEADER_LEN - 20) / SIMPLE_CONN_SIZE;
 438                 sync_send_mesg_maxlen =
 439                         SYNC_MESG_HEADER_LEN + SIMPLE_CONN_SIZE * num;
 440                 IP_VS_DBG(7, "setting the maximum length of sync sending "
 441                           "message %d.\n", sync_send_mesg_maxlen);
 442         } else if (sync_state == IP_VS_STATE_BACKUP) {
 443                 if ((dev = __dev_get_by_name(&init_net, ip_vs_backup_mcast_ifn)) == NULL)
 444                         return -ENODEV;
 445
 446                 sync_recv_mesg_maxlen = dev->mtu -
 447                         sizeof(struct iphdr) - sizeof(struct udphdr);
 448                 IP_VS_DBG(7, "setting the maximum length of sync receiving "
 449                           "message %d.\n", sync_recv_mesg_maxlen);
 450         }
 451
 452         return 0;
 453 }
 454
 455
 456 /*
 457  *      Join a multicast group.
 458  *      the group is specified by a class D multicast address 224.0.0.0/8
 459  *      in the in_addr structure passed in as a parameter.
 460  */
 461 static int
 462 join_mcast_group(struct sock *sk, struct in_addr *addr, char *ifname)
 463 {
 464         struct ip_mreqn mreq;
 465         struct net_device *dev;
 466         int ret;
 467
 468         memset(&mreq, 0, sizeof(mreq));
 469         memcpy(&mreq.imr_multiaddr, addr, sizeof(struct in_addr));
 470
 471         if ((dev = __dev_get_by_name(&init_net, ifname)) == NULL)
 472                 return -ENODEV;
 473         if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
 474                 return -EINVAL;
 475
 476         mreq.imr_ifindex = dev->ifindex;
 477
 478         lock_sock(sk);
 479         ret = ip_mc_join_group(sk, &mreq);
 480         release_sock(sk);
 481
 482         return ret;
 483 }
 484
 485
 486 static int bind_mcastif_addr(struct socket *sock, char *ifname)
 487 {
 488         struct net_device *dev;
 489         __be32 addr;
 490         struct sockaddr_in sin;
 491
 492         if ((dev = __dev_get_by_name(&init_net, ifname)) == NULL)
 493                 return -ENODEV;
 494
 495         addr = inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE);
 496         if (!addr)
 497                 IP_VS_ERR("You probably need to specify IP address on "
 498                           "multicast interface.\n");
 499
 500         IP_VS_DBG(7, "binding socket with (%s) %u.%u.%u.%u\n",
 501                   ifname, NIPQUAD(addr));
 502
 503         /* Now bind the socket with the address of multicast interface */
 504         sin.sin_family       = AF_INET;
 505         sin.sin_addr.s_addr  = addr;
 506         sin.sin_port         = 0;
 507
 508         return sock->ops->bind(sock, (struct sockaddr*)&sin, sizeof(sin));
 509 }
 510
 511 /*
 512  *      Set up sending multicast socket over UDP
 513  */
 514 static struct socket * make_send_sock(void)
 515 {
 516         struct socket *sock;
 517
 518         /* First create a socket */
 519         if (sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock) < 0) {
 520                 IP_VS_ERR("Error during creation of socket; terminating\n");
 521                 return NULL;
 522         }
 523
 524         if (set_mcast_if(sock->sk, ip_vs_master_mcast_ifn) < 0) {
 525                 IP_VS_ERR("Error setting outbound mcast interface\n");
 526                 goto error;
 527         }
 528
 529         set_mcast_loop(sock->sk, 0);
 530         set_mcast_ttl(sock->sk, 1);
 531
 532         if (bind_mcastif_addr(sock, ip_vs_master_mcast_ifn) < 0) {
 533                 IP_VS_ERR("Error binding address of the mcast interface\n");
 534                 goto error;
 535         }
 536
 537         if (sock->ops->connect(sock,
 538                                (struct sockaddr*)&mcast_addr,
 539                                sizeof(struct sockaddr), 0) < 0) {
 540                 IP_VS_ERR("Error connecting to the multicast addr\n");
 541                 goto error;
 542         }
 543
 544         return sock;
 545
 546   error:
 547         sock_release(sock);
 548         return NULL;
 549 }
 550
 551
 552 /*
 553  *      Set up receiving multicast socket over UDP
 554  */
 555 static struct socket * make_receive_sock(void)
 556 {
 557         struct socket *sock;
 558
 559         /* First create a socket */
 560         if (sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock) < 0) {
 561                 IP_VS_ERR("Error during creation of socket; terminating\n");
 562                 return NULL;
 563         }
 564
 565         /* it is equivalent to the REUSEADDR option in user-space */
 566         sock->sk->sk_reuse = 1;
 567
 568         if (sock->ops->bind(sock,
 569                             (struct sockaddr*)&mcast_addr,
 570                             sizeof(struct sockaddr)) < 0) {
 571                 IP_VS_ERR("Error binding to the multicast addr\n");
 572                 goto error;
 573         }
 574
 575         /* join the multicast group */
 576         if (join_mcast_group(sock->sk,
 577                              (struct in_addr*)&mcast_addr.sin_addr,
 578                              ip_vs_backup_mcast_ifn) < 0) {
 579                 IP_VS_ERR("Error joining to the multicast group\n");
 580                 goto error;
 581         }
 582
 583         return sock;
 584
 585   error:
 586         sock_release(sock);
 587         return NULL;
 588 }
 589
 590
 591 static int
 592 ip_vs_send_async(struct socket *sock, const char *buffer, const size_t length)
 593 {
 594         struct msghdr   msg = {.msg_flags = MSG_DONTWAIT|MSG_NOSIGNAL};
 595         struct kvec     iov;
 596         int             len;
 597
 598         EnterFunction(7);
 599         iov.iov_base     = (void *)buffer;
 600         iov.iov_len      = length;
 601
 602         len = kernel_sendmsg(sock, &msg, &iov, 1, (size_t)(length));
 603
 604         LeaveFunction(7);
 605         return len;
 606 }
 607
 608 static void
 609 ip_vs_send_sync_msg(struct socket *sock, struct ip_vs_sync_mesg *msg)
 610 {
 611         int msize;
 612
 613         msize = msg->size;
 614
 615         /* Put size in network byte order */
 616         msg->size = htons(msg->size);
 617
 618         if (ip_vs_send_async(sock, (char *)msg, msize) != msize)
 619                 IP_VS_ERR("ip_vs_send_async error\n");
 620 }
 621
 622 static int
 623 ip_vs_receive(struct socket *sock, char *buffer, const size_t buflen)
 624 {
 625         struct msghdr           msg = {NULL,};
 626         struct kvec             iov;
 627         int                     len;
 628
 629         EnterFunction(7);
 630
 631         /* Receive a packet */
 632         iov.iov_base     = buffer;
 633         iov.iov_len      = (size_t)buflen;
 634
 635         len = kernel_recvmsg(sock, &msg, &iov, 1, buflen, 0);
 636
 637         if (len < 0)
 638                 return -1;
 639
 640         LeaveFunction(7);
 641         return len;
 642 }
 643
 644
 645 static DECLARE_WAIT_QUEUE_HEAD(sync_wait);
 646 static pid_t sync_master_pid = 0;
 647 static pid_t sync_backup_pid = 0;
 648
 649 static DECLARE_WAIT_QUEUE_HEAD(stop_sync_wait);
 650 static int stop_master_sync = 0;
 651 static int stop_backup_sync = 0;
 652
 653 static void sync_master_loop(void)
 654 {
 655         struct socket *sock;
 656         struct ip_vs_sync_buff *sb;
 657
 658         /* create the sending multicast socket */
 659         sock = make_send_sock();
 660         if (!sock)
 661                 return;
 662
 663         IP_VS_INFO("sync thread started: state = MASTER, mcast_ifn = %s, "
 664                    "syncid = %d\n",
 665                    ip_vs_master_mcast_ifn, ip_vs_master_syncid);
 666
 667         for (;;) {
 668                 while ((sb=sb_dequeue())) {
 669                         ip_vs_send_sync_msg(sock, sb->mesg);
 670                         ip_vs_sync_buff_release(sb);
 671                 }
 672
 673                 /* check if entries stay in curr_sb for 2 seconds */
 674                 if ((sb = get_curr_sync_buff(2*HZ))) {
 675                         ip_vs_send_sync_msg(sock, sb->mesg);
 676                         ip_vs_sync_buff_release(sb);
 677                 }
 678
 679                 if (stop_master_sync)
 680                         break;
 681
 682                 msleep_interruptible(1000);
 683         }
 684
 685         /* clean up the sync_buff queue */
 686         while ((sb=sb_dequeue())) {
 687                 ip_vs_sync_buff_release(sb);
 688         }
 689
 690         /* clean up the current sync_buff */
 691         if ((sb = get_curr_sync_buff(0))) {
 692                 ip_vs_sync_buff_release(sb);
 693         }
 694
 695         /* release the sending multicast socket */
 696         sock_release(sock);
 697 }
 698
 699
 700 static void sync_backup_loop(void)
 701 {
 702         struct socket *sock;
 703         char *buf;
 704         int len;
 705
 706         if (!(buf = kmalloc(sync_recv_mesg_maxlen, GFP_ATOMIC))) {
 707                 IP_VS_ERR("sync_backup_loop: kmalloc error\n");
 708                 return;
 709         }
 710
 711         /* create the receiving multicast socket */
 712         sock = make_receive_sock();
 713         if (!sock)
 714                 goto out;
 715
 716         IP_VS_INFO("sync thread started: state = BACKUP, mcast_ifn = %s, "
 717                    "syncid = %d\n",
 718                    ip_vs_backup_mcast_ifn, ip_vs_backup_syncid);
 719
 720         for (;;) {
 721                 /* do you have data now? */
 722                 while (!skb_queue_empty(&(sock->sk->sk_receive_queue))) {
 723                         if ((len =
 724                              ip_vs_receive(sock, buf,
 725                                            sync_recv_mesg_maxlen)) <= 0) {
 726                                 IP_VS_ERR("receiving message error\n");
 727                                 break;
 728                         }
 729                         /* disable bottom half, because it accessed the data
 730                            shared by softirq while getting/creating conns */
 731                         local_bh_disable();
 732                         ip_vs_process_message(buf, len);
 733                         local_bh_enable();
 734                 }
 735
 736                 if (stop_backup_sync)
 737                         break;
 738
 739                 msleep_interruptible(1000);
 740         }
 741
 742         /* release the sending multicast socket */
 743         sock_release(sock);
 744
 745   out:
 746         kfree(buf);
 747 }
 748
 749
 750 static void set_sync_pid(int sync_state, pid_t sync_pid)
 751 {
 752         if (sync_state == IP_VS_STATE_MASTER)
 753                 sync_master_pid = sync_pid;
 754         else if (sync_state == IP_VS_STATE_BACKUP)
 755                 sync_backup_pid = sync_pid;
 756 }
 757
 758 static void set_stop_sync(int sync_state, int set)
 759 {
 760         if (sync_state == IP_VS_STATE_MASTER)
 761                 stop_master_sync = set;
 762         else if (sync_state == IP_VS_STATE_BACKUP)
 763                 stop_backup_sync = set;
 764         else {
 765                 stop_master_sync = set;
 766                 stop_backup_sync = set;
 767         }
 768 }
 769
 770 static int sync_thread(void *startup)
 771 {
 772         DECLARE_WAITQUEUE(wait, current);
 773         mm_segment_t oldmm;
 774         int state;
 775         const char *name;
 776         struct ip_vs_sync_thread_data *tinfo = startup;
 777
 778         /* increase the module use count */
 779         ip_vs_use_count_inc();
 780
 781         if (ip_vs_sync_state & IP_VS_STATE_MASTER && !sync_master_pid) {
 782                 state = IP_VS_STATE_MASTER;
 783                 name = "ipvs_syncmaster";
 784         } else if (ip_vs_sync_state & IP_VS_STATE_BACKUP && !sync_backup_pid) {
 785                 state = IP_VS_STATE_BACKUP;
 786                 name = "ipvs_syncbackup";
 787         } else {
 788                 IP_VS_BUG();
 789                 ip_vs_use_count_dec();
 790                 return -EINVAL;
 791         }
 792
 793         daemonize(name);
 794
 795         oldmm = get_fs();
 796         set_fs(KERNEL_DS);
 797
 798         /* Block all signals */
 799         spin_lock_irq(&current->sighand->siglock);
 800         siginitsetinv(&current->blocked, 0);
 801         recalc_sigpending();
 802         spin_unlock_irq(&current->sighand->siglock);
 803
 804         /* set the maximum length of sync message */
 805         set_sync_mesg_maxlen(state);
 806
 807         /* set up multicast address */
 808         mcast_addr.sin_family = AF_INET;
 809         mcast_addr.sin_port = htons(IP_VS_SYNC_PORT);
 810         mcast_addr.sin_addr.s_addr = htonl(IP_VS_SYNC_GROUP);
 811
 812         add_wait_queue(&sync_wait, &wait);
 813
 814         set_sync_pid(state, task_pid_nr(current));
 815         complete(tinfo->startup);
 816
 817         /*
 818          * once we call the completion queue above, we should
 819          * null out that reference, since its allocated on the
 820          * stack of the creating kernel thread
 821          */
 822         tinfo->startup = NULL;
 823
 824         /* processing master/backup loop here */
 825         if (state == IP_VS_STATE_MASTER)
 826                 sync_master_loop();
 827         else if (state == IP_VS_STATE_BACKUP)
 828                 sync_backup_loop();
 829         else IP_VS_BUG();
 830
 831         remove_wait_queue(&sync_wait, &wait);
 832
 833         /* thread exits */
 834
 835         /*
 836          * If we weren't explicitly stopped, then we
 837          * exited in error, and should undo our state
 838          */
 839         if ((!stop_master_sync) && (!stop_backup_sync))
 840                 ip_vs_sync_state -= tinfo->state;
 841
 842         set_sync_pid(state, 0);
 843         IP_VS_INFO("sync thread stopped!\n");
 844
 845         set_fs(oldmm);
 846
 847         /* decrease the module use count */
 848         ip_vs_use_count_dec();
 849
 850         set_stop_sync(state, 0);
 851         wake_up(&stop_sync_wait);
 852
 853         /*
 854          * we need to free the structure that was allocated
 855          * for us in start_sync_thread
 856          */
 857         kfree(tinfo);
 858         return 0;
 859 }
 860
 861
 862 static int fork_sync_thread(void *startup)
 863 {
 864         pid_t pid;
 865
 866         /* fork the sync thread here, then the parent process of the
 867            sync thread is the init process after this thread exits. */
 868   repeat:
 869         if ((pid = kernel_thread(sync_thread, startup, 0)) < 0) {
 870                 IP_VS_ERR("could not create sync_thread due to %d... "
 871                           "retrying.\n", pid);
 872                 msleep_interruptible(1000);
 873                 goto repeat;
 874         }
 875
 876         return 0;
 877 }
 878
 879
 880 int start_sync_thread(int state, char *mcast_ifn, __u8 syncid)
 881 {
 882         DECLARE_COMPLETION_ONSTACK(startup);
 883         pid_t pid;
 884         struct ip_vs_sync_thread_data *tinfo;
 885
 886         if ((state == IP_VS_STATE_MASTER && sync_master_pid) ||
 887             (state == IP_VS_STATE_BACKUP && sync_backup_pid))
 888                 return -EEXIST;
 889
 890         /*
 891          * Note that tinfo will be freed in sync_thread on exit
 892          */
 893         tinfo = kmalloc(sizeof(struct ip_vs_sync_thread_data), GFP_KERNEL);
 894         if (!tinfo)
 895                 return -ENOMEM;
 896
 897         IP_VS_DBG(7, "%s: pid %d\n", __FUNCTION__, task_pid_nr(current));
 898         IP_VS_DBG(7, "Each ip_vs_sync_conn entry need %Zd bytes\n",
 899                   sizeof(struct ip_vs_sync_conn));
 900
 901         ip_vs_sync_state |= state;
 902         if (state == IP_VS_STATE_MASTER) {
 903                 strlcpy(ip_vs_master_mcast_ifn, mcast_ifn,
 904                         sizeof(ip_vs_master_mcast_ifn));
 905                 ip_vs_master_syncid = syncid;
 906         } else {
 907                 strlcpy(ip_vs_backup_mcast_ifn, mcast_ifn,
 908                         sizeof(ip_vs_backup_mcast_ifn));
 909                 ip_vs_backup_syncid = syncid;
 910         }
 911
 912         tinfo->state = state;
 913         tinfo->startup = &startup;
 914
 915   repeat:
 916         if ((pid = kernel_thread(fork_sync_thread, tinfo, 0)) < 0) {
 917                 IP_VS_ERR("could not create fork_sync_thread due to %d... "
 918                           "retrying.\n", pid);
 919                 msleep_interruptible(1000);
 920                 goto repeat;
 921         }
 922
 923         wait_for_completion(&startup);
 924
 925         return 0;
 926 }
 927
 928
 929 int stop_sync_thread(int state)
 930 {
 931         DECLARE_WAITQUEUE(wait, current);
 932
 933         if ((state == IP_VS_STATE_MASTER && !sync_master_pid) ||
 934             (state == IP_VS_STATE_BACKUP && !sync_backup_pid))
 935                 return -ESRCH;
 936
 937         IP_VS_DBG(7, "%s: pid %d\n", __FUNCTION__, task_pid_nr(current));
 938         IP_VS_INFO("stopping sync thread %d ...\n",
 939                    (state == IP_VS_STATE_MASTER) ?
 940                    sync_master_pid : sync_backup_pid);
 941
 942         __set_current_state(TASK_UNINTERRUPTIBLE);
 943         add_wait_queue(&stop_sync_wait, &wait);
 944         set_stop_sync(state, 1);
 945         ip_vs_sync_state -= state;
 946         wake_up(&sync_wait);
 947         schedule();
 948         __set_current_state(TASK_RUNNING);
 949         remove_wait_queue(&stop_sync_wait, &wait);
 950
 951         /* Note: no need to reap the sync thread, because its parent
 952            process is the init process */
 953
 954         if ((state == IP_VS_STATE_MASTER && stop_master_sync) ||
 955             (state == IP_VS_STATE_BACKUP && stop_backup_sync))
 956                 IP_VS_BUG();
 957
 958         return 0;
 959 }