7461eeb3a3dd7a8e860a0c46df62f5668ae3884f
[linux-2.6.git] / 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 #define IP_VS_SYNC_CONN_TIMEOUT (3*60*HZ)
71 #define SIMPLE_CONN_SIZE  (sizeof(struct ip_vs_sync_conn))
72 #define FULL_CONN_SIZE  \
73 (sizeof(struct ip_vs_sync_conn) + sizeof(struct ip_vs_sync_conn_options))
74
75
76 /*
77   The master mulitcasts messages to the backup load balancers in the
78   following format.
79
80        0                   1                   2                   3
81        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
82       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
83       |  Count Conns  |    SyncID     |            Size               |
84       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
85       |                                                               |
86       |                    IPVS Sync Connection (1)                   |
87       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
88       |                            .                                  |
89       |                            .                                  |
90       |                            .                                  |
91       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
92       |                                                               |
93       |                    IPVS Sync Connection (n)                   |
94       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
95 */
96
97 #define SYNC_MESG_HEADER_LEN    4
98
99 struct ip_vs_sync_mesg {
100         __u8                    nr_conns;
101         __u8                    syncid;
102         __u16                   size;
103
104         /* ip_vs_sync_conn entries start here */
105 };
106
107 /* the maximum length of sync (sending/receiving) message */
108 static int sync_send_mesg_maxlen;
109 static int sync_recv_mesg_maxlen;
110
111 struct ip_vs_sync_buff {
112         struct list_head        list;
113         unsigned long           firstuse;
114
115         /* pointers for the message data */
116         struct ip_vs_sync_mesg  *mesg;
117         unsigned char           *head;
118         unsigned char           *end;
119 };
120
121
122 /* the sync_buff list head and the lock */
123 static LIST_HEAD(ip_vs_sync_queue);
124 static DEFINE_SPINLOCK(ip_vs_sync_lock);
125
126 /* current sync_buff for accepting new conn entries */
127 static struct ip_vs_sync_buff   *curr_sb = NULL;
128 static DEFINE_SPINLOCK(curr_sb_lock);
129
130 /* ipvs sync daemon state */
131 volatile int ip_vs_sync_state = IP_VS_STATE_NONE;
132 volatile int ip_vs_master_syncid = 0;
133 volatile int ip_vs_backup_syncid = 0;
134
135 /* multicast interface name */
136 char ip_vs_master_mcast_ifn[IP_VS_IFNAME_MAXLEN];
137 char ip_vs_backup_mcast_ifn[IP_VS_IFNAME_MAXLEN];
138
139 /* multicast addr */
140 static struct sockaddr_in mcast_addr;
141
142
143 static inline void sb_queue_tail(struct ip_vs_sync_buff *sb)
144 {
145         spin_lock(&ip_vs_sync_lock);
146         list_add_tail(&sb->list, &ip_vs_sync_queue);
147         spin_unlock(&ip_vs_sync_lock);
148 }
149
150 static inline struct ip_vs_sync_buff * sb_dequeue(void)
151 {
152         struct ip_vs_sync_buff *sb;
153
154         spin_lock_bh(&ip_vs_sync_lock);
155         if (list_empty(&ip_vs_sync_queue)) {
156                 sb = NULL;
157         } else {
158                 sb = list_entry(ip_vs_sync_queue.next,
159                                 struct ip_vs_sync_buff,
160                                 list);
161                 list_del(&sb->list);
162         }
163         spin_unlock_bh(&ip_vs_sync_lock);
164
165         return sb;
166 }
167
168 static inline struct ip_vs_sync_buff * ip_vs_sync_buff_create(void)
169 {
170         struct ip_vs_sync_buff *sb;
171
172         if (!(sb=kmalloc(sizeof(struct ip_vs_sync_buff), GFP_ATOMIC)))
173                 return NULL;
174
175         if (!(sb->mesg=kmalloc(sync_send_mesg_maxlen, GFP_ATOMIC))) {
176                 kfree(sb);
177                 return NULL;
178         }
179         sb->mesg->nr_conns = 0;
180         sb->mesg->syncid = ip_vs_master_syncid;
181         sb->mesg->size = 4;
182         sb->head = (unsigned char *)sb->mesg + 4;
183         sb->end = (unsigned char *)sb->mesg + sync_send_mesg_maxlen;
184         sb->firstuse = jiffies;
185         return sb;
186 }
187
188 static inline void ip_vs_sync_buff_release(struct ip_vs_sync_buff *sb)
189 {
190         kfree(sb->mesg);
191         kfree(sb);
192 }
193
194 /*
195  *      Get the current sync buffer if it has been created for more
196  *      than the specified time or the specified time is zero.
197  */
198 static inline struct ip_vs_sync_buff *
199 get_curr_sync_buff(unsigned long time)
200 {
201         struct ip_vs_sync_buff *sb;
202
203         spin_lock_bh(&curr_sb_lock);
204         if (curr_sb && (time == 0 ||
205                         time_before(jiffies - curr_sb->firstuse, time))) {
206                 sb = curr_sb;
207                 curr_sb = NULL;
208         } else
209                 sb = NULL;
210         spin_unlock_bh(&curr_sb_lock);
211         return sb;
212 }
213
214
215 /*
216  *      Add an ip_vs_conn information into the current sync_buff.
217  *      Called by ip_vs_in.
218  */
219 void ip_vs_sync_conn(struct ip_vs_conn *cp)
220 {
221         struct ip_vs_sync_mesg *m;
222         struct ip_vs_sync_conn *s;
223         int len;
224
225         spin_lock(&curr_sb_lock);
226         if (!curr_sb) {
227                 if (!(curr_sb=ip_vs_sync_buff_create())) {
228                         spin_unlock(&curr_sb_lock);
229                         IP_VS_ERR("ip_vs_sync_buff_create failed.\n");
230                         return;
231                 }
232         }
233
234         len = (cp->flags & IP_VS_CONN_F_SEQ_MASK) ? FULL_CONN_SIZE :
235                 SIMPLE_CONN_SIZE;
236         m = curr_sb->mesg;
237         s = (struct ip_vs_sync_conn *)curr_sb->head;
238
239         /* copy members */
240         s->protocol = cp->protocol;
241         s->cport = cp->cport;
242         s->vport = cp->vport;
243         s->dport = cp->dport;
244         s->caddr = cp->caddr;
245         s->vaddr = cp->vaddr;
246         s->daddr = cp->daddr;
247         s->flags = htons(cp->flags & ~IP_VS_CONN_F_HASHED);
248         s->state = htons(cp->state);
249         if (cp->flags & IP_VS_CONN_F_SEQ_MASK) {
250                 struct ip_vs_sync_conn_options *opt =
251                         (struct ip_vs_sync_conn_options *)&s[1];
252                 memcpy(opt, &cp->in_seq, sizeof(*opt));
253         }
254
255         m->nr_conns++;
256         m->size += len;
257         curr_sb->head += len;
258
259         /* check if there is a space for next one */
260         if (curr_sb->head+FULL_CONN_SIZE > curr_sb->end) {
261                 sb_queue_tail(curr_sb);
262                 curr_sb = NULL;
263         }
264         spin_unlock(&curr_sb_lock);
265
266         /* synchronize its controller if it has */
267         if (cp->control)
268                 ip_vs_sync_conn(cp->control);
269 }
270
271
272 /*
273  *      Process received multicast message and create the corresponding
274  *      ip_vs_conn entries.
275  */
276 static void ip_vs_process_message(const char *buffer, const size_t buflen)
277 {
278         struct ip_vs_sync_mesg *m = (struct ip_vs_sync_mesg *)buffer;
279         struct ip_vs_sync_conn *s;
280         struct ip_vs_sync_conn_options *opt;
281         struct ip_vs_conn *cp;
282         char *p;
283         int i;
284
285         /* Convert size back to host byte order */
286         m->size = ntohs(m->size);
287
288         if (buflen != m->size) {
289                 IP_VS_ERR("bogus message\n");
290                 return;
291         }
292
293         /* SyncID sanity check */
294         if (ip_vs_backup_syncid != 0 && m->syncid != ip_vs_backup_syncid) {
295                 IP_VS_DBG(7, "Ignoring incoming msg with syncid = %d\n",
296                           m->syncid);
297                 return;
298         }
299
300         p = (char *)buffer + sizeof(struct ip_vs_sync_mesg);
301         for (i=0; i<m->nr_conns; i++) {
302                 unsigned flags;
303
304                 s = (struct ip_vs_sync_conn *)p;
305                 flags = ntohs(s->flags);
306                 if (!(flags & IP_VS_CONN_F_TEMPLATE))
307                         cp = ip_vs_conn_in_get(s->protocol,
308                                                s->caddr, s->cport,
309                                                s->vaddr, s->vport);
310                 else
311                         cp = ip_vs_ct_in_get(s->protocol,
312                                                s->caddr, s->cport,
313                                                s->vaddr, s->vport);
314                 if (!cp) {
315                         cp = ip_vs_conn_new(s->protocol,
316                                             s->caddr, s->cport,
317                                             s->vaddr, s->vport,
318                                             s->daddr, s->dport,
319                                             flags, NULL);
320                         if (!cp) {
321                                 IP_VS_ERR("ip_vs_conn_new failed\n");
322                                 return;
323                         }
324                         cp->state = ntohs(s->state);
325                 } else if (!cp->dest) {
326                         /* it is an entry created by the synchronization */
327                         cp->state = ntohs(s->state);
328                         cp->flags = flags | IP_VS_CONN_F_HASHED;
329                 }       /* Note that we don't touch its state and flags
330                            if it is a normal entry. */
331
332                 if (flags & IP_VS_CONN_F_SEQ_MASK) {
333                         opt = (struct ip_vs_sync_conn_options *)&s[1];
334                         memcpy(&cp->in_seq, opt, sizeof(*opt));
335                         p += FULL_CONN_SIZE;
336                 } else
337                         p += SIMPLE_CONN_SIZE;
338
339                 atomic_set(&cp->in_pkts, sysctl_ip_vs_sync_threshold[0]);
340                 cp->timeout = IP_VS_SYNC_CONN_TIMEOUT;
341                 ip_vs_conn_put(cp);
342
343                 if (p > buffer+buflen) {
344                         IP_VS_ERR("bogus message\n");
345                         return;
346                 }
347         }
348 }
349
350
351 /*
352  *      Setup loopback of outgoing multicasts on a sending socket
353  */
354 static void set_mcast_loop(struct sock *sk, u_char loop)
355 {
356         struct inet_sock *inet = inet_sk(sk);
357
358         /* setsockopt(sock, SOL_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)); */
359         lock_sock(sk);
360         inet->mc_loop = loop ? 1 : 0;
361         release_sock(sk);
362 }
363
364 /*
365  *      Specify TTL for outgoing multicasts on a sending socket
366  */
367 static void set_mcast_ttl(struct sock *sk, u_char ttl)
368 {
369         struct inet_sock *inet = inet_sk(sk);
370
371         /* setsockopt(sock, SOL_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); */
372         lock_sock(sk);
373         inet->mc_ttl = ttl;
374         release_sock(sk);
375 }
376
377 /*
378  *      Specifiy default interface for outgoing multicasts
379  */
380 static int set_mcast_if(struct sock *sk, char *ifname)
381 {
382         struct net_device *dev;
383         struct inet_sock *inet = inet_sk(sk);
384
385         if ((dev = __dev_get_by_name(ifname)) == NULL)
386                 return -ENODEV;
387
388         if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
389                 return -EINVAL;
390
391         lock_sock(sk);
392         inet->mc_index = dev->ifindex;
393         /*  inet->mc_addr  = 0; */
394         release_sock(sk);
395
396         return 0;
397 }
398
399
400 /*
401  *      Set the maximum length of sync message according to the
402  *      specified interface's MTU.
403  */
404 static int set_sync_mesg_maxlen(int sync_state)
405 {
406         struct net_device *dev;
407         int num;
408
409         if (sync_state == IP_VS_STATE_MASTER) {
410                 if ((dev = __dev_get_by_name(ip_vs_master_mcast_ifn)) == NULL)
411                         return -ENODEV;
412
413                 num = (dev->mtu - sizeof(struct iphdr) -
414                        sizeof(struct udphdr) -
415                        SYNC_MESG_HEADER_LEN - 20) / SIMPLE_CONN_SIZE;
416                 sync_send_mesg_maxlen =
417                         SYNC_MESG_HEADER_LEN + SIMPLE_CONN_SIZE * num;
418                 IP_VS_DBG(7, "setting the maximum length of sync sending "
419                           "message %d.\n", sync_send_mesg_maxlen);
420         } else if (sync_state == IP_VS_STATE_BACKUP) {
421                 if ((dev = __dev_get_by_name(ip_vs_backup_mcast_ifn)) == NULL)
422                         return -ENODEV;
423
424                 sync_recv_mesg_maxlen = dev->mtu -
425                         sizeof(struct iphdr) - sizeof(struct udphdr);
426                 IP_VS_DBG(7, "setting the maximum length of sync receiving "
427                           "message %d.\n", sync_recv_mesg_maxlen);
428         }
429
430         return 0;
431 }
432
433
434 /*
435  *      Join a multicast group.
436  *      the group is specified by a class D multicast address 224.0.0.0/8
437  *      in the in_addr structure passed in as a parameter.
438  */
439 static int
440 join_mcast_group(struct sock *sk, struct in_addr *addr, char *ifname)
441 {
442         struct ip_mreqn mreq;
443         struct net_device *dev;
444         int ret;
445
446         memset(&mreq, 0, sizeof(mreq));
447         memcpy(&mreq.imr_multiaddr, addr, sizeof(struct in_addr));
448
449         if ((dev = __dev_get_by_name(ifname)) == NULL)
450                 return -ENODEV;
451         if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
452                 return -EINVAL;
453
454         mreq.imr_ifindex = dev->ifindex;
455
456         lock_sock(sk);
457         ret = ip_mc_join_group(sk, &mreq);
458         release_sock(sk);
459
460         return ret;
461 }
462
463
464 static int bind_mcastif_addr(struct socket *sock, char *ifname)
465 {
466         struct net_device *dev;
467         __be32 addr;
468         struct sockaddr_in sin;
469
470         if ((dev = __dev_get_by_name(ifname)) == NULL)
471                 return -ENODEV;
472
473         addr = inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE);
474         if (!addr)
475                 IP_VS_ERR("You probably need to specify IP address on "
476                           "multicast interface.\n");
477
478         IP_VS_DBG(7, "binding socket with (%s) %u.%u.%u.%u\n",
479                   ifname, NIPQUAD(addr));
480
481         /* Now bind the socket with the address of multicast interface */
482         sin.sin_family       = AF_INET;
483         sin.sin_addr.s_addr  = addr;
484         sin.sin_port         = 0;
485
486         return sock->ops->bind(sock, (struct sockaddr*)&sin, sizeof(sin));
487 }
488
489 /*
490  *      Set up sending multicast socket over UDP
491  */
492 static struct socket * make_send_sock(void)
493 {
494         struct socket *sock;
495
496         /* First create a socket */
497         if (sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock) < 0) {
498                 IP_VS_ERR("Error during creation of socket; terminating\n");
499                 return NULL;
500         }
501
502         if (set_mcast_if(sock->sk, ip_vs_master_mcast_ifn) < 0) {
503                 IP_VS_ERR("Error setting outbound mcast interface\n");
504                 goto error;
505         }
506
507         set_mcast_loop(sock->sk, 0);
508         set_mcast_ttl(sock->sk, 1);
509
510         if (bind_mcastif_addr(sock, ip_vs_master_mcast_ifn) < 0) {
511                 IP_VS_ERR("Error binding address of the mcast interface\n");
512                 goto error;
513         }
514
515         if (sock->ops->connect(sock,
516                                (struct sockaddr*)&mcast_addr,
517                                sizeof(struct sockaddr), 0) < 0) {
518                 IP_VS_ERR("Error connecting to the multicast addr\n");
519                 goto error;
520         }
521
522         return sock;
523
524   error:
525         sock_release(sock);
526         return NULL;
527 }
528
529
530 /*
531  *      Set up receiving multicast socket over UDP
532  */
533 static struct socket * make_receive_sock(void)
534 {
535         struct socket *sock;
536
537         /* First create a socket */
538         if (sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock) < 0) {
539                 IP_VS_ERR("Error during creation of socket; terminating\n");
540                 return NULL;
541         }
542
543         /* it is equivalent to the REUSEADDR option in user-space */
544         sock->sk->sk_reuse = 1;
545
546         if (sock->ops->bind(sock,
547                             (struct sockaddr*)&mcast_addr,
548                             sizeof(struct sockaddr)) < 0) {
549                 IP_VS_ERR("Error binding to the multicast addr\n");
550                 goto error;
551         }
552
553         /* join the multicast group */
554         if (join_mcast_group(sock->sk,
555                              (struct in_addr*)&mcast_addr.sin_addr,
556                              ip_vs_backup_mcast_ifn) < 0) {
557                 IP_VS_ERR("Error joining to the multicast group\n");
558                 goto error;
559         }
560
561         return sock;
562
563   error:
564         sock_release(sock);
565         return NULL;
566 }
567
568
569 static int
570 ip_vs_send_async(struct socket *sock, const char *buffer, const size_t length)
571 {
572         struct msghdr   msg = {.msg_flags = MSG_DONTWAIT|MSG_NOSIGNAL};
573         struct kvec     iov;
574         int             len;
575
576         EnterFunction(7);
577         iov.iov_base     = (void *)buffer;
578         iov.iov_len      = length;
579
580         len = kernel_sendmsg(sock, &msg, &iov, 1, (size_t)(length));
581
582         LeaveFunction(7);
583         return len;
584 }
585
586 static void
587 ip_vs_send_sync_msg(struct socket *sock, struct ip_vs_sync_mesg *msg)
588 {
589         int msize;
590
591         msize = msg->size;
592
593         /* Put size in network byte order */
594         msg->size = htons(msg->size);
595
596         if (ip_vs_send_async(sock, (char *)msg, msize) != msize)
597                 IP_VS_ERR("ip_vs_send_async error\n");
598 }
599
600 static int
601 ip_vs_receive(struct socket *sock, char *buffer, const size_t buflen)
602 {
603         struct msghdr           msg = {NULL,};
604         struct kvec             iov;
605         int                     len;
606
607         EnterFunction(7);
608
609         /* Receive a packet */
610         iov.iov_base     = buffer;
611         iov.iov_len      = (size_t)buflen;
612
613         len = kernel_recvmsg(sock, &msg, &iov, 1, buflen, 0);
614
615         if (len < 0)
616                 return -1;
617
618         LeaveFunction(7);
619         return len;
620 }
621
622
623 static DECLARE_WAIT_QUEUE_HEAD(sync_wait);
624 static pid_t sync_master_pid = 0;
625 static pid_t sync_backup_pid = 0;
626
627 static DECLARE_WAIT_QUEUE_HEAD(stop_sync_wait);
628 static int stop_master_sync = 0;
629 static int stop_backup_sync = 0;
630
631 static void sync_master_loop(void)
632 {
633         struct socket *sock;
634         struct ip_vs_sync_buff *sb;
635
636         /* create the sending multicast socket */
637         sock = make_send_sock();
638         if (!sock)
639                 return;
640
641         IP_VS_INFO("sync thread started: state = MASTER, mcast_ifn = %s, "
642                    "syncid = %d\n",
643                    ip_vs_master_mcast_ifn, ip_vs_master_syncid);
644
645         for (;;) {
646                 while ((sb=sb_dequeue())) {
647                         ip_vs_send_sync_msg(sock, sb->mesg);
648                         ip_vs_sync_buff_release(sb);
649                 }
650
651                 /* check if entries stay in curr_sb for 2 seconds */
652                 if ((sb = get_curr_sync_buff(2*HZ))) {
653                         ip_vs_send_sync_msg(sock, sb->mesg);
654                         ip_vs_sync_buff_release(sb);
655                 }
656
657                 if (stop_master_sync)
658                         break;
659
660                 msleep_interruptible(1000);
661         }
662
663         /* clean up the sync_buff queue */
664         while ((sb=sb_dequeue())) {
665                 ip_vs_sync_buff_release(sb);
666         }
667
668         /* clean up the current sync_buff */
669         if ((sb = get_curr_sync_buff(0))) {
670                 ip_vs_sync_buff_release(sb);
671         }
672
673         /* release the sending multicast socket */
674         sock_release(sock);
675 }
676
677
678 static void sync_backup_loop(void)
679 {
680         struct socket *sock;
681         char *buf;
682         int len;
683
684         if (!(buf = kmalloc(sync_recv_mesg_maxlen, GFP_ATOMIC))) {
685                 IP_VS_ERR("sync_backup_loop: kmalloc error\n");
686                 return;
687         }
688
689         /* create the receiving multicast socket */
690         sock = make_receive_sock();
691         if (!sock)
692                 goto out;
693
694         IP_VS_INFO("sync thread started: state = BACKUP, mcast_ifn = %s, "
695                    "syncid = %d\n",
696                    ip_vs_backup_mcast_ifn, ip_vs_backup_syncid);
697
698         for (;;) {
699                 /* do you have data now? */
700                 while (!skb_queue_empty(&(sock->sk->sk_receive_queue))) {
701                         if ((len =
702                              ip_vs_receive(sock, buf,
703                                            sync_recv_mesg_maxlen)) <= 0) {
704                                 IP_VS_ERR("receiving message error\n");
705                                 break;
706                         }
707                         /* disable bottom half, because it accessed the data
708                            shared by softirq while getting/creating conns */
709                         local_bh_disable();
710                         ip_vs_process_message(buf, len);
711                         local_bh_enable();
712                 }
713
714                 if (stop_backup_sync)
715                         break;
716
717                 msleep_interruptible(1000);
718         }
719
720         /* release the sending multicast socket */
721         sock_release(sock);
722
723   out:
724         kfree(buf);
725 }
726
727
728 static void set_sync_pid(int sync_state, pid_t sync_pid)
729 {
730         if (sync_state == IP_VS_STATE_MASTER)
731                 sync_master_pid = sync_pid;
732         else if (sync_state == IP_VS_STATE_BACKUP)
733                 sync_backup_pid = sync_pid;
734 }
735
736 static void set_stop_sync(int sync_state, int set)
737 {
738         if (sync_state == IP_VS_STATE_MASTER)
739                 stop_master_sync = set;
740         else if (sync_state == IP_VS_STATE_BACKUP)
741                 stop_backup_sync = set;
742         else {
743                 stop_master_sync = set;
744                 stop_backup_sync = set;
745         }
746 }
747
748 static int sync_thread(void *startup)
749 {
750         DECLARE_WAITQUEUE(wait, current);
751         mm_segment_t oldmm;
752         int state;
753         const char *name;
754
755         /* increase the module use count */
756         ip_vs_use_count_inc();
757
758         if (ip_vs_sync_state & IP_VS_STATE_MASTER && !sync_master_pid) {
759                 state = IP_VS_STATE_MASTER;
760                 name = "ipvs_syncmaster";
761         } else if (ip_vs_sync_state & IP_VS_STATE_BACKUP && !sync_backup_pid) {
762                 state = IP_VS_STATE_BACKUP;
763                 name = "ipvs_syncbackup";
764         } else {
765                 IP_VS_BUG();
766                 ip_vs_use_count_dec();
767                 return -EINVAL;
768         }
769
770         daemonize(name);
771
772         oldmm = get_fs();
773         set_fs(KERNEL_DS);
774
775         /* Block all signals */
776         spin_lock_irq(&current->sighand->siglock);
777         siginitsetinv(&current->blocked, 0);
778         recalc_sigpending();
779         spin_unlock_irq(&current->sighand->siglock);
780
781         /* set the maximum length of sync message */
782         set_sync_mesg_maxlen(state);
783
784         /* set up multicast address */
785         mcast_addr.sin_family = AF_INET;
786         mcast_addr.sin_port = htons(IP_VS_SYNC_PORT);
787         mcast_addr.sin_addr.s_addr = htonl(IP_VS_SYNC_GROUP);
788
789         add_wait_queue(&sync_wait, &wait);
790
791         set_sync_pid(state, current->pid);
792         complete((struct completion *)startup);
793
794         /* processing master/backup loop here */
795         if (state == IP_VS_STATE_MASTER)
796                 sync_master_loop();
797         else if (state == IP_VS_STATE_BACKUP)
798                 sync_backup_loop();
799         else IP_VS_BUG();
800
801         remove_wait_queue(&sync_wait, &wait);
802
803         /* thread exits */
804         set_sync_pid(state, 0);
805         IP_VS_INFO("sync thread stopped!\n");
806
807         set_fs(oldmm);
808
809         /* decrease the module use count */
810         ip_vs_use_count_dec();
811
812         set_stop_sync(state, 0);
813         wake_up(&stop_sync_wait);
814
815         return 0;
816 }
817
818
819 static int fork_sync_thread(void *startup)
820 {
821         pid_t pid;
822
823         /* fork the sync thread here, then the parent process of the
824            sync thread is the init process after this thread exits. */
825   repeat:
826         if ((pid = kernel_thread(sync_thread, startup, 0)) < 0) {
827                 IP_VS_ERR("could not create sync_thread due to %d... "
828                           "retrying.\n", pid);
829                 msleep_interruptible(1000);
830                 goto repeat;
831         }
832
833         return 0;
834 }
835
836
837 int start_sync_thread(int state, char *mcast_ifn, __u8 syncid)
838 {
839         DECLARE_COMPLETION_ONSTACK(startup);
840         pid_t pid;
841
842         if ((state == IP_VS_STATE_MASTER && sync_master_pid) ||
843             (state == IP_VS_STATE_BACKUP && sync_backup_pid))
844                 return -EEXIST;
845
846         IP_VS_DBG(7, "%s: pid %d\n", __FUNCTION__, current->pid);
847         IP_VS_DBG(7, "Each ip_vs_sync_conn entry need %Zd bytes\n",
848                   sizeof(struct ip_vs_sync_conn));
849
850         ip_vs_sync_state |= state;
851         if (state == IP_VS_STATE_MASTER) {
852                 strlcpy(ip_vs_master_mcast_ifn, mcast_ifn, sizeof(ip_vs_master_mcast_ifn));
853                 ip_vs_master_syncid = syncid;
854         } else {
855                 strlcpy(ip_vs_backup_mcast_ifn, mcast_ifn, sizeof(ip_vs_backup_mcast_ifn));
856                 ip_vs_backup_syncid = syncid;
857         }
858
859   repeat:
860         if ((pid = kernel_thread(fork_sync_thread, &startup, 0)) < 0) {
861                 IP_VS_ERR("could not create fork_sync_thread due to %d... "
862                           "retrying.\n", pid);
863                 msleep_interruptible(1000);
864                 goto repeat;
865         }
866
867         wait_for_completion(&startup);
868
869         return 0;
870 }
871
872
873 int stop_sync_thread(int state)
874 {
875         DECLARE_WAITQUEUE(wait, current);
876
877         if ((state == IP_VS_STATE_MASTER && !sync_master_pid) ||
878             (state == IP_VS_STATE_BACKUP && !sync_backup_pid))
879                 return -ESRCH;
880
881         IP_VS_DBG(7, "%s: pid %d\n", __FUNCTION__, current->pid);
882         IP_VS_INFO("stopping sync thread %d ...\n",
883                    (state == IP_VS_STATE_MASTER) ? sync_master_pid : sync_backup_pid);
884
885         __set_current_state(TASK_UNINTERRUPTIBLE);
886         add_wait_queue(&stop_sync_wait, &wait);
887         set_stop_sync(state, 1);
888         ip_vs_sync_state -= state;
889         wake_up(&sync_wait);
890         schedule();
891         __set_current_state(TASK_RUNNING);
892         remove_wait_queue(&stop_sync_wait, &wait);
893
894         /* Note: no need to reap the sync thread, because its parent
895            process is the init process */
896
897         if ((state == IP_VS_STATE_MASTER && stop_master_sync) ||
898             (state == IP_VS_STATE_BACKUP && stop_backup_sync))
899                 IP_VS_BUG();
900
901         return 0;
902 }