Merge master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6
[linux-2.6] / 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(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(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(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(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(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 }