Merge branches 'release' and 'ppc-workaround' into release
[linux-2.6] / fs / dlm / lowcomms.c
1 /******************************************************************************
2 *******************************************************************************
3 **
4 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
5 **  Copyright (C) 2004-2007 Red Hat, Inc.  All rights reserved.
6 **
7 **  This copyrighted material is made available to anyone wishing to use,
8 **  modify, copy, or redistribute it subject to the terms and conditions
9 **  of the GNU General Public License v.2.
10 **
11 *******************************************************************************
12 ******************************************************************************/
13
14 /*
15  * lowcomms.c
16  *
17  * This is the "low-level" comms layer.
18  *
19  * It is responsible for sending/receiving messages
20  * from other nodes in the cluster.
21  *
22  * Cluster nodes are referred to by their nodeids. nodeids are
23  * simply 32 bit numbers to the locking module - if they need to
24  * be expanded for the cluster infrastructure then that is it's
25  * responsibility. It is this layer's
26  * responsibility to resolve these into IP address or
27  * whatever it needs for inter-node communication.
28  *
29  * The comms level is two kernel threads that deal mainly with
30  * the receiving of messages from other nodes and passing them
31  * up to the mid-level comms layer (which understands the
32  * message format) for execution by the locking core, and
33  * a send thread which does all the setting up of connections
34  * to remote nodes and the sending of data. Threads are not allowed
35  * to send their own data because it may cause them to wait in times
36  * of high load. Also, this way, the sending thread can collect together
37  * messages bound for one node and send them in one block.
38  *
39  * lowcomms will choose to use wither TCP or SCTP as its transport layer
40  * depending on the configuration variable 'protocol'. This should be set
41  * to 0 (default) for TCP or 1 for SCTP. It shouldbe configured using a
42  * cluster-wide mechanism as it must be the same on all nodes of the cluster
43  * for the DLM to function.
44  *
45  */
46
47 #include <asm/ioctls.h>
48 #include <net/sock.h>
49 #include <net/tcp.h>
50 #include <linux/pagemap.h>
51 #include <linux/idr.h>
52 #include <linux/file.h>
53 #include <linux/sctp.h>
54 #include <net/sctp/user.h>
55
56 #include "dlm_internal.h"
57 #include "lowcomms.h"
58 #include "midcomms.h"
59 #include "config.h"
60
61 #define NEEDED_RMEM (4*1024*1024)
62
63 struct cbuf {
64         unsigned int base;
65         unsigned int len;
66         unsigned int mask;
67 };
68
69 static void cbuf_add(struct cbuf *cb, int n)
70 {
71         cb->len += n;
72 }
73
74 static int cbuf_data(struct cbuf *cb)
75 {
76         return ((cb->base + cb->len) & cb->mask);
77 }
78
79 static void cbuf_init(struct cbuf *cb, int size)
80 {
81         cb->base = cb->len = 0;
82         cb->mask = size-1;
83 }
84
85 static void cbuf_eat(struct cbuf *cb, int n)
86 {
87         cb->len  -= n;
88         cb->base += n;
89         cb->base &= cb->mask;
90 }
91
92 static bool cbuf_empty(struct cbuf *cb)
93 {
94         return cb->len == 0;
95 }
96
97 struct connection {
98         struct socket *sock;    /* NULL if not connected */
99         uint32_t nodeid;        /* So we know who we are in the list */
100         struct mutex sock_mutex;
101         unsigned long flags;
102 #define CF_READ_PENDING 1
103 #define CF_WRITE_PENDING 2
104 #define CF_CONNECT_PENDING 3
105 #define CF_INIT_PENDING 4
106 #define CF_IS_OTHERCON 5
107         struct list_head writequeue;  /* List of outgoing writequeue_entries */
108         spinlock_t writequeue_lock;
109         int (*rx_action) (struct connection *); /* What to do when active */
110         void (*connect_action) (struct connection *);   /* What to do to connect */
111         struct page *rx_page;
112         struct cbuf cb;
113         int retries;
114 #define MAX_CONNECT_RETRIES 3
115         int sctp_assoc;
116         struct connection *othercon;
117         struct work_struct rwork; /* Receive workqueue */
118         struct work_struct swork; /* Send workqueue */
119 };
120 #define sock2con(x) ((struct connection *)(x)->sk_user_data)
121
122 /* An entry waiting to be sent */
123 struct writequeue_entry {
124         struct list_head list;
125         struct page *page;
126         int offset;
127         int len;
128         int end;
129         int users;
130         struct connection *con;
131 };
132
133 static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
134 static int dlm_local_count;
135
136 /* Work queues */
137 static struct workqueue_struct *recv_workqueue;
138 static struct workqueue_struct *send_workqueue;
139
140 static DEFINE_IDR(connections_idr);
141 static DECLARE_MUTEX(connections_lock);
142 static int max_nodeid;
143 static struct kmem_cache *con_cache;
144
145 static void process_recv_sockets(struct work_struct *work);
146 static void process_send_sockets(struct work_struct *work);
147
148 /*
149  * If 'allocation' is zero then we don't attempt to create a new
150  * connection structure for this node.
151  */
152 static struct connection *__nodeid2con(int nodeid, gfp_t alloc)
153 {
154         struct connection *con = NULL;
155         int r;
156         int n;
157
158         con = idr_find(&connections_idr, nodeid);
159         if (con || !alloc)
160                 return con;
161
162         r = idr_pre_get(&connections_idr, alloc);
163         if (!r)
164                 return NULL;
165
166         con = kmem_cache_zalloc(con_cache, alloc);
167         if (!con)
168                 return NULL;
169
170         r = idr_get_new_above(&connections_idr, con, nodeid, &n);
171         if (r) {
172                 kmem_cache_free(con_cache, con);
173                 return NULL;
174         }
175
176         if (n != nodeid) {
177                 idr_remove(&connections_idr, n);
178                 kmem_cache_free(con_cache, con);
179                 return NULL;
180         }
181
182         con->nodeid = nodeid;
183         mutex_init(&con->sock_mutex);
184         INIT_LIST_HEAD(&con->writequeue);
185         spin_lock_init(&con->writequeue_lock);
186         INIT_WORK(&con->swork, process_send_sockets);
187         INIT_WORK(&con->rwork, process_recv_sockets);
188
189         /* Setup action pointers for child sockets */
190         if (con->nodeid) {
191                 struct connection *zerocon = idr_find(&connections_idr, 0);
192
193                 con->connect_action = zerocon->connect_action;
194                 if (!con->rx_action)
195                         con->rx_action = zerocon->rx_action;
196         }
197
198         if (nodeid > max_nodeid)
199                 max_nodeid = nodeid;
200
201         return con;
202 }
203
204 static struct connection *nodeid2con(int nodeid, gfp_t allocation)
205 {
206         struct connection *con;
207
208         down(&connections_lock);
209         con = __nodeid2con(nodeid, allocation);
210         up(&connections_lock);
211
212         return con;
213 }
214
215 /* This is a bit drastic, but only called when things go wrong */
216 static struct connection *assoc2con(int assoc_id)
217 {
218         int i;
219         struct connection *con;
220
221         down(&connections_lock);
222         for (i=0; i<=max_nodeid; i++) {
223                 con = __nodeid2con(i, 0);
224                 if (con && con->sctp_assoc == assoc_id) {
225                         up(&connections_lock);
226                         return con;
227                 }
228         }
229         up(&connections_lock);
230         return NULL;
231 }
232
233 static int nodeid_to_addr(int nodeid, struct sockaddr *retaddr)
234 {
235         struct sockaddr_storage addr;
236         int error;
237
238         if (!dlm_local_count)
239                 return -1;
240
241         error = dlm_nodeid_to_addr(nodeid, &addr);
242         if (error)
243                 return error;
244
245         if (dlm_local_addr[0]->ss_family == AF_INET) {
246                 struct sockaddr_in *in4  = (struct sockaddr_in *) &addr;
247                 struct sockaddr_in *ret4 = (struct sockaddr_in *) retaddr;
248                 ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
249         } else {
250                 struct sockaddr_in6 *in6  = (struct sockaddr_in6 *) &addr;
251                 struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) retaddr;
252                 memcpy(&ret6->sin6_addr, &in6->sin6_addr,
253                        sizeof(in6->sin6_addr));
254         }
255
256         return 0;
257 }
258
259 /* Data available on socket or listen socket received a connect */
260 static void lowcomms_data_ready(struct sock *sk, int count_unused)
261 {
262         struct connection *con = sock2con(sk);
263         if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
264                 queue_work(recv_workqueue, &con->rwork);
265 }
266
267 static void lowcomms_write_space(struct sock *sk)
268 {
269         struct connection *con = sock2con(sk);
270
271         if (con && !test_and_set_bit(CF_WRITE_PENDING, &con->flags))
272                 queue_work(send_workqueue, &con->swork);
273 }
274
275 static inline void lowcomms_connect_sock(struct connection *con)
276 {
277         if (!test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
278                 queue_work(send_workqueue, &con->swork);
279 }
280
281 static void lowcomms_state_change(struct sock *sk)
282 {
283         if (sk->sk_state == TCP_ESTABLISHED)
284                 lowcomms_write_space(sk);
285 }
286
287 /* Make a socket active */
288 static int add_sock(struct socket *sock, struct connection *con)
289 {
290         con->sock = sock;
291
292         /* Install a data_ready callback */
293         con->sock->sk->sk_data_ready = lowcomms_data_ready;
294         con->sock->sk->sk_write_space = lowcomms_write_space;
295         con->sock->sk->sk_state_change = lowcomms_state_change;
296         con->sock->sk->sk_user_data = con;
297         return 0;
298 }
299
300 /* Add the port number to an IPv6 or 4 sockaddr and return the address
301    length */
302 static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
303                           int *addr_len)
304 {
305         saddr->ss_family =  dlm_local_addr[0]->ss_family;
306         if (saddr->ss_family == AF_INET) {
307                 struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
308                 in4_addr->sin_port = cpu_to_be16(port);
309                 *addr_len = sizeof(struct sockaddr_in);
310                 memset(&in4_addr->sin_zero, 0, sizeof(in4_addr->sin_zero));
311         } else {
312                 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
313                 in6_addr->sin6_port = cpu_to_be16(port);
314                 *addr_len = sizeof(struct sockaddr_in6);
315         }
316         memset((char *)saddr + *addr_len, 0, sizeof(struct sockaddr_storage) - *addr_len);
317 }
318
319 /* Close a remote connection and tidy up */
320 static void close_connection(struct connection *con, bool and_other)
321 {
322         mutex_lock(&con->sock_mutex);
323
324         if (con->sock) {
325                 sock_release(con->sock);
326                 con->sock = NULL;
327         }
328         if (con->othercon && and_other) {
329                 /* Will only re-enter once. */
330                 close_connection(con->othercon, false);
331         }
332         if (con->rx_page) {
333                 __free_page(con->rx_page);
334                 con->rx_page = NULL;
335         }
336
337         con->retries = 0;
338         mutex_unlock(&con->sock_mutex);
339 }
340
341 /* We only send shutdown messages to nodes that are not part of the cluster */
342 static void sctp_send_shutdown(sctp_assoc_t associd)
343 {
344         static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
345         struct msghdr outmessage;
346         struct cmsghdr *cmsg;
347         struct sctp_sndrcvinfo *sinfo;
348         int ret;
349         struct connection *con;
350
351         con = nodeid2con(0,0);
352         BUG_ON(con == NULL);
353
354         outmessage.msg_name = NULL;
355         outmessage.msg_namelen = 0;
356         outmessage.msg_control = outcmsg;
357         outmessage.msg_controllen = sizeof(outcmsg);
358         outmessage.msg_flags = MSG_EOR;
359
360         cmsg = CMSG_FIRSTHDR(&outmessage);
361         cmsg->cmsg_level = IPPROTO_SCTP;
362         cmsg->cmsg_type = SCTP_SNDRCV;
363         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
364         outmessage.msg_controllen = cmsg->cmsg_len;
365         sinfo = CMSG_DATA(cmsg);
366         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
367
368         sinfo->sinfo_flags |= MSG_EOF;
369         sinfo->sinfo_assoc_id = associd;
370
371         ret = kernel_sendmsg(con->sock, &outmessage, NULL, 0, 0);
372
373         if (ret != 0)
374                 log_print("send EOF to node failed: %d", ret);
375 }
376
377 /* INIT failed but we don't know which node...
378    restart INIT on all pending nodes */
379 static void sctp_init_failed(void)
380 {
381         int i;
382         struct connection *con;
383
384         down(&connections_lock);
385         for (i=1; i<=max_nodeid; i++) {
386                 con = __nodeid2con(i, 0);
387                 if (!con)
388                         continue;
389                 con->sctp_assoc = 0;
390                 if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
391                         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
392                                 queue_work(send_workqueue, &con->swork);
393                         }
394                 }
395         }
396         up(&connections_lock);
397 }
398
399 /* Something happened to an association */
400 static void process_sctp_notification(struct connection *con,
401                                       struct msghdr *msg, char *buf)
402 {
403         union sctp_notification *sn = (union sctp_notification *)buf;
404
405         if (sn->sn_header.sn_type == SCTP_ASSOC_CHANGE) {
406                 switch (sn->sn_assoc_change.sac_state) {
407
408                 case SCTP_COMM_UP:
409                 case SCTP_RESTART:
410                 {
411                         /* Check that the new node is in the lockspace */
412                         struct sctp_prim prim;
413                         int nodeid;
414                         int prim_len, ret;
415                         int addr_len;
416                         struct connection *new_con;
417                         struct file *file;
418                         sctp_peeloff_arg_t parg;
419                         int parglen = sizeof(parg);
420
421                         /*
422                          * We get this before any data for an association.
423                          * We verify that the node is in the cluster and
424                          * then peel off a socket for it.
425                          */
426                         if ((int)sn->sn_assoc_change.sac_assoc_id <= 0) {
427                                 log_print("COMM_UP for invalid assoc ID %d",
428                                          (int)sn->sn_assoc_change.sac_assoc_id);
429                                 sctp_init_failed();
430                                 return;
431                         }
432                         memset(&prim, 0, sizeof(struct sctp_prim));
433                         prim_len = sizeof(struct sctp_prim);
434                         prim.ssp_assoc_id = sn->sn_assoc_change.sac_assoc_id;
435
436                         ret = kernel_getsockopt(con->sock,
437                                                 IPPROTO_SCTP,
438                                                 SCTP_PRIMARY_ADDR,
439                                                 (char*)&prim,
440                                                 &prim_len);
441                         if (ret < 0) {
442                                 log_print("getsockopt/sctp_primary_addr on "
443                                           "new assoc %d failed : %d",
444                                           (int)sn->sn_assoc_change.sac_assoc_id,
445                                           ret);
446
447                                 /* Retry INIT later */
448                                 new_con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
449                                 if (new_con)
450                                         clear_bit(CF_CONNECT_PENDING, &con->flags);
451                                 return;
452                         }
453                         make_sockaddr(&prim.ssp_addr, 0, &addr_len);
454                         if (dlm_addr_to_nodeid(&prim.ssp_addr, &nodeid)) {
455                                 int i;
456                                 unsigned char *b=(unsigned char *)&prim.ssp_addr;
457                                 log_print("reject connect from unknown addr");
458                                 for (i=0; i<sizeof(struct sockaddr_storage);i++)
459                                         printk("%02x ", b[i]);
460                                 printk("\n");
461                                 sctp_send_shutdown(prim.ssp_assoc_id);
462                                 return;
463                         }
464
465                         new_con = nodeid2con(nodeid, GFP_KERNEL);
466                         if (!new_con)
467                                 return;
468
469                         /* Peel off a new sock */
470                         parg.associd = sn->sn_assoc_change.sac_assoc_id;
471                         ret = kernel_getsockopt(con->sock, IPPROTO_SCTP,
472                                                 SCTP_SOCKOPT_PEELOFF,
473                                                 (void *)&parg, &parglen);
474                         if (ret) {
475                                 log_print("Can't peel off a socket for "
476                                           "connection %d to node %d: err=%d\n",
477                                           parg.associd, nodeid, ret);
478                         }
479                         file = fget(parg.sd);
480                         new_con->sock = SOCKET_I(file->f_dentry->d_inode);
481                         add_sock(new_con->sock, new_con);
482                         fput(file);
483                         put_unused_fd(parg.sd);
484
485                         log_print("got new/restarted association %d nodeid %d",
486                                  (int)sn->sn_assoc_change.sac_assoc_id, nodeid);
487
488                         /* Send any pending writes */
489                         clear_bit(CF_CONNECT_PENDING, &new_con->flags);
490                         clear_bit(CF_INIT_PENDING, &con->flags);
491                         if (!test_and_set_bit(CF_WRITE_PENDING, &new_con->flags)) {
492                                 queue_work(send_workqueue, &new_con->swork);
493                         }
494                         if (!test_and_set_bit(CF_READ_PENDING, &new_con->flags))
495                                 queue_work(recv_workqueue, &new_con->rwork);
496                 }
497                 break;
498
499                 case SCTP_COMM_LOST:
500                 case SCTP_SHUTDOWN_COMP:
501                 {
502                         con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
503                         if (con) {
504                                 con->sctp_assoc = 0;
505                         }
506                 }
507                 break;
508
509                 /* We don't know which INIT failed, so clear the PENDING flags
510                  * on them all.  if assoc_id is zero then it will then try
511                  * again */
512
513                 case SCTP_CANT_STR_ASSOC:
514                 {
515                         log_print("Can't start SCTP association - retrying");
516                         sctp_init_failed();
517                 }
518                 break;
519
520                 default:
521                         log_print("unexpected SCTP assoc change id=%d state=%d",
522                                   (int)sn->sn_assoc_change.sac_assoc_id,
523                                   sn->sn_assoc_change.sac_state);
524                 }
525         }
526 }
527
528 /* Data received from remote end */
529 static int receive_from_sock(struct connection *con)
530 {
531         int ret = 0;
532         struct msghdr msg = {};
533         struct kvec iov[2];
534         unsigned len;
535         int r;
536         int call_again_soon = 0;
537         int nvec;
538         char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
539
540         mutex_lock(&con->sock_mutex);
541
542         if (con->sock == NULL) {
543                 ret = -EAGAIN;
544                 goto out_close;
545         }
546
547         if (con->rx_page == NULL) {
548                 /*
549                  * This doesn't need to be atomic, but I think it should
550                  * improve performance if it is.
551                  */
552                 con->rx_page = alloc_page(GFP_ATOMIC);
553                 if (con->rx_page == NULL)
554                         goto out_resched;
555                 cbuf_init(&con->cb, PAGE_CACHE_SIZE);
556         }
557
558         /* Only SCTP needs these really */
559         memset(&incmsg, 0, sizeof(incmsg));
560         msg.msg_control = incmsg;
561         msg.msg_controllen = sizeof(incmsg);
562
563         /*
564          * iov[0] is the bit of the circular buffer between the current end
565          * point (cb.base + cb.len) and the end of the buffer.
566          */
567         iov[0].iov_len = con->cb.base - cbuf_data(&con->cb);
568         iov[0].iov_base = page_address(con->rx_page) + cbuf_data(&con->cb);
569         iov[1].iov_len = 0;
570         nvec = 1;
571
572         /*
573          * iov[1] is the bit of the circular buffer between the start of the
574          * buffer and the start of the currently used section (cb.base)
575          */
576         if (cbuf_data(&con->cb) >= con->cb.base) {
577                 iov[0].iov_len = PAGE_CACHE_SIZE - cbuf_data(&con->cb);
578                 iov[1].iov_len = con->cb.base;
579                 iov[1].iov_base = page_address(con->rx_page);
580                 nvec = 2;
581         }
582         len = iov[0].iov_len + iov[1].iov_len;
583
584         r = ret = kernel_recvmsg(con->sock, &msg, iov, nvec, len,
585                                MSG_DONTWAIT | MSG_NOSIGNAL);
586         if (ret <= 0)
587                 goto out_close;
588
589         /* Process SCTP notifications */
590         if (msg.msg_flags & MSG_NOTIFICATION) {
591                 msg.msg_control = incmsg;
592                 msg.msg_controllen = sizeof(incmsg);
593
594                 process_sctp_notification(con, &msg,
595                                 page_address(con->rx_page) + con->cb.base);
596                 mutex_unlock(&con->sock_mutex);
597                 return 0;
598         }
599         BUG_ON(con->nodeid == 0);
600
601         if (ret == len)
602                 call_again_soon = 1;
603         cbuf_add(&con->cb, ret);
604         ret = dlm_process_incoming_buffer(con->nodeid,
605                                           page_address(con->rx_page),
606                                           con->cb.base, con->cb.len,
607                                           PAGE_CACHE_SIZE);
608         if (ret == -EBADMSG) {
609                 log_print("lowcomms: addr=%p, base=%u, len=%u, "
610                           "iov_len=%u, iov_base[0]=%p, read=%d",
611                           page_address(con->rx_page), con->cb.base, con->cb.len,
612                           len, iov[0].iov_base, r);
613         }
614         if (ret < 0)
615                 goto out_close;
616         cbuf_eat(&con->cb, ret);
617
618         if (cbuf_empty(&con->cb) && !call_again_soon) {
619                 __free_page(con->rx_page);
620                 con->rx_page = NULL;
621         }
622
623         if (call_again_soon)
624                 goto out_resched;
625         mutex_unlock(&con->sock_mutex);
626         return 0;
627
628 out_resched:
629         if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
630                 queue_work(recv_workqueue, &con->rwork);
631         mutex_unlock(&con->sock_mutex);
632         return -EAGAIN;
633
634 out_close:
635         mutex_unlock(&con->sock_mutex);
636         if (ret != -EAGAIN) {
637                 close_connection(con, false);
638                 /* Reconnect when there is something to send */
639         }
640         /* Don't return success if we really got EOF */
641         if (ret == 0)
642                 ret = -EAGAIN;
643
644         return ret;
645 }
646
647 /* Listening socket is busy, accept a connection */
648 static int tcp_accept_from_sock(struct connection *con)
649 {
650         int result;
651         struct sockaddr_storage peeraddr;
652         struct socket *newsock;
653         int len;
654         int nodeid;
655         struct connection *newcon;
656         struct connection *addcon;
657
658         memset(&peeraddr, 0, sizeof(peeraddr));
659         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
660                                   IPPROTO_TCP, &newsock);
661         if (result < 0)
662                 return -ENOMEM;
663
664         mutex_lock_nested(&con->sock_mutex, 0);
665
666         result = -ENOTCONN;
667         if (con->sock == NULL)
668                 goto accept_err;
669
670         newsock->type = con->sock->type;
671         newsock->ops = con->sock->ops;
672
673         result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK);
674         if (result < 0)
675                 goto accept_err;
676
677         /* Get the connected socket's peer */
678         memset(&peeraddr, 0, sizeof(peeraddr));
679         if (newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr,
680                                   &len, 2)) {
681                 result = -ECONNABORTED;
682                 goto accept_err;
683         }
684
685         /* Get the new node's NODEID */
686         make_sockaddr(&peeraddr, 0, &len);
687         if (dlm_addr_to_nodeid(&peeraddr, &nodeid)) {
688                 log_print("connect from non cluster node");
689                 sock_release(newsock);
690                 mutex_unlock(&con->sock_mutex);
691                 return -1;
692         }
693
694         log_print("got connection from %d", nodeid);
695
696         /*  Check to see if we already have a connection to this node. This
697          *  could happen if the two nodes initiate a connection at roughly
698          *  the same time and the connections cross on the wire.
699          *  In this case we store the incoming one in "othercon"
700          */
701         newcon = nodeid2con(nodeid, GFP_KERNEL);
702         if (!newcon) {
703                 result = -ENOMEM;
704                 goto accept_err;
705         }
706         mutex_lock_nested(&newcon->sock_mutex, 1);
707         if (newcon->sock) {
708                 struct connection *othercon = newcon->othercon;
709
710                 if (!othercon) {
711                         othercon = kmem_cache_zalloc(con_cache, GFP_KERNEL);
712                         if (!othercon) {
713                                 log_print("failed to allocate incoming socket");
714                                 mutex_unlock(&newcon->sock_mutex);
715                                 result = -ENOMEM;
716                                 goto accept_err;
717                         }
718                         othercon->nodeid = nodeid;
719                         othercon->rx_action = receive_from_sock;
720                         mutex_init(&othercon->sock_mutex);
721                         INIT_WORK(&othercon->swork, process_send_sockets);
722                         INIT_WORK(&othercon->rwork, process_recv_sockets);
723                         set_bit(CF_IS_OTHERCON, &othercon->flags);
724                 }
725                 if (!othercon->sock) {
726                         newcon->othercon = othercon;
727                         othercon->sock = newsock;
728                         newsock->sk->sk_user_data = othercon;
729                         add_sock(newsock, othercon);
730                         addcon = othercon;
731                 }
732                 else {
733                         printk("Extra connection from node %d attempted\n", nodeid);
734                         result = -EAGAIN;
735                         mutex_unlock(&newcon->sock_mutex);
736                         goto accept_err;
737                 }
738         }
739         else {
740                 newsock->sk->sk_user_data = newcon;
741                 newcon->rx_action = receive_from_sock;
742                 add_sock(newsock, newcon);
743                 addcon = newcon;
744         }
745
746         mutex_unlock(&newcon->sock_mutex);
747
748         /*
749          * Add it to the active queue in case we got data
750          * beween processing the accept adding the socket
751          * to the read_sockets list
752          */
753         if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
754                 queue_work(recv_workqueue, &addcon->rwork);
755         mutex_unlock(&con->sock_mutex);
756
757         return 0;
758
759 accept_err:
760         mutex_unlock(&con->sock_mutex);
761         sock_release(newsock);
762
763         if (result != -EAGAIN)
764                 log_print("error accepting connection from node: %d", result);
765         return result;
766 }
767
768 static void free_entry(struct writequeue_entry *e)
769 {
770         __free_page(e->page);
771         kfree(e);
772 }
773
774 /* Initiate an SCTP association.
775    This is a special case of send_to_sock() in that we don't yet have a
776    peeled-off socket for this association, so we use the listening socket
777    and add the primary IP address of the remote node.
778  */
779 static void sctp_init_assoc(struct connection *con)
780 {
781         struct sockaddr_storage rem_addr;
782         char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
783         struct msghdr outmessage;
784         struct cmsghdr *cmsg;
785         struct sctp_sndrcvinfo *sinfo;
786         struct connection *base_con;
787         struct writequeue_entry *e;
788         int len, offset;
789         int ret;
790         int addrlen;
791         struct kvec iov[1];
792
793         if (test_and_set_bit(CF_INIT_PENDING, &con->flags))
794                 return;
795
796         if (con->retries++ > MAX_CONNECT_RETRIES)
797                 return;
798
799         log_print("Initiating association with node %d", con->nodeid);
800
801         if (nodeid_to_addr(con->nodeid, (struct sockaddr *)&rem_addr)) {
802                 log_print("no address for nodeid %d", con->nodeid);
803                 return;
804         }
805         base_con = nodeid2con(0, 0);
806         BUG_ON(base_con == NULL);
807
808         make_sockaddr(&rem_addr, dlm_config.ci_tcp_port, &addrlen);
809
810         outmessage.msg_name = &rem_addr;
811         outmessage.msg_namelen = addrlen;
812         outmessage.msg_control = outcmsg;
813         outmessage.msg_controllen = sizeof(outcmsg);
814         outmessage.msg_flags = MSG_EOR;
815
816         spin_lock(&con->writequeue_lock);
817         e = list_entry(con->writequeue.next, struct writequeue_entry,
818                        list);
819
820         BUG_ON((struct list_head *) e == &con->writequeue);
821
822         len = e->len;
823         offset = e->offset;
824         spin_unlock(&con->writequeue_lock);
825         kmap(e->page);
826
827         /* Send the first block off the write queue */
828         iov[0].iov_base = page_address(e->page)+offset;
829         iov[0].iov_len = len;
830
831         cmsg = CMSG_FIRSTHDR(&outmessage);
832         cmsg->cmsg_level = IPPROTO_SCTP;
833         cmsg->cmsg_type = SCTP_SNDRCV;
834         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
835         sinfo = CMSG_DATA(cmsg);
836         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
837         sinfo->sinfo_ppid = cpu_to_le32(dlm_our_nodeid());
838         outmessage.msg_controllen = cmsg->cmsg_len;
839
840         ret = kernel_sendmsg(base_con->sock, &outmessage, iov, 1, len);
841         if (ret < 0) {
842                 log_print("Send first packet to node %d failed: %d",
843                           con->nodeid, ret);
844
845                 /* Try again later */
846                 clear_bit(CF_CONNECT_PENDING, &con->flags);
847                 clear_bit(CF_INIT_PENDING, &con->flags);
848         }
849         else {
850                 spin_lock(&con->writequeue_lock);
851                 e->offset += ret;
852                 e->len -= ret;
853
854                 if (e->len == 0 && e->users == 0) {
855                         list_del(&e->list);
856                         kunmap(e->page);
857                         free_entry(e);
858                 }
859                 spin_unlock(&con->writequeue_lock);
860         }
861 }
862
863 /* Connect a new socket to its peer */
864 static void tcp_connect_to_sock(struct connection *con)
865 {
866         int result = -EHOSTUNREACH;
867         struct sockaddr_storage saddr, src_addr;
868         int addr_len;
869         struct socket *sock;
870
871         if (con->nodeid == 0) {
872                 log_print("attempt to connect sock 0 foiled");
873                 return;
874         }
875
876         mutex_lock(&con->sock_mutex);
877         if (con->retries++ > MAX_CONNECT_RETRIES)
878                 goto out;
879
880         /* Some odd races can cause double-connects, ignore them */
881         if (con->sock) {
882                 result = 0;
883                 goto out;
884         }
885
886         /* Create a socket to communicate with */
887         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
888                                   IPPROTO_TCP, &sock);
889         if (result < 0)
890                 goto out_err;
891
892         memset(&saddr, 0, sizeof(saddr));
893         if (dlm_nodeid_to_addr(con->nodeid, &saddr))
894                 goto out_err;
895
896         sock->sk->sk_user_data = con;
897         con->rx_action = receive_from_sock;
898         con->connect_action = tcp_connect_to_sock;
899         add_sock(sock, con);
900
901         /* Bind to our cluster-known address connecting to avoid
902            routing problems */
903         memcpy(&src_addr, dlm_local_addr[0], sizeof(src_addr));
904         make_sockaddr(&src_addr, 0, &addr_len);
905         result = sock->ops->bind(sock, (struct sockaddr *) &src_addr,
906                                  addr_len);
907         if (result < 0) {
908                 log_print("could not bind for connect: %d", result);
909                 /* This *may* not indicate a critical error */
910         }
911
912         make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);
913
914         log_print("connecting to %d", con->nodeid);
915         result =
916                 sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
917                                    O_NONBLOCK);
918         if (result == -EINPROGRESS)
919                 result = 0;
920         if (result == 0)
921                 goto out;
922
923 out_err:
924         if (con->sock) {
925                 sock_release(con->sock);
926                 con->sock = NULL;
927         }
928         /*
929          * Some errors are fatal and this list might need adjusting. For other
930          * errors we try again until the max number of retries is reached.
931          */
932         if (result != -EHOSTUNREACH && result != -ENETUNREACH &&
933             result != -ENETDOWN && result != EINVAL
934             && result != -EPROTONOSUPPORT) {
935                 lowcomms_connect_sock(con);
936                 result = 0;
937         }
938 out:
939         mutex_unlock(&con->sock_mutex);
940         return;
941 }
942
943 static struct socket *tcp_create_listen_sock(struct connection *con,
944                                              struct sockaddr_storage *saddr)
945 {
946         struct socket *sock = NULL;
947         int result = 0;
948         int one = 1;
949         int addr_len;
950
951         if (dlm_local_addr[0]->ss_family == AF_INET)
952                 addr_len = sizeof(struct sockaddr_in);
953         else
954                 addr_len = sizeof(struct sockaddr_in6);
955
956         /* Create a socket to communicate with */
957         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
958                                   IPPROTO_TCP, &sock);
959         if (result < 0) {
960                 log_print("Can't create listening comms socket");
961                 goto create_out;
962         }
963
964         result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
965                                    (char *)&one, sizeof(one));
966
967         if (result < 0) {
968                 log_print("Failed to set SO_REUSEADDR on socket: %d", result);
969         }
970         sock->sk->sk_user_data = con;
971         con->rx_action = tcp_accept_from_sock;
972         con->connect_action = tcp_connect_to_sock;
973         con->sock = sock;
974
975         /* Bind to our port */
976         make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
977         result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
978         if (result < 0) {
979                 log_print("Can't bind to port %d", dlm_config.ci_tcp_port);
980                 sock_release(sock);
981                 sock = NULL;
982                 con->sock = NULL;
983                 goto create_out;
984         }
985         result = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
986                                  (char *)&one, sizeof(one));
987         if (result < 0) {
988                 log_print("Set keepalive failed: %d", result);
989         }
990
991         result = sock->ops->listen(sock, 5);
992         if (result < 0) {
993                 log_print("Can't listen on port %d", dlm_config.ci_tcp_port);
994                 sock_release(sock);
995                 sock = NULL;
996                 goto create_out;
997         }
998
999 create_out:
1000         return sock;
1001 }
1002
1003 /* Get local addresses */
1004 static void init_local(void)
1005 {
1006         struct sockaddr_storage sas, *addr;
1007         int i;
1008
1009         dlm_local_count = 0;
1010         for (i = 0; i < DLM_MAX_ADDR_COUNT - 1; i++) {
1011                 if (dlm_our_addr(&sas, i))
1012                         break;
1013
1014                 addr = kmalloc(sizeof(*addr), GFP_KERNEL);
1015                 if (!addr)
1016                         break;
1017                 memcpy(addr, &sas, sizeof(*addr));
1018                 dlm_local_addr[dlm_local_count++] = addr;
1019         }
1020 }
1021
1022 /* Bind to an IP address. SCTP allows multiple address so it can do
1023    multi-homing */
1024 static int add_sctp_bind_addr(struct connection *sctp_con,
1025                               struct sockaddr_storage *addr,
1026                               int addr_len, int num)
1027 {
1028         int result = 0;
1029
1030         if (num == 1)
1031                 result = kernel_bind(sctp_con->sock,
1032                                      (struct sockaddr *) addr,
1033                                      addr_len);
1034         else
1035                 result = kernel_setsockopt(sctp_con->sock, SOL_SCTP,
1036                                            SCTP_SOCKOPT_BINDX_ADD,
1037                                            (char *)addr, addr_len);
1038
1039         if (result < 0)
1040                 log_print("Can't bind to port %d addr number %d",
1041                           dlm_config.ci_tcp_port, num);
1042
1043         return result;
1044 }
1045
1046 /* Initialise SCTP socket and bind to all interfaces */
1047 static int sctp_listen_for_all(void)
1048 {
1049         struct socket *sock = NULL;
1050         struct sockaddr_storage localaddr;
1051         struct sctp_event_subscribe subscribe;
1052         int result = -EINVAL, num = 1, i, addr_len;
1053         struct connection *con = nodeid2con(0, GFP_KERNEL);
1054         int bufsize = NEEDED_RMEM;
1055
1056         if (!con)
1057                 return -ENOMEM;
1058
1059         log_print("Using SCTP for communications");
1060
1061         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_SEQPACKET,
1062                                   IPPROTO_SCTP, &sock);
1063         if (result < 0) {
1064                 log_print("Can't create comms socket, check SCTP is loaded");
1065                 goto out;
1066         }
1067
1068         /* Listen for events */
1069         memset(&subscribe, 0, sizeof(subscribe));
1070         subscribe.sctp_data_io_event = 1;
1071         subscribe.sctp_association_event = 1;
1072         subscribe.sctp_send_failure_event = 1;
1073         subscribe.sctp_shutdown_event = 1;
1074         subscribe.sctp_partial_delivery_event = 1;
1075
1076         result = kernel_setsockopt(sock, SOL_SOCKET, SO_RCVBUFFORCE,
1077                                  (char *)&bufsize, sizeof(bufsize));
1078         if (result)
1079                 log_print("Error increasing buffer space on socket %d", result);
1080
1081         result = kernel_setsockopt(sock, SOL_SCTP, SCTP_EVENTS,
1082                                    (char *)&subscribe, sizeof(subscribe));
1083         if (result < 0) {
1084                 log_print("Failed to set SCTP_EVENTS on socket: result=%d",
1085                           result);
1086                 goto create_delsock;
1087         }
1088
1089         /* Init con struct */
1090         sock->sk->sk_user_data = con;
1091         con->sock = sock;
1092         con->sock->sk->sk_data_ready = lowcomms_data_ready;
1093         con->rx_action = receive_from_sock;
1094         con->connect_action = sctp_init_assoc;
1095
1096         /* Bind to all interfaces. */
1097         for (i = 0; i < dlm_local_count; i++) {
1098                 memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
1099                 make_sockaddr(&localaddr, dlm_config.ci_tcp_port, &addr_len);
1100
1101                 result = add_sctp_bind_addr(con, &localaddr, addr_len, num);
1102                 if (result)
1103                         goto create_delsock;
1104                 ++num;
1105         }
1106
1107         result = sock->ops->listen(sock, 5);
1108         if (result < 0) {
1109                 log_print("Can't set socket listening");
1110                 goto create_delsock;
1111         }
1112
1113         return 0;
1114
1115 create_delsock:
1116         sock_release(sock);
1117         con->sock = NULL;
1118 out:
1119         return result;
1120 }
1121
1122 static int tcp_listen_for_all(void)
1123 {
1124         struct socket *sock = NULL;
1125         struct connection *con = nodeid2con(0, GFP_KERNEL);
1126         int result = -EINVAL;
1127
1128         if (!con)
1129                 return -ENOMEM;
1130
1131         /* We don't support multi-homed hosts */
1132         if (dlm_local_addr[1] != NULL) {
1133                 log_print("TCP protocol can't handle multi-homed hosts, "
1134                           "try SCTP");
1135                 return -EINVAL;
1136         }
1137
1138         log_print("Using TCP for communications");
1139
1140         sock = tcp_create_listen_sock(con, dlm_local_addr[0]);
1141         if (sock) {
1142                 add_sock(sock, con);
1143                 result = 0;
1144         }
1145         else {
1146                 result = -EADDRINUSE;
1147         }
1148
1149         return result;
1150 }
1151
1152
1153
1154 static struct writequeue_entry *new_writequeue_entry(struct connection *con,
1155                                                      gfp_t allocation)
1156 {
1157         struct writequeue_entry *entry;
1158
1159         entry = kmalloc(sizeof(struct writequeue_entry), allocation);
1160         if (!entry)
1161                 return NULL;
1162
1163         entry->page = alloc_page(allocation);
1164         if (!entry->page) {
1165                 kfree(entry);
1166                 return NULL;
1167         }
1168
1169         entry->offset = 0;
1170         entry->len = 0;
1171         entry->end = 0;
1172         entry->users = 0;
1173         entry->con = con;
1174
1175         return entry;
1176 }
1177
1178 void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
1179 {
1180         struct connection *con;
1181         struct writequeue_entry *e;
1182         int offset = 0;
1183         int users = 0;
1184
1185         con = nodeid2con(nodeid, allocation);
1186         if (!con)
1187                 return NULL;
1188
1189         spin_lock(&con->writequeue_lock);
1190         e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
1191         if ((&e->list == &con->writequeue) ||
1192             (PAGE_CACHE_SIZE - e->end < len)) {
1193                 e = NULL;
1194         } else {
1195                 offset = e->end;
1196                 e->end += len;
1197                 users = e->users++;
1198         }
1199         spin_unlock(&con->writequeue_lock);
1200
1201         if (e) {
1202         got_one:
1203                 if (users == 0)
1204                         kmap(e->page);
1205                 *ppc = page_address(e->page) + offset;
1206                 return e;
1207         }
1208
1209         e = new_writequeue_entry(con, allocation);
1210         if (e) {
1211                 spin_lock(&con->writequeue_lock);
1212                 offset = e->end;
1213                 e->end += len;
1214                 users = e->users++;
1215                 list_add_tail(&e->list, &con->writequeue);
1216                 spin_unlock(&con->writequeue_lock);
1217                 goto got_one;
1218         }
1219         return NULL;
1220 }
1221
1222 void dlm_lowcomms_commit_buffer(void *mh)
1223 {
1224         struct writequeue_entry *e = (struct writequeue_entry *)mh;
1225         struct connection *con = e->con;
1226         int users;
1227
1228         spin_lock(&con->writequeue_lock);
1229         users = --e->users;
1230         if (users)
1231                 goto out;
1232         e->len = e->end - e->offset;
1233         kunmap(e->page);
1234         spin_unlock(&con->writequeue_lock);
1235
1236         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
1237                 queue_work(send_workqueue, &con->swork);
1238         }
1239         return;
1240
1241 out:
1242         spin_unlock(&con->writequeue_lock);
1243         return;
1244 }
1245
1246 /* Send a message */
1247 static void send_to_sock(struct connection *con)
1248 {
1249         int ret = 0;
1250         ssize_t(*sendpage) (struct socket *, struct page *, int, size_t, int);
1251         const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
1252         struct writequeue_entry *e;
1253         int len, offset;
1254
1255         mutex_lock(&con->sock_mutex);
1256         if (con->sock == NULL)
1257                 goto out_connect;
1258
1259         sendpage = con->sock->ops->sendpage;
1260
1261         spin_lock(&con->writequeue_lock);
1262         for (;;) {
1263                 e = list_entry(con->writequeue.next, struct writequeue_entry,
1264                                list);
1265                 if ((struct list_head *) e == &con->writequeue)
1266                         break;
1267
1268                 len = e->len;
1269                 offset = e->offset;
1270                 BUG_ON(len == 0 && e->users == 0);
1271                 spin_unlock(&con->writequeue_lock);
1272                 kmap(e->page);
1273
1274                 ret = 0;
1275                 if (len) {
1276                         ret = sendpage(con->sock, e->page, offset, len,
1277                                        msg_flags);
1278                         if (ret == -EAGAIN || ret == 0) {
1279                                 cond_resched();
1280                                 goto out;
1281                         }
1282                         if (ret <= 0)
1283                                 goto send_error;
1284                 }
1285                         /* Don't starve people filling buffers */
1286                         cond_resched();
1287
1288                 spin_lock(&con->writequeue_lock);
1289                 e->offset += ret;
1290                 e->len -= ret;
1291
1292                 if (e->len == 0 && e->users == 0) {
1293                         list_del(&e->list);
1294                         kunmap(e->page);
1295                         free_entry(e);
1296                         continue;
1297                 }
1298         }
1299         spin_unlock(&con->writequeue_lock);
1300 out:
1301         mutex_unlock(&con->sock_mutex);
1302         return;
1303
1304 send_error:
1305         mutex_unlock(&con->sock_mutex);
1306         close_connection(con, false);
1307         lowcomms_connect_sock(con);
1308         return;
1309
1310 out_connect:
1311         mutex_unlock(&con->sock_mutex);
1312         if (!test_bit(CF_INIT_PENDING, &con->flags))
1313                 lowcomms_connect_sock(con);
1314         return;
1315 }
1316
1317 static void clean_one_writequeue(struct connection *con)
1318 {
1319         struct list_head *list;
1320         struct list_head *temp;
1321
1322         spin_lock(&con->writequeue_lock);
1323         list_for_each_safe(list, temp, &con->writequeue) {
1324                 struct writequeue_entry *e =
1325                         list_entry(list, struct writequeue_entry, list);
1326                 list_del(&e->list);
1327                 free_entry(e);
1328         }
1329         spin_unlock(&con->writequeue_lock);
1330 }
1331
1332 /* Called from recovery when it knows that a node has
1333    left the cluster */
1334 int dlm_lowcomms_close(int nodeid)
1335 {
1336         struct connection *con;
1337
1338         log_print("closing connection to node %d", nodeid);
1339         con = nodeid2con(nodeid, 0);
1340         if (con) {
1341                 clean_one_writequeue(con);
1342                 close_connection(con, true);
1343         }
1344         return 0;
1345 }
1346
1347 /* Receive workqueue function */
1348 static void process_recv_sockets(struct work_struct *work)
1349 {
1350         struct connection *con = container_of(work, struct connection, rwork);
1351         int err;
1352
1353         clear_bit(CF_READ_PENDING, &con->flags);
1354         do {
1355                 err = con->rx_action(con);
1356         } while (!err);
1357 }
1358
1359 /* Send workqueue function */
1360 static void process_send_sockets(struct work_struct *work)
1361 {
1362         struct connection *con = container_of(work, struct connection, swork);
1363
1364         if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
1365                 con->connect_action(con);
1366         }
1367         clear_bit(CF_WRITE_PENDING, &con->flags);
1368         send_to_sock(con);
1369 }
1370
1371
1372 /* Discard all entries on the write queues */
1373 static void clean_writequeues(void)
1374 {
1375         int nodeid;
1376
1377         for (nodeid = 1; nodeid <= max_nodeid; nodeid++) {
1378                 struct connection *con = __nodeid2con(nodeid, 0);
1379
1380                 if (con)
1381                         clean_one_writequeue(con);
1382         }
1383 }
1384
1385 static void work_stop(void)
1386 {
1387         destroy_workqueue(recv_workqueue);
1388         destroy_workqueue(send_workqueue);
1389 }
1390
1391 static int work_start(void)
1392 {
1393         int error;
1394         recv_workqueue = create_workqueue("dlm_recv");
1395         error = IS_ERR(recv_workqueue);
1396         if (error) {
1397                 log_print("can't start dlm_recv %d", error);
1398                 return error;
1399         }
1400
1401         send_workqueue = create_singlethread_workqueue("dlm_send");
1402         error = IS_ERR(send_workqueue);
1403         if (error) {
1404                 log_print("can't start dlm_send %d", error);
1405                 destroy_workqueue(recv_workqueue);
1406                 return error;
1407         }
1408
1409         return 0;
1410 }
1411
1412 void dlm_lowcomms_stop(void)
1413 {
1414         int i;
1415         struct connection *con;
1416
1417         /* Set all the flags to prevent any
1418            socket activity.
1419         */
1420         down(&connections_lock);
1421         for (i = 0; i <= max_nodeid; i++) {
1422                 con = __nodeid2con(i, 0);
1423                 if (con) {
1424                         con->flags |= 0x0F;
1425                         if (con->sock)
1426                                 con->sock->sk->sk_user_data = NULL;
1427                 }
1428         }
1429         up(&connections_lock);
1430
1431         work_stop();
1432
1433         down(&connections_lock);
1434         clean_writequeues();
1435
1436         for (i = 0; i <= max_nodeid; i++) {
1437                 con = __nodeid2con(i, 0);
1438                 if (con) {
1439                         close_connection(con, true);
1440                         if (con->othercon)
1441                                 kmem_cache_free(con_cache, con->othercon);
1442                         kmem_cache_free(con_cache, con);
1443                 }
1444         }
1445         max_nodeid = 0;
1446         up(&connections_lock);
1447         kmem_cache_destroy(con_cache);
1448         idr_init(&connections_idr);
1449 }
1450
1451 int dlm_lowcomms_start(void)
1452 {
1453         int error = -EINVAL;
1454         struct connection *con;
1455
1456         init_local();
1457         if (!dlm_local_count) {
1458                 error = -ENOTCONN;
1459                 log_print("no local IP address has been set");
1460                 goto out;
1461         }
1462
1463         error = -ENOMEM;
1464         con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
1465                                       __alignof__(struct connection), 0,
1466                                       NULL);
1467         if (!con_cache)
1468                 goto out;
1469
1470         /* Start listening */
1471         if (dlm_config.ci_protocol == 0)
1472                 error = tcp_listen_for_all();
1473         else
1474                 error = sctp_listen_for_all();
1475         if (error)
1476                 goto fail_unlisten;
1477
1478         error = work_start();
1479         if (error)
1480                 goto fail_unlisten;
1481
1482         return 0;
1483
1484 fail_unlisten:
1485         con = nodeid2con(0,0);
1486         if (con) {
1487                 close_connection(con, false);
1488                 kmem_cache_free(con_cache, con);
1489         }
1490         kmem_cache_destroy(con_cache);
1491
1492 out:
1493         return error;
1494 }