0553a6158dcbcf1bcc89d4e5d0733419ffc88214
[linux-2.6.git] / 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 }
317
318 /* Close a remote connection and tidy up */
319 static void close_connection(struct connection *con, bool and_other)
320 {
321         mutex_lock(&con->sock_mutex);
322
323         if (con->sock) {
324                 sock_release(con->sock);
325                 con->sock = NULL;
326         }
327         if (con->othercon && and_other) {
328                 /* Will only re-enter once. */
329                 close_connection(con->othercon, false);
330         }
331         if (con->rx_page) {
332                 __free_page(con->rx_page);
333                 con->rx_page = NULL;
334         }
335         con->retries = 0;
336         mutex_unlock(&con->sock_mutex);
337 }
338
339 /* We only send shutdown messages to nodes that are not part of the cluster */
340 static void sctp_send_shutdown(sctp_assoc_t associd)
341 {
342         static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
343         struct msghdr outmessage;
344         struct cmsghdr *cmsg;
345         struct sctp_sndrcvinfo *sinfo;
346         int ret;
347         struct connection *con;
348
349         con = nodeid2con(0,0);
350         BUG_ON(con == NULL);
351
352         outmessage.msg_name = NULL;
353         outmessage.msg_namelen = 0;
354         outmessage.msg_control = outcmsg;
355         outmessage.msg_controllen = sizeof(outcmsg);
356         outmessage.msg_flags = MSG_EOR;
357
358         cmsg = CMSG_FIRSTHDR(&outmessage);
359         cmsg->cmsg_level = IPPROTO_SCTP;
360         cmsg->cmsg_type = SCTP_SNDRCV;
361         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
362         outmessage.msg_controllen = cmsg->cmsg_len;
363         sinfo = CMSG_DATA(cmsg);
364         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
365
366         sinfo->sinfo_flags |= MSG_EOF;
367         sinfo->sinfo_assoc_id = associd;
368
369         ret = kernel_sendmsg(con->sock, &outmessage, NULL, 0, 0);
370
371         if (ret != 0)
372                 log_print("send EOF to node failed: %d", ret);
373 }
374
375 /* INIT failed but we don't know which node...
376    restart INIT on all pending nodes */
377 static void sctp_init_failed(void)
378 {
379         int i;
380         struct connection *con;
381
382         down(&connections_lock);
383         for (i=1; i<=max_nodeid; i++) {
384                 con = __nodeid2con(i, 0);
385                 if (!con)
386                         continue;
387                 con->sctp_assoc = 0;
388                 if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
389                         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
390                                 queue_work(send_workqueue, &con->swork);
391                         }
392                 }
393         }
394         up(&connections_lock);
395 }
396
397 /* Something happened to an association */
398 static void process_sctp_notification(struct connection *con,
399                                       struct msghdr *msg, char *buf)
400 {
401         union sctp_notification *sn = (union sctp_notification *)buf;
402
403         if (sn->sn_header.sn_type == SCTP_ASSOC_CHANGE) {
404                 switch (sn->sn_assoc_change.sac_state) {
405
406                 case SCTP_COMM_UP:
407                 case SCTP_RESTART:
408                 {
409                         /* Check that the new node is in the lockspace */
410                         struct sctp_prim prim;
411                         int nodeid;
412                         int prim_len, ret;
413                         int addr_len;
414                         struct connection *new_con;
415                         struct file *file;
416                         sctp_peeloff_arg_t parg;
417                         int parglen = sizeof(parg);
418
419                         /*
420                          * We get this before any data for an association.
421                          * We verify that the node is in the cluster and
422                          * then peel off a socket for it.
423                          */
424                         if ((int)sn->sn_assoc_change.sac_assoc_id <= 0) {
425                                 log_print("COMM_UP for invalid assoc ID %d",
426                                          (int)sn->sn_assoc_change.sac_assoc_id);
427                                 sctp_init_failed();
428                                 return;
429                         }
430                         memset(&prim, 0, sizeof(struct sctp_prim));
431                         prim_len = sizeof(struct sctp_prim);
432                         prim.ssp_assoc_id = sn->sn_assoc_change.sac_assoc_id;
433
434                         ret = kernel_getsockopt(con->sock,
435                                                 IPPROTO_SCTP,
436                                                 SCTP_PRIMARY_ADDR,
437                                                 (char*)&prim,
438                                                 &prim_len);
439                         if (ret < 0) {
440                                 log_print("getsockopt/sctp_primary_addr on "
441                                           "new assoc %d failed : %d",
442                                           (int)sn->sn_assoc_change.sac_assoc_id,
443                                           ret);
444
445                                 /* Retry INIT later */
446                                 new_con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
447                                 if (new_con)
448                                         clear_bit(CF_CONNECT_PENDING, &con->flags);
449                                 return;
450                         }
451                         make_sockaddr(&prim.ssp_addr, 0, &addr_len);
452                         if (dlm_addr_to_nodeid(&prim.ssp_addr, &nodeid)) {
453                                 int i;
454                                 unsigned char *b=(unsigned char *)&prim.ssp_addr;
455                                 log_print("reject connect from unknown addr");
456                                 for (i=0; i<sizeof(struct sockaddr_storage);i++)
457                                         printk("%02x ", b[i]);
458                                 printk("\n");
459                                 sctp_send_shutdown(prim.ssp_assoc_id);
460                                 return;
461                         }
462
463                         new_con = nodeid2con(nodeid, GFP_KERNEL);
464                         if (!new_con)
465                                 return;
466
467                         /* Peel off a new sock */
468                         parg.associd = sn->sn_assoc_change.sac_assoc_id;
469                         ret = kernel_getsockopt(con->sock, IPPROTO_SCTP,
470                                                 SCTP_SOCKOPT_PEELOFF,
471                                                 (void *)&parg, &parglen);
472                         if (ret) {
473                                 log_print("Can't peel off a socket for "
474                                           "connection %d to node %d: err=%d\n",
475                                           parg.associd, nodeid, ret);
476                         }
477                         file = fget(parg.sd);
478                         new_con->sock = SOCKET_I(file->f_dentry->d_inode);
479                         add_sock(new_con->sock, new_con);
480                         fput(file);
481                         put_unused_fd(parg.sd);
482
483                         log_print("got new/restarted association %d nodeid %d",
484                                  (int)sn->sn_assoc_change.sac_assoc_id, nodeid);
485
486                         /* Send any pending writes */
487                         clear_bit(CF_CONNECT_PENDING, &new_con->flags);
488                         clear_bit(CF_INIT_PENDING, &con->flags);
489                         if (!test_and_set_bit(CF_WRITE_PENDING, &new_con->flags)) {
490                                 queue_work(send_workqueue, &new_con->swork);
491                         }
492                         if (!test_and_set_bit(CF_READ_PENDING, &new_con->flags))
493                                 queue_work(recv_workqueue, &new_con->rwork);
494                 }
495                 break;
496
497                 case SCTP_COMM_LOST:
498                 case SCTP_SHUTDOWN_COMP:
499                 {
500                         con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
501                         if (con) {
502                                 con->sctp_assoc = 0;
503                         }
504                 }
505                 break;
506
507                 /* We don't know which INIT failed, so clear the PENDING flags
508                  * on them all.  if assoc_id is zero then it will then try
509                  * again */
510
511                 case SCTP_CANT_STR_ASSOC:
512                 {
513                         log_print("Can't start SCTP association - retrying");
514                         sctp_init_failed();
515                 }
516                 break;
517
518                 default:
519                         log_print("unexpected SCTP assoc change id=%d state=%d",
520                                   (int)sn->sn_assoc_change.sac_assoc_id,
521                                   sn->sn_assoc_change.sac_state);
522                 }
523         }
524 }
525
526 /* Data received from remote end */
527 static int receive_from_sock(struct connection *con)
528 {
529         int ret = 0;
530         struct msghdr msg = {};
531         struct kvec iov[2];
532         unsigned len;
533         int r;
534         int call_again_soon = 0;
535         int nvec;
536         char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
537
538         mutex_lock(&con->sock_mutex);
539
540         if (con->sock == NULL) {
541                 ret = -EAGAIN;
542                 goto out_close;
543         }
544
545         if (con->rx_page == NULL) {
546                 /*
547                  * This doesn't need to be atomic, but I think it should
548                  * improve performance if it is.
549                  */
550                 con->rx_page = alloc_page(GFP_ATOMIC);
551                 if (con->rx_page == NULL)
552                         goto out_resched;
553                 cbuf_init(&con->cb, PAGE_CACHE_SIZE);
554         }
555
556         /* Only SCTP needs these really */
557         memset(&incmsg, 0, sizeof(incmsg));
558         msg.msg_control = incmsg;
559         msg.msg_controllen = sizeof(incmsg);
560
561         /*
562          * iov[0] is the bit of the circular buffer between the current end
563          * point (cb.base + cb.len) and the end of the buffer.
564          */
565         iov[0].iov_len = con->cb.base - cbuf_data(&con->cb);
566         iov[0].iov_base = page_address(con->rx_page) + cbuf_data(&con->cb);
567         iov[1].iov_len = 0;
568         nvec = 1;
569
570         /*
571          * iov[1] is the bit of the circular buffer between the start of the
572          * buffer and the start of the currently used section (cb.base)
573          */
574         if (cbuf_data(&con->cb) >= con->cb.base) {
575                 iov[0].iov_len = PAGE_CACHE_SIZE - cbuf_data(&con->cb);
576                 iov[1].iov_len = con->cb.base;
577                 iov[1].iov_base = page_address(con->rx_page);
578                 nvec = 2;
579         }
580         len = iov[0].iov_len + iov[1].iov_len;
581
582         r = ret = kernel_recvmsg(con->sock, &msg, iov, nvec, len,
583                                MSG_DONTWAIT | MSG_NOSIGNAL);
584         if (ret <= 0)
585                 goto out_close;
586
587         /* Process SCTP notifications */
588         if (msg.msg_flags & MSG_NOTIFICATION) {
589                 msg.msg_control = incmsg;
590                 msg.msg_controllen = sizeof(incmsg);
591
592                 process_sctp_notification(con, &msg,
593                                 page_address(con->rx_page) + con->cb.base);
594                 mutex_unlock(&con->sock_mutex);
595                 return 0;
596         }
597         BUG_ON(con->nodeid == 0);
598
599         if (ret == len)
600                 call_again_soon = 1;
601         cbuf_add(&con->cb, ret);
602         ret = dlm_process_incoming_buffer(con->nodeid,
603                                           page_address(con->rx_page),
604                                           con->cb.base, con->cb.len,
605                                           PAGE_CACHE_SIZE);
606         if (ret == -EBADMSG) {
607                 log_print("lowcomms: addr=%p, base=%u, len=%u, "
608                           "iov_len=%u, iov_base[0]=%p, read=%d",
609                           page_address(con->rx_page), con->cb.base, con->cb.len,
610                           len, iov[0].iov_base, r);
611         }
612         if (ret < 0)
613                 goto out_close;
614         cbuf_eat(&con->cb, ret);
615
616         if (cbuf_empty(&con->cb) && !call_again_soon) {
617                 __free_page(con->rx_page);
618                 con->rx_page = NULL;
619         }
620
621         if (call_again_soon)
622                 goto out_resched;
623         mutex_unlock(&con->sock_mutex);
624         return 0;
625
626 out_resched:
627         if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
628                 queue_work(recv_workqueue, &con->rwork);
629         mutex_unlock(&con->sock_mutex);
630         return -EAGAIN;
631
632 out_close:
633         mutex_unlock(&con->sock_mutex);
634         if (ret != -EAGAIN && !test_bit(CF_IS_OTHERCON, &con->flags)) {
635                 close_connection(con, false);
636                 /* Reconnect when there is something to send */
637         }
638         /* Don't return success if we really got EOF */
639         if (ret == 0)
640                 ret = -EAGAIN;
641
642         return ret;
643 }
644
645 /* Listening socket is busy, accept a connection */
646 static int tcp_accept_from_sock(struct connection *con)
647 {
648         int result;
649         struct sockaddr_storage peeraddr;
650         struct socket *newsock;
651         int len;
652         int nodeid;
653         struct connection *newcon;
654         struct connection *addcon;
655
656         memset(&peeraddr, 0, sizeof(peeraddr));
657         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
658                                   IPPROTO_TCP, &newsock);
659         if (result < 0)
660                 return -ENOMEM;
661
662         mutex_lock_nested(&con->sock_mutex, 0);
663
664         result = -ENOTCONN;
665         if (con->sock == NULL)
666                 goto accept_err;
667
668         newsock->type = con->sock->type;
669         newsock->ops = con->sock->ops;
670
671         result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK);
672         if (result < 0)
673                 goto accept_err;
674
675         /* Get the connected socket's peer */
676         memset(&peeraddr, 0, sizeof(peeraddr));
677         if (newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr,
678                                   &len, 2)) {
679                 result = -ECONNABORTED;
680                 goto accept_err;
681         }
682
683         /* Get the new node's NODEID */
684         make_sockaddr(&peeraddr, 0, &len);
685         if (dlm_addr_to_nodeid(&peeraddr, &nodeid)) {
686                 log_print("connect from non cluster node");
687                 sock_release(newsock);
688                 mutex_unlock(&con->sock_mutex);
689                 return -1;
690         }
691
692         log_print("got connection from %d", nodeid);
693
694         /*  Check to see if we already have a connection to this node. This
695          *  could happen if the two nodes initiate a connection at roughly
696          *  the same time and the connections cross on the wire.
697          *  In this case we store the incoming one in "othercon"
698          */
699         newcon = nodeid2con(nodeid, GFP_KERNEL);
700         if (!newcon) {
701                 result = -ENOMEM;
702                 goto accept_err;
703         }
704         mutex_lock_nested(&newcon->sock_mutex, 1);
705         if (newcon->sock) {
706                 struct connection *othercon = newcon->othercon;
707
708                 if (!othercon) {
709                         othercon = kmem_cache_zalloc(con_cache, GFP_KERNEL);
710                         if (!othercon) {
711                                 log_print("failed to allocate incoming socket");
712                                 mutex_unlock(&newcon->sock_mutex);
713                                 result = -ENOMEM;
714                                 goto accept_err;
715                         }
716                         othercon->nodeid = nodeid;
717                         othercon->rx_action = receive_from_sock;
718                         mutex_init(&othercon->sock_mutex);
719                         INIT_WORK(&othercon->swork, process_send_sockets);
720                         INIT_WORK(&othercon->rwork, process_recv_sockets);
721                         set_bit(CF_IS_OTHERCON, &othercon->flags);
722                         newcon->othercon = othercon;
723                         othercon->sock = newsock;
724                         newsock->sk->sk_user_data = othercon;
725                         add_sock(newsock, othercon);
726                         addcon = othercon;
727                 }
728                 else {
729                         printk("Extra connection from node %d attempted\n", nodeid);
730                         result = -EAGAIN;
731                         mutex_unlock(&newcon->sock_mutex);
732                         goto accept_err;
733                 }
734         }
735         else {
736                 newsock->sk->sk_user_data = newcon;
737                 newcon->rx_action = receive_from_sock;
738                 add_sock(newsock, newcon);
739                 addcon = newcon;
740         }
741
742         mutex_unlock(&newcon->sock_mutex);
743
744         /*
745          * Add it to the active queue in case we got data
746          * beween processing the accept adding the socket
747          * to the read_sockets list
748          */
749         if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
750                 queue_work(recv_workqueue, &addcon->rwork);
751         mutex_unlock(&con->sock_mutex);
752
753         return 0;
754
755 accept_err:
756         mutex_unlock(&con->sock_mutex);
757         sock_release(newsock);
758
759         if (result != -EAGAIN)
760                 log_print("error accepting connection from node: %d", result);
761         return result;
762 }
763
764 static void free_entry(struct writequeue_entry *e)
765 {
766         __free_page(e->page);
767         kfree(e);
768 }
769
770 /* Initiate an SCTP association.
771    This is a special case of send_to_sock() in that we don't yet have a
772    peeled-off socket for this association, so we use the listening socket
773    and add the primary IP address of the remote node.
774  */
775 static void sctp_init_assoc(struct connection *con)
776 {
777         struct sockaddr_storage rem_addr;
778         char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
779         struct msghdr outmessage;
780         struct cmsghdr *cmsg;
781         struct sctp_sndrcvinfo *sinfo;
782         struct connection *base_con;
783         struct writequeue_entry *e;
784         int len, offset;
785         int ret;
786         int addrlen;
787         struct kvec iov[1];
788
789         if (test_and_set_bit(CF_INIT_PENDING, &con->flags))
790                 return;
791
792         if (con->retries++ > MAX_CONNECT_RETRIES)
793                 return;
794
795         log_print("Initiating association with node %d", con->nodeid);
796
797         if (nodeid_to_addr(con->nodeid, (struct sockaddr *)&rem_addr)) {
798                 log_print("no address for nodeid %d", con->nodeid);
799                 return;
800         }
801         base_con = nodeid2con(0, 0);
802         BUG_ON(base_con == NULL);
803
804         make_sockaddr(&rem_addr, dlm_config.ci_tcp_port, &addrlen);
805
806         outmessage.msg_name = &rem_addr;
807         outmessage.msg_namelen = addrlen;
808         outmessage.msg_control = outcmsg;
809         outmessage.msg_controllen = sizeof(outcmsg);
810         outmessage.msg_flags = MSG_EOR;
811
812         spin_lock(&con->writequeue_lock);
813         e = list_entry(con->writequeue.next, struct writequeue_entry,
814                        list);
815
816         BUG_ON((struct list_head *) e == &con->writequeue);
817
818         len = e->len;
819         offset = e->offset;
820         spin_unlock(&con->writequeue_lock);
821         kmap(e->page);
822
823         /* Send the first block off the write queue */
824         iov[0].iov_base = page_address(e->page)+offset;
825         iov[0].iov_len = len;
826
827         cmsg = CMSG_FIRSTHDR(&outmessage);
828         cmsg->cmsg_level = IPPROTO_SCTP;
829         cmsg->cmsg_type = SCTP_SNDRCV;
830         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
831         sinfo = CMSG_DATA(cmsg);
832         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
833         sinfo->sinfo_ppid = cpu_to_le32(dlm_our_nodeid());
834         outmessage.msg_controllen = cmsg->cmsg_len;
835
836         ret = kernel_sendmsg(base_con->sock, &outmessage, iov, 1, len);
837         if (ret < 0) {
838                 log_print("Send first packet to node %d failed: %d",
839                           con->nodeid, ret);
840
841                 /* Try again later */
842                 clear_bit(CF_CONNECT_PENDING, &con->flags);
843                 clear_bit(CF_INIT_PENDING, &con->flags);
844         }
845         else {
846                 spin_lock(&con->writequeue_lock);
847                 e->offset += ret;
848                 e->len -= ret;
849
850                 if (e->len == 0 && e->users == 0) {
851                         list_del(&e->list);
852                         kunmap(e->page);
853                         free_entry(e);
854                 }
855                 spin_unlock(&con->writequeue_lock);
856         }
857 }
858
859 /* Connect a new socket to its peer */
860 static void tcp_connect_to_sock(struct connection *con)
861 {
862         int result = -EHOSTUNREACH;
863         struct sockaddr_storage saddr;
864         int addr_len;
865         struct socket *sock;
866
867         if (con->nodeid == 0) {
868                 log_print("attempt to connect sock 0 foiled");
869                 return;
870         }
871
872         mutex_lock(&con->sock_mutex);
873         if (con->retries++ > MAX_CONNECT_RETRIES)
874                 goto out;
875
876         /* Some odd races can cause double-connects, ignore them */
877         if (con->sock) {
878                 result = 0;
879                 goto out;
880         }
881
882         /* Create a socket to communicate with */
883         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
884                                   IPPROTO_TCP, &sock);
885         if (result < 0)
886                 goto out_err;
887
888         memset(&saddr, 0, sizeof(saddr));
889         if (dlm_nodeid_to_addr(con->nodeid, &saddr))
890                 goto out_err;
891
892         sock->sk->sk_user_data = con;
893         con->rx_action = receive_from_sock;
894         con->connect_action = tcp_connect_to_sock;
895         add_sock(sock, con);
896
897         make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);
898
899         log_print("connecting to %d", con->nodeid);
900         result =
901                 sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
902                                    O_NONBLOCK);
903         if (result == -EINPROGRESS)
904                 result = 0;
905         if (result == 0)
906                 goto out;
907
908 out_err:
909         if (con->sock) {
910                 sock_release(con->sock);
911                 con->sock = NULL;
912         }
913         /*
914          * Some errors are fatal and this list might need adjusting. For other
915          * errors we try again until the max number of retries is reached.
916          */
917         if (result != -EHOSTUNREACH && result != -ENETUNREACH &&
918             result != -ENETDOWN && result != EINVAL
919             && result != -EPROTONOSUPPORT) {
920                 lowcomms_connect_sock(con);
921                 result = 0;
922         }
923 out:
924         mutex_unlock(&con->sock_mutex);
925         return;
926 }
927
928 static struct socket *tcp_create_listen_sock(struct connection *con,
929                                              struct sockaddr_storage *saddr)
930 {
931         struct socket *sock = NULL;
932         int result = 0;
933         int one = 1;
934         int addr_len;
935
936         if (dlm_local_addr[0]->ss_family == AF_INET)
937                 addr_len = sizeof(struct sockaddr_in);
938         else
939                 addr_len = sizeof(struct sockaddr_in6);
940
941         /* Create a socket to communicate with */
942         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
943                                   IPPROTO_TCP, &sock);
944         if (result < 0) {
945                 log_print("Can't create listening comms socket");
946                 goto create_out;
947         }
948
949         result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
950                                    (char *)&one, sizeof(one));
951
952         if (result < 0) {
953                 log_print("Failed to set SO_REUSEADDR on socket: %d", result);
954         }
955         sock->sk->sk_user_data = con;
956         con->rx_action = tcp_accept_from_sock;
957         con->connect_action = tcp_connect_to_sock;
958         con->sock = sock;
959
960         /* Bind to our port */
961         make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
962         result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
963         if (result < 0) {
964                 log_print("Can't bind to port %d", dlm_config.ci_tcp_port);
965                 sock_release(sock);
966                 sock = NULL;
967                 con->sock = NULL;
968                 goto create_out;
969         }
970         result = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
971                                  (char *)&one, sizeof(one));
972         if (result < 0) {
973                 log_print("Set keepalive failed: %d", result);
974         }
975
976         result = sock->ops->listen(sock, 5);
977         if (result < 0) {
978                 log_print("Can't listen on port %d", dlm_config.ci_tcp_port);
979                 sock_release(sock);
980                 sock = NULL;
981                 goto create_out;
982         }
983
984 create_out:
985         return sock;
986 }
987
988 /* Get local addresses */
989 static void init_local(void)
990 {
991         struct sockaddr_storage sas, *addr;
992         int i;
993
994         dlm_local_count = 0;
995         for (i = 0; i < DLM_MAX_ADDR_COUNT - 1; i++) {
996                 if (dlm_our_addr(&sas, i))
997                         break;
998
999                 addr = kmalloc(sizeof(*addr), GFP_KERNEL);
1000                 if (!addr)
1001                         break;
1002                 memcpy(addr, &sas, sizeof(*addr));
1003                 dlm_local_addr[dlm_local_count++] = addr;
1004         }
1005 }
1006
1007 /* Bind to an IP address. SCTP allows multiple address so it can do
1008    multi-homing */
1009 static int add_sctp_bind_addr(struct connection *sctp_con,
1010                               struct sockaddr_storage *addr,
1011                               int addr_len, int num)
1012 {
1013         int result = 0;
1014
1015         if (num == 1)
1016                 result = kernel_bind(sctp_con->sock,
1017                                      (struct sockaddr *) addr,
1018                                      addr_len);
1019         else
1020                 result = kernel_setsockopt(sctp_con->sock, SOL_SCTP,
1021                                            SCTP_SOCKOPT_BINDX_ADD,
1022                                            (char *)addr, addr_len);
1023
1024         if (result < 0)
1025                 log_print("Can't bind to port %d addr number %d",
1026                           dlm_config.ci_tcp_port, num);
1027
1028         return result;
1029 }
1030
1031 /* Initialise SCTP socket and bind to all interfaces */
1032 static int sctp_listen_for_all(void)
1033 {
1034         struct socket *sock = NULL;
1035         struct sockaddr_storage localaddr;
1036         struct sctp_event_subscribe subscribe;
1037         int result = -EINVAL, num = 1, i, addr_len;
1038         struct connection *con = nodeid2con(0, GFP_KERNEL);
1039         int bufsize = NEEDED_RMEM;
1040
1041         if (!con)
1042                 return -ENOMEM;
1043
1044         log_print("Using SCTP for communications");
1045
1046         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_SEQPACKET,
1047                                   IPPROTO_SCTP, &sock);
1048         if (result < 0) {
1049                 log_print("Can't create comms socket, check SCTP is loaded");
1050                 goto out;
1051         }
1052
1053         /* Listen for events */
1054         memset(&subscribe, 0, sizeof(subscribe));
1055         subscribe.sctp_data_io_event = 1;
1056         subscribe.sctp_association_event = 1;
1057         subscribe.sctp_send_failure_event = 1;
1058         subscribe.sctp_shutdown_event = 1;
1059         subscribe.sctp_partial_delivery_event = 1;
1060
1061         result = kernel_setsockopt(sock, SOL_SOCKET, SO_RCVBUF,
1062                                  (char *)&bufsize, sizeof(bufsize));
1063         if (result)
1064                 log_print("Error increasing buffer space on socket %d", result);
1065
1066         result = kernel_setsockopt(sock, SOL_SCTP, SCTP_EVENTS,
1067                                    (char *)&subscribe, sizeof(subscribe));
1068         if (result < 0) {
1069                 log_print("Failed to set SCTP_EVENTS on socket: result=%d",
1070                           result);
1071                 goto create_delsock;
1072         }
1073
1074         /* Init con struct */
1075         sock->sk->sk_user_data = con;
1076         con->sock = sock;
1077         con->sock->sk->sk_data_ready = lowcomms_data_ready;
1078         con->rx_action = receive_from_sock;
1079         con->connect_action = sctp_init_assoc;
1080
1081         /* Bind to all interfaces. */
1082         for (i = 0; i < dlm_local_count; i++) {
1083                 memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
1084                 make_sockaddr(&localaddr, dlm_config.ci_tcp_port, &addr_len);
1085
1086                 result = add_sctp_bind_addr(con, &localaddr, addr_len, num);
1087                 if (result)
1088                         goto create_delsock;
1089                 ++num;
1090         }
1091
1092         result = sock->ops->listen(sock, 5);
1093         if (result < 0) {
1094                 log_print("Can't set socket listening");
1095                 goto create_delsock;
1096         }
1097
1098         return 0;
1099
1100 create_delsock:
1101         sock_release(sock);
1102         con->sock = NULL;
1103 out:
1104         return result;
1105 }
1106
1107 static int tcp_listen_for_all(void)
1108 {
1109         struct socket *sock = NULL;
1110         struct connection *con = nodeid2con(0, GFP_KERNEL);
1111         int result = -EINVAL;
1112
1113         if (!con)
1114                 return -ENOMEM;
1115
1116         /* We don't support multi-homed hosts */
1117         if (dlm_local_addr[1] != NULL) {
1118                 log_print("TCP protocol can't handle multi-homed hosts, "
1119                           "try SCTP");
1120                 return -EINVAL;
1121         }
1122
1123         log_print("Using TCP for communications");
1124
1125         set_bit(CF_IS_OTHERCON, &con->flags);
1126
1127         sock = tcp_create_listen_sock(con, dlm_local_addr[0]);
1128         if (sock) {
1129                 add_sock(sock, con);
1130                 result = 0;
1131         }
1132         else {
1133                 result = -EADDRINUSE;
1134         }
1135
1136         return result;
1137 }
1138
1139
1140
1141 static struct writequeue_entry *new_writequeue_entry(struct connection *con,
1142                                                      gfp_t allocation)
1143 {
1144         struct writequeue_entry *entry;
1145
1146         entry = kmalloc(sizeof(struct writequeue_entry), allocation);
1147         if (!entry)
1148                 return NULL;
1149
1150         entry->page = alloc_page(allocation);
1151         if (!entry->page) {
1152                 kfree(entry);
1153                 return NULL;
1154         }
1155
1156         entry->offset = 0;
1157         entry->len = 0;
1158         entry->end = 0;
1159         entry->users = 0;
1160         entry->con = con;
1161
1162         return entry;
1163 }
1164
1165 void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
1166 {
1167         struct connection *con;
1168         struct writequeue_entry *e;
1169         int offset = 0;
1170         int users = 0;
1171
1172         con = nodeid2con(nodeid, allocation);
1173         if (!con)
1174                 return NULL;
1175
1176         spin_lock(&con->writequeue_lock);
1177         e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
1178         if ((&e->list == &con->writequeue) ||
1179             (PAGE_CACHE_SIZE - e->end < len)) {
1180                 e = NULL;
1181         } else {
1182                 offset = e->end;
1183                 e->end += len;
1184                 users = e->users++;
1185         }
1186         spin_unlock(&con->writequeue_lock);
1187
1188         if (e) {
1189         got_one:
1190                 if (users == 0)
1191                         kmap(e->page);
1192                 *ppc = page_address(e->page) + offset;
1193                 return e;
1194         }
1195
1196         e = new_writequeue_entry(con, allocation);
1197         if (e) {
1198                 spin_lock(&con->writequeue_lock);
1199                 offset = e->end;
1200                 e->end += len;
1201                 users = e->users++;
1202                 list_add_tail(&e->list, &con->writequeue);
1203                 spin_unlock(&con->writequeue_lock);
1204                 goto got_one;
1205         }
1206         return NULL;
1207 }
1208
1209 void dlm_lowcomms_commit_buffer(void *mh)
1210 {
1211         struct writequeue_entry *e = (struct writequeue_entry *)mh;
1212         struct connection *con = e->con;
1213         int users;
1214
1215         spin_lock(&con->writequeue_lock);
1216         users = --e->users;
1217         if (users)
1218                 goto out;
1219         e->len = e->end - e->offset;
1220         kunmap(e->page);
1221         spin_unlock(&con->writequeue_lock);
1222
1223         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
1224                 queue_work(send_workqueue, &con->swork);
1225         }
1226         return;
1227
1228 out:
1229         spin_unlock(&con->writequeue_lock);
1230         return;
1231 }
1232
1233 /* Send a message */
1234 static void send_to_sock(struct connection *con)
1235 {
1236         int ret = 0;
1237         ssize_t(*sendpage) (struct socket *, struct page *, int, size_t, int);
1238         const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
1239         struct writequeue_entry *e;
1240         int len, offset;
1241
1242         mutex_lock(&con->sock_mutex);
1243         if (con->sock == NULL)
1244                 goto out_connect;
1245
1246         sendpage = con->sock->ops->sendpage;
1247
1248         spin_lock(&con->writequeue_lock);
1249         for (;;) {
1250                 e = list_entry(con->writequeue.next, struct writequeue_entry,
1251                                list);
1252                 if ((struct list_head *) e == &con->writequeue)
1253                         break;
1254
1255                 len = e->len;
1256                 offset = e->offset;
1257                 BUG_ON(len == 0 && e->users == 0);
1258                 spin_unlock(&con->writequeue_lock);
1259                 kmap(e->page);
1260
1261                 ret = 0;
1262                 if (len) {
1263                         ret = sendpage(con->sock, e->page, offset, len,
1264                                        msg_flags);
1265                         if (ret == -EAGAIN || ret == 0)
1266                                 goto out;
1267                         if (ret <= 0)
1268                                 goto send_error;
1269                 } else {
1270                         /* Don't starve people filling buffers */
1271                         cond_resched();
1272                 }
1273
1274                 spin_lock(&con->writequeue_lock);
1275                 e->offset += ret;
1276                 e->len -= ret;
1277
1278                 if (e->len == 0 && e->users == 0) {
1279                         list_del(&e->list);
1280                         kunmap(e->page);
1281                         free_entry(e);
1282                         continue;
1283                 }
1284         }
1285         spin_unlock(&con->writequeue_lock);
1286 out:
1287         mutex_unlock(&con->sock_mutex);
1288         return;
1289
1290 send_error:
1291         mutex_unlock(&con->sock_mutex);
1292         close_connection(con, false);
1293         lowcomms_connect_sock(con);
1294         return;
1295
1296 out_connect:
1297         mutex_unlock(&con->sock_mutex);
1298         if (!test_bit(CF_INIT_PENDING, &con->flags))
1299                 lowcomms_connect_sock(con);
1300         return;
1301 }
1302
1303 static void clean_one_writequeue(struct connection *con)
1304 {
1305         struct list_head *list;
1306         struct list_head *temp;
1307
1308         spin_lock(&con->writequeue_lock);
1309         list_for_each_safe(list, temp, &con->writequeue) {
1310                 struct writequeue_entry *e =
1311                         list_entry(list, struct writequeue_entry, list);
1312                 list_del(&e->list);
1313                 free_entry(e);
1314         }
1315         spin_unlock(&con->writequeue_lock);
1316 }
1317
1318 /* Called from recovery when it knows that a node has
1319    left the cluster */
1320 int dlm_lowcomms_close(int nodeid)
1321 {
1322         struct connection *con;
1323
1324         log_print("closing connection to node %d", nodeid);
1325         con = nodeid2con(nodeid, 0);
1326         if (con) {
1327                 clean_one_writequeue(con);
1328                 close_connection(con, true);
1329         }
1330         return 0;
1331 }
1332
1333 /* Receive workqueue function */
1334 static void process_recv_sockets(struct work_struct *work)
1335 {
1336         struct connection *con = container_of(work, struct connection, rwork);
1337         int err;
1338
1339         clear_bit(CF_READ_PENDING, &con->flags);
1340         do {
1341                 err = con->rx_action(con);
1342         } while (!err);
1343 }
1344
1345 /* Send workqueue function */
1346 static void process_send_sockets(struct work_struct *work)
1347 {
1348         struct connection *con = container_of(work, struct connection, swork);
1349
1350         if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
1351                 con->connect_action(con);
1352         }
1353         clear_bit(CF_WRITE_PENDING, &con->flags);
1354         send_to_sock(con);
1355 }
1356
1357
1358 /* Discard all entries on the write queues */
1359 static void clean_writequeues(void)
1360 {
1361         int nodeid;
1362
1363         for (nodeid = 1; nodeid <= max_nodeid; nodeid++) {
1364                 struct connection *con = __nodeid2con(nodeid, 0);
1365
1366                 if (con)
1367                         clean_one_writequeue(con);
1368         }
1369 }
1370
1371 static void work_stop(void)
1372 {
1373         destroy_workqueue(recv_workqueue);
1374         destroy_workqueue(send_workqueue);
1375 }
1376
1377 static int work_start(void)
1378 {
1379         int error;
1380         recv_workqueue = create_workqueue("dlm_recv");
1381         error = IS_ERR(recv_workqueue);
1382         if (error) {
1383                 log_print("can't start dlm_recv %d", error);
1384                 return error;
1385         }
1386
1387         send_workqueue = create_singlethread_workqueue("dlm_send");
1388         error = IS_ERR(send_workqueue);
1389         if (error) {
1390                 log_print("can't start dlm_send %d", error);
1391                 destroy_workqueue(recv_workqueue);
1392                 return error;
1393         }
1394
1395         return 0;
1396 }
1397
1398 void dlm_lowcomms_stop(void)
1399 {
1400         int i;
1401         struct connection *con;
1402
1403         /* Set all the flags to prevent any
1404            socket activity.
1405         */
1406         down(&connections_lock);
1407         for (i = 0; i <= max_nodeid; i++) {
1408                 con = __nodeid2con(i, 0);
1409                 if (con) {
1410                         con->flags |= 0xFF;
1411                         if (con->sock)
1412                                 con->sock->sk->sk_user_data = NULL;
1413                 }
1414         }
1415         up(&connections_lock);
1416
1417         work_stop();
1418
1419         down(&connections_lock);
1420         clean_writequeues();
1421
1422         for (i = 0; i <= max_nodeid; i++) {
1423                 con = __nodeid2con(i, 0);
1424                 if (con) {
1425                         close_connection(con, true);
1426                         if (con->othercon)
1427                                 kmem_cache_free(con_cache, con->othercon);
1428                         kmem_cache_free(con_cache, con);
1429                 }
1430         }
1431         max_nodeid = 0;
1432         up(&connections_lock);
1433         kmem_cache_destroy(con_cache);
1434         idr_init(&connections_idr);
1435 }
1436
1437 int dlm_lowcomms_start(void)
1438 {
1439         int error = -EINVAL;
1440         struct connection *con;
1441
1442         init_local();
1443         if (!dlm_local_count) {
1444                 error = -ENOTCONN;
1445                 log_print("no local IP address has been set");
1446                 goto out;
1447         }
1448
1449         error = -ENOMEM;
1450         con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
1451                                       __alignof__(struct connection), 0,
1452                                       NULL, NULL);
1453         if (!con_cache)
1454                 goto out;
1455
1456         /* Set some sysctl minima */
1457         if (sysctl_rmem_max < NEEDED_RMEM)
1458                 sysctl_rmem_max = NEEDED_RMEM;
1459
1460         /* Start listening */
1461         if (dlm_config.ci_protocol == 0)
1462                 error = tcp_listen_for_all();
1463         else
1464                 error = sctp_listen_for_all();
1465         if (error)
1466                 goto fail_unlisten;
1467
1468         error = work_start();
1469         if (error)
1470                 goto fail_unlisten;
1471
1472         return 0;
1473
1474 fail_unlisten:
1475         con = nodeid2con(0,0);
1476         if (con) {
1477                 close_connection(con, false);
1478                 kmem_cache_free(con_cache, con);
1479         }
1480         kmem_cache_destroy(con_cache);
1481
1482 out:
1483         return error;
1484 }