git.oblomov.eu Git - linux-2.6/blob - 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 (!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 (!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                 }
 724                 othercon->sock = newsock;
 725                 newsock->sk->sk_user_data = othercon;
 726                 add_sock(newsock, othercon);
 727                 addcon = othercon;
 728         }
 729         else {
 730                 newsock->sk->sk_user_data = newcon;
 731                 newcon->rx_action = receive_from_sock;
 732                 add_sock(newsock, newcon);
 733                 addcon = newcon;
 734         }
 735
 736         mutex_unlock(&newcon->sock_mutex);
 737
 738         /*
 739          * Add it to the active queue in case we got data
 740          * beween processing the accept adding the socket
 741          * to the read_sockets list
 742          */
 743         if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
 744                 queue_work(recv_workqueue, &addcon->rwork);
 745         mutex_unlock(&con->sock_mutex);
 746
 747         return 0;
 748
 749 accept_err:
 750         mutex_unlock(&con->sock_mutex);
 751         sock_release(newsock);
 752
 753         if (result != -EAGAIN)
 754                 log_print("error accepting connection from node: %d", result);
 755         return result;
 756 }
 757
 758 static void free_entry(struct writequeue_entry *e)
 759 {
 760         __free_page(e->page);
 761         kfree(e);
 762 }
 763
 764 /* Initiate an SCTP association.
 765    This is a special case of send_to_sock() in that we don't yet have a
 766    peeled-off socket for this association, so we use the listening socket
 767    and add the primary IP address of the remote node.
 768  */
 769 static void sctp_init_assoc(struct connection *con)
 770 {
 771         struct sockaddr_storage rem_addr;
 772         char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 773         struct msghdr outmessage;
 774         struct cmsghdr *cmsg;
 775         struct sctp_sndrcvinfo *sinfo;
 776         struct connection *base_con;
 777         struct writequeue_entry *e;
 778         int len, offset;
 779         int ret;
 780         int addrlen;
 781         struct kvec iov[1];
 782
 783         if (test_and_set_bit(CF_INIT_PENDING, &con->flags))
 784                 return;
 785
 786         if (con->retries++ > MAX_CONNECT_RETRIES)
 787                 return;
 788
 789         log_print("Initiating association with node %d", con->nodeid);
 790
 791         if (nodeid_to_addr(con->nodeid, (struct sockaddr *)&rem_addr)) {
 792                 log_print("no address for nodeid %d", con->nodeid);
 793                 return;
 794         }
 795         base_con = nodeid2con(0, 0);
 796         BUG_ON(base_con == NULL);
 797
 798         make_sockaddr(&rem_addr, dlm_config.ci_tcp_port, &addrlen);
 799
 800         outmessage.msg_name = &rem_addr;
 801         outmessage.msg_namelen = addrlen;
 802         outmessage.msg_control = outcmsg;
 803         outmessage.msg_controllen = sizeof(outcmsg);
 804         outmessage.msg_flags = MSG_EOR;
 805
 806         spin_lock(&con->writequeue_lock);
 807         e = list_entry(con->writequeue.next, struct writequeue_entry,
 808                        list);
 809
 810         BUG_ON((struct list_head *) e == &con->writequeue);
 811
 812         len = e->len;
 813         offset = e->offset;
 814         spin_unlock(&con->writequeue_lock);
 815         kmap(e->page);
 816
 817         /* Send the first block off the write queue */
 818         iov[0].iov_base = page_address(e->page)+offset;
 819         iov[0].iov_len = len;
 820
 821         cmsg = CMSG_FIRSTHDR(&outmessage);
 822         cmsg->cmsg_level = IPPROTO_SCTP;
 823         cmsg->cmsg_type = SCTP_SNDRCV;
 824         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
 825         sinfo = CMSG_DATA(cmsg);
 826         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
 827         sinfo->sinfo_ppid = cpu_to_le32(dlm_our_nodeid());
 828         outmessage.msg_controllen = cmsg->cmsg_len;
 829
 830         ret = kernel_sendmsg(base_con->sock, &outmessage, iov, 1, len);
 831         if (ret < 0) {
 832                 log_print("Send first packet to node %d failed: %d",
 833                           con->nodeid, ret);
 834
 835                 /* Try again later */
 836                 clear_bit(CF_CONNECT_PENDING, &con->flags);
 837                 clear_bit(CF_INIT_PENDING, &con->flags);
 838         }
 839         else {
 840                 spin_lock(&con->writequeue_lock);
 841                 e->offset += ret;
 842                 e->len -= ret;
 843
 844                 if (e->len == 0 && e->users == 0) {
 845                         list_del(&e->list);
 846                         kunmap(e->page);
 847                         free_entry(e);
 848                 }
 849                 spin_unlock(&con->writequeue_lock);
 850         }
 851 }
 852
 853 /* Connect a new socket to its peer */
 854 static void tcp_connect_to_sock(struct connection *con)
 855 {
 856         int result = -EHOSTUNREACH;
 857         struct sockaddr_storage saddr;
 858         int addr_len;
 859         struct socket *sock;
 860
 861         if (con->nodeid == 0) {
 862                 log_print("attempt to connect sock 0 foiled");
 863                 return;
 864         }
 865
 866         mutex_lock(&con->sock_mutex);
 867         if (con->retries++ > MAX_CONNECT_RETRIES)
 868                 goto out;
 869
 870         /* Some odd races can cause double-connects, ignore them */
 871         if (con->sock) {
 872                 result = 0;
 873                 goto out;
 874         }
 875
 876         /* Create a socket to communicate with */
 877         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 878                                   IPPROTO_TCP, &sock);
 879         if (result < 0)
 880                 goto out_err;
 881
 882         memset(&saddr, 0, sizeof(saddr));
 883         if (dlm_nodeid_to_addr(con->nodeid, &saddr))
 884                 goto out_err;
 885
 886         sock->sk->sk_user_data = con;
 887         con->rx_action = receive_from_sock;
 888         con->connect_action = tcp_connect_to_sock;
 889         add_sock(sock, con);
 890
 891         make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);
 892
 893         log_print("connecting to %d", con->nodeid);
 894         result =
 895                 sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
 896                                    O_NONBLOCK);
 897         if (result == -EINPROGRESS)
 898                 result = 0;
 899         if (result == 0)
 900                 goto out;
 901
 902 out_err:
 903         if (con->sock) {
 904                 sock_release(con->sock);
 905                 con->sock = NULL;
 906         }
 907         /*
 908          * Some errors are fatal and this list might need adjusting. For other
 909          * errors we try again until the max number of retries is reached.
 910          */
 911         if (result != -EHOSTUNREACH && result != -ENETUNREACH &&
 912             result != -ENETDOWN && result != EINVAL
 913             && result != -EPROTONOSUPPORT) {
 914                 lowcomms_connect_sock(con);
 915                 result = 0;
 916         }
 917 out:
 918         mutex_unlock(&con->sock_mutex);
 919         return;
 920 }
 921
 922 static struct socket *tcp_create_listen_sock(struct connection *con,
 923                                              struct sockaddr_storage *saddr)
 924 {
 925         struct socket *sock = NULL;
 926         int result = 0;
 927         int one = 1;
 928         int addr_len;
 929
 930         if (dlm_local_addr[0]->ss_family == AF_INET)
 931                 addr_len = sizeof(struct sockaddr_in);
 932         else
 933                 addr_len = sizeof(struct sockaddr_in6);
 934
 935         /* Create a socket to communicate with */
 936         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 937                                   IPPROTO_TCP, &sock);
 938         if (result < 0) {
 939                 log_print("Can't create listening comms socket");
 940                 goto create_out;
 941         }
 942
 943         result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
 944                                    (char *)&one, sizeof(one));
 945
 946         if (result < 0) {
 947                 log_print("Failed to set SO_REUSEADDR on socket: %d", result);
 948         }
 949         sock->sk->sk_user_data = con;
 950         con->rx_action = tcp_accept_from_sock;
 951         con->connect_action = tcp_connect_to_sock;
 952         con->sock = sock;
 953
 954         /* Bind to our port */
 955         make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
 956         result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
 957         if (result < 0) {
 958                 log_print("Can't bind to port %d", dlm_config.ci_tcp_port);
 959                 sock_release(sock);
 960                 sock = NULL;
 961                 con->sock = NULL;
 962                 goto create_out;
 963         }
 964         result = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
 965                                  (char *)&one, sizeof(one));
 966         if (result < 0) {
 967                 log_print("Set keepalive failed: %d", result);
 968         }
 969
 970         result = sock->ops->listen(sock, 5);
 971         if (result < 0) {
 972                 log_print("Can't listen on port %d", dlm_config.ci_tcp_port);
 973                 sock_release(sock);
 974                 sock = NULL;
 975                 goto create_out;
 976         }
 977
 978 create_out:
 979         return sock;
 980 }
 981
 982 /* Get local addresses */
 983 static void init_local(void)
 984 {
 985         struct sockaddr_storage sas, *addr;
 986         int i;
 987
 988         dlm_local_count = 0;
 989         for (i = 0; i < DLM_MAX_ADDR_COUNT - 1; i++) {
 990                 if (dlm_our_addr(&sas, i))
 991                         break;
 992
 993                 addr = kmalloc(sizeof(*addr), GFP_KERNEL);
 994                 if (!addr)
 995                         break;
 996                 memcpy(addr, &sas, sizeof(*addr));
 997                 dlm_local_addr[dlm_local_count++] = addr;
 998         }
 999 }
1000
1001 /* Bind to an IP address. SCTP allows multiple address so it can do
1002    multi-homing */
1003 static int add_sctp_bind_addr(struct connection *sctp_con,
1004                               struct sockaddr_storage *addr,
1005                               int addr_len, int num)
1006 {
1007         int result = 0;
1008
1009         if (num == 1)
1010                 result = kernel_bind(sctp_con->sock,
1011                                      (struct sockaddr *) addr,
1012                                      addr_len);
1013         else
1014                 result = kernel_setsockopt(sctp_con->sock, SOL_SCTP,
1015                                            SCTP_SOCKOPT_BINDX_ADD,
1016                                            (char *)addr, addr_len);
1017
1018         if (result < 0)
1019                 log_print("Can't bind to port %d addr number %d",
1020                           dlm_config.ci_tcp_port, num);
1021
1022         return result;
1023 }
1024
1025 /* Initialise SCTP socket and bind to all interfaces */
1026 static int sctp_listen_for_all(void)
1027 {
1028         struct socket *sock = NULL;
1029         struct sockaddr_storage localaddr;
1030         struct sctp_event_subscribe subscribe;
1031         int result = -EINVAL, num = 1, i, addr_len;
1032         struct connection *con = nodeid2con(0, GFP_KERNEL);
1033         int bufsize = NEEDED_RMEM;
1034
1035         if (!con)
1036                 return -ENOMEM;
1037
1038         log_print("Using SCTP for communications");
1039
1040         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_SEQPACKET,
1041                                   IPPROTO_SCTP, &sock);
1042         if (result < 0) {
1043                 log_print("Can't create comms socket, check SCTP is loaded");
1044                 goto out;
1045         }
1046
1047         /* Listen for events */
1048         memset(&subscribe, 0, sizeof(subscribe));
1049         subscribe.sctp_data_io_event = 1;
1050         subscribe.sctp_association_event = 1;
1051         subscribe.sctp_send_failure_event = 1;
1052         subscribe.sctp_shutdown_event = 1;
1053         subscribe.sctp_partial_delivery_event = 1;
1054
1055         result = kernel_setsockopt(sock, SOL_SOCKET, SO_RCVBUF,
1056                                  (char *)&bufsize, sizeof(bufsize));
1057         if (result)
1058                 log_print("Error increasing buffer space on socket %d", result);
1059
1060         result = kernel_setsockopt(sock, SOL_SCTP, SCTP_EVENTS,
1061                                    (char *)&subscribe, sizeof(subscribe));
1062         if (result < 0) {
1063                 log_print("Failed to set SCTP_EVENTS on socket: result=%d",
1064                           result);
1065                 goto create_delsock;
1066         }
1067
1068         /* Init con struct */
1069         sock->sk->sk_user_data = con;
1070         con->sock = sock;
1071         con->sock->sk->sk_data_ready = lowcomms_data_ready;
1072         con->rx_action = receive_from_sock;
1073         con->connect_action = sctp_init_assoc;
1074
1075         /* Bind to all interfaces. */
1076         for (i = 0; i < dlm_local_count; i++) {
1077                 memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
1078                 make_sockaddr(&localaddr, dlm_config.ci_tcp_port, &addr_len);
1079
1080                 result = add_sctp_bind_addr(con, &localaddr, addr_len, num);
1081                 if (result)
1082                         goto create_delsock;
1083                 ++num;
1084         }
1085
1086         result = sock->ops->listen(sock, 5);
1087         if (result < 0) {
1088                 log_print("Can't set socket listening");
1089                 goto create_delsock;
1090         }
1091
1092         return 0;
1093
1094 create_delsock:
1095         sock_release(sock);
1096         con->sock = NULL;
1097 out:
1098         return result;
1099 }
1100
1101 static int tcp_listen_for_all(void)
1102 {
1103         struct socket *sock = NULL;
1104         struct connection *con = nodeid2con(0, GFP_KERNEL);
1105         int result = -EINVAL;
1106
1107         if (!con)
1108                 return -ENOMEM;
1109
1110         /* We don't support multi-homed hosts */
1111         if (dlm_local_addr[1] != NULL) {
1112                 log_print("TCP protocol can't handle multi-homed hosts, "
1113                           "try SCTP");
1114                 return -EINVAL;
1115         }
1116
1117         log_print("Using TCP for communications");
1118
1119         set_bit(CF_IS_OTHERCON, &con->flags);
1120
1121         sock = tcp_create_listen_sock(con, dlm_local_addr[0]);
1122         if (sock) {
1123                 add_sock(sock, con);
1124                 result = 0;
1125         }
1126         else {
1127                 result = -EADDRINUSE;
1128         }
1129
1130         return result;
1131 }
1132
1133
1134
1135 static struct writequeue_entry *new_writequeue_entry(struct connection *con,
1136                                                      gfp_t allocation)
1137 {
1138         struct writequeue_entry *entry;
1139
1140         entry = kmalloc(sizeof(struct writequeue_entry), allocation);
1141         if (!entry)
1142                 return NULL;
1143
1144         entry->page = alloc_page(allocation);
1145         if (!entry->page) {
1146                 kfree(entry);
1147                 return NULL;
1148         }
1149
1150         entry->offset = 0;
1151         entry->len = 0;
1152         entry->end = 0;
1153         entry->users = 0;
1154         entry->con = con;
1155
1156         return entry;
1157 }
1158
1159 void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
1160 {
1161         struct connection *con;
1162         struct writequeue_entry *e;
1163         int offset = 0;
1164         int users = 0;
1165
1166         con = nodeid2con(nodeid, allocation);
1167         if (!con)
1168                 return NULL;
1169
1170         spin_lock(&con->writequeue_lock);
1171         e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
1172         if ((&e->list == &con->writequeue) ||
1173             (PAGE_CACHE_SIZE - e->end < len)) {
1174                 e = NULL;
1175         } else {
1176                 offset = e->end;
1177                 e->end += len;
1178                 users = e->users++;
1179         }
1180         spin_unlock(&con->writequeue_lock);
1181
1182         if (e) {
1183         got_one:
1184                 if (users == 0)
1185                         kmap(e->page);
1186                 *ppc = page_address(e->page) + offset;
1187                 return e;
1188         }
1189
1190         e = new_writequeue_entry(con, allocation);
1191         if (e) {
1192                 spin_lock(&con->writequeue_lock);
1193                 offset = e->end;
1194                 e->end += len;
1195                 users = e->users++;
1196                 list_add_tail(&e->list, &con->writequeue);
1197                 spin_unlock(&con->writequeue_lock);
1198                 goto got_one;
1199         }
1200         return NULL;
1201 }
1202
1203 void dlm_lowcomms_commit_buffer(void *mh)
1204 {
1205         struct writequeue_entry *e = (struct writequeue_entry *)mh;
1206         struct connection *con = e->con;
1207         int users;
1208
1209         spin_lock(&con->writequeue_lock);
1210         users = --e->users;
1211         if (users)
1212                 goto out;
1213         e->len = e->end - e->offset;
1214         kunmap(e->page);
1215         spin_unlock(&con->writequeue_lock);
1216
1217         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
1218                 queue_work(send_workqueue, &con->swork);
1219         }
1220         return;
1221
1222 out:
1223         spin_unlock(&con->writequeue_lock);
1224         return;
1225 }
1226
1227 /* Send a message */
1228 static void send_to_sock(struct connection *con)
1229 {
1230         int ret = 0;
1231         ssize_t(*sendpage) (struct socket *, struct page *, int, size_t, int);
1232         const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
1233         struct writequeue_entry *e;
1234         int len, offset;
1235
1236         mutex_lock(&con->sock_mutex);
1237         if (con->sock == NULL)
1238                 goto out_connect;
1239
1240         sendpage = con->sock->ops->sendpage;
1241
1242         spin_lock(&con->writequeue_lock);
1243         for (;;) {
1244                 e = list_entry(con->writequeue.next, struct writequeue_entry,
1245                                list);
1246                 if ((struct list_head *) e == &con->writequeue)
1247                         break;
1248
1249                 len = e->len;
1250                 offset = e->offset;
1251                 BUG_ON(len == 0 && e->users == 0);
1252                 spin_unlock(&con->writequeue_lock);
1253                 kmap(e->page);
1254
1255                 ret = 0;
1256                 if (len) {
1257                         ret = sendpage(con->sock, e->page, offset, len,
1258                                        msg_flags);
1259                         if (ret == -EAGAIN || ret == 0)
1260                                 goto out;
1261                         if (ret <= 0)
1262                                 goto send_error;
1263                 } else {
1264                         /* Don't starve people filling buffers */
1265                         cond_resched();
1266                 }
1267
1268                 spin_lock(&con->writequeue_lock);
1269                 e->offset += ret;
1270                 e->len -= ret;
1271
1272                 if (e->len == 0 && e->users == 0) {
1273                         list_del(&e->list);
1274                         kunmap(e->page);
1275                         free_entry(e);
1276                         continue;
1277                 }
1278         }
1279         spin_unlock(&con->writequeue_lock);
1280 out:
1281         mutex_unlock(&con->sock_mutex);
1282         return;
1283
1284 send_error:
1285         mutex_unlock(&con->sock_mutex);
1286         close_connection(con, false);
1287         lowcomms_connect_sock(con);
1288         return;
1289
1290 out_connect:
1291         mutex_unlock(&con->sock_mutex);
1292         if (!test_bit(CF_INIT_PENDING, &con->flags))
1293                 lowcomms_connect_sock(con);
1294         return;
1295 }
1296
1297 static void clean_one_writequeue(struct connection *con)
1298 {
1299         struct list_head *list;
1300         struct list_head *temp;
1301
1302         spin_lock(&con->writequeue_lock);
1303         list_for_each_safe(list, temp, &con->writequeue) {
1304                 struct writequeue_entry *e =
1305                         list_entry(list, struct writequeue_entry, list);
1306                 list_del(&e->list);
1307                 free_entry(e);
1308         }
1309         spin_unlock(&con->writequeue_lock);
1310 }
1311
1312 /* Called from recovery when it knows that a node has
1313    left the cluster */
1314 int dlm_lowcomms_close(int nodeid)
1315 {
1316         struct connection *con;
1317
1318         log_print("closing connection to node %d", nodeid);
1319         con = nodeid2con(nodeid, 0);
1320         if (con) {
1321                 clean_one_writequeue(con);
1322                 close_connection(con, true);
1323         }
1324         return 0;
1325 }
1326
1327 /* Receive workqueue function */
1328 static void process_recv_sockets(struct work_struct *work)
1329 {
1330         struct connection *con = container_of(work, struct connection, rwork);
1331         int err;
1332
1333         clear_bit(CF_READ_PENDING, &con->flags);
1334         do {
1335                 err = con->rx_action(con);
1336         } while (!err);
1337 }
1338
1339 /* Send workqueue function */
1340 static void process_send_sockets(struct work_struct *work)
1341 {
1342         struct connection *con = container_of(work, struct connection, swork);
1343
1344         if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
1345                 con->connect_action(con);
1346         }
1347         clear_bit(CF_WRITE_PENDING, &con->flags);
1348         send_to_sock(con);
1349 }
1350
1351
1352 /* Discard all entries on the write queues */
1353 static void clean_writequeues(void)
1354 {
1355         int nodeid;
1356
1357         for (nodeid = 1; nodeid <= max_nodeid; nodeid++) {
1358                 struct connection *con = __nodeid2con(nodeid, 0);
1359
1360                 if (con)
1361                         clean_one_writequeue(con);
1362         }
1363 }
1364
1365 static void work_stop(void)
1366 {
1367         destroy_workqueue(recv_workqueue);
1368         destroy_workqueue(send_workqueue);
1369 }
1370
1371 static int work_start(void)
1372 {
1373         int error;
1374         recv_workqueue = create_workqueue("dlm_recv");
1375         error = IS_ERR(recv_workqueue);
1376         if (error) {
1377                 log_print("can't start dlm_recv %d", error);
1378                 return error;
1379         }
1380
1381         send_workqueue = create_singlethread_workqueue("dlm_send");
1382         error = IS_ERR(send_workqueue);
1383         if (error) {
1384                 log_print("can't start dlm_send %d", error);
1385                 destroy_workqueue(recv_workqueue);
1386                 return error;
1387         }
1388
1389         return 0;
1390 }
1391
1392 void dlm_lowcomms_stop(void)
1393 {
1394         int i;
1395         struct connection *con;
1396
1397         /* Set all the flags to prevent any
1398            socket activity.
1399         */
1400         down(&connections_lock);
1401         for (i = 0; i <= max_nodeid; i++) {
1402                 con = __nodeid2con(i, 0);
1403                 if (con)
1404                         con->flags |= 0xFF;
1405         }
1406         up(&connections_lock);
1407
1408         work_stop();
1409
1410         down(&connections_lock);
1411         clean_writequeues();
1412
1413         for (i = 0; i <= max_nodeid; i++) {
1414                 con = __nodeid2con(i, 0);
1415                 if (con) {
1416                         close_connection(con, true);
1417                         if (con->othercon)
1418                                 kmem_cache_free(con_cache, con->othercon);
1419                         kmem_cache_free(con_cache, con);
1420                 }
1421         }
1422         max_nodeid = 0;
1423         up(&connections_lock);
1424         kmem_cache_destroy(con_cache);
1425         idr_init(&connections_idr);
1426 }
1427
1428 int dlm_lowcomms_start(void)
1429 {
1430         int error = -EINVAL;
1431         struct connection *con;
1432
1433         init_local();
1434         if (!dlm_local_count) {
1435                 error = -ENOTCONN;
1436                 log_print("no local IP address has been set");
1437                 goto out;
1438         }
1439
1440         error = -ENOMEM;
1441         con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
1442                                       __alignof__(struct connection), 0,
1443                                       NULL, NULL);
1444         if (!con_cache)
1445                 goto out;
1446
1447         /* Set some sysctl minima */
1448         if (sysctl_rmem_max < NEEDED_RMEM)
1449                 sysctl_rmem_max = NEEDED_RMEM;
1450
1451         /* Start listening */
1452         if (dlm_config.ci_protocol == 0)
1453                 error = tcp_listen_for_all();
1454         else
1455                 error = sctp_listen_for_all();
1456         if (error)
1457                 goto fail_unlisten;
1458
1459         error = work_start();
1460         if (error)
1461                 goto fail_unlisten;
1462
1463         return 0;
1464
1465 fail_unlisten:
1466         con = nodeid2con(0,0);
1467         if (con) {
1468                 close_connection(con, false);
1469                 kmem_cache_free(con_cache, con);
1470         }
1471         kmem_cache_destroy(con_cache);
1472
1473 out:
1474         return error;
1475 }