fs/dlm/lowcomms.c

   1 /******************************************************************************
   2 *******************************************************************************
   3 **
   4 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
   5 **  Copyright (C) 2004-2009 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 its
  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 either 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 should be 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/file.h>
  52 #include <linux/mutex.h>
  53 #include <linux/sctp.h>
  54 #include <net/sctp/user.h>
  55 #include <net/ipv6.h>
  56
  57 #include "dlm_internal.h"
  58 #include "lowcomms.h"
  59 #include "midcomms.h"
  60 #include "config.h"
  61
  62 #define NEEDED_RMEM (4*1024*1024)
  63 #define CONN_HASH_SIZE 32
  64
  65 struct cbuf {
  66         unsigned int base;
  67         unsigned int len;
  68         unsigned int mask;
  69 };
  70
  71 static void cbuf_add(struct cbuf *cb, int n)
  72 {
  73         cb->len += n;
  74 }
  75
  76 static int cbuf_data(struct cbuf *cb)
  77 {
  78         return ((cb->base + cb->len) & cb->mask);
  79 }
  80
  81 static void cbuf_init(struct cbuf *cb, int size)
  82 {
  83         cb->base = cb->len = 0;
  84         cb->mask = size-1;
  85 }
  86
  87 static void cbuf_eat(struct cbuf *cb, int n)
  88 {
  89         cb->len  -= n;
  90         cb->base += n;
  91         cb->base &= cb->mask;
  92 }
  93
  94 static bool cbuf_empty(struct cbuf *cb)
  95 {
  96         return cb->len == 0;
  97 }
  98
  99 struct connection {
 100         struct socket *sock;    /* NULL if not connected */
 101         uint32_t nodeid;        /* So we know who we are in the list */
 102         struct mutex sock_mutex;
 103         unsigned long flags;
 104 #define CF_READ_PENDING 1
 105 #define CF_WRITE_PENDING 2
 106 #define CF_CONNECT_PENDING 3
 107 #define CF_INIT_PENDING 4
 108 #define CF_IS_OTHERCON 5
 109         struct list_head writequeue;  /* List of outgoing writequeue_entries */
 110         spinlock_t writequeue_lock;
 111         int (*rx_action) (struct connection *); /* What to do when active */
 112         void (*connect_action) (struct connection *);   /* What to do to connect */
 113         struct page *rx_page;
 114         struct cbuf cb;
 115         int retries;
 116 #define MAX_CONNECT_RETRIES 3
 117         int sctp_assoc;
 118         struct hlist_node list;
 119         struct connection *othercon;
 120         struct work_struct rwork; /* Receive workqueue */
 121         struct work_struct swork; /* Send workqueue */
 122 };
 123 #define sock2con(x) ((struct connection *)(x)->sk_user_data)
 124
 125 /* An entry waiting to be sent */
 126 struct writequeue_entry {
 127         struct list_head list;
 128         struct page *page;
 129         int offset;
 130         int len;
 131         int end;
 132         int users;
 133         struct connection *con;
 134 };
 135
 136 static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
 137 static int dlm_local_count;
 138
 139 /* Work queues */
 140 static struct workqueue_struct *recv_workqueue;
 141 static struct workqueue_struct *send_workqueue;
 142
 143 static struct hlist_head connection_hash[CONN_HASH_SIZE];
 144 static DEFINE_MUTEX(connections_lock);
 145 static struct kmem_cache *con_cache;
 146
 147 static void process_recv_sockets(struct work_struct *work);
 148 static void process_send_sockets(struct work_struct *work);
 149
 150
 151 /* This is deliberately very simple because most clusters have simple
 152    sequential nodeids, so we should be able to go straight to a connection
 153    struct in the array */
 154 static inline int nodeid_hash(int nodeid)
 155 {
 156         return nodeid & (CONN_HASH_SIZE-1);
 157 }
 158
 159 static struct connection *__find_con(int nodeid)
 160 {
 161         int r;
 162         struct hlist_node *h;
 163         struct connection *con;
 164
 165         r = nodeid_hash(nodeid);
 166
 167         hlist_for_each_entry(con, h, &connection_hash[r], list) {
 168                 if (con->nodeid == nodeid)
 169                         return con;
 170         }
 171         return NULL;
 172 }
 173
 174 /*
 175  * If 'allocation' is zero then we don't attempt to create a new
 176  * connection structure for this node.
 177  */
 178 static struct connection *__nodeid2con(int nodeid, gfp_t alloc)
 179 {
 180         struct connection *con = NULL;
 181         int r;
 182
 183         con = __find_con(nodeid);
 184         if (con || !alloc)
 185                 return con;
 186
 187         con = kmem_cache_zalloc(con_cache, alloc);
 188         if (!con)
 189                 return NULL;
 190
 191         r = nodeid_hash(nodeid);
 192         hlist_add_head(&con->list, &connection_hash[r]);
 193
 194         con->nodeid = nodeid;
 195         mutex_init(&con->sock_mutex);
 196         INIT_LIST_HEAD(&con->writequeue);
 197         spin_lock_init(&con->writequeue_lock);
 198         INIT_WORK(&con->swork, process_send_sockets);
 199         INIT_WORK(&con->rwork, process_recv_sockets);
 200
 201         /* Setup action pointers for child sockets */
 202         if (con->nodeid) {
 203                 struct connection *zerocon = __find_con(0);
 204
 205                 con->connect_action = zerocon->connect_action;
 206                 if (!con->rx_action)
 207                         con->rx_action = zerocon->rx_action;
 208         }
 209
 210         return con;
 211 }
 212
 213 /* Loop round all connections */
 214 static void foreach_conn(void (*conn_func)(struct connection *c))
 215 {
 216         int i;
 217         struct hlist_node *h, *n;
 218         struct connection *con;
 219
 220         for (i = 0; i < CONN_HASH_SIZE; i++) {
 221                 hlist_for_each_entry_safe(con, h, n, &connection_hash[i], list){
 222                         conn_func(con);
 223                 }
 224         }
 225 }
 226
 227 static struct connection *nodeid2con(int nodeid, gfp_t allocation)
 228 {
 229         struct connection *con;
 230
 231         mutex_lock(&connections_lock);
 232         con = __nodeid2con(nodeid, allocation);
 233         mutex_unlock(&connections_lock);
 234
 235         return con;
 236 }
 237
 238 /* This is a bit drastic, but only called when things go wrong */
 239 static struct connection *assoc2con(int assoc_id)
 240 {
 241         int i;
 242         struct hlist_node *h;
 243         struct connection *con;
 244
 245         mutex_lock(&connections_lock);
 246
 247         for (i = 0 ; i < CONN_HASH_SIZE; i++) {
 248                 hlist_for_each_entry(con, h, &connection_hash[i], list) {
 249                         if (con && con->sctp_assoc == assoc_id) {
 250                                 mutex_unlock(&connections_lock);
 251                                 return con;
 252                         }
 253                 }
 254         }
 255         mutex_unlock(&connections_lock);
 256         return NULL;
 257 }
 258
 259 static int nodeid_to_addr(int nodeid, struct sockaddr *retaddr)
 260 {
 261         struct sockaddr_storage addr;
 262         int error;
 263
 264         if (!dlm_local_count)
 265                 return -1;
 266
 267         error = dlm_nodeid_to_addr(nodeid, &addr);
 268         if (error)
 269                 return error;
 270
 271         if (dlm_local_addr[0]->ss_family == AF_INET) {
 272                 struct sockaddr_in *in4  = (struct sockaddr_in *) &addr;
 273                 struct sockaddr_in *ret4 = (struct sockaddr_in *) retaddr;
 274                 ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
 275         } else {
 276                 struct sockaddr_in6 *in6  = (struct sockaddr_in6 *) &addr;
 277                 struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) retaddr;
 278                 ipv6_addr_copy(&ret6->sin6_addr, &in6->sin6_addr);
 279         }
 280
 281         return 0;
 282 }
 283
 284 /* Data available on socket or listen socket received a connect */
 285 static void lowcomms_data_ready(struct sock *sk, int count_unused)
 286 {
 287         struct connection *con = sock2con(sk);
 288         if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
 289                 queue_work(recv_workqueue, &con->rwork);
 290 }
 291
 292 static void lowcomms_write_space(struct sock *sk)
 293 {
 294         struct connection *con = sock2con(sk);
 295
 296         if (con && !test_and_set_bit(CF_WRITE_PENDING, &con->flags))
 297                 queue_work(send_workqueue, &con->swork);
 298 }
 299
 300 static inline void lowcomms_connect_sock(struct connection *con)
 301 {
 302         if (!test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
 303                 queue_work(send_workqueue, &con->swork);
 304 }
 305
 306 static void lowcomms_state_change(struct sock *sk)
 307 {
 308         if (sk->sk_state == TCP_ESTABLISHED)
 309                 lowcomms_write_space(sk);
 310 }
 311
 312 int dlm_lowcomms_connect_node(int nodeid)
 313 {
 314         struct connection *con;
 315
 316         if (nodeid == dlm_our_nodeid())
 317                 return 0;
 318
 319         con = nodeid2con(nodeid, GFP_NOFS);
 320         if (!con)
 321                 return -ENOMEM;
 322         lowcomms_connect_sock(con);
 323         return 0;
 324 }
 325
 326 /* Make a socket active */
 327 static int add_sock(struct socket *sock, struct connection *con)
 328 {
 329         con->sock = sock;
 330
 331         /* Install a data_ready callback */
 332         con->sock->sk->sk_data_ready = lowcomms_data_ready;
 333         con->sock->sk->sk_write_space = lowcomms_write_space;
 334         con->sock->sk->sk_state_change = lowcomms_state_change;
 335         con->sock->sk->sk_user_data = con;
 336         con->sock->sk->sk_allocation = GFP_NOFS;
 337         return 0;
 338 }
 339
 340 /* Add the port number to an IPv6 or 4 sockaddr and return the address
 341    length */
 342 static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
 343                           int *addr_len)
 344 {
 345         saddr->ss_family =  dlm_local_addr[0]->ss_family;
 346         if (saddr->ss_family == AF_INET) {
 347                 struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
 348                 in4_addr->sin_port = cpu_to_be16(port);
 349                 *addr_len = sizeof(struct sockaddr_in);
 350                 memset(&in4_addr->sin_zero, 0, sizeof(in4_addr->sin_zero));
 351         } else {
 352                 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
 353                 in6_addr->sin6_port = cpu_to_be16(port);
 354                 *addr_len = sizeof(struct sockaddr_in6);
 355         }
 356         memset((char *)saddr + *addr_len, 0, sizeof(struct sockaddr_storage) - *addr_len);
 357 }
 358
 359 /* Close a remote connection and tidy up */
 360 static void close_connection(struct connection *con, bool and_other)
 361 {
 362         mutex_lock(&con->sock_mutex);
 363
 364         if (con->sock) {
 365                 sock_release(con->sock);
 366                 con->sock = NULL;
 367         }
 368         if (con->othercon && and_other) {
 369                 /* Will only re-enter once. */
 370                 close_connection(con->othercon, false);
 371         }
 372         if (con->rx_page) {
 373                 __free_page(con->rx_page);
 374                 con->rx_page = NULL;
 375         }
 376
 377         con->retries = 0;
 378         mutex_unlock(&con->sock_mutex);
 379 }
 380
 381 /* We only send shutdown messages to nodes that are not part of the cluster */
 382 static void sctp_send_shutdown(sctp_assoc_t associd)
 383 {
 384         static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 385         struct msghdr outmessage;
 386         struct cmsghdr *cmsg;
 387         struct sctp_sndrcvinfo *sinfo;
 388         int ret;
 389         struct connection *con;
 390
 391         con = nodeid2con(0,0);
 392         BUG_ON(con == NULL);
 393
 394         outmessage.msg_name = NULL;
 395         outmessage.msg_namelen = 0;
 396         outmessage.msg_control = outcmsg;
 397         outmessage.msg_controllen = sizeof(outcmsg);
 398         outmessage.msg_flags = MSG_EOR;
 399
 400         cmsg = CMSG_FIRSTHDR(&outmessage);
 401         cmsg->cmsg_level = IPPROTO_SCTP;
 402         cmsg->cmsg_type = SCTP_SNDRCV;
 403         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
 404         outmessage.msg_controllen = cmsg->cmsg_len;
 405         sinfo = CMSG_DATA(cmsg);
 406         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
 407
 408         sinfo->sinfo_flags |= MSG_EOF;
 409         sinfo->sinfo_assoc_id = associd;
 410
 411         ret = kernel_sendmsg(con->sock, &outmessage, NULL, 0, 0);
 412
 413         if (ret != 0)
 414                 log_print("send EOF to node failed: %d", ret);
 415 }
 416
 417 static void sctp_init_failed_foreach(struct connection *con)
 418 {
 419         con->sctp_assoc = 0;
 420         if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
 421                 if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags))
 422                         queue_work(send_workqueue, &con->swork);
 423         }
 424 }
 425
 426 /* INIT failed but we don't know which node...
 427    restart INIT on all pending nodes */
 428 static void sctp_init_failed(void)
 429 {
 430         mutex_lock(&connections_lock);
 431
 432         foreach_conn(sctp_init_failed_foreach);
 433
 434         mutex_unlock(&connections_lock);
 435 }
 436
 437 /* Something happened to an association */
 438 static void process_sctp_notification(struct connection *con,
 439                                       struct msghdr *msg, char *buf)
 440 {
 441         union sctp_notification *sn = (union sctp_notification *)buf;
 442
 443         if (sn->sn_header.sn_type == SCTP_ASSOC_CHANGE) {
 444                 switch (sn->sn_assoc_change.sac_state) {
 445
 446                 case SCTP_COMM_UP:
 447                 case SCTP_RESTART:
 448                 {
 449                         /* Check that the new node is in the lockspace */
 450                         struct sctp_prim prim;
 451                         int nodeid;
 452                         int prim_len, ret;
 453                         int addr_len;
 454                         struct connection *new_con;
 455                         struct file *file;
 456                         sctp_peeloff_arg_t parg;
 457                         int parglen = sizeof(parg);
 458
 459                         /*
 460                          * We get this before any data for an association.
 461                          * We verify that the node is in the cluster and
 462                          * then peel off a socket for it.
 463                          */
 464                         if ((int)sn->sn_assoc_change.sac_assoc_id <= 0) {
 465                                 log_print("COMM_UP for invalid assoc ID %d",
 466                                          (int)sn->sn_assoc_change.sac_assoc_id);
 467                                 sctp_init_failed();
 468                                 return;
 469                         }
 470                         memset(&prim, 0, sizeof(struct sctp_prim));
 471                         prim_len = sizeof(struct sctp_prim);
 472                         prim.ssp_assoc_id = sn->sn_assoc_change.sac_assoc_id;
 473
 474                         ret = kernel_getsockopt(con->sock,
 475                                                 IPPROTO_SCTP,
 476                                                 SCTP_PRIMARY_ADDR,
 477                                                 (char*)&prim,
 478                                                 &prim_len);
 479                         if (ret < 0) {
 480                                 log_print("getsockopt/sctp_primary_addr on "
 481                                           "new assoc %d failed : %d",
 482                                           (int)sn->sn_assoc_change.sac_assoc_id,
 483                                           ret);
 484
 485                                 /* Retry INIT later */
 486                                 new_con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
 487                                 if (new_con)
 488                                         clear_bit(CF_CONNECT_PENDING, &con->flags);
 489                                 return;
 490                         }
 491                         make_sockaddr(&prim.ssp_addr, 0, &addr_len);
 492                         if (dlm_addr_to_nodeid(&prim.ssp_addr, &nodeid)) {
 493                                 int i;
 494                                 unsigned char *b=(unsigned char *)&prim.ssp_addr;
 495                                 log_print("reject connect from unknown addr");
 496                                 for (i=0; i<sizeof(struct sockaddr_storage);i++)
 497                                         printk("%02x ", b[i]);
 498                                 printk("\n");
 499                                 sctp_send_shutdown(prim.ssp_assoc_id);
 500                                 return;
 501                         }
 502
 503                         new_con = nodeid2con(nodeid, GFP_NOFS);
 504                         if (!new_con)
 505                                 return;
 506
 507                         /* Peel off a new sock */
 508                         parg.associd = sn->sn_assoc_change.sac_assoc_id;
 509                         ret = kernel_getsockopt(con->sock, IPPROTO_SCTP,
 510                                                 SCTP_SOCKOPT_PEELOFF,
 511                                                 (void *)&parg, &parglen);
 512                         if (ret) {
 513                                 log_print("Can't peel off a socket for "
 514                                           "connection %d to node %d: err=%d\n",
 515                                           parg.associd, nodeid, ret);
 516                         }
 517                         file = fget(parg.sd);
 518                         new_con->sock = SOCKET_I(file->f_dentry->d_inode);
 519                         add_sock(new_con->sock, new_con);
 520                         fput(file);
 521                         put_unused_fd(parg.sd);
 522
 523                         log_print("got new/restarted association %d nodeid %d",
 524                                  (int)sn->sn_assoc_change.sac_assoc_id, nodeid);
 525
 526                         /* Send any pending writes */
 527                         clear_bit(CF_CONNECT_PENDING, &new_con->flags);
 528                         clear_bit(CF_INIT_PENDING, &con->flags);
 529                         if (!test_and_set_bit(CF_WRITE_PENDING, &new_con->flags)) {
 530                                 queue_work(send_workqueue, &new_con->swork);
 531                         }
 532                         if (!test_and_set_bit(CF_READ_PENDING, &new_con->flags))
 533                                 queue_work(recv_workqueue, &new_con->rwork);
 534                 }
 535                 break;
 536
 537                 case SCTP_COMM_LOST:
 538                 case SCTP_SHUTDOWN_COMP:
 539                 {
 540                         con = assoc2con(sn->sn_assoc_change.sac_assoc_id);
 541                         if (con) {
 542                                 con->sctp_assoc = 0;
 543                         }
 544                 }
 545                 break;
 546
 547                 /* We don't know which INIT failed, so clear the PENDING flags
 548                  * on them all.  if assoc_id is zero then it will then try
 549                  * again */
 550
 551                 case SCTP_CANT_STR_ASSOC:
 552                 {
 553                         log_print("Can't start SCTP association - retrying");
 554                         sctp_init_failed();
 555                 }
 556                 break;
 557
 558                 default:
 559                         log_print("unexpected SCTP assoc change id=%d state=%d",
 560                                   (int)sn->sn_assoc_change.sac_assoc_id,
 561                                   sn->sn_assoc_change.sac_state);
 562                 }
 563         }
 564 }
 565
 566 /* Data received from remote end */
 567 static int receive_from_sock(struct connection *con)
 568 {
 569         int ret = 0;
 570         struct msghdr msg = {};
 571         struct kvec iov[2];
 572         unsigned len;
 573         int r;
 574         int call_again_soon = 0;
 575         int nvec;
 576         char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 577
 578         mutex_lock(&con->sock_mutex);
 579
 580         if (con->sock == NULL) {
 581                 ret = -EAGAIN;
 582                 goto out_close;
 583         }
 584
 585         if (con->rx_page == NULL) {
 586                 /*
 587                  * This doesn't need to be atomic, but I think it should
 588                  * improve performance if it is.
 589                  */
 590                 con->rx_page = alloc_page(GFP_ATOMIC);
 591                 if (con->rx_page == NULL)
 592                         goto out_resched;
 593                 cbuf_init(&con->cb, PAGE_CACHE_SIZE);
 594         }
 595
 596         /* Only SCTP needs these really */
 597         memset(&incmsg, 0, sizeof(incmsg));
 598         msg.msg_control = incmsg;
 599         msg.msg_controllen = sizeof(incmsg);
 600
 601         /*
 602          * iov[0] is the bit of the circular buffer between the current end
 603          * point (cb.base + cb.len) and the end of the buffer.
 604          */
 605         iov[0].iov_len = con->cb.base - cbuf_data(&con->cb);
 606         iov[0].iov_base = page_address(con->rx_page) + cbuf_data(&con->cb);
 607         iov[1].iov_len = 0;
 608         nvec = 1;
 609
 610         /*
 611          * iov[1] is the bit of the circular buffer between the start of the
 612          * buffer and the start of the currently used section (cb.base)
 613          */
 614         if (cbuf_data(&con->cb) >= con->cb.base) {
 615                 iov[0].iov_len = PAGE_CACHE_SIZE - cbuf_data(&con->cb);
 616                 iov[1].iov_len = con->cb.base;
 617                 iov[1].iov_base = page_address(con->rx_page);
 618                 nvec = 2;
 619         }
 620         len = iov[0].iov_len + iov[1].iov_len;
 621
 622         r = ret = kernel_recvmsg(con->sock, &msg, iov, nvec, len,
 623                                MSG_DONTWAIT | MSG_NOSIGNAL);
 624         if (ret <= 0)
 625                 goto out_close;
 626
 627         /* Process SCTP notifications */
 628         if (msg.msg_flags & MSG_NOTIFICATION) {
 629                 msg.msg_control = incmsg;
 630                 msg.msg_controllen = sizeof(incmsg);
 631
 632                 process_sctp_notification(con, &msg,
 633                                 page_address(con->rx_page) + con->cb.base);
 634                 mutex_unlock(&con->sock_mutex);
 635                 return 0;
 636         }
 637         BUG_ON(con->nodeid == 0);
 638
 639         if (ret == len)
 640                 call_again_soon = 1;
 641         cbuf_add(&con->cb, ret);
 642         ret = dlm_process_incoming_buffer(con->nodeid,
 643                                           page_address(con->rx_page),
 644                                           con->cb.base, con->cb.len,
 645                                           PAGE_CACHE_SIZE);
 646         if (ret == -EBADMSG) {
 647                 log_print("lowcomms: addr=%p, base=%u, len=%u, "
 648                           "iov_len=%u, iov_base[0]=%p, read=%d",
 649                           page_address(con->rx_page), con->cb.base, con->cb.len,
 650                           len, iov[0].iov_base, r);
 651         }
 652         if (ret < 0)
 653                 goto out_close;
 654         cbuf_eat(&con->cb, ret);
 655
 656         if (cbuf_empty(&con->cb) && !call_again_soon) {
 657                 __free_page(con->rx_page);
 658                 con->rx_page = NULL;
 659         }
 660
 661         if (call_again_soon)
 662                 goto out_resched;
 663         mutex_unlock(&con->sock_mutex);
 664         return 0;
 665
 666 out_resched:
 667         if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
 668                 queue_work(recv_workqueue, &con->rwork);
 669         mutex_unlock(&con->sock_mutex);
 670         return -EAGAIN;
 671
 672 out_close:
 673         mutex_unlock(&con->sock_mutex);
 674         if (ret != -EAGAIN) {
 675                 close_connection(con, false);
 676                 /* Reconnect when there is something to send */
 677         }
 678         /* Don't return success if we really got EOF */
 679         if (ret == 0)
 680                 ret = -EAGAIN;
 681
 682         return ret;
 683 }
 684
 685 /* Listening socket is busy, accept a connection */
 686 static int tcp_accept_from_sock(struct connection *con)
 687 {
 688         int result;
 689         struct sockaddr_storage peeraddr;
 690         struct socket *newsock;
 691         int len;
 692         int nodeid;
 693         struct connection *newcon;
 694         struct connection *addcon;
 695
 696         memset(&peeraddr, 0, sizeof(peeraddr));
 697         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 698                                   IPPROTO_TCP, &newsock);
 699         if (result < 0)
 700                 return -ENOMEM;
 701
 702         mutex_lock_nested(&con->sock_mutex, 0);
 703
 704         result = -ENOTCONN;
 705         if (con->sock == NULL)
 706                 goto accept_err;
 707
 708         newsock->type = con->sock->type;
 709         newsock->ops = con->sock->ops;
 710
 711         result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK);
 712         if (result < 0)
 713                 goto accept_err;
 714
 715         /* Get the connected socket's peer */
 716         memset(&peeraddr, 0, sizeof(peeraddr));
 717         if (newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr,
 718                                   &len, 2)) {
 719                 result = -ECONNABORTED;
 720                 goto accept_err;
 721         }
 722
 723         /* Get the new node's NODEID */
 724         make_sockaddr(&peeraddr, 0, &len);
 725         if (dlm_addr_to_nodeid(&peeraddr, &nodeid)) {
 726                 log_print("connect from non cluster node");
 727                 sock_release(newsock);
 728                 mutex_unlock(&con->sock_mutex);
 729                 return -1;
 730         }
 731
 732         log_print("got connection from %d", nodeid);
 733
 734         /*  Check to see if we already have a connection to this node. This
 735          *  could happen if the two nodes initiate a connection at roughly
 736          *  the same time and the connections cross on the wire.
 737          *  In this case we store the incoming one in "othercon"
 738          */
 739         newcon = nodeid2con(nodeid, GFP_NOFS);
 740         if (!newcon) {
 741                 result = -ENOMEM;
 742                 goto accept_err;
 743         }
 744         mutex_lock_nested(&newcon->sock_mutex, 1);
 745         if (newcon->sock) {
 746                 struct connection *othercon = newcon->othercon;
 747
 748                 if (!othercon) {
 749                         othercon = kmem_cache_zalloc(con_cache, GFP_NOFS);
 750                         if (!othercon) {
 751                                 log_print("failed to allocate incoming socket");
 752                                 mutex_unlock(&newcon->sock_mutex);
 753                                 result = -ENOMEM;
 754                                 goto accept_err;
 755                         }
 756                         othercon->nodeid = nodeid;
 757                         othercon->rx_action = receive_from_sock;
 758                         mutex_init(&othercon->sock_mutex);
 759                         INIT_WORK(&othercon->swork, process_send_sockets);
 760                         INIT_WORK(&othercon->rwork, process_recv_sockets);
 761                         set_bit(CF_IS_OTHERCON, &othercon->flags);
 762                 }
 763                 if (!othercon->sock) {
 764                         newcon->othercon = othercon;
 765                         othercon->sock = newsock;
 766                         newsock->sk->sk_user_data = othercon;
 767                         add_sock(newsock, othercon);
 768                         addcon = othercon;
 769                 }
 770                 else {
 771                         printk("Extra connection from node %d attempted\n", nodeid);
 772                         result = -EAGAIN;
 773                         mutex_unlock(&newcon->sock_mutex);
 774                         goto accept_err;
 775                 }
 776         }
 777         else {
 778                 newsock->sk->sk_user_data = newcon;
 779                 newcon->rx_action = receive_from_sock;
 780                 add_sock(newsock, newcon);
 781                 addcon = newcon;
 782         }
 783
 784         mutex_unlock(&newcon->sock_mutex);
 785
 786         /*
 787          * Add it to the active queue in case we got data
 788          * beween processing the accept adding the socket
 789          * to the read_sockets list
 790          */
 791         if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
 792                 queue_work(recv_workqueue, &addcon->rwork);
 793         mutex_unlock(&con->sock_mutex);
 794
 795         return 0;
 796
 797 accept_err:
 798         mutex_unlock(&con->sock_mutex);
 799         sock_release(newsock);
 800
 801         if (result != -EAGAIN)
 802                 log_print("error accepting connection from node: %d", result);
 803         return result;
 804 }
 805
 806 static void free_entry(struct writequeue_entry *e)
 807 {
 808         __free_page(e->page);
 809         kfree(e);
 810 }
 811
 812 /* Initiate an SCTP association.
 813    This is a special case of send_to_sock() in that we don't yet have a
 814    peeled-off socket for this association, so we use the listening socket
 815    and add the primary IP address of the remote node.
 816  */
 817 static void sctp_init_assoc(struct connection *con)
 818 {
 819         struct sockaddr_storage rem_addr;
 820         char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
 821         struct msghdr outmessage;
 822         struct cmsghdr *cmsg;
 823         struct sctp_sndrcvinfo *sinfo;
 824         struct connection *base_con;
 825         struct writequeue_entry *e;
 826         int len, offset;
 827         int ret;
 828         int addrlen;
 829         struct kvec iov[1];
 830
 831         if (test_and_set_bit(CF_INIT_PENDING, &con->flags))
 832                 return;
 833
 834         if (con->retries++ > MAX_CONNECT_RETRIES)
 835                 return;
 836
 837         log_print("Initiating association with node %d", con->nodeid);
 838
 839         if (nodeid_to_addr(con->nodeid, (struct sockaddr *)&rem_addr)) {
 840                 log_print("no address for nodeid %d", con->nodeid);
 841                 return;
 842         }
 843         base_con = nodeid2con(0, 0);
 844         BUG_ON(base_con == NULL);
 845
 846         make_sockaddr(&rem_addr, dlm_config.ci_tcp_port, &addrlen);
 847
 848         outmessage.msg_name = &rem_addr;
 849         outmessage.msg_namelen = addrlen;
 850         outmessage.msg_control = outcmsg;
 851         outmessage.msg_controllen = sizeof(outcmsg);
 852         outmessage.msg_flags = MSG_EOR;
 853
 854         spin_lock(&con->writequeue_lock);
 855         e = list_entry(con->writequeue.next, struct writequeue_entry,
 856                        list);
 857
 858         BUG_ON((struct list_head *) e == &con->writequeue);
 859
 860         len = e->len;
 861         offset = e->offset;
 862         spin_unlock(&con->writequeue_lock);
 863
 864         /* Send the first block off the write queue */
 865         iov[0].iov_base = page_address(e->page)+offset;
 866         iov[0].iov_len = len;
 867
 868         cmsg = CMSG_FIRSTHDR(&outmessage);
 869         cmsg->cmsg_level = IPPROTO_SCTP;
 870         cmsg->cmsg_type = SCTP_SNDRCV;
 871         cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
 872         sinfo = CMSG_DATA(cmsg);
 873         memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
 874         sinfo->sinfo_ppid = cpu_to_le32(dlm_our_nodeid());
 875         outmessage.msg_controllen = cmsg->cmsg_len;
 876
 877         ret = kernel_sendmsg(base_con->sock, &outmessage, iov, 1, len);
 878         if (ret < 0) {
 879                 log_print("Send first packet to node %d failed: %d",
 880                           con->nodeid, ret);
 881
 882                 /* Try again later */
 883                 clear_bit(CF_CONNECT_PENDING, &con->flags);
 884                 clear_bit(CF_INIT_PENDING, &con->flags);
 885         }
 886         else {
 887                 spin_lock(&con->writequeue_lock);
 888                 e->offset += ret;
 889                 e->len -= ret;
 890
 891                 if (e->len == 0 && e->users == 0) {
 892                         list_del(&e->list);
 893                         free_entry(e);
 894                 }
 895                 spin_unlock(&con->writequeue_lock);
 896         }
 897 }
 898
 899 /* Connect a new socket to its peer */
 900 static void tcp_connect_to_sock(struct connection *con)
 901 {
 902         int result = -EHOSTUNREACH;
 903         struct sockaddr_storage saddr, src_addr;
 904         int addr_len;
 905         struct socket *sock;
 906
 907         if (con->nodeid == 0) {
 908                 log_print("attempt to connect sock 0 foiled");
 909                 return;
 910         }
 911
 912         mutex_lock(&con->sock_mutex);
 913         if (con->retries++ > MAX_CONNECT_RETRIES)
 914                 goto out;
 915
 916         /* Some odd races can cause double-connects, ignore them */
 917         if (con->sock) {
 918                 result = 0;
 919                 goto out;
 920         }
 921
 922         /* Create a socket to communicate with */
 923         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 924                                   IPPROTO_TCP, &sock);
 925         if (result < 0)
 926                 goto out_err;
 927
 928         memset(&saddr, 0, sizeof(saddr));
 929         if (dlm_nodeid_to_addr(con->nodeid, &saddr)) {
 930                 sock_release(sock);
 931                 goto out_err;
 932         }
 933
 934         sock->sk->sk_user_data = con;
 935         con->rx_action = receive_from_sock;
 936         con->connect_action = tcp_connect_to_sock;
 937         add_sock(sock, con);
 938
 939         /* Bind to our cluster-known address connecting to avoid
 940            routing problems */
 941         memcpy(&src_addr, dlm_local_addr[0], sizeof(src_addr));
 942         make_sockaddr(&src_addr, 0, &addr_len);
 943         result = sock->ops->bind(sock, (struct sockaddr *) &src_addr,
 944                                  addr_len);
 945         if (result < 0) {
 946                 log_print("could not bind for connect: %d", result);
 947                 /* This *may* not indicate a critical error */
 948         }
 949
 950         make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);
 951
 952         log_print("connecting to %d", con->nodeid);
 953         result =
 954                 sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
 955                                    O_NONBLOCK);
 956         if (result == -EINPROGRESS)
 957                 result = 0;
 958         if (result == 0)
 959                 goto out;
 960
 961 out_err:
 962         if (con->sock) {
 963                 sock_release(con->sock);
 964                 con->sock = NULL;
 965         }
 966         /*
 967          * Some errors are fatal and this list might need adjusting. For other
 968          * errors we try again until the max number of retries is reached.
 969          */
 970         if (result != -EHOSTUNREACH && result != -ENETUNREACH &&
 971             result != -ENETDOWN && result != -EINVAL
 972             && result != -EPROTONOSUPPORT) {
 973                 lowcomms_connect_sock(con);
 974                 result = 0;
 975         }
 976 out:
 977         mutex_unlock(&con->sock_mutex);
 978         return;
 979 }
 980
 981 static struct socket *tcp_create_listen_sock(struct connection *con,
 982                                              struct sockaddr_storage *saddr)
 983 {
 984         struct socket *sock = NULL;
 985         int result = 0;
 986         int one = 1;
 987         int addr_len;
 988
 989         if (dlm_local_addr[0]->ss_family == AF_INET)
 990                 addr_len = sizeof(struct sockaddr_in);
 991         else
 992                 addr_len = sizeof(struct sockaddr_in6);
 993
 994         /* Create a socket to communicate with */
 995         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
 996                                   IPPROTO_TCP, &sock);
 997         if (result < 0) {
 998                 log_print("Can't create listening comms socket");
 999                 goto create_out;
1000         }
1001
1002         result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
1003                                    (char *)&one, sizeof(one));
1004
1005         if (result < 0) {
1006                 log_print("Failed to set SO_REUSEADDR on socket: %d", result);
1007         }
1008         sock->sk->sk_user_data = con;
1009         con->rx_action = tcp_accept_from_sock;
1010         con->connect_action = tcp_connect_to_sock;
1011         con->sock = sock;
1012
1013         /* Bind to our port */
1014         make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
1015         result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
1016         if (result < 0) {
1017                 log_print("Can't bind to port %d", dlm_config.ci_tcp_port);
1018                 sock_release(sock);
1019                 sock = NULL;
1020                 con->sock = NULL;
1021                 goto create_out;
1022         }
1023         result = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
1024                                  (char *)&one, sizeof(one));
1025         if (result < 0) {
1026                 log_print("Set keepalive failed: %d", result);
1027         }
1028
1029         result = sock->ops->listen(sock, 5);
1030         if (result < 0) {
1031                 log_print("Can't listen on port %d", dlm_config.ci_tcp_port);
1032                 sock_release(sock);
1033                 sock = NULL;
1034                 goto create_out;
1035         }
1036
1037 create_out:
1038         return sock;
1039 }
1040
1041 /* Get local addresses */
1042 static void init_local(void)
1043 {
1044         struct sockaddr_storage sas, *addr;
1045         int i;
1046
1047         dlm_local_count = 0;
1048         for (i = 0; i < DLM_MAX_ADDR_COUNT - 1; i++) {
1049                 if (dlm_our_addr(&sas, i))
1050                         break;
1051
1052                 addr = kmalloc(sizeof(*addr), GFP_KERNEL);
1053                 if (!addr)
1054                         break;
1055                 memcpy(addr, &sas, sizeof(*addr));
1056                 dlm_local_addr[dlm_local_count++] = addr;
1057         }
1058 }
1059
1060 /* Bind to an IP address. SCTP allows multiple address so it can do
1061    multi-homing */
1062 static int add_sctp_bind_addr(struct connection *sctp_con,
1063                               struct sockaddr_storage *addr,
1064                               int addr_len, int num)
1065 {
1066         int result = 0;
1067
1068         if (num == 1)
1069                 result = kernel_bind(sctp_con->sock,
1070                                      (struct sockaddr *) addr,
1071                                      addr_len);
1072         else
1073                 result = kernel_setsockopt(sctp_con->sock, SOL_SCTP,
1074                                            SCTP_SOCKOPT_BINDX_ADD,
1075                                            (char *)addr, addr_len);
1076
1077         if (result < 0)
1078                 log_print("Can't bind to port %d addr number %d",
1079                           dlm_config.ci_tcp_port, num);
1080
1081         return result;
1082 }
1083
1084 /* Initialise SCTP socket and bind to all interfaces */
1085 static int sctp_listen_for_all(void)
1086 {
1087         struct socket *sock = NULL;
1088         struct sockaddr_storage localaddr;
1089         struct sctp_event_subscribe subscribe;
1090         int result = -EINVAL, num = 1, i, addr_len;
1091         struct connection *con = nodeid2con(0, GFP_KERNEL);
1092         int bufsize = NEEDED_RMEM;
1093
1094         if (!con)
1095                 return -ENOMEM;
1096
1097         log_print("Using SCTP for communications");
1098
1099         result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_SEQPACKET,
1100                                   IPPROTO_SCTP, &sock);
1101         if (result < 0) {
1102                 log_print("Can't create comms socket, check SCTP is loaded");
1103                 goto out;
1104         }
1105
1106         /* Listen for events */
1107         memset(&subscribe, 0, sizeof(subscribe));
1108         subscribe.sctp_data_io_event = 1;
1109         subscribe.sctp_association_event = 1;
1110         subscribe.sctp_send_failure_event = 1;
1111         subscribe.sctp_shutdown_event = 1;
1112         subscribe.sctp_partial_delivery_event = 1;
1113
1114         result = kernel_setsockopt(sock, SOL_SOCKET, SO_RCVBUFFORCE,
1115                                  (char *)&bufsize, sizeof(bufsize));
1116         if (result)
1117                 log_print("Error increasing buffer space on socket %d", result);
1118
1119         result = kernel_setsockopt(sock, SOL_SCTP, SCTP_EVENTS,
1120                                    (char *)&subscribe, sizeof(subscribe));
1121         if (result < 0) {
1122                 log_print("Failed to set SCTP_EVENTS on socket: result=%d",
1123                           result);
1124                 goto create_delsock;
1125         }
1126
1127         /* Init con struct */
1128         sock->sk->sk_user_data = con;
1129         con->sock = sock;
1130         con->sock->sk->sk_data_ready = lowcomms_data_ready;
1131         con->rx_action = receive_from_sock;
1132         con->connect_action = sctp_init_assoc;
1133
1134         /* Bind to all interfaces. */
1135         for (i = 0; i < dlm_local_count; i++) {
1136                 memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
1137                 make_sockaddr(&localaddr, dlm_config.ci_tcp_port, &addr_len);
1138
1139                 result = add_sctp_bind_addr(con, &localaddr, addr_len, num);
1140                 if (result)
1141                         goto create_delsock;
1142                 ++num;
1143         }
1144
1145         result = sock->ops->listen(sock, 5);
1146         if (result < 0) {
1147                 log_print("Can't set socket listening");
1148                 goto create_delsock;
1149         }
1150
1151         return 0;
1152
1153 create_delsock:
1154         sock_release(sock);
1155         con->sock = NULL;
1156 out:
1157         return result;
1158 }
1159
1160 static int tcp_listen_for_all(void)
1161 {
1162         struct socket *sock = NULL;
1163         struct connection *con = nodeid2con(0, GFP_KERNEL);
1164         int result = -EINVAL;
1165
1166         if (!con)
1167                 return -ENOMEM;
1168
1169         /* We don't support multi-homed hosts */
1170         if (dlm_local_addr[1] != NULL) {
1171                 log_print("TCP protocol can't handle multi-homed hosts, "
1172                           "try SCTP");
1173                 return -EINVAL;
1174         }
1175
1176         log_print("Using TCP for communications");
1177
1178         sock = tcp_create_listen_sock(con, dlm_local_addr[0]);
1179         if (sock) {
1180                 add_sock(sock, con);
1181                 result = 0;
1182         }
1183         else {
1184                 result = -EADDRINUSE;
1185         }
1186
1187         return result;
1188 }
1189
1190
1191
1192 static struct writequeue_entry *new_writequeue_entry(struct connection *con,
1193                                                      gfp_t allocation)
1194 {
1195         struct writequeue_entry *entry;
1196
1197         entry = kmalloc(sizeof(struct writequeue_entry), allocation);
1198         if (!entry)
1199                 return NULL;
1200
1201         entry->page = alloc_page(allocation);
1202         if (!entry->page) {
1203                 kfree(entry);
1204                 return NULL;
1205         }
1206
1207         entry->offset = 0;
1208         entry->len = 0;
1209         entry->end = 0;
1210         entry->users = 0;
1211         entry->con = con;
1212
1213         return entry;
1214 }
1215
1216 void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
1217 {
1218         struct connection *con;
1219         struct writequeue_entry *e;
1220         int offset = 0;
1221         int users = 0;
1222
1223         con = nodeid2con(nodeid, allocation);
1224         if (!con)
1225                 return NULL;
1226
1227         spin_lock(&con->writequeue_lock);
1228         e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
1229         if ((&e->list == &con->writequeue) ||
1230             (PAGE_CACHE_SIZE - e->end < len)) {
1231                 e = NULL;
1232         } else {
1233                 offset = e->end;
1234                 e->end += len;
1235                 users = e->users++;
1236         }
1237         spin_unlock(&con->writequeue_lock);
1238
1239         if (e) {
1240         got_one:
1241                 *ppc = page_address(e->page) + offset;
1242                 return e;
1243         }
1244
1245         e = new_writequeue_entry(con, allocation);
1246         if (e) {
1247                 spin_lock(&con->writequeue_lock);
1248                 offset = e->end;
1249                 e->end += len;
1250                 users = e->users++;
1251                 list_add_tail(&e->list, &con->writequeue);
1252                 spin_unlock(&con->writequeue_lock);
1253                 goto got_one;
1254         }
1255         return NULL;
1256 }
1257
1258 void dlm_lowcomms_commit_buffer(void *mh)
1259 {
1260         struct writequeue_entry *e = (struct writequeue_entry *)mh;
1261         struct connection *con = e->con;
1262         int users;
1263
1264         spin_lock(&con->writequeue_lock);
1265         users = --e->users;
1266         if (users)
1267                 goto out;
1268         e->len = e->end - e->offset;
1269         spin_unlock(&con->writequeue_lock);
1270
1271         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
1272                 queue_work(send_workqueue, &con->swork);
1273         }
1274         return;
1275
1276 out:
1277         spin_unlock(&con->writequeue_lock);
1278         return;
1279 }
1280
1281 /* Send a message */
1282 static void send_to_sock(struct connection *con)
1283 {
1284         int ret = 0;
1285         ssize_t(*sendpage) (struct socket *, struct page *, int, size_t, int);
1286         const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
1287         struct writequeue_entry *e;
1288         int len, offset;
1289
1290         mutex_lock(&con->sock_mutex);
1291         if (con->sock == NULL)
1292                 goto out_connect;
1293
1294         sendpage = con->sock->ops->sendpage;
1295
1296         spin_lock(&con->writequeue_lock);
1297         for (;;) {
1298                 e = list_entry(con->writequeue.next, struct writequeue_entry,
1299                                list);
1300                 if ((struct list_head *) e == &con->writequeue)
1301                         break;
1302
1303                 len = e->len;
1304                 offset = e->offset;
1305                 BUG_ON(len == 0 && e->users == 0);
1306                 spin_unlock(&con->writequeue_lock);
1307
1308                 ret = 0;
1309                 if (len) {
1310                         ret = sendpage(con->sock, e->page, offset, len,
1311                                        msg_flags);
1312                         if (ret == -EAGAIN || ret == 0) {
1313                                 cond_resched();
1314                                 goto out;
1315                         }
1316                         if (ret <= 0)
1317                                 goto send_error;
1318                 }
1319                         /* Don't starve people filling buffers */
1320                         cond_resched();
1321
1322                 spin_lock(&con->writequeue_lock);
1323                 e->offset += ret;
1324                 e->len -= ret;
1325
1326                 if (e->len == 0 && e->users == 0) {
1327                         list_del(&e->list);
1328                         free_entry(e);
1329                         continue;
1330                 }
1331         }
1332         spin_unlock(&con->writequeue_lock);
1333 out:
1334         mutex_unlock(&con->sock_mutex);
1335         return;
1336
1337 send_error:
1338         mutex_unlock(&con->sock_mutex);
1339         close_connection(con, false);
1340         lowcomms_connect_sock(con);
1341         return;
1342
1343 out_connect:
1344         mutex_unlock(&con->sock_mutex);
1345         if (!test_bit(CF_INIT_PENDING, &con->flags))
1346                 lowcomms_connect_sock(con);
1347         return;
1348 }
1349
1350 static void clean_one_writequeue(struct connection *con)
1351 {
1352         struct writequeue_entry *e, *safe;
1353
1354         spin_lock(&con->writequeue_lock);
1355         list_for_each_entry_safe(e, safe, &con->writequeue, list) {
1356                 list_del(&e->list);
1357                 free_entry(e);
1358         }
1359         spin_unlock(&con->writequeue_lock);
1360 }
1361
1362 /* Called from recovery when it knows that a node has
1363    left the cluster */
1364 int dlm_lowcomms_close(int nodeid)
1365 {
1366         struct connection *con;
1367
1368         log_print("closing connection to node %d", nodeid);
1369         con = nodeid2con(nodeid, 0);
1370         if (con) {
1371                 clean_one_writequeue(con);
1372                 close_connection(con, true);
1373         }
1374         return 0;
1375 }
1376
1377 /* Receive workqueue function */
1378 static void process_recv_sockets(struct work_struct *work)
1379 {
1380         struct connection *con = container_of(work, struct connection, rwork);
1381         int err;
1382
1383         clear_bit(CF_READ_PENDING, &con->flags);
1384         do {
1385                 err = con->rx_action(con);
1386         } while (!err);
1387 }
1388
1389 /* Send workqueue function */
1390 static void process_send_sockets(struct work_struct *work)
1391 {
1392         struct connection *con = container_of(work, struct connection, swork);
1393
1394         if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
1395                 con->connect_action(con);
1396         }
1397         clear_bit(CF_WRITE_PENDING, &con->flags);
1398         send_to_sock(con);
1399 }
1400
1401
1402 /* Discard all entries on the write queues */
1403 static void clean_writequeues(void)
1404 {
1405         foreach_conn(clean_one_writequeue);
1406 }
1407
1408 static void work_stop(void)
1409 {
1410         destroy_workqueue(recv_workqueue);
1411         destroy_workqueue(send_workqueue);
1412 }
1413
1414 static int work_start(void)
1415 {
1416         int error;
1417         recv_workqueue = create_workqueue("dlm_recv");
1418         error = IS_ERR(recv_workqueue);
1419         if (error) {
1420                 log_print("can't start dlm_recv %d", error);
1421                 return error;
1422         }
1423
1424         send_workqueue = create_singlethread_workqueue("dlm_send");
1425         error = IS_ERR(send_workqueue);
1426         if (error) {
1427                 log_print("can't start dlm_send %d", error);
1428                 destroy_workqueue(recv_workqueue);
1429                 return error;
1430         }
1431
1432         return 0;
1433 }
1434
1435 static void stop_conn(struct connection *con)
1436 {
1437         con->flags |= 0x0F;
1438         if (con->sock && con->sock->sk)
1439                 con->sock->sk->sk_user_data = NULL;
1440 }
1441
1442 static void free_conn(struct connection *con)
1443 {
1444         close_connection(con, true);
1445         if (con->othercon)
1446                 kmem_cache_free(con_cache, con->othercon);
1447         hlist_del(&con->list);
1448         kmem_cache_free(con_cache, con);
1449 }
1450
1451 void dlm_lowcomms_stop(void)
1452 {
1453         /* Set all the flags to prevent any
1454            socket activity.
1455         */
1456         mutex_lock(&connections_lock);
1457         foreach_conn(stop_conn);
1458         mutex_unlock(&connections_lock);
1459
1460         work_stop();
1461
1462         mutex_lock(&connections_lock);
1463         clean_writequeues();
1464
1465         foreach_conn(free_conn);
1466
1467         mutex_unlock(&connections_lock);
1468         kmem_cache_destroy(con_cache);
1469 }
1470
1471 int dlm_lowcomms_start(void)
1472 {
1473         int error = -EINVAL;
1474         struct connection *con;
1475         int i;
1476
1477         for (i = 0; i < CONN_HASH_SIZE; i++)
1478                 INIT_HLIST_HEAD(&connection_hash[i]);
1479
1480         init_local();
1481         if (!dlm_local_count) {
1482                 error = -ENOTCONN;
1483                 log_print("no local IP address has been set");
1484                 goto out;
1485         }
1486
1487         error = -ENOMEM;
1488         con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
1489                                       __alignof__(struct connection), 0,
1490                                       NULL);
1491         if (!con_cache)
1492                 goto out;
1493
1494         /* Start listening */
1495         if (dlm_config.ci_protocol == 0)
1496                 error = tcp_listen_for_all();
1497         else
1498                 error = sctp_listen_for_all();
1499         if (error)
1500                 goto fail_unlisten;
1501
1502         error = work_start();
1503         if (error)
1504                 goto fail_unlisten;
1505
1506         return 0;
1507
1508 fail_unlisten:
1509         con = nodeid2con(0,0);
1510         if (con) {
1511                 close_connection(con, false);
1512                 kmem_cache_free(con_cache, con);
1513         }
1514         kmem_cache_destroy(con_cache);
1515
1516 out:
1517         return error;
1518 }