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0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /******************************************************************************
0003 *******************************************************************************
0004 **
0005 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
0006 **  Copyright (C) 2004-2021 Red Hat, Inc.  All rights reserved.
0007 **
0008 **
0009 *******************************************************************************
0010 ******************************************************************************/
0011 
0012 /*
0013  * midcomms.c
0014  *
0015  * This is the appallingly named "mid-level" comms layer. It takes care about
0016  * deliver an on application layer "reliable" communication above the used
0017  * lowcomms transport layer.
0018  *
0019  * How it works:
0020  *
0021  * Each nodes keeps track of all send DLM messages in send_queue with a sequence
0022  * number. The receive will send an DLM_ACK message back for every DLM message
0023  * received at the other side. If a reconnect happens in lowcomms we will send
0024  * all unacknowledged dlm messages again. The receiving side might drop any already
0025  * received message by comparing sequence numbers.
0026  *
0027  * How version detection works:
0028  *
0029  * Due the fact that dlm has pre-configured node addresses on every side
0030  * it is in it's nature that every side connects at starts to transmit
0031  * dlm messages which ends in a race. However DLM_RCOM_NAMES, DLM_RCOM_STATUS
0032  * and their replies are the first messages which are exchanges. Due backwards
0033  * compatibility these messages are not covered by the midcomms re-transmission
0034  * layer. These messages have their own re-transmission handling in the dlm
0035  * application layer. The version field of every node will be set on these RCOM
0036  * messages as soon as they arrived and the node isn't yet part of the nodes
0037  * hash. There exists also logic to detect version mismatched if something weird
0038  * going on or the first messages isn't an expected one.
0039  *
0040  * Termination:
0041  *
0042  * The midcomms layer does a 4 way handshake for termination on DLM protocol
0043  * like TCP supports it with half-closed socket support. SCTP doesn't support
0044  * half-closed socket, so we do it on DLM layer. Also socket shutdown() can be
0045  * interrupted by .e.g. tcp reset itself. Additional there exists the othercon
0046  * paradigm in lowcomms which cannot be easily without breaking backwards
0047  * compatibility. A node cannot send anything to another node when a DLM_FIN
0048  * message was send. There exists additional logic to print a warning if
0049  * DLM wants to do it. There exists a state handling like RFC 793 but reduced
0050  * to termination only. The event "member removal event" describes the cluster
0051  * manager removed the node from internal lists, at this point DLM does not
0052  * send any message to the other node. There exists two cases:
0053  *
0054  * 1. The cluster member was removed and we received a FIN
0055  * OR
0056  * 2. We received a FIN but the member was not removed yet
0057  *
0058  * One of these cases will do the CLOSE_WAIT to LAST_ACK change.
0059  *
0060  *
0061  *                              +---------+
0062  *                              | CLOSED  |
0063  *                              +---------+
0064  *                                   | add member/receive RCOM version
0065  *                                   |            detection msg
0066  *                                   V
0067  *                              +---------+
0068  *                              |  ESTAB  |
0069  *                              +---------+
0070  *                       CLOSE    |     |    rcv FIN
0071  *                      -------   |     |    -------
0072  * +---------+          snd FIN  /       \   snd ACK          +---------+
0073  * |  FIN    |<-----------------           ------------------>|  CLOSE  |
0074  * | WAIT-1  |------------------                              |   WAIT  |
0075  * +---------+          rcv FIN  \                            +---------+
0076  * | rcv ACK of FIN   -------   |                            CLOSE  | member
0077  * | --------------   snd ACK   |                           ------- | removal
0078  * V        x                   V                           snd FIN V event
0079  * +---------+                  +---------+                   +---------+
0080  * |FINWAIT-2|                  | CLOSING |                   | LAST-ACK|
0081  * +---------+                  +---------+                   +---------+
0082  * |                rcv ACK of FIN |                 rcv ACK of FIN |
0083  * |  rcv FIN       -------------- |                 -------------- |
0084  * |  -------              x       V                        x       V
0085  *  \ snd ACK                 +---------+                   +---------+
0086  *   ------------------------>| CLOSED  |                   | CLOSED  |
0087  *                            +---------+                   +---------+
0088  *
0089  * NOTE: any state can interrupted by midcomms_close() and state will be
0090  * switched to CLOSED in case of fencing. There exists also some timeout
0091  * handling when we receive the version detection RCOM messages which is
0092  * made by observation.
0093  *
0094  * Future improvements:
0095  *
0096  * There exists some known issues/improvements of the dlm handling. Some
0097  * of them should be done in a next major dlm version bump which makes
0098  * it incompatible with previous versions.
0099  *
0100  * Unaligned memory access:
0101  *
0102  * There exists cases when the dlm message buffer length is not aligned
0103  * to 8 byte. However seems nobody detected any problem with it. This
0104  * can be fixed in the next major version bump of dlm.
0105  *
0106  * Version detection:
0107  *
0108  * The version detection and how it's done is related to backwards
0109  * compatibility. There exists better ways to make a better handling.
0110  * However this should be changed in the next major version bump of dlm.
0111  *
0112  * Tail Size checking:
0113  *
0114  * There exists a message tail payload in e.g. DLM_MSG however we don't
0115  * check it against the message length yet regarding to the receive buffer
0116  * length. That need to be validated.
0117  *
0118  * Fencing bad nodes:
0119  *
0120  * At timeout places or weird sequence number behaviours we should send
0121  * a fencing request to the cluster manager.
0122  */
0123 
0124 /* Debug switch to enable a 5 seconds sleep waiting of a termination.
0125  * This can be useful to test fencing while termination is running.
0126  * This requires a setup with only gfs2 as dlm user, so that the
0127  * last umount will terminate the connection.
0128  *
0129  * However it became useful to test, while the 5 seconds block in umount
0130  * just press the reset button. In a lot of dropping the termination
0131  * process can could take several seconds.
0132  */
0133 #define DLM_DEBUG_FENCE_TERMINATION 0
0134 
0135 #include <net/tcp.h>
0136 
0137 #include "dlm_internal.h"
0138 #include "lockspace.h"
0139 #include "lowcomms.h"
0140 #include "config.h"
0141 #include "memory.h"
0142 #include "lock.h"
0143 #include "util.h"
0144 #include "midcomms.h"
0145 
0146 /* init value for sequence numbers for testing purpose only e.g. overflows */
0147 #define DLM_SEQ_INIT        0
0148 /* 3 minutes wait to sync ending of dlm */
0149 #define DLM_SHUTDOWN_TIMEOUT    msecs_to_jiffies(3 * 60 * 1000)
0150 #define DLM_VERSION_NOT_SET 0
0151 
0152 struct midcomms_node {
0153     int nodeid;
0154     uint32_t version;
0155     uint32_t seq_send;
0156     uint32_t seq_next;
0157     /* These queues are unbound because we cannot drop any message in dlm.
0158      * We could send a fence signal for a specific node to the cluster
0159      * manager if queues hits some maximum value, however this handling
0160      * not supported yet.
0161      */
0162     struct list_head send_queue;
0163     spinlock_t send_queue_lock;
0164     atomic_t send_queue_cnt;
0165 #define DLM_NODE_FLAG_CLOSE 1
0166 #define DLM_NODE_FLAG_STOP_TX   2
0167 #define DLM_NODE_FLAG_STOP_RX   3
0168 #define DLM_NODE_ULP_DELIVERED  4
0169     unsigned long flags;
0170     wait_queue_head_t shutdown_wait;
0171 
0172     /* dlm tcp termination state */
0173 #define DLM_CLOSED  1
0174 #define DLM_ESTABLISHED 2
0175 #define DLM_FIN_WAIT1   3
0176 #define DLM_FIN_WAIT2   4
0177 #define DLM_CLOSE_WAIT  5
0178 #define DLM_LAST_ACK    6
0179 #define DLM_CLOSING 7
0180     int state;
0181     spinlock_t state_lock;
0182 
0183     /* counts how many lockspaces are using this node
0184      * this refcount is necessary to determine if the
0185      * node wants to disconnect.
0186      */
0187     int users;
0188 
0189     /* not protected by srcu, node_hash lifetime */
0190     void *debugfs;
0191 
0192     struct hlist_node hlist;
0193     struct rcu_head rcu;
0194 };
0195 
0196 struct dlm_mhandle {
0197     const struct dlm_header *inner_hd;
0198     struct midcomms_node *node;
0199     struct dlm_opts *opts;
0200     struct dlm_msg *msg;
0201     bool committed;
0202     uint32_t seq;
0203 
0204     void (*ack_rcv)(struct midcomms_node *node);
0205 
0206     /* get_mhandle/commit srcu idx exchange */
0207     int idx;
0208 
0209     struct list_head list;
0210     struct rcu_head rcu;
0211 };
0212 
0213 static struct hlist_head node_hash[CONN_HASH_SIZE];
0214 static DEFINE_SPINLOCK(nodes_lock);
0215 DEFINE_STATIC_SRCU(nodes_srcu);
0216 
0217 /* This mutex prevents that midcomms_close() is running while
0218  * stop() or remove(). As I experienced invalid memory access
0219  * behaviours when DLM_DEBUG_FENCE_TERMINATION is enabled and
0220  * resetting machines. I will end in some double deletion in nodes
0221  * datastructure.
0222  */
0223 static DEFINE_MUTEX(close_lock);
0224 
0225 struct kmem_cache *dlm_midcomms_cache_create(void)
0226 {
0227     return kmem_cache_create("dlm_mhandle", sizeof(struct dlm_mhandle),
0228                  0, 0, NULL);
0229 }
0230 
0231 static inline const char *dlm_state_str(int state)
0232 {
0233     switch (state) {
0234     case DLM_CLOSED:
0235         return "CLOSED";
0236     case DLM_ESTABLISHED:
0237         return "ESTABLISHED";
0238     case DLM_FIN_WAIT1:
0239         return "FIN_WAIT1";
0240     case DLM_FIN_WAIT2:
0241         return "FIN_WAIT2";
0242     case DLM_CLOSE_WAIT:
0243         return "CLOSE_WAIT";
0244     case DLM_LAST_ACK:
0245         return "LAST_ACK";
0246     case DLM_CLOSING:
0247         return "CLOSING";
0248     default:
0249         return "UNKNOWN";
0250     }
0251 }
0252 
0253 const char *dlm_midcomms_state(struct midcomms_node *node)
0254 {
0255     return dlm_state_str(node->state);
0256 }
0257 
0258 unsigned long dlm_midcomms_flags(struct midcomms_node *node)
0259 {
0260     return node->flags;
0261 }
0262 
0263 int dlm_midcomms_send_queue_cnt(struct midcomms_node *node)
0264 {
0265     return atomic_read(&node->send_queue_cnt);
0266 }
0267 
0268 uint32_t dlm_midcomms_version(struct midcomms_node *node)
0269 {
0270     return node->version;
0271 }
0272 
0273 static struct midcomms_node *__find_node(int nodeid, int r)
0274 {
0275     struct midcomms_node *node;
0276 
0277     hlist_for_each_entry_rcu(node, &node_hash[r], hlist) {
0278         if (node->nodeid == nodeid)
0279             return node;
0280     }
0281 
0282     return NULL;
0283 }
0284 
0285 static void dlm_mhandle_release(struct rcu_head *rcu)
0286 {
0287     struct dlm_mhandle *mh = container_of(rcu, struct dlm_mhandle, rcu);
0288 
0289     dlm_lowcomms_put_msg(mh->msg);
0290     dlm_free_mhandle(mh);
0291 }
0292 
0293 static void dlm_mhandle_delete(struct midcomms_node *node,
0294                    struct dlm_mhandle *mh)
0295 {
0296     list_del_rcu(&mh->list);
0297     atomic_dec(&node->send_queue_cnt);
0298     call_rcu(&mh->rcu, dlm_mhandle_release);
0299 }
0300 
0301 static void dlm_send_queue_flush(struct midcomms_node *node)
0302 {
0303     struct dlm_mhandle *mh;
0304 
0305     pr_debug("flush midcomms send queue of node %d\n", node->nodeid);
0306 
0307     rcu_read_lock();
0308     spin_lock(&node->send_queue_lock);
0309     list_for_each_entry_rcu(mh, &node->send_queue, list) {
0310         dlm_mhandle_delete(node, mh);
0311     }
0312     spin_unlock(&node->send_queue_lock);
0313     rcu_read_unlock();
0314 }
0315 
0316 static void midcomms_node_reset(struct midcomms_node *node)
0317 {
0318     pr_debug("reset node %d\n", node->nodeid);
0319 
0320     node->seq_next = DLM_SEQ_INIT;
0321     node->seq_send = DLM_SEQ_INIT;
0322     node->version = DLM_VERSION_NOT_SET;
0323     node->flags = 0;
0324 
0325     dlm_send_queue_flush(node);
0326     node->state = DLM_CLOSED;
0327     wake_up(&node->shutdown_wait);
0328 }
0329 
0330 static struct midcomms_node *nodeid2node(int nodeid, gfp_t alloc)
0331 {
0332     struct midcomms_node *node, *tmp;
0333     int r = nodeid_hash(nodeid);
0334 
0335     node = __find_node(nodeid, r);
0336     if (node || !alloc)
0337         return node;
0338 
0339     node = kmalloc(sizeof(*node), alloc);
0340     if (!node)
0341         return NULL;
0342 
0343     node->nodeid = nodeid;
0344     spin_lock_init(&node->state_lock);
0345     spin_lock_init(&node->send_queue_lock);
0346     atomic_set(&node->send_queue_cnt, 0);
0347     INIT_LIST_HEAD(&node->send_queue);
0348     init_waitqueue_head(&node->shutdown_wait);
0349     node->users = 0;
0350     midcomms_node_reset(node);
0351 
0352     spin_lock(&nodes_lock);
0353     /* check again if there was somebody else
0354      * earlier here to add the node
0355      */
0356     tmp = __find_node(nodeid, r);
0357     if (tmp) {
0358         spin_unlock(&nodes_lock);
0359         kfree(node);
0360         return tmp;
0361     }
0362 
0363     hlist_add_head_rcu(&node->hlist, &node_hash[r]);
0364     spin_unlock(&nodes_lock);
0365 
0366     node->debugfs = dlm_create_debug_comms_file(nodeid, node);
0367     return node;
0368 }
0369 
0370 static int dlm_send_ack(int nodeid, uint32_t seq)
0371 {
0372     int mb_len = sizeof(struct dlm_header);
0373     struct dlm_header *m_header;
0374     struct dlm_msg *msg;
0375     char *ppc;
0376 
0377     msg = dlm_lowcomms_new_msg(nodeid, mb_len, GFP_NOFS, &ppc,
0378                    NULL, NULL);
0379     if (!msg)
0380         return -ENOMEM;
0381 
0382     m_header = (struct dlm_header *)ppc;
0383 
0384     m_header->h_version = cpu_to_le32(DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
0385     m_header->h_nodeid = cpu_to_le32(dlm_our_nodeid());
0386     m_header->h_length = cpu_to_le16(mb_len);
0387     m_header->h_cmd = DLM_ACK;
0388     m_header->u.h_seq = cpu_to_le32(seq);
0389 
0390     dlm_lowcomms_commit_msg(msg);
0391     dlm_lowcomms_put_msg(msg);
0392 
0393     return 0;
0394 }
0395 
0396 static int dlm_send_fin(struct midcomms_node *node,
0397             void (*ack_rcv)(struct midcomms_node *node))
0398 {
0399     int mb_len = sizeof(struct dlm_header);
0400     struct dlm_header *m_header;
0401     struct dlm_mhandle *mh;
0402     char *ppc;
0403 
0404     mh = dlm_midcomms_get_mhandle(node->nodeid, mb_len, GFP_NOFS, &ppc);
0405     if (!mh)
0406         return -ENOMEM;
0407 
0408     mh->ack_rcv = ack_rcv;
0409 
0410     m_header = (struct dlm_header *)ppc;
0411 
0412     m_header->h_version = cpu_to_le32(DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
0413     m_header->h_nodeid = cpu_to_le32(dlm_our_nodeid());
0414     m_header->h_length = cpu_to_le16(mb_len);
0415     m_header->h_cmd = DLM_FIN;
0416 
0417     pr_debug("sending fin msg to node %d\n", node->nodeid);
0418     dlm_midcomms_commit_mhandle(mh);
0419     set_bit(DLM_NODE_FLAG_STOP_TX, &node->flags);
0420 
0421     return 0;
0422 }
0423 
0424 static void dlm_receive_ack(struct midcomms_node *node, uint32_t seq)
0425 {
0426     struct dlm_mhandle *mh;
0427 
0428     rcu_read_lock();
0429     list_for_each_entry_rcu(mh, &node->send_queue, list) {
0430         if (before(mh->seq, seq)) {
0431             if (mh->ack_rcv)
0432                 mh->ack_rcv(node);
0433         } else {
0434             /* send queue should be ordered */
0435             break;
0436         }
0437     }
0438 
0439     spin_lock(&node->send_queue_lock);
0440     list_for_each_entry_rcu(mh, &node->send_queue, list) {
0441         if (before(mh->seq, seq)) {
0442             dlm_mhandle_delete(node, mh);
0443         } else {
0444             /* send queue should be ordered */
0445             break;
0446         }
0447     }
0448     spin_unlock(&node->send_queue_lock);
0449     rcu_read_unlock();
0450 }
0451 
0452 static void dlm_pas_fin_ack_rcv(struct midcomms_node *node)
0453 {
0454     spin_lock(&node->state_lock);
0455     pr_debug("receive passive fin ack from node %d with state %s\n",
0456          node->nodeid, dlm_state_str(node->state));
0457 
0458     switch (node->state) {
0459     case DLM_LAST_ACK:
0460         /* DLM_CLOSED */
0461         midcomms_node_reset(node);
0462         break;
0463     case DLM_CLOSED:
0464         /* not valid but somehow we got what we want */
0465         wake_up(&node->shutdown_wait);
0466         break;
0467     default:
0468         spin_unlock(&node->state_lock);
0469         log_print("%s: unexpected state: %d\n",
0470               __func__, node->state);
0471         WARN_ON(1);
0472         return;
0473     }
0474     spin_unlock(&node->state_lock);
0475 }
0476 
0477 static void dlm_midcomms_receive_buffer(union dlm_packet *p,
0478                     struct midcomms_node *node,
0479                     uint32_t seq)
0480 {
0481     if (seq == node->seq_next) {
0482         node->seq_next++;
0483 
0484         switch (p->header.h_cmd) {
0485         case DLM_FIN:
0486             /* send ack before fin */
0487             dlm_send_ack(node->nodeid, node->seq_next);
0488 
0489             spin_lock(&node->state_lock);
0490             pr_debug("receive fin msg from node %d with state %s\n",
0491                  node->nodeid, dlm_state_str(node->state));
0492 
0493             switch (node->state) {
0494             case DLM_ESTABLISHED:
0495                 node->state = DLM_CLOSE_WAIT;
0496                 pr_debug("switch node %d to state %s\n",
0497                      node->nodeid, dlm_state_str(node->state));
0498                 /* passive shutdown DLM_LAST_ACK case 1
0499                  * additional we check if the node is used by
0500                  * cluster manager events at all.
0501                  */
0502                 if (node->users == 0) {
0503                     node->state = DLM_LAST_ACK;
0504                     pr_debug("switch node %d to state %s case 1\n",
0505                          node->nodeid, dlm_state_str(node->state));
0506                     spin_unlock(&node->state_lock);
0507                     goto send_fin;
0508                 }
0509                 break;
0510             case DLM_FIN_WAIT1:
0511                 node->state = DLM_CLOSING;
0512                 pr_debug("switch node %d to state %s\n",
0513                      node->nodeid, dlm_state_str(node->state));
0514                 break;
0515             case DLM_FIN_WAIT2:
0516                 midcomms_node_reset(node);
0517                 pr_debug("switch node %d to state %s\n",
0518                      node->nodeid, dlm_state_str(node->state));
0519                 wake_up(&node->shutdown_wait);
0520                 break;
0521             case DLM_LAST_ACK:
0522                 /* probably remove_member caught it, do nothing */
0523                 break;
0524             default:
0525                 spin_unlock(&node->state_lock);
0526                 log_print("%s: unexpected state: %d\n",
0527                       __func__, node->state);
0528                 WARN_ON(1);
0529                 return;
0530             }
0531             spin_unlock(&node->state_lock);
0532 
0533             set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
0534             break;
0535         default:
0536             WARN_ON(test_bit(DLM_NODE_FLAG_STOP_RX, &node->flags));
0537             dlm_receive_buffer(p, node->nodeid);
0538             set_bit(DLM_NODE_ULP_DELIVERED, &node->flags);
0539             break;
0540         }
0541     } else {
0542         /* retry to ack message which we already have by sending back
0543          * current node->seq_next number as ack.
0544          */
0545         if (seq < node->seq_next)
0546             dlm_send_ack(node->nodeid, node->seq_next);
0547 
0548         log_print_ratelimited("ignore dlm msg because seq mismatch, seq: %u, expected: %u, nodeid: %d",
0549                       seq, node->seq_next, node->nodeid);
0550     }
0551 
0552     return;
0553 
0554 send_fin:
0555     set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
0556     dlm_send_fin(node, dlm_pas_fin_ack_rcv);
0557 }
0558 
0559 static struct midcomms_node *
0560 dlm_midcomms_recv_node_lookup(int nodeid, const union dlm_packet *p,
0561                   uint16_t msglen, int (*cb)(struct midcomms_node *node))
0562 {
0563     struct midcomms_node *node = NULL;
0564     gfp_t allocation = 0;
0565     int ret;
0566 
0567     switch (p->header.h_cmd) {
0568     case DLM_RCOM:
0569         if (msglen < sizeof(struct dlm_rcom)) {
0570             log_print("rcom msg too small: %u, will skip this message from node %d",
0571                   msglen, nodeid);
0572             return NULL;
0573         }
0574 
0575         switch (p->rcom.rc_type) {
0576         case cpu_to_le32(DLM_RCOM_NAMES):
0577             fallthrough;
0578         case cpu_to_le32(DLM_RCOM_NAMES_REPLY):
0579             fallthrough;
0580         case cpu_to_le32(DLM_RCOM_STATUS):
0581             fallthrough;
0582         case cpu_to_le32(DLM_RCOM_STATUS_REPLY):
0583             node = nodeid2node(nodeid, 0);
0584             if (node) {
0585                 spin_lock(&node->state_lock);
0586                 if (node->state != DLM_ESTABLISHED)
0587                     pr_debug("receive begin RCOM msg from node %d with state %s\n",
0588                          node->nodeid, dlm_state_str(node->state));
0589 
0590                 switch (node->state) {
0591                 case DLM_CLOSED:
0592                     node->state = DLM_ESTABLISHED;
0593                     pr_debug("switch node %d to state %s\n",
0594                          node->nodeid, dlm_state_str(node->state));
0595                     break;
0596                 case DLM_ESTABLISHED:
0597                     break;
0598                 default:
0599                     /* some invalid state passive shutdown
0600                      * was failed, we try to reset and
0601                      * hope it will go on.
0602                      */
0603                     log_print("reset node %d because shutdown stuck",
0604                           node->nodeid);
0605 
0606                     midcomms_node_reset(node);
0607                     node->state = DLM_ESTABLISHED;
0608                     break;
0609                 }
0610                 spin_unlock(&node->state_lock);
0611             }
0612 
0613             allocation = GFP_NOFS;
0614             break;
0615         default:
0616             break;
0617         }
0618 
0619         break;
0620     default:
0621         break;
0622     }
0623 
0624     node = nodeid2node(nodeid, allocation);
0625     if (!node) {
0626         switch (p->header.h_cmd) {
0627         case DLM_OPTS:
0628             if (msglen < sizeof(struct dlm_opts)) {
0629                 log_print("opts msg too small: %u, will skip this message from node %d",
0630                       msglen, nodeid);
0631                 return NULL;
0632             }
0633 
0634             log_print_ratelimited("received dlm opts message nextcmd %d from node %d in an invalid sequence",
0635                           p->opts.o_nextcmd, nodeid);
0636             break;
0637         default:
0638             log_print_ratelimited("received dlm message cmd %d from node %d in an invalid sequence",
0639                           p->header.h_cmd, nodeid);
0640             break;
0641         }
0642 
0643         return NULL;
0644     }
0645 
0646     ret = cb(node);
0647     if (ret < 0)
0648         return NULL;
0649 
0650     return node;
0651 }
0652 
0653 static int dlm_midcomms_version_check_3_2(struct midcomms_node *node)
0654 {
0655     switch (node->version) {
0656     case DLM_VERSION_NOT_SET:
0657         node->version = DLM_VERSION_3_2;
0658         log_print("version 0x%08x for node %d detected", DLM_VERSION_3_2,
0659               node->nodeid);
0660         break;
0661     case DLM_VERSION_3_2:
0662         break;
0663     default:
0664         log_print_ratelimited("version mismatch detected, assumed 0x%08x but node %d has 0x%08x",
0665                       DLM_VERSION_3_2, node->nodeid, node->version);
0666         return -1;
0667     }
0668 
0669     return 0;
0670 }
0671 
0672 static int dlm_opts_check_msglen(union dlm_packet *p, uint16_t msglen, int nodeid)
0673 {
0674     int len = msglen;
0675 
0676     /* we only trust outer header msglen because
0677      * it's checked against receive buffer length.
0678      */
0679     if (len < sizeof(struct dlm_opts))
0680         return -1;
0681     len -= sizeof(struct dlm_opts);
0682 
0683     if (len < le16_to_cpu(p->opts.o_optlen))
0684         return -1;
0685     len -= le16_to_cpu(p->opts.o_optlen);
0686 
0687     switch (p->opts.o_nextcmd) {
0688     case DLM_FIN:
0689         if (len < sizeof(struct dlm_header)) {
0690             log_print("fin too small: %d, will skip this message from node %d",
0691                   len, nodeid);
0692             return -1;
0693         }
0694 
0695         break;
0696     case DLM_MSG:
0697         if (len < sizeof(struct dlm_message)) {
0698             log_print("msg too small: %d, will skip this message from node %d",
0699                   msglen, nodeid);
0700             return -1;
0701         }
0702 
0703         break;
0704     case DLM_RCOM:
0705         if (len < sizeof(struct dlm_rcom)) {
0706             log_print("rcom msg too small: %d, will skip this message from node %d",
0707                   len, nodeid);
0708             return -1;
0709         }
0710 
0711         break;
0712     default:
0713         log_print("unsupported o_nextcmd received: %u, will skip this message from node %d",
0714               p->opts.o_nextcmd, nodeid);
0715         return -1;
0716     }
0717 
0718     return 0;
0719 }
0720 
0721 static void dlm_midcomms_receive_buffer_3_2(union dlm_packet *p, int nodeid)
0722 {
0723     uint16_t msglen = le16_to_cpu(p->header.h_length);
0724     struct midcomms_node *node;
0725     uint32_t seq;
0726     int ret, idx;
0727 
0728     idx = srcu_read_lock(&nodes_srcu);
0729     node = dlm_midcomms_recv_node_lookup(nodeid, p, msglen,
0730                          dlm_midcomms_version_check_3_2);
0731     if (!node)
0732         goto out;
0733 
0734     switch (p->header.h_cmd) {
0735     case DLM_RCOM:
0736         /* these rcom message we use to determine version.
0737          * they have their own retransmission handling and
0738          * are the first messages of dlm.
0739          *
0740          * length already checked.
0741          */
0742         switch (p->rcom.rc_type) {
0743         case cpu_to_le32(DLM_RCOM_NAMES):
0744             fallthrough;
0745         case cpu_to_le32(DLM_RCOM_NAMES_REPLY):
0746             fallthrough;
0747         case cpu_to_le32(DLM_RCOM_STATUS):
0748             fallthrough;
0749         case cpu_to_le32(DLM_RCOM_STATUS_REPLY):
0750             break;
0751         default:
0752             log_print("unsupported rcom type received: %u, will skip this message from node %d",
0753                   le32_to_cpu(p->rcom.rc_type), nodeid);
0754             goto out;
0755         }
0756 
0757         WARN_ON(test_bit(DLM_NODE_FLAG_STOP_RX, &node->flags));
0758         dlm_receive_buffer(p, nodeid);
0759         break;
0760     case DLM_OPTS:
0761         seq = le32_to_cpu(p->header.u.h_seq);
0762 
0763         ret = dlm_opts_check_msglen(p, msglen, nodeid);
0764         if (ret < 0) {
0765             log_print("opts msg too small: %u, will skip this message from node %d",
0766                   msglen, nodeid);
0767             goto out;
0768         }
0769 
0770         p = (union dlm_packet *)((unsigned char *)p->opts.o_opts +
0771                      le16_to_cpu(p->opts.o_optlen));
0772 
0773         /* recheck inner msglen just if it's not garbage */
0774         msglen = le16_to_cpu(p->header.h_length);
0775         switch (p->header.h_cmd) {
0776         case DLM_RCOM:
0777             if (msglen < sizeof(struct dlm_rcom)) {
0778                 log_print("inner rcom msg too small: %u, will skip this message from node %d",
0779                       msglen, nodeid);
0780                 goto out;
0781             }
0782 
0783             break;
0784         case DLM_MSG:
0785             if (msglen < sizeof(struct dlm_message)) {
0786                 log_print("inner msg too small: %u, will skip this message from node %d",
0787                       msglen, nodeid);
0788                 goto out;
0789             }
0790 
0791             break;
0792         case DLM_FIN:
0793             if (msglen < sizeof(struct dlm_header)) {
0794                 log_print("inner fin too small: %u, will skip this message from node %d",
0795                       msglen, nodeid);
0796                 goto out;
0797             }
0798 
0799             break;
0800         default:
0801             log_print("unsupported inner h_cmd received: %u, will skip this message from node %d",
0802                   msglen, nodeid);
0803             goto out;
0804         }
0805 
0806         dlm_midcomms_receive_buffer(p, node, seq);
0807         break;
0808     case DLM_ACK:
0809         seq = le32_to_cpu(p->header.u.h_seq);
0810         dlm_receive_ack(node, seq);
0811         break;
0812     default:
0813         log_print("unsupported h_cmd received: %u, will skip this message from node %d",
0814               p->header.h_cmd, nodeid);
0815         break;
0816     }
0817 
0818 out:
0819     srcu_read_unlock(&nodes_srcu, idx);
0820 }
0821 
0822 static int dlm_midcomms_version_check_3_1(struct midcomms_node *node)
0823 {
0824     switch (node->version) {
0825     case DLM_VERSION_NOT_SET:
0826         node->version = DLM_VERSION_3_1;
0827         log_print("version 0x%08x for node %d detected", DLM_VERSION_3_1,
0828               node->nodeid);
0829         break;
0830     case DLM_VERSION_3_1:
0831         break;
0832     default:
0833         log_print_ratelimited("version mismatch detected, assumed 0x%08x but node %d has 0x%08x",
0834                       DLM_VERSION_3_1, node->nodeid, node->version);
0835         return -1;
0836     }
0837 
0838     return 0;
0839 }
0840 
0841 static void dlm_midcomms_receive_buffer_3_1(union dlm_packet *p, int nodeid)
0842 {
0843     uint16_t msglen = le16_to_cpu(p->header.h_length);
0844     struct midcomms_node *node;
0845     int idx;
0846 
0847     idx = srcu_read_lock(&nodes_srcu);
0848     node = dlm_midcomms_recv_node_lookup(nodeid, p, msglen,
0849                          dlm_midcomms_version_check_3_1);
0850     if (!node) {
0851         srcu_read_unlock(&nodes_srcu, idx);
0852         return;
0853     }
0854     srcu_read_unlock(&nodes_srcu, idx);
0855 
0856     switch (p->header.h_cmd) {
0857     case DLM_RCOM:
0858         /* length already checked */
0859         break;
0860     case DLM_MSG:
0861         if (msglen < sizeof(struct dlm_message)) {
0862             log_print("msg too small: %u, will skip this message from node %d",
0863                   msglen, nodeid);
0864             return;
0865         }
0866 
0867         break;
0868     default:
0869         log_print("unsupported h_cmd received: %u, will skip this message from node %d",
0870               p->header.h_cmd, nodeid);
0871         return;
0872     }
0873 
0874     dlm_receive_buffer(p, nodeid);
0875 }
0876 
0877 /*
0878  * Called from the low-level comms layer to process a buffer of
0879  * commands.
0880  */
0881 
0882 int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
0883 {
0884     const unsigned char *ptr = buf;
0885     const struct dlm_header *hd;
0886     uint16_t msglen;
0887     int ret = 0;
0888 
0889     while (len >= sizeof(struct dlm_header)) {
0890         hd = (struct dlm_header *)ptr;
0891 
0892         /* no message should be more than DLM_MAX_SOCKET_BUFSIZE or
0893          * less than dlm_header size.
0894          *
0895          * Some messages does not have a 8 byte length boundary yet
0896          * which can occur in a unaligned memory access of some dlm
0897          * messages. However this problem need to be fixed at the
0898          * sending side, for now it seems nobody run into architecture
0899          * related issues yet but it slows down some processing.
0900          * Fixing this issue should be scheduled in future by doing
0901          * the next major version bump.
0902          */
0903         msglen = le16_to_cpu(hd->h_length);
0904         if (msglen > DLM_MAX_SOCKET_BUFSIZE ||
0905             msglen < sizeof(struct dlm_header)) {
0906             log_print("received invalid length header: %u from node %d, will abort message parsing",
0907                   msglen, nodeid);
0908             return -EBADMSG;
0909         }
0910 
0911         /* caller will take care that leftover
0912          * will be parsed next call with more data
0913          */
0914         if (msglen > len)
0915             break;
0916 
0917         switch (hd->h_version) {
0918         case cpu_to_le32(DLM_VERSION_3_1):
0919             dlm_midcomms_receive_buffer_3_1((union dlm_packet *)ptr, nodeid);
0920             break;
0921         case cpu_to_le32(DLM_VERSION_3_2):
0922             dlm_midcomms_receive_buffer_3_2((union dlm_packet *)ptr, nodeid);
0923             break;
0924         default:
0925             log_print("received invalid version header: %u from node %d, will skip this message",
0926                   le32_to_cpu(hd->h_version), nodeid);
0927             break;
0928         }
0929 
0930         ret += msglen;
0931         len -= msglen;
0932         ptr += msglen;
0933     }
0934 
0935     return ret;
0936 }
0937 
0938 void dlm_midcomms_receive_done(int nodeid)
0939 {
0940     struct midcomms_node *node;
0941     int idx;
0942 
0943     idx = srcu_read_lock(&nodes_srcu);
0944     node = nodeid2node(nodeid, 0);
0945     if (!node) {
0946         srcu_read_unlock(&nodes_srcu, idx);
0947         return;
0948     }
0949 
0950     /* old protocol, we do nothing */
0951     switch (node->version) {
0952     case DLM_VERSION_3_2:
0953         break;
0954     default:
0955         srcu_read_unlock(&nodes_srcu, idx);
0956         return;
0957     }
0958 
0959     /* do nothing if we didn't delivered stateful to ulp */
0960     if (!test_and_clear_bit(DLM_NODE_ULP_DELIVERED,
0961                 &node->flags)) {
0962         srcu_read_unlock(&nodes_srcu, idx);
0963         return;
0964     }
0965 
0966     spin_lock(&node->state_lock);
0967     /* we only ack if state is ESTABLISHED */
0968     switch (node->state) {
0969     case DLM_ESTABLISHED:
0970         spin_unlock(&node->state_lock);
0971         dlm_send_ack(node->nodeid, node->seq_next);
0972         break;
0973     default:
0974         spin_unlock(&node->state_lock);
0975         /* do nothing FIN has it's own ack send */
0976         break;
0977     }
0978     srcu_read_unlock(&nodes_srcu, idx);
0979 }
0980 
0981 void dlm_midcomms_unack_msg_resend(int nodeid)
0982 {
0983     struct midcomms_node *node;
0984     struct dlm_mhandle *mh;
0985     int idx, ret;
0986 
0987     idx = srcu_read_lock(&nodes_srcu);
0988     node = nodeid2node(nodeid, 0);
0989     if (!node) {
0990         srcu_read_unlock(&nodes_srcu, idx);
0991         return;
0992     }
0993 
0994     /* old protocol, we don't support to retransmit on failure */
0995     switch (node->version) {
0996     case DLM_VERSION_3_2:
0997         break;
0998     default:
0999         srcu_read_unlock(&nodes_srcu, idx);
1000         return;
1001     }
1002 
1003     rcu_read_lock();
1004     list_for_each_entry_rcu(mh, &node->send_queue, list) {
1005         if (!mh->committed)
1006             continue;
1007 
1008         ret = dlm_lowcomms_resend_msg(mh->msg);
1009         if (!ret)
1010             log_print_ratelimited("retransmit dlm msg, seq %u, nodeid %d",
1011                           mh->seq, node->nodeid);
1012     }
1013     rcu_read_unlock();
1014     srcu_read_unlock(&nodes_srcu, idx);
1015 }
1016 
1017 static void dlm_fill_opts_header(struct dlm_opts *opts, uint16_t inner_len,
1018                  uint32_t seq)
1019 {
1020     opts->o_header.h_cmd = DLM_OPTS;
1021     opts->o_header.h_version = cpu_to_le32(DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
1022     opts->o_header.h_nodeid = cpu_to_le32(dlm_our_nodeid());
1023     opts->o_header.h_length = cpu_to_le16(DLM_MIDCOMMS_OPT_LEN + inner_len);
1024     opts->o_header.u.h_seq = cpu_to_le32(seq);
1025 }
1026 
1027 static void midcomms_new_msg_cb(void *data)
1028 {
1029     struct dlm_mhandle *mh = data;
1030 
1031     atomic_inc(&mh->node->send_queue_cnt);
1032 
1033     spin_lock(&mh->node->send_queue_lock);
1034     list_add_tail_rcu(&mh->list, &mh->node->send_queue);
1035     spin_unlock(&mh->node->send_queue_lock);
1036 
1037     mh->seq = mh->node->seq_send++;
1038 }
1039 
1040 static struct dlm_msg *dlm_midcomms_get_msg_3_2(struct dlm_mhandle *mh, int nodeid,
1041                         int len, gfp_t allocation, char **ppc)
1042 {
1043     struct dlm_opts *opts;
1044     struct dlm_msg *msg;
1045 
1046     msg = dlm_lowcomms_new_msg(nodeid, len + DLM_MIDCOMMS_OPT_LEN,
1047                    allocation, ppc, midcomms_new_msg_cb, mh);
1048     if (!msg)
1049         return NULL;
1050 
1051     opts = (struct dlm_opts *)*ppc;
1052     mh->opts = opts;
1053 
1054     /* add possible options here */
1055     dlm_fill_opts_header(opts, len, mh->seq);
1056 
1057     *ppc += sizeof(*opts);
1058     mh->inner_hd = (const struct dlm_header *)*ppc;
1059     return msg;
1060 }
1061 
1062 /* avoid false positive for nodes_srcu, unlock happens in
1063  * dlm_midcomms_commit_mhandle which is a must call if success
1064  */
1065 #ifndef __CHECKER__
1066 struct dlm_mhandle *dlm_midcomms_get_mhandle(int nodeid, int len,
1067                          gfp_t allocation, char **ppc)
1068 {
1069     struct midcomms_node *node;
1070     struct dlm_mhandle *mh;
1071     struct dlm_msg *msg;
1072     int idx;
1073 
1074     idx = srcu_read_lock(&nodes_srcu);
1075     node = nodeid2node(nodeid, 0);
1076     if (!node) {
1077         WARN_ON_ONCE(1);
1078         goto err;
1079     }
1080 
1081     /* this is a bug, however we going on and hope it will be resolved */
1082     WARN_ON(test_bit(DLM_NODE_FLAG_STOP_TX, &node->flags));
1083 
1084     mh = dlm_allocate_mhandle();
1085     if (!mh)
1086         goto err;
1087 
1088     mh->committed = false;
1089     mh->ack_rcv = NULL;
1090     mh->idx = idx;
1091     mh->node = node;
1092 
1093     switch (node->version) {
1094     case DLM_VERSION_3_1:
1095         msg = dlm_lowcomms_new_msg(nodeid, len, allocation, ppc,
1096                        NULL, NULL);
1097         if (!msg) {
1098             dlm_free_mhandle(mh);
1099             goto err;
1100         }
1101 
1102         break;
1103     case DLM_VERSION_3_2:
1104         msg = dlm_midcomms_get_msg_3_2(mh, nodeid, len, allocation,
1105                            ppc);
1106         if (!msg) {
1107             dlm_free_mhandle(mh);
1108             goto err;
1109         }
1110 
1111         break;
1112     default:
1113         dlm_free_mhandle(mh);
1114         WARN_ON(1);
1115         goto err;
1116     }
1117 
1118     mh->msg = msg;
1119 
1120     /* keep in mind that is a must to call
1121      * dlm_midcomms_commit_msg() which releases
1122      * nodes_srcu using mh->idx which is assumed
1123      * here that the application will call it.
1124      */
1125     return mh;
1126 
1127 err:
1128     srcu_read_unlock(&nodes_srcu, idx);
1129     return NULL;
1130 }
1131 #endif
1132 
1133 static void dlm_midcomms_commit_msg_3_2(struct dlm_mhandle *mh)
1134 {
1135     /* nexthdr chain for fast lookup */
1136     mh->opts->o_nextcmd = mh->inner_hd->h_cmd;
1137     mh->committed = true;
1138     dlm_lowcomms_commit_msg(mh->msg);
1139 }
1140 
1141 /* avoid false positive for nodes_srcu, lock was happen in
1142  * dlm_midcomms_get_mhandle
1143  */
1144 #ifndef __CHECKER__
1145 void dlm_midcomms_commit_mhandle(struct dlm_mhandle *mh)
1146 {
1147     switch (mh->node->version) {
1148     case DLM_VERSION_3_1:
1149         srcu_read_unlock(&nodes_srcu, mh->idx);
1150 
1151         dlm_lowcomms_commit_msg(mh->msg);
1152         dlm_lowcomms_put_msg(mh->msg);
1153         /* mh is not part of rcu list in this case */
1154         dlm_free_mhandle(mh);
1155         break;
1156     case DLM_VERSION_3_2:
1157         dlm_midcomms_commit_msg_3_2(mh);
1158         srcu_read_unlock(&nodes_srcu, mh->idx);
1159         break;
1160     default:
1161         srcu_read_unlock(&nodes_srcu, mh->idx);
1162         WARN_ON(1);
1163         break;
1164     }
1165 }
1166 #endif
1167 
1168 int dlm_midcomms_start(void)
1169 {
1170     int i;
1171 
1172     for (i = 0; i < CONN_HASH_SIZE; i++)
1173         INIT_HLIST_HEAD(&node_hash[i]);
1174 
1175     return dlm_lowcomms_start();
1176 }
1177 
1178 static void dlm_act_fin_ack_rcv(struct midcomms_node *node)
1179 {
1180     spin_lock(&node->state_lock);
1181     pr_debug("receive active fin ack from node %d with state %s\n",
1182          node->nodeid, dlm_state_str(node->state));
1183 
1184     switch (node->state) {
1185     case DLM_FIN_WAIT1:
1186         node->state = DLM_FIN_WAIT2;
1187         pr_debug("switch node %d to state %s\n",
1188              node->nodeid, dlm_state_str(node->state));
1189         break;
1190     case DLM_CLOSING:
1191         midcomms_node_reset(node);
1192         pr_debug("switch node %d to state %s\n",
1193              node->nodeid, dlm_state_str(node->state));
1194         wake_up(&node->shutdown_wait);
1195         break;
1196     case DLM_CLOSED:
1197         /* not valid but somehow we got what we want */
1198         wake_up(&node->shutdown_wait);
1199         break;
1200     default:
1201         spin_unlock(&node->state_lock);
1202         log_print("%s: unexpected state: %d\n",
1203               __func__, node->state);
1204         WARN_ON(1);
1205         return;
1206     }
1207     spin_unlock(&node->state_lock);
1208 }
1209 
1210 void dlm_midcomms_add_member(int nodeid)
1211 {
1212     struct midcomms_node *node;
1213     int idx;
1214 
1215     if (nodeid == dlm_our_nodeid())
1216         return;
1217 
1218     idx = srcu_read_lock(&nodes_srcu);
1219     node = nodeid2node(nodeid, GFP_NOFS);
1220     if (!node) {
1221         srcu_read_unlock(&nodes_srcu, idx);
1222         return;
1223     }
1224 
1225     spin_lock(&node->state_lock);
1226     if (!node->users) {
1227         pr_debug("receive add member from node %d with state %s\n",
1228              node->nodeid, dlm_state_str(node->state));
1229         switch (node->state) {
1230         case DLM_ESTABLISHED:
1231             break;
1232         case DLM_CLOSED:
1233             node->state = DLM_ESTABLISHED;
1234             pr_debug("switch node %d to state %s\n",
1235                  node->nodeid, dlm_state_str(node->state));
1236             break;
1237         default:
1238             /* some invalid state passive shutdown
1239              * was failed, we try to reset and
1240              * hope it will go on.
1241              */
1242             log_print("reset node %d because shutdown stuck",
1243                   node->nodeid);
1244 
1245             midcomms_node_reset(node);
1246             node->state = DLM_ESTABLISHED;
1247             break;
1248         }
1249     }
1250 
1251     node->users++;
1252     pr_debug("node %d users inc count %d\n", nodeid, node->users);
1253     spin_unlock(&node->state_lock);
1254 
1255     srcu_read_unlock(&nodes_srcu, idx);
1256 }
1257 
1258 void dlm_midcomms_remove_member(int nodeid)
1259 {
1260     struct midcomms_node *node;
1261     int idx;
1262 
1263     if (nodeid == dlm_our_nodeid())
1264         return;
1265 
1266     idx = srcu_read_lock(&nodes_srcu);
1267     node = nodeid2node(nodeid, 0);
1268     if (!node) {
1269         srcu_read_unlock(&nodes_srcu, idx);
1270         return;
1271     }
1272 
1273     spin_lock(&node->state_lock);
1274     node->users--;
1275     pr_debug("node %d users dec count %d\n", nodeid, node->users);
1276 
1277     /* hitting users count to zero means the
1278      * other side is running dlm_midcomms_stop()
1279      * we meet us to have a clean disconnect.
1280      */
1281     if (node->users == 0) {
1282         pr_debug("receive remove member from node %d with state %s\n",
1283              node->nodeid, dlm_state_str(node->state));
1284         switch (node->state) {
1285         case DLM_ESTABLISHED:
1286             break;
1287         case DLM_CLOSE_WAIT:
1288             /* passive shutdown DLM_LAST_ACK case 2 */
1289             node->state = DLM_LAST_ACK;
1290             spin_unlock(&node->state_lock);
1291 
1292             pr_debug("switch node %d to state %s case 2\n",
1293                  node->nodeid, dlm_state_str(node->state));
1294             goto send_fin;
1295         case DLM_LAST_ACK:
1296             /* probably receive fin caught it, do nothing */
1297             break;
1298         case DLM_CLOSED:
1299             /* already gone, do nothing */
1300             break;
1301         default:
1302             log_print("%s: unexpected state: %d\n",
1303                   __func__, node->state);
1304             break;
1305         }
1306     }
1307     spin_unlock(&node->state_lock);
1308 
1309     srcu_read_unlock(&nodes_srcu, idx);
1310     return;
1311 
1312 send_fin:
1313     set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
1314     dlm_send_fin(node, dlm_pas_fin_ack_rcv);
1315     srcu_read_unlock(&nodes_srcu, idx);
1316 }
1317 
1318 static void midcomms_node_release(struct rcu_head *rcu)
1319 {
1320     struct midcomms_node *node = container_of(rcu, struct midcomms_node, rcu);
1321 
1322     WARN_ON(atomic_read(&node->send_queue_cnt));
1323     kfree(node);
1324 }
1325 
1326 static void midcomms_shutdown(struct midcomms_node *node)
1327 {
1328     int ret;
1329 
1330     /* old protocol, we don't wait for pending operations */
1331     switch (node->version) {
1332     case DLM_VERSION_3_2:
1333         break;
1334     default:
1335         return;
1336     }
1337 
1338     spin_lock(&node->state_lock);
1339     pr_debug("receive active shutdown for node %d with state %s\n",
1340          node->nodeid, dlm_state_str(node->state));
1341     switch (node->state) {
1342     case DLM_ESTABLISHED:
1343         node->state = DLM_FIN_WAIT1;
1344         pr_debug("switch node %d to state %s case 2\n",
1345              node->nodeid, dlm_state_str(node->state));
1346         break;
1347     case DLM_CLOSED:
1348         /* we have what we want */
1349         spin_unlock(&node->state_lock);
1350         return;
1351     default:
1352         /* busy to enter DLM_FIN_WAIT1, wait until passive
1353          * done in shutdown_wait to enter DLM_CLOSED.
1354          */
1355         break;
1356     }
1357     spin_unlock(&node->state_lock);
1358 
1359     if (node->state == DLM_FIN_WAIT1) {
1360         dlm_send_fin(node, dlm_act_fin_ack_rcv);
1361 
1362         if (DLM_DEBUG_FENCE_TERMINATION)
1363             msleep(5000);
1364     }
1365 
1366     /* wait for other side dlm + fin */
1367     ret = wait_event_timeout(node->shutdown_wait,
1368                  node->state == DLM_CLOSED ||
1369                  test_bit(DLM_NODE_FLAG_CLOSE, &node->flags),
1370                  DLM_SHUTDOWN_TIMEOUT);
1371     if (!ret || test_bit(DLM_NODE_FLAG_CLOSE, &node->flags)) {
1372         pr_debug("active shutdown timed out for node %d with state %s\n",
1373              node->nodeid, dlm_state_str(node->state));
1374         midcomms_node_reset(node);
1375         return;
1376     }
1377 
1378     pr_debug("active shutdown done for node %d with state %s\n",
1379          node->nodeid, dlm_state_str(node->state));
1380 }
1381 
1382 void dlm_midcomms_shutdown(void)
1383 {
1384     struct midcomms_node *node;
1385     int i, idx;
1386 
1387     mutex_lock(&close_lock);
1388     idx = srcu_read_lock(&nodes_srcu);
1389     for (i = 0; i < CONN_HASH_SIZE; i++) {
1390         hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
1391             midcomms_shutdown(node);
1392 
1393             dlm_delete_debug_comms_file(node->debugfs);
1394 
1395             spin_lock(&nodes_lock);
1396             hlist_del_rcu(&node->hlist);
1397             spin_unlock(&nodes_lock);
1398 
1399             call_srcu(&nodes_srcu, &node->rcu, midcomms_node_release);
1400         }
1401     }
1402     srcu_read_unlock(&nodes_srcu, idx);
1403     mutex_unlock(&close_lock);
1404 
1405     dlm_lowcomms_shutdown();
1406 }
1407 
1408 int dlm_midcomms_close(int nodeid)
1409 {
1410     struct midcomms_node *node;
1411     int idx, ret;
1412 
1413     if (nodeid == dlm_our_nodeid())
1414         return 0;
1415 
1416     dlm_stop_lockspaces_check();
1417 
1418     idx = srcu_read_lock(&nodes_srcu);
1419     /* Abort pending close/remove operation */
1420     node = nodeid2node(nodeid, 0);
1421     if (node) {
1422         /* let shutdown waiters leave */
1423         set_bit(DLM_NODE_FLAG_CLOSE, &node->flags);
1424         wake_up(&node->shutdown_wait);
1425     }
1426     srcu_read_unlock(&nodes_srcu, idx);
1427 
1428     synchronize_srcu(&nodes_srcu);
1429 
1430     idx = srcu_read_lock(&nodes_srcu);
1431     mutex_lock(&close_lock);
1432     node = nodeid2node(nodeid, 0);
1433     if (!node) {
1434         mutex_unlock(&close_lock);
1435         srcu_read_unlock(&nodes_srcu, idx);
1436         return dlm_lowcomms_close(nodeid);
1437     }
1438 
1439     ret = dlm_lowcomms_close(nodeid);
1440     spin_lock(&node->state_lock);
1441     midcomms_node_reset(node);
1442     spin_unlock(&node->state_lock);
1443     srcu_read_unlock(&nodes_srcu, idx);
1444     mutex_unlock(&close_lock);
1445 
1446     return ret;
1447 }
1448 
1449 /* debug functionality to send raw dlm msg from user space */
1450 struct dlm_rawmsg_data {
1451     struct midcomms_node *node;
1452     void *buf;
1453 };
1454 
1455 static void midcomms_new_rawmsg_cb(void *data)
1456 {
1457     struct dlm_rawmsg_data *rd = data;
1458     struct dlm_header *h = rd->buf;
1459 
1460     switch (h->h_version) {
1461     case cpu_to_le32(DLM_VERSION_3_1):
1462         break;
1463     default:
1464         switch (h->h_cmd) {
1465         case DLM_OPTS:
1466             if (!h->u.h_seq)
1467                 h->u.h_seq = cpu_to_le32(rd->node->seq_send++);
1468             break;
1469         default:
1470             break;
1471         }
1472         break;
1473     }
1474 }
1475 
1476 int dlm_midcomms_rawmsg_send(struct midcomms_node *node, void *buf,
1477                  int buflen)
1478 {
1479     struct dlm_rawmsg_data rd;
1480     struct dlm_msg *msg;
1481     char *msgbuf;
1482 
1483     rd.node = node;
1484     rd.buf = buf;
1485 
1486     msg = dlm_lowcomms_new_msg(node->nodeid, buflen, GFP_NOFS,
1487                    &msgbuf, midcomms_new_rawmsg_cb, &rd);
1488     if (!msg)
1489         return -ENOMEM;
1490 
1491     memcpy(msgbuf, buf, buflen);
1492     dlm_lowcomms_commit_msg(msg);
1493     return 0;
1494 }
1495
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