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1// SPDX-License-Identifier: GPL-2.0-only
2/******************************************************************************
3*******************************************************************************
4**
5** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
6** Copyright (C) 2004-2021 Red Hat, Inc. All rights reserved.
7**
8**
9*******************************************************************************
10******************************************************************************/
11
12/*
13 * midcomms.c
14 *
15 * This is the appallingly named "mid-level" comms layer. It takes care about
16 * deliver an on application layer "reliable" communication above the used
17 * lowcomms transport layer.
18 *
19 * How it works:
20 *
21 * Each nodes keeps track of all send DLM messages in send_queue with a sequence
22 * number. The receive will send an DLM_ACK message back for every DLM message
23 * received at the other side. If a reconnect happens in lowcomms we will send
24 * all unacknowledged dlm messages again. The receiving side might drop any already
25 * received message by comparing sequence numbers.
26 *
27 * How version detection works:
28 *
29 * Due the fact that dlm has pre-configured node addresses on every side
30 * it is in it's nature that every side connects at starts to transmit
31 * dlm messages which ends in a race. However DLM_RCOM_NAMES, DLM_RCOM_STATUS
32 * and their replies are the first messages which are exchanges. Due backwards
33 * compatibility these messages are not covered by the midcomms re-transmission
34 * layer. These messages have their own re-transmission handling in the dlm
35 * application layer. The version field of every node will be set on these RCOM
36 * messages as soon as they arrived and the node isn't yet part of the nodes
37 * hash. There exists also logic to detect version mismatched if something weird
38 * going on or the first messages isn't an expected one.
39 *
40 * Termination:
41 *
42 * The midcomms layer does a 4 way handshake for termination on DLM protocol
43 * like TCP supports it with half-closed socket support. SCTP doesn't support
44 * half-closed socket, so we do it on DLM layer. Also socket shutdown() can be
45 * interrupted by .e.g. tcp reset itself. Additional there exists the othercon
46 * paradigm in lowcomms which cannot be easily without breaking backwards
47 * compatibility. A node cannot send anything to another node when a DLM_FIN
48 * message was send. There exists additional logic to print a warning if
49 * DLM wants to do it. There exists a state handling like RFC 793 but reduced
50 * to termination only. The event "member removal event" describes the cluster
51 * manager removed the node from internal lists, at this point DLM does not
52 * send any message to the other node. There exists two cases:
53 *
54 * 1. The cluster member was removed and we received a FIN
55 * OR
56 * 2. We received a FIN but the member was not removed yet
57 *
58 * One of these cases will do the CLOSE_WAIT to LAST_ACK change.
59 *
60 *
61 * +---------+
62 * | CLOSED |
63 * +---------+
64 * | add member/receive RCOM version
65 * | detection msg
66 * V
67 * +---------+
68 * | ESTAB |
69 * +---------+
70 * CLOSE | | rcv FIN
71 * ------- | | -------
72 * +---------+ snd FIN / \ snd ACK +---------+
73 * | FIN |<----------------- ------------------>| CLOSE |
74 * | WAIT-1 |------------------ | WAIT |
75 * +---------+ rcv FIN \ +---------+
76 * | rcv ACK of FIN ------- | CLOSE | member
77 * | -------------- snd ACK | ------- | removal
78 * V x V snd FIN V event
79 * +---------+ +---------+ +---------+
80 * |FINWAIT-2| | CLOSING | | LAST-ACK|
81 * +---------+ +---------+ +---------+
82 * | rcv ACK of FIN | rcv ACK of FIN |
83 * | rcv FIN -------------- | -------------- |
84 * | ------- x V x V
85 * \ snd ACK +---------+ +---------+
86 * ------------------------>| CLOSED | | CLOSED |
87 * +---------+ +---------+
88 *
89 * NOTE: any state can interrupted by midcomms_close() and state will be
90 * switched to CLOSED in case of fencing. There exists also some timeout
91 * handling when we receive the version detection RCOM messages which is
92 * made by observation.
93 *
94 * Future improvements:
95 *
96 * There exists some known issues/improvements of the dlm handling. Some
97 * of them should be done in a next major dlm version bump which makes
98 * it incompatible with previous versions.
99 *
100 * Unaligned memory access:
101 *
102 * There exists cases when the dlm message buffer length is not aligned
103 * to 8 byte. However seems nobody detected any problem with it. This
104 * can be fixed in the next major version bump of dlm.
105 *
106 * Version detection:
107 *
108 * The version detection and how it's done is related to backwards
109 * compatibility. There exists better ways to make a better handling.
110 * However this should be changed in the next major version bump of dlm.
111 *
112 * Ack handling:
113 *
114 * Currently we send an ack message for every dlm message. However we
115 * can ack multiple dlm messages with one ack by just delaying the ack
116 * message. Will reduce some traffic but makes the drop detection slower.
117 *
118 * Tail Size checking:
119 *
120 * There exists a message tail payload in e.g. DLM_MSG however we don't
121 * check it against the message length yet regarding to the receive buffer
122 * length. That need to be validated.
123 *
124 * Fencing bad nodes:
125 *
126 * At timeout places or weird sequence number behaviours we should send
127 * a fencing request to the cluster manager.
128 */
129
130/* Debug switch to enable a 5 seconds sleep waiting of a termination.
131 * This can be useful to test fencing while termination is running.
132 * This requires a setup with only gfs2 as dlm user, so that the
133 * last umount will terminate the connection.
134 *
135 * However it became useful to test, while the 5 seconds block in umount
136 * just press the reset button. In a lot of dropping the termination
137 * process can could take several seconds.
138 */
139#define DLM_DEBUG_FENCE_TERMINATION 0
140
141#include <net/tcp.h>
142
143#include "dlm_internal.h"
144#include "lowcomms.h"
145#include "config.h"
146#include "lock.h"
147#include "util.h"
148#include "midcomms.h"
149
150/* init value for sequence numbers for testing purpose only e.g. overflows */
151#define DLM_SEQ_INIT 0
152/* 3 minutes wait to sync ending of dlm */
153#define DLM_SHUTDOWN_TIMEOUT msecs_to_jiffies(3 * 60 * 1000)
154#define DLM_VERSION_NOT_SET 0
155
156struct midcomms_node {
157 int nodeid;
158 uint32_t version;
159 uint32_t seq_send;
160 uint32_t seq_next;
161 /* These queues are unbound because we cannot drop any message in dlm.
162 * We could send a fence signal for a specific node to the cluster
163 * manager if queues hits some maximum value, however this handling
164 * not supported yet.
165 */
166 struct list_head send_queue;
167 spinlock_t send_queue_lock;
168 atomic_t send_queue_cnt;
169#define DLM_NODE_FLAG_CLOSE 1
170#define DLM_NODE_FLAG_STOP_TX 2
171#define DLM_NODE_FLAG_STOP_RX 3
172 unsigned long flags;
173 wait_queue_head_t shutdown_wait;
174
175 /* dlm tcp termination state */
176#define DLM_CLOSED 1
177#define DLM_ESTABLISHED 2
178#define DLM_FIN_WAIT1 3
179#define DLM_FIN_WAIT2 4
180#define DLM_CLOSE_WAIT 5
181#define DLM_LAST_ACK 6
182#define DLM_CLOSING 7
183 int state;
184 spinlock_t state_lock;
185
186 /* counts how many lockspaces are using this node
187 * this refcount is necessary to determine if the
188 * node wants to disconnect.
189 */
190 int users;
191
192 /* not protected by srcu, node_hash lifetime */
193 void *debugfs;
194
195 struct hlist_node hlist;
196 struct rcu_head rcu;
197};
198
199struct dlm_mhandle {
200 const struct dlm_header *inner_hd;
201 struct midcomms_node *node;
202 struct dlm_opts *opts;
203 struct dlm_msg *msg;
204 bool committed;
205 uint32_t seq;
206
207 void (*ack_rcv)(struct midcomms_node *node);
208
209 /* get_mhandle/commit srcu idx exchange */
210 int idx;
211
212 struct list_head list;
213 struct rcu_head rcu;
214};
215
216static struct hlist_head node_hash[CONN_HASH_SIZE];
217static DEFINE_SPINLOCK(nodes_lock);
218DEFINE_STATIC_SRCU(nodes_srcu);
219
220/* This mutex prevents that midcomms_close() is running while
221 * stop() or remove(). As I experienced invalid memory access
222 * behaviours when DLM_DEBUG_FENCE_TERMINATION is enabled and
223 * resetting machines. I will end in some double deletion in nodes
224 * datastructure.
225 */
226static DEFINE_MUTEX(close_lock);
227
228static inline const char *dlm_state_str(int state)
229{
230 switch (state) {
231 case DLM_CLOSED:
232 return "CLOSED";
233 case DLM_ESTABLISHED:
234 return "ESTABLISHED";
235 case DLM_FIN_WAIT1:
236 return "FIN_WAIT1";
237 case DLM_FIN_WAIT2:
238 return "FIN_WAIT2";
239 case DLM_CLOSE_WAIT:
240 return "CLOSE_WAIT";
241 case DLM_LAST_ACK:
242 return "LAST_ACK";
243 case DLM_CLOSING:
244 return "CLOSING";
245 default:
246 return "UNKNOWN";
247 }
248}
249
250const char *dlm_midcomms_state(struct midcomms_node *node)
251{
252 return dlm_state_str(node->state);
253}
254
255unsigned long dlm_midcomms_flags(struct midcomms_node *node)
256{
257 return node->flags;
258}
259
260int dlm_midcomms_send_queue_cnt(struct midcomms_node *node)
261{
262 return atomic_read(&node->send_queue_cnt);
263}
264
265uint32_t dlm_midcomms_version(struct midcomms_node *node)
266{
267 return node->version;
268}
269
270static struct midcomms_node *__find_node(int nodeid, int r)
271{
272 struct midcomms_node *node;
273
274 hlist_for_each_entry_rcu(node, &node_hash[r], hlist) {
275 if (node->nodeid == nodeid)
276 return node;
277 }
278
279 return NULL;
280}
281
282static void dlm_mhandle_release(struct rcu_head *rcu)
283{
284 struct dlm_mhandle *mh = container_of(rcu, struct dlm_mhandle, rcu);
285
286 dlm_lowcomms_put_msg(mh->msg);
287 kfree(mh);
288}
289
290static void dlm_mhandle_delete(struct midcomms_node *node,
291 struct dlm_mhandle *mh)
292{
293 list_del_rcu(&mh->list);
294 atomic_dec(&node->send_queue_cnt);
295 call_rcu(&mh->rcu, dlm_mhandle_release);
296}
297
298static void dlm_send_queue_flush(struct midcomms_node *node)
299{
300 struct dlm_mhandle *mh;
301
302 pr_debug("flush midcomms send queue of node %d\n", node->nodeid);
303
304 rcu_read_lock();
305 spin_lock(&node->send_queue_lock);
306 list_for_each_entry_rcu(mh, &node->send_queue, list) {
307 dlm_mhandle_delete(node, mh);
308 }
309 spin_unlock(&node->send_queue_lock);
310 rcu_read_unlock();
311}
312
313static void midcomms_node_reset(struct midcomms_node *node)
314{
315 pr_debug("reset node %d\n", node->nodeid);
316
317 node->seq_next = DLM_SEQ_INIT;
318 node->seq_send = DLM_SEQ_INIT;
319 node->version = DLM_VERSION_NOT_SET;
320 node->flags = 0;
321
322 dlm_send_queue_flush(node);
323 node->state = DLM_CLOSED;
324 wake_up(&node->shutdown_wait);
325}
326
327static struct midcomms_node *nodeid2node(int nodeid, gfp_t alloc)
328{
329 struct midcomms_node *node, *tmp;
330 int r = nodeid_hash(nodeid);
331
332 node = __find_node(nodeid, r);
333 if (node || !alloc)
334 return node;
335
336 node = kmalloc(sizeof(*node), alloc);
337 if (!node)
338 return NULL;
339
340 node->nodeid = nodeid;
341 spin_lock_init(&node->state_lock);
342 spin_lock_init(&node->send_queue_lock);
343 atomic_set(&node->send_queue_cnt, 0);
344 INIT_LIST_HEAD(&node->send_queue);
345 init_waitqueue_head(&node->shutdown_wait);
346 node->users = 0;
347 midcomms_node_reset(node);
348
349 spin_lock(&nodes_lock);
350 /* check again if there was somebody else
351 * earlier here to add the node
352 */
353 tmp = __find_node(nodeid, r);
354 if (tmp) {
355 spin_unlock(&nodes_lock);
356 kfree(node);
357 return tmp;
358 }
359
360 hlist_add_head_rcu(&node->hlist, &node_hash[r]);
361 spin_unlock(&nodes_lock);
362
363 node->debugfs = dlm_create_debug_comms_file(nodeid, node);
364 return node;
365}
366
367static int dlm_send_ack(int nodeid, uint32_t seq)
368{
369 int mb_len = sizeof(struct dlm_header);
370 struct dlm_header *m_header;
371 struct dlm_msg *msg;
372 char *ppc;
373
374 msg = dlm_lowcomms_new_msg(nodeid, mb_len, GFP_NOFS, &ppc,
375 NULL, NULL);
376 if (!msg)
377 return -ENOMEM;
378
379 m_header = (struct dlm_header *)ppc;
380
381 m_header->h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
382 m_header->h_nodeid = dlm_our_nodeid();
383 m_header->h_length = mb_len;
384 m_header->h_cmd = DLM_ACK;
385 m_header->u.h_seq = seq;
386
387 header_out(m_header);
388 dlm_lowcomms_commit_msg(msg);
389 dlm_lowcomms_put_msg(msg);
390
391 return 0;
392}
393
394static int dlm_send_fin(struct midcomms_node *node,
395 void (*ack_rcv)(struct midcomms_node *node))
396{
397 int mb_len = sizeof(struct dlm_header);
398 struct dlm_header *m_header;
399 struct dlm_mhandle *mh;
400 char *ppc;
401
402 mh = dlm_midcomms_get_mhandle(node->nodeid, mb_len, GFP_NOFS, &ppc);
403 if (!mh)
404 return -ENOMEM;
405
406 mh->ack_rcv = ack_rcv;
407
408 m_header = (struct dlm_header *)ppc;
409
410 m_header->h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
411 m_header->h_nodeid = dlm_our_nodeid();
412 m_header->h_length = mb_len;
413 m_header->h_cmd = DLM_FIN;
414
415 header_out(m_header);
416
417 pr_debug("sending fin msg to node %d\n", node->nodeid);
418 dlm_midcomms_commit_mhandle(mh);
419 set_bit(DLM_NODE_FLAG_STOP_TX, &node->flags);
420
421 return 0;
422}
423
424static void dlm_receive_ack(struct midcomms_node *node, uint32_t seq)
425{
426 struct dlm_mhandle *mh;
427
428 rcu_read_lock();
429 list_for_each_entry_rcu(mh, &node->send_queue, list) {
430 if (before(mh->seq, seq)) {
431 if (mh->ack_rcv)
432 mh->ack_rcv(node);
433 } else {
434 /* send queue should be ordered */
435 break;
436 }
437 }
438
439 spin_lock(&node->send_queue_lock);
440 list_for_each_entry_rcu(mh, &node->send_queue, list) {
441 if (before(mh->seq, seq)) {
442 dlm_mhandle_delete(node, mh);
443 } else {
444 /* send queue should be ordered */
445 break;
446 }
447 }
448 spin_unlock(&node->send_queue_lock);
449 rcu_read_unlock();
450}
451
452static void dlm_pas_fin_ack_rcv(struct midcomms_node *node)
453{
454 spin_lock(&node->state_lock);
455 pr_debug("receive passive fin ack from node %d with state %s\n",
456 node->nodeid, dlm_state_str(node->state));
457
458 switch (node->state) {
459 case DLM_LAST_ACK:
460 /* DLM_CLOSED */
461 midcomms_node_reset(node);
462 break;
463 case DLM_CLOSED:
464 /* not valid but somehow we got what we want */
465 wake_up(&node->shutdown_wait);
466 break;
467 default:
468 spin_unlock(&node->state_lock);
469 log_print("%s: unexpected state: %d\n",
470 __func__, node->state);
471 WARN_ON(1);
472 return;
473 }
474 spin_unlock(&node->state_lock);
475}
476
477static void dlm_midcomms_receive_buffer(union dlm_packet *p,
478 struct midcomms_node *node,
479 uint32_t seq)
480{
481 if (seq == node->seq_next) {
482 node->seq_next++;
483 /* send ack before fin */
484 dlm_send_ack(node->nodeid, node->seq_next);
485
486 switch (p->header.h_cmd) {
487 case DLM_FIN:
488 spin_lock(&node->state_lock);
489 pr_debug("receive fin msg from node %d with state %s\n",
490 node->nodeid, dlm_state_str(node->state));
491
492 switch (node->state) {
493 case DLM_ESTABLISHED:
494 node->state = DLM_CLOSE_WAIT;
495 pr_debug("switch node %d to state %s\n",
496 node->nodeid, dlm_state_str(node->state));
497 /* passive shutdown DLM_LAST_ACK case 1
498 * additional we check if the node is used by
499 * cluster manager events at all.
500 */
501 if (node->users == 0) {
502 node->state = DLM_LAST_ACK;
503 pr_debug("switch node %d to state %s case 1\n",
504 node->nodeid, dlm_state_str(node->state));
505 spin_unlock(&node->state_lock);
506 goto send_fin;
507 }
508 break;
509 case DLM_FIN_WAIT1:
510 node->state = DLM_CLOSING;
511 pr_debug("switch node %d to state %s\n",
512 node->nodeid, dlm_state_str(node->state));
513 break;
514 case DLM_FIN_WAIT2:
515 midcomms_node_reset(node);
516 pr_debug("switch node %d to state %s\n",
517 node->nodeid, dlm_state_str(node->state));
518 wake_up(&node->shutdown_wait);
519 break;
520 case DLM_LAST_ACK:
521 /* probably remove_member caught it, do nothing */
522 break;
523 default:
524 spin_unlock(&node->state_lock);
525 log_print("%s: unexpected state: %d\n",
526 __func__, node->state);
527 WARN_ON(1);
528 return;
529 }
530 spin_unlock(&node->state_lock);
531
532 set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
533 break;
534 default:
535 WARN_ON(test_bit(DLM_NODE_FLAG_STOP_RX, &node->flags));
536 dlm_receive_buffer(p, node->nodeid);
537 break;
538 }
539 } else {
540 /* retry to ack message which we already have by sending back
541 * current node->seq_next number as ack.
542 */
543 if (seq < node->seq_next)
544 dlm_send_ack(node->nodeid, node->seq_next);
545
546 log_print_ratelimited("ignore dlm msg because seq mismatch, seq: %u, expected: %u, nodeid: %d",
547 seq, node->seq_next, node->nodeid);
548 }
549
550 return;
551
552send_fin:
553 set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
554 dlm_send_fin(node, dlm_pas_fin_ack_rcv);
555}
556
557static struct midcomms_node *
558dlm_midcomms_recv_node_lookup(int nodeid, const union dlm_packet *p,
559 uint16_t msglen, int (*cb)(struct midcomms_node *node))
560{
561 struct midcomms_node *node = NULL;
562 gfp_t allocation = 0;
563 int ret;
564
565 switch (p->header.h_cmd) {
566 case DLM_RCOM:
567 if (msglen < sizeof(struct dlm_rcom)) {
568 log_print("rcom msg too small: %u, will skip this message from node %d",
569 msglen, nodeid);
570 return NULL;
571 }
572
573 switch (le32_to_cpu(p->rcom.rc_type)) {
574 case DLM_RCOM_NAMES:
575 fallthrough;
576 case DLM_RCOM_NAMES_REPLY:
577 fallthrough;
578 case DLM_RCOM_STATUS:
579 fallthrough;
580 case DLM_RCOM_STATUS_REPLY:
581 node = nodeid2node(nodeid, 0);
582 if (node) {
583 spin_lock(&node->state_lock);
584 if (node->state != DLM_ESTABLISHED)
585 pr_debug("receive begin RCOM msg from node %d with state %s\n",
586 node->nodeid, dlm_state_str(node->state));
587
588 switch (node->state) {
589 case DLM_CLOSED:
590 node->state = DLM_ESTABLISHED;
591 pr_debug("switch node %d to state %s\n",
592 node->nodeid, dlm_state_str(node->state));
593 break;
594 case DLM_ESTABLISHED:
595 break;
596 default:
597 /* some invalid state passive shutdown
598 * was failed, we try to reset and
599 * hope it will go on.
600 */
601 log_print("reset node %d because shutdown stuck",
602 node->nodeid);
603
604 midcomms_node_reset(node);
605 node->state = DLM_ESTABLISHED;
606 break;
607 }
608 spin_unlock(&node->state_lock);
609 }
610
611 allocation = GFP_NOFS;
612 break;
613 default:
614 break;
615 }
616
617 break;
618 default:
619 break;
620 }
621
622 node = nodeid2node(nodeid, allocation);
623 if (!node) {
624 switch (p->header.h_cmd) {
625 case DLM_OPTS:
626 if (msglen < sizeof(struct dlm_opts)) {
627 log_print("opts msg too small: %u, will skip this message from node %d",
628 msglen, nodeid);
629 return NULL;
630 }
631
632 log_print_ratelimited("received dlm opts message nextcmd %d from node %d in an invalid sequence",
633 p->opts.o_nextcmd, nodeid);
634 break;
635 default:
636 log_print_ratelimited("received dlm message cmd %d from node %d in an invalid sequence",
637 p->header.h_cmd, nodeid);
638 break;
639 }
640
641 return NULL;
642 }
643
644 ret = cb(node);
645 if (ret < 0)
646 return NULL;
647
648 return node;
649}
650
651static int dlm_midcomms_version_check_3_2(struct midcomms_node *node)
652{
653 switch (node->version) {
654 case DLM_VERSION_NOT_SET:
655 node->version = DLM_VERSION_3_2;
656 log_print("version 0x%08x for node %d detected", DLM_VERSION_3_2,
657 node->nodeid);
658 break;
659 case DLM_VERSION_3_2:
660 break;
661 default:
662 log_print_ratelimited("version mismatch detected, assumed 0x%08x but node %d has 0x%08x",
663 DLM_VERSION_3_2, node->nodeid, node->version);
664 return -1;
665 }
666
667 return 0;
668}
669
670static int dlm_opts_check_msglen(union dlm_packet *p, uint16_t msglen, int nodeid)
671{
672 int len = msglen;
673
674 /* we only trust outer header msglen because
675 * it's checked against receive buffer length.
676 */
677 if (len < sizeof(struct dlm_opts))
678 return -1;
679 len -= sizeof(struct dlm_opts);
680
681 if (len < le16_to_cpu(p->opts.o_optlen))
682 return -1;
683 len -= le16_to_cpu(p->opts.o_optlen);
684
685 switch (p->opts.o_nextcmd) {
686 case DLM_FIN:
687 if (len < sizeof(struct dlm_header)) {
688 log_print("fin too small: %d, will skip this message from node %d",
689 len, nodeid);
690 return -1;
691 }
692
693 break;
694 case DLM_MSG:
695 if (len < sizeof(struct dlm_message)) {
696 log_print("msg too small: %d, will skip this message from node %d",
697 msglen, nodeid);
698 return -1;
699 }
700
701 break;
702 case DLM_RCOM:
703 if (len < sizeof(struct dlm_rcom)) {
704 log_print("rcom msg too small: %d, will skip this message from node %d",
705 len, nodeid);
706 return -1;
707 }
708
709 break;
710 default:
711 log_print("unsupported o_nextcmd received: %u, will skip this message from node %d",
712 p->opts.o_nextcmd, nodeid);
713 return -1;
714 }
715
716 return 0;
717}
718
719static void dlm_midcomms_receive_buffer_3_2(union dlm_packet *p, int nodeid)
720{
721 uint16_t msglen = le16_to_cpu(p->header.h_length);
722 struct midcomms_node *node;
723 uint32_t seq;
724 int ret, idx;
725
726 idx = srcu_read_lock(&nodes_srcu);
727 node = dlm_midcomms_recv_node_lookup(nodeid, p, msglen,
728 dlm_midcomms_version_check_3_2);
729 if (!node)
730 goto out;
731
732 switch (p->header.h_cmd) {
733 case DLM_RCOM:
734 /* these rcom message we use to determine version.
735 * they have their own retransmission handling and
736 * are the first messages of dlm.
737 *
738 * length already checked.
739 */
740 switch (le32_to_cpu(p->rcom.rc_type)) {
741 case DLM_RCOM_NAMES:
742 fallthrough;
743 case DLM_RCOM_NAMES_REPLY:
744 fallthrough;
745 case DLM_RCOM_STATUS:
746 fallthrough;
747 case DLM_RCOM_STATUS_REPLY:
748 break;
749 default:
750 log_print("unsupported rcom type received: %u, will skip this message from node %d",
751 le32_to_cpu(p->rcom.rc_type), nodeid);
752 goto out;
753 }
754
755 WARN_ON(test_bit(DLM_NODE_FLAG_STOP_RX, &node->flags));
756 dlm_receive_buffer(p, nodeid);
757 break;
758 case DLM_OPTS:
759 seq = le32_to_cpu(p->header.u.h_seq);
760
761 ret = dlm_opts_check_msglen(p, msglen, nodeid);
762 if (ret < 0) {
763 log_print("opts msg too small: %u, will skip this message from node %d",
764 msglen, nodeid);
765 goto out;
766 }
767
768 p = (union dlm_packet *)((unsigned char *)p->opts.o_opts +
769 le16_to_cpu(p->opts.o_optlen));
770
771 /* recheck inner msglen just if it's not garbage */
772 msglen = le16_to_cpu(p->header.h_length);
773 switch (p->header.h_cmd) {
774 case DLM_RCOM:
775 if (msglen < sizeof(struct dlm_rcom)) {
776 log_print("inner rcom msg too small: %u, will skip this message from node %d",
777 msglen, nodeid);
778 goto out;
779 }
780
781 break;
782 case DLM_MSG:
783 if (msglen < sizeof(struct dlm_message)) {
784 log_print("inner msg too small: %u, will skip this message from node %d",
785 msglen, nodeid);
786 goto out;
787 }
788
789 break;
790 case DLM_FIN:
791 if (msglen < sizeof(struct dlm_header)) {
792 log_print("inner fin too small: %u, will skip this message from node %d",
793 msglen, nodeid);
794 goto out;
795 }
796
797 break;
798 default:
799 log_print("unsupported inner h_cmd received: %u, will skip this message from node %d",
800 msglen, nodeid);
801 goto out;
802 }
803
804 dlm_midcomms_receive_buffer(p, node, seq);
805 break;
806 case DLM_ACK:
807 seq = le32_to_cpu(p->header.u.h_seq);
808 dlm_receive_ack(node, seq);
809 break;
810 default:
811 log_print("unsupported h_cmd received: %u, will skip this message from node %d",
812 p->header.h_cmd, nodeid);
813 break;
814 }
815
816out:
817 srcu_read_unlock(&nodes_srcu, idx);
818}
819
820static int dlm_midcomms_version_check_3_1(struct midcomms_node *node)
821{
822 switch (node->version) {
823 case DLM_VERSION_NOT_SET:
824 node->version = DLM_VERSION_3_1;
825 log_print("version 0x%08x for node %d detected", DLM_VERSION_3_1,
826 node->nodeid);
827 break;
828 case DLM_VERSION_3_1:
829 break;
830 default:
831 log_print_ratelimited("version mismatch detected, assumed 0x%08x but node %d has 0x%08x",
832 DLM_VERSION_3_1, node->nodeid, node->version);
833 return -1;
834 }
835
836 return 0;
837}
838
839static void dlm_midcomms_receive_buffer_3_1(union dlm_packet *p, int nodeid)
840{
841 uint16_t msglen = le16_to_cpu(p->header.h_length);
842 struct midcomms_node *node;
843 int idx;
844
845 idx = srcu_read_lock(&nodes_srcu);
846 node = dlm_midcomms_recv_node_lookup(nodeid, p, msglen,
847 dlm_midcomms_version_check_3_1);
848 if (!node) {
849 srcu_read_unlock(&nodes_srcu, idx);
850 return;
851 }
852 srcu_read_unlock(&nodes_srcu, idx);
853
854 switch (p->header.h_cmd) {
855 case DLM_RCOM:
856 /* length already checked */
857 break;
858 case DLM_MSG:
859 if (msglen < sizeof(struct dlm_message)) {
860 log_print("msg too small: %u, will skip this message from node %d",
861 msglen, nodeid);
862 return;
863 }
864
865 break;
866 default:
867 log_print("unsupported h_cmd received: %u, will skip this message from node %d",
868 p->header.h_cmd, nodeid);
869 return;
870 }
871
872 dlm_receive_buffer(p, nodeid);
873}
874
875/*
876 * Called from the low-level comms layer to process a buffer of
877 * commands.
878 */
879
880int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
881{
882 const unsigned char *ptr = buf;
883 const struct dlm_header *hd;
884 uint16_t msglen;
885 int ret = 0;
886
887 while (len >= sizeof(struct dlm_header)) {
888 hd = (struct dlm_header *)ptr;
889
890 /* no message should be more than DLM_MAX_SOCKET_BUFSIZE or
891 * less than dlm_header size.
892 *
893 * Some messages does not have a 8 byte length boundary yet
894 * which can occur in a unaligned memory access of some dlm
895 * messages. However this problem need to be fixed at the
896 * sending side, for now it seems nobody run into architecture
897 * related issues yet but it slows down some processing.
898 * Fixing this issue should be scheduled in future by doing
899 * the next major version bump.
900 */
901 msglen = le16_to_cpu(hd->h_length);
902 if (msglen > DLM_MAX_SOCKET_BUFSIZE ||
903 msglen < sizeof(struct dlm_header)) {
904 log_print("received invalid length header: %u from node %d, will abort message parsing",
905 msglen, nodeid);
906 return -EBADMSG;
907 }
908
909 /* caller will take care that leftover
910 * will be parsed next call with more data
911 */
912 if (msglen > len)
913 break;
914
915 switch (le32_to_cpu(hd->h_version)) {
916 case DLM_VERSION_3_1:
917 dlm_midcomms_receive_buffer_3_1((union dlm_packet *)ptr, nodeid);
918 break;
919 case DLM_VERSION_3_2:
920 dlm_midcomms_receive_buffer_3_2((union dlm_packet *)ptr, nodeid);
921 break;
922 default:
923 log_print("received invalid version header: %u from node %d, will skip this message",
924 le32_to_cpu(hd->h_version), nodeid);
925 break;
926 }
927
928 ret += msglen;
929 len -= msglen;
930 ptr += msglen;
931 }
932
933 return ret;
934}
935
936void dlm_midcomms_unack_msg_resend(int nodeid)
937{
938 struct midcomms_node *node;
939 struct dlm_mhandle *mh;
940 int idx, ret;
941
942 idx = srcu_read_lock(&nodes_srcu);
943 node = nodeid2node(nodeid, 0);
944 if (!node) {
945 srcu_read_unlock(&nodes_srcu, idx);
946 return;
947 }
948
949 /* old protocol, we don't support to retransmit on failure */
950 switch (node->version) {
951 case DLM_VERSION_3_2:
952 break;
953 default:
954 srcu_read_unlock(&nodes_srcu, idx);
955 return;
956 }
957
958 rcu_read_lock();
959 list_for_each_entry_rcu(mh, &node->send_queue, list) {
960 if (!mh->committed)
961 continue;
962
963 ret = dlm_lowcomms_resend_msg(mh->msg);
964 if (!ret)
965 log_print_ratelimited("retransmit dlm msg, seq %u, nodeid %d",
966 mh->seq, node->nodeid);
967 }
968 rcu_read_unlock();
969 srcu_read_unlock(&nodes_srcu, idx);
970}
971
972static void dlm_fill_opts_header(struct dlm_opts *opts, uint16_t inner_len,
973 uint32_t seq)
974{
975 opts->o_header.h_cmd = DLM_OPTS;
976 opts->o_header.h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
977 opts->o_header.h_nodeid = dlm_our_nodeid();
978 opts->o_header.h_length = DLM_MIDCOMMS_OPT_LEN + inner_len;
979 opts->o_header.u.h_seq = seq;
980 header_out(&opts->o_header);
981}
982
983static void midcomms_new_msg_cb(struct dlm_mhandle *mh)
984{
985 atomic_inc(&mh->node->send_queue_cnt);
986
987 spin_lock(&mh->node->send_queue_lock);
988 list_add_tail_rcu(&mh->list, &mh->node->send_queue);
989 spin_unlock(&mh->node->send_queue_lock);
990
991 mh->seq = mh->node->seq_send++;
992}
993
994static struct dlm_msg *dlm_midcomms_get_msg_3_2(struct dlm_mhandle *mh, int nodeid,
995 int len, gfp_t allocation, char **ppc)
996{
997 struct dlm_opts *opts;
998 struct dlm_msg *msg;
999
1000 msg = dlm_lowcomms_new_msg(nodeid, len + DLM_MIDCOMMS_OPT_LEN,
1001 allocation, ppc, midcomms_new_msg_cb, mh);
1002 if (!msg)
1003 return NULL;
1004
1005 opts = (struct dlm_opts *)*ppc;
1006 mh->opts = opts;
1007
1008 /* add possible options here */
1009 dlm_fill_opts_header(opts, len, mh->seq);
1010
1011 *ppc += sizeof(*opts);
1012 mh->inner_hd = (const struct dlm_header *)*ppc;
1013 return msg;
1014}
1015
1016struct dlm_mhandle *dlm_midcomms_get_mhandle(int nodeid, int len,
1017 gfp_t allocation, char **ppc)
1018{
1019 struct midcomms_node *node;
1020 struct dlm_mhandle *mh;
1021 struct dlm_msg *msg;
1022 int idx;
1023
1024 idx = srcu_read_lock(&nodes_srcu);
1025 node = nodeid2node(nodeid, 0);
1026 if (!node) {
1027 WARN_ON_ONCE(1);
1028 goto err;
1029 }
1030
1031 /* this is a bug, however we going on and hope it will be resolved */
1032 WARN_ON(test_bit(DLM_NODE_FLAG_STOP_TX, &node->flags));
1033
1034 mh = kzalloc(sizeof(*mh), GFP_NOFS);
1035 if (!mh)
1036 goto err;
1037
1038 mh->idx = idx;
1039 mh->node = node;
1040
1041 switch (node->version) {
1042 case DLM_VERSION_3_1:
1043 msg = dlm_lowcomms_new_msg(nodeid, len, allocation, ppc,
1044 NULL, NULL);
1045 if (!msg) {
1046 kfree(mh);
1047 goto err;
1048 }
1049
1050 break;
1051 case DLM_VERSION_3_2:
1052 msg = dlm_midcomms_get_msg_3_2(mh, nodeid, len, allocation,
1053 ppc);
1054 if (!msg) {
1055 kfree(mh);
1056 goto err;
1057 }
1058
1059 break;
1060 default:
1061 kfree(mh);
1062 WARN_ON(1);
1063 goto err;
1064 }
1065
1066 mh->msg = msg;
1067
1068 /* keep in mind that is a must to call
1069 * dlm_midcomms_commit_msg() which releases
1070 * nodes_srcu using mh->idx which is assumed
1071 * here that the application will call it.
1072 */
1073 return mh;
1074
1075err:
1076 srcu_read_unlock(&nodes_srcu, idx);
1077 return NULL;
1078}
1079
1080static void dlm_midcomms_commit_msg_3_2(struct dlm_mhandle *mh)
1081{
1082 /* nexthdr chain for fast lookup */
1083 mh->opts->o_nextcmd = mh->inner_hd->h_cmd;
1084 mh->committed = true;
1085 dlm_lowcomms_commit_msg(mh->msg);
1086}
1087
1088void dlm_midcomms_commit_mhandle(struct dlm_mhandle *mh)
1089{
1090 switch (mh->node->version) {
1091 case DLM_VERSION_3_1:
1092 srcu_read_unlock(&nodes_srcu, mh->idx);
1093
1094 dlm_lowcomms_commit_msg(mh->msg);
1095 dlm_lowcomms_put_msg(mh->msg);
1096 /* mh is not part of rcu list in this case */
1097 kfree(mh);
1098 break;
1099 case DLM_VERSION_3_2:
1100 dlm_midcomms_commit_msg_3_2(mh);
1101 srcu_read_unlock(&nodes_srcu, mh->idx);
1102 break;
1103 default:
1104 srcu_read_unlock(&nodes_srcu, mh->idx);
1105 WARN_ON(1);
1106 break;
1107 }
1108}
1109
1110int dlm_midcomms_start(void)
1111{
1112 int i;
1113
1114 for (i = 0; i < CONN_HASH_SIZE; i++)
1115 INIT_HLIST_HEAD(&node_hash[i]);
1116
1117 return dlm_lowcomms_start();
1118}
1119
1120static void dlm_act_fin_ack_rcv(struct midcomms_node *node)
1121{
1122 spin_lock(&node->state_lock);
1123 pr_debug("receive active fin ack from node %d with state %s\n",
1124 node->nodeid, dlm_state_str(node->state));
1125
1126 switch (node->state) {
1127 case DLM_FIN_WAIT1:
1128 node->state = DLM_FIN_WAIT2;
1129 pr_debug("switch node %d to state %s\n",
1130 node->nodeid, dlm_state_str(node->state));
1131 break;
1132 case DLM_CLOSING:
1133 midcomms_node_reset(node);
1134 pr_debug("switch node %d to state %s\n",
1135 node->nodeid, dlm_state_str(node->state));
1136 wake_up(&node->shutdown_wait);
1137 break;
1138 case DLM_CLOSED:
1139 /* not valid but somehow we got what we want */
1140 wake_up(&node->shutdown_wait);
1141 break;
1142 default:
1143 spin_unlock(&node->state_lock);
1144 log_print("%s: unexpected state: %d\n",
1145 __func__, node->state);
1146 WARN_ON(1);
1147 return;
1148 }
1149 spin_unlock(&node->state_lock);
1150}
1151
1152void dlm_midcomms_add_member(int nodeid)
1153{
1154 struct midcomms_node *node;
1155 int idx;
1156
1157 if (nodeid == dlm_our_nodeid())
1158 return;
1159
1160 idx = srcu_read_lock(&nodes_srcu);
1161 node = nodeid2node(nodeid, GFP_NOFS);
1162 if (!node) {
1163 srcu_read_unlock(&nodes_srcu, idx);
1164 return;
1165 }
1166
1167 spin_lock(&node->state_lock);
1168 if (!node->users) {
1169 pr_debug("receive add member from node %d with state %s\n",
1170 node->nodeid, dlm_state_str(node->state));
1171 switch (node->state) {
1172 case DLM_ESTABLISHED:
1173 break;
1174 case DLM_CLOSED:
1175 node->state = DLM_ESTABLISHED;
1176 pr_debug("switch node %d to state %s\n",
1177 node->nodeid, dlm_state_str(node->state));
1178 break;
1179 default:
1180 /* some invalid state passive shutdown
1181 * was failed, we try to reset and
1182 * hope it will go on.
1183 */
1184 log_print("reset node %d because shutdown stuck",
1185 node->nodeid);
1186
1187 midcomms_node_reset(node);
1188 node->state = DLM_ESTABLISHED;
1189 break;
1190 }
1191 }
1192
1193 node->users++;
1194 pr_debug("users inc count %d\n", node->users);
1195 spin_unlock(&node->state_lock);
1196
1197 srcu_read_unlock(&nodes_srcu, idx);
1198}
1199
1200void dlm_midcomms_remove_member(int nodeid)
1201{
1202 struct midcomms_node *node;
1203 int idx;
1204
1205 if (nodeid == dlm_our_nodeid())
1206 return;
1207
1208 idx = srcu_read_lock(&nodes_srcu);
1209 node = nodeid2node(nodeid, 0);
1210 if (!node) {
1211 srcu_read_unlock(&nodes_srcu, idx);
1212 return;
1213 }
1214
1215 spin_lock(&node->state_lock);
1216 node->users--;
1217 pr_debug("users dec count %d\n", node->users);
1218
1219 /* hitting users count to zero means the
1220 * other side is running dlm_midcomms_stop()
1221 * we meet us to have a clean disconnect.
1222 */
1223 if (node->users == 0) {
1224 pr_debug("receive remove member from node %d with state %s\n",
1225 node->nodeid, dlm_state_str(node->state));
1226 switch (node->state) {
1227 case DLM_ESTABLISHED:
1228 break;
1229 case DLM_CLOSE_WAIT:
1230 /* passive shutdown DLM_LAST_ACK case 2 */
1231 node->state = DLM_LAST_ACK;
1232 spin_unlock(&node->state_lock);
1233
1234 pr_debug("switch node %d to state %s case 2\n",
1235 node->nodeid, dlm_state_str(node->state));
1236 goto send_fin;
1237 case DLM_LAST_ACK:
1238 /* probably receive fin caught it, do nothing */
1239 break;
1240 case DLM_CLOSED:
1241 /* already gone, do nothing */
1242 break;
1243 default:
1244 log_print("%s: unexpected state: %d\n",
1245 __func__, node->state);
1246 break;
1247 }
1248 }
1249 spin_unlock(&node->state_lock);
1250
1251 srcu_read_unlock(&nodes_srcu, idx);
1252 return;
1253
1254send_fin:
1255 set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
1256 dlm_send_fin(node, dlm_pas_fin_ack_rcv);
1257 srcu_read_unlock(&nodes_srcu, idx);
1258}
1259
1260static void midcomms_node_release(struct rcu_head *rcu)
1261{
1262 struct midcomms_node *node = container_of(rcu, struct midcomms_node, rcu);
1263
1264 WARN_ON(atomic_read(&node->send_queue_cnt));
1265 kfree(node);
1266}
1267
1268static void midcomms_shutdown(struct midcomms_node *node)
1269{
1270 int ret;
1271
1272 /* old protocol, we don't wait for pending operations */
1273 switch (node->version) {
1274 case DLM_VERSION_3_2:
1275 break;
1276 default:
1277 return;
1278 }
1279
1280 spin_lock(&node->state_lock);
1281 pr_debug("receive active shutdown for node %d with state %s\n",
1282 node->nodeid, dlm_state_str(node->state));
1283 switch (node->state) {
1284 case DLM_ESTABLISHED:
1285 node->state = DLM_FIN_WAIT1;
1286 pr_debug("switch node %d to state %s case 2\n",
1287 node->nodeid, dlm_state_str(node->state));
1288 break;
1289 case DLM_CLOSED:
1290 /* we have what we want */
1291 spin_unlock(&node->state_lock);
1292 return;
1293 default:
1294 /* busy to enter DLM_FIN_WAIT1, wait until passive
1295 * done in shutdown_wait to enter DLM_CLOSED.
1296 */
1297 break;
1298 }
1299 spin_unlock(&node->state_lock);
1300
1301 if (node->state == DLM_FIN_WAIT1) {
1302 dlm_send_fin(node, dlm_act_fin_ack_rcv);
1303
1304 if (DLM_DEBUG_FENCE_TERMINATION)
1305 msleep(5000);
1306 }
1307
1308 /* wait for other side dlm + fin */
1309 ret = wait_event_timeout(node->shutdown_wait,
1310 node->state == DLM_CLOSED ||
1311 test_bit(DLM_NODE_FLAG_CLOSE, &node->flags),
1312 DLM_SHUTDOWN_TIMEOUT);
1313 if (!ret || test_bit(DLM_NODE_FLAG_CLOSE, &node->flags)) {
1314 pr_debug("active shutdown timed out for node %d with state %s\n",
1315 node->nodeid, dlm_state_str(node->state));
1316 midcomms_node_reset(node);
1317 return;
1318 }
1319
1320 pr_debug("active shutdown done for node %d with state %s\n",
1321 node->nodeid, dlm_state_str(node->state));
1322}
1323
1324void dlm_midcomms_shutdown(void)
1325{
1326 struct midcomms_node *node;
1327 int i, idx;
1328
1329 mutex_lock(&close_lock);
1330 idx = srcu_read_lock(&nodes_srcu);
1331 for (i = 0; i < CONN_HASH_SIZE; i++) {
1332 hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
1333 midcomms_shutdown(node);
1334
1335 dlm_delete_debug_comms_file(node->debugfs);
1336
1337 spin_lock(&nodes_lock);
1338 hlist_del_rcu(&node->hlist);
1339 spin_unlock(&nodes_lock);
1340
1341 call_srcu(&nodes_srcu, &node->rcu, midcomms_node_release);
1342 }
1343 }
1344 srcu_read_unlock(&nodes_srcu, idx);
1345 mutex_unlock(&close_lock);
1346
1347 dlm_lowcomms_shutdown();
1348}
1349
1350int dlm_midcomms_close(int nodeid)
1351{
1352 struct midcomms_node *node;
1353 int idx, ret;
1354
1355 if (nodeid == dlm_our_nodeid())
1356 return 0;
1357
1358 idx = srcu_read_lock(&nodes_srcu);
1359 /* Abort pending close/remove operation */
1360 node = nodeid2node(nodeid, 0);
1361 if (node) {
1362 /* let shutdown waiters leave */
1363 set_bit(DLM_NODE_FLAG_CLOSE, &node->flags);
1364 wake_up(&node->shutdown_wait);
1365 }
1366 srcu_read_unlock(&nodes_srcu, idx);
1367
1368 synchronize_srcu(&nodes_srcu);
1369
1370 idx = srcu_read_lock(&nodes_srcu);
1371 mutex_lock(&close_lock);
1372 node = nodeid2node(nodeid, 0);
1373 if (!node) {
1374 mutex_unlock(&close_lock);
1375 srcu_read_unlock(&nodes_srcu, idx);
1376 return dlm_lowcomms_close(nodeid);
1377 }
1378
1379 ret = dlm_lowcomms_close(nodeid);
1380 spin_lock(&node->state_lock);
1381 midcomms_node_reset(node);
1382 spin_unlock(&node->state_lock);
1383 srcu_read_unlock(&nodes_srcu, idx);
1384 mutex_unlock(&close_lock);
1385
1386 return ret;
1387}
1// SPDX-License-Identifier: GPL-2.0-only
2/******************************************************************************
3*******************************************************************************
4**
5** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
6** Copyright (C) 2004-2021 Red Hat, Inc. All rights reserved.
7**
8**
9*******************************************************************************
10******************************************************************************/
11
12/*
13 * midcomms.c
14 *
15 * This is the appallingly named "mid-level" comms layer. It takes care about
16 * deliver an on application layer "reliable" communication above the used
17 * lowcomms transport layer.
18 *
19 * How it works:
20 *
21 * Each nodes keeps track of all send DLM messages in send_queue with a sequence
22 * number. The receive will send an DLM_ACK message back for every DLM message
23 * received at the other side. If a reconnect happens in lowcomms we will send
24 * all unacknowledged dlm messages again. The receiving side might drop any already
25 * received message by comparing sequence numbers.
26 *
27 * How version detection works:
28 *
29 * Due the fact that dlm has pre-configured node addresses on every side
30 * it is in it's nature that every side connects at starts to transmit
31 * dlm messages which ends in a race. However DLM_RCOM_NAMES, DLM_RCOM_STATUS
32 * and their replies are the first messages which are exchanges. Due backwards
33 * compatibility these messages are not covered by the midcomms re-transmission
34 * layer. These messages have their own re-transmission handling in the dlm
35 * application layer. The version field of every node will be set on these RCOM
36 * messages as soon as they arrived and the node isn't yet part of the nodes
37 * hash. There exists also logic to detect version mismatched if something weird
38 * going on or the first messages isn't an expected one.
39 *
40 * Termination:
41 *
42 * The midcomms layer does a 4 way handshake for termination on DLM protocol
43 * like TCP supports it with half-closed socket support. SCTP doesn't support
44 * half-closed socket, so we do it on DLM layer. Also socket shutdown() can be
45 * interrupted by .e.g. tcp reset itself. Additional there exists the othercon
46 * paradigm in lowcomms which cannot be easily without breaking backwards
47 * compatibility. A node cannot send anything to another node when a DLM_FIN
48 * message was send. There exists additional logic to print a warning if
49 * DLM wants to do it. There exists a state handling like RFC 793 but reduced
50 * to termination only. The event "member removal event" describes the cluster
51 * manager removed the node from internal lists, at this point DLM does not
52 * send any message to the other node. There exists two cases:
53 *
54 * 1. The cluster member was removed and we received a FIN
55 * OR
56 * 2. We received a FIN but the member was not removed yet
57 *
58 * One of these cases will do the CLOSE_WAIT to LAST_ACK change.
59 *
60 *
61 * +---------+
62 * | CLOSED |
63 * +---------+
64 * | add member/receive RCOM version
65 * | detection msg
66 * V
67 * +---------+
68 * | ESTAB |
69 * +---------+
70 * CLOSE | | rcv FIN
71 * ------- | | -------
72 * +---------+ snd FIN / \ snd ACK +---------+
73 * | FIN |<----------------- ------------------>| CLOSE |
74 * | WAIT-1 |------------------ | WAIT |
75 * +---------+ rcv FIN \ +---------+
76 * | rcv ACK of FIN ------- | CLOSE | member
77 * | -------------- snd ACK | ------- | removal
78 * V x V snd FIN V event
79 * +---------+ +---------+ +---------+
80 * |FINWAIT-2| | CLOSING | | LAST-ACK|
81 * +---------+ +---------+ +---------+
82 * | rcv ACK of FIN | rcv ACK of FIN |
83 * | rcv FIN -------------- | -------------- |
84 * | ------- x V x V
85 * \ snd ACK +---------+ +---------+
86 * ------------------------>| CLOSED | | CLOSED |
87 * +---------+ +---------+
88 *
89 * NOTE: any state can interrupted by midcomms_close() and state will be
90 * switched to CLOSED in case of fencing. There exists also some timeout
91 * handling when we receive the version detection RCOM messages which is
92 * made by observation.
93 *
94 * Future improvements:
95 *
96 * There exists some known issues/improvements of the dlm handling. Some
97 * of them should be done in a next major dlm version bump which makes
98 * it incompatible with previous versions.
99 *
100 * Unaligned memory access:
101 *
102 * There exists cases when the dlm message buffer length is not aligned
103 * to 8 byte. However seems nobody detected any problem with it. This
104 * can be fixed in the next major version bump of dlm.
105 *
106 * Version detection:
107 *
108 * The version detection and how it's done is related to backwards
109 * compatibility. There exists better ways to make a better handling.
110 * However this should be changed in the next major version bump of dlm.
111 *
112 * Tail Size checking:
113 *
114 * There exists a message tail payload in e.g. DLM_MSG however we don't
115 * check it against the message length yet regarding to the receive buffer
116 * length. That need to be validated.
117 *
118 * Fencing bad nodes:
119 *
120 * At timeout places or weird sequence number behaviours we should send
121 * a fencing request to the cluster manager.
122 */
123
124/* Debug switch to enable a 5 seconds sleep waiting of a termination.
125 * This can be useful to test fencing while termination is running.
126 * This requires a setup with only gfs2 as dlm user, so that the
127 * last umount will terminate the connection.
128 *
129 * However it became useful to test, while the 5 seconds block in umount
130 * just press the reset button. In a lot of dropping the termination
131 * process can could take several seconds.
132 */
133#define DLM_DEBUG_FENCE_TERMINATION 0
134
135#include <trace/events/dlm.h>
136#include <net/tcp.h>
137
138#include "dlm_internal.h"
139#include "lowcomms.h"
140#include "config.h"
141#include "memory.h"
142#include "lock.h"
143#include "util.h"
144#include "midcomms.h"
145
146/* init value for sequence numbers for testing purpose only e.g. overflows */
147#define DLM_SEQ_INIT 0
148/* 5 seconds wait to sync ending of dlm */
149#define DLM_SHUTDOWN_TIMEOUT msecs_to_jiffies(5000)
150#define DLM_VERSION_NOT_SET 0
151#define DLM_SEND_ACK_BACK_MSG_THRESHOLD 32
152#define DLM_RECV_ACK_BACK_MSG_THRESHOLD (DLM_SEND_ACK_BACK_MSG_THRESHOLD * 8)
153
154struct midcomms_node {
155 int nodeid;
156 uint32_t version;
157 atomic_t seq_send;
158 atomic_t seq_next;
159 /* These queues are unbound because we cannot drop any message in dlm.
160 * We could send a fence signal for a specific node to the cluster
161 * manager if queues hits some maximum value, however this handling
162 * not supported yet.
163 */
164 struct list_head send_queue;
165 spinlock_t send_queue_lock;
166 atomic_t send_queue_cnt;
167#define DLM_NODE_FLAG_CLOSE 1
168#define DLM_NODE_FLAG_STOP_TX 2
169#define DLM_NODE_FLAG_STOP_RX 3
170 atomic_t ulp_delivered;
171 unsigned long flags;
172 wait_queue_head_t shutdown_wait;
173
174 /* dlm tcp termination state */
175#define DLM_CLOSED 1
176#define DLM_ESTABLISHED 2
177#define DLM_FIN_WAIT1 3
178#define DLM_FIN_WAIT2 4
179#define DLM_CLOSE_WAIT 5
180#define DLM_LAST_ACK 6
181#define DLM_CLOSING 7
182 int state;
183 spinlock_t state_lock;
184
185 /* counts how many lockspaces are using this node
186 * this refcount is necessary to determine if the
187 * node wants to disconnect.
188 */
189 int users;
190
191 /* not protected by srcu, node_hash lifetime */
192 void *debugfs;
193
194 struct hlist_node hlist;
195 struct rcu_head rcu;
196};
197
198struct dlm_mhandle {
199 const union dlm_packet *inner_p;
200 struct midcomms_node *node;
201 struct dlm_opts *opts;
202 struct dlm_msg *msg;
203 bool committed;
204 uint32_t seq;
205
206 void (*ack_rcv)(struct midcomms_node *node);
207
208 /* get_mhandle/commit srcu idx exchange */
209 int idx;
210
211 struct list_head list;
212 struct rcu_head rcu;
213};
214
215static struct hlist_head node_hash[CONN_HASH_SIZE];
216static DEFINE_SPINLOCK(nodes_lock);
217DEFINE_STATIC_SRCU(nodes_srcu);
218
219/* This mutex prevents that midcomms_close() is running while
220 * stop() or remove(). As I experienced invalid memory access
221 * behaviours when DLM_DEBUG_FENCE_TERMINATION is enabled and
222 * resetting machines. I will end in some double deletion in nodes
223 * datastructure.
224 */
225static DEFINE_MUTEX(close_lock);
226
227struct kmem_cache *dlm_midcomms_cache_create(void)
228{
229 return kmem_cache_create("dlm_mhandle", sizeof(struct dlm_mhandle),
230 0, 0, NULL);
231}
232
233static inline const char *dlm_state_str(int state)
234{
235 switch (state) {
236 case DLM_CLOSED:
237 return "CLOSED";
238 case DLM_ESTABLISHED:
239 return "ESTABLISHED";
240 case DLM_FIN_WAIT1:
241 return "FIN_WAIT1";
242 case DLM_FIN_WAIT2:
243 return "FIN_WAIT2";
244 case DLM_CLOSE_WAIT:
245 return "CLOSE_WAIT";
246 case DLM_LAST_ACK:
247 return "LAST_ACK";
248 case DLM_CLOSING:
249 return "CLOSING";
250 default:
251 return "UNKNOWN";
252 }
253}
254
255const char *dlm_midcomms_state(struct midcomms_node *node)
256{
257 return dlm_state_str(node->state);
258}
259
260unsigned long dlm_midcomms_flags(struct midcomms_node *node)
261{
262 return node->flags;
263}
264
265int dlm_midcomms_send_queue_cnt(struct midcomms_node *node)
266{
267 return atomic_read(&node->send_queue_cnt);
268}
269
270uint32_t dlm_midcomms_version(struct midcomms_node *node)
271{
272 return node->version;
273}
274
275static struct midcomms_node *__find_node(int nodeid, int r)
276{
277 struct midcomms_node *node;
278
279 hlist_for_each_entry_rcu(node, &node_hash[r], hlist) {
280 if (node->nodeid == nodeid)
281 return node;
282 }
283
284 return NULL;
285}
286
287static void dlm_mhandle_release(struct rcu_head *rcu)
288{
289 struct dlm_mhandle *mh = container_of(rcu, struct dlm_mhandle, rcu);
290
291 dlm_lowcomms_put_msg(mh->msg);
292 dlm_free_mhandle(mh);
293}
294
295static void dlm_mhandle_delete(struct midcomms_node *node,
296 struct dlm_mhandle *mh)
297{
298 list_del_rcu(&mh->list);
299 atomic_dec(&node->send_queue_cnt);
300 call_rcu(&mh->rcu, dlm_mhandle_release);
301}
302
303static void dlm_send_queue_flush(struct midcomms_node *node)
304{
305 struct dlm_mhandle *mh;
306
307 pr_debug("flush midcomms send queue of node %d\n", node->nodeid);
308
309 rcu_read_lock();
310 spin_lock_bh(&node->send_queue_lock);
311 list_for_each_entry_rcu(mh, &node->send_queue, list) {
312 dlm_mhandle_delete(node, mh);
313 }
314 spin_unlock_bh(&node->send_queue_lock);
315 rcu_read_unlock();
316}
317
318static void midcomms_node_reset(struct midcomms_node *node)
319{
320 pr_debug("reset node %d\n", node->nodeid);
321
322 atomic_set(&node->seq_next, DLM_SEQ_INIT);
323 atomic_set(&node->seq_send, DLM_SEQ_INIT);
324 atomic_set(&node->ulp_delivered, 0);
325 node->version = DLM_VERSION_NOT_SET;
326 node->flags = 0;
327
328 dlm_send_queue_flush(node);
329 node->state = DLM_CLOSED;
330 wake_up(&node->shutdown_wait);
331}
332
333static struct midcomms_node *nodeid2node(int nodeid)
334{
335 return __find_node(nodeid, nodeid_hash(nodeid));
336}
337
338int dlm_midcomms_addr(int nodeid, struct sockaddr_storage *addr, int len)
339{
340 int ret, idx, r = nodeid_hash(nodeid);
341 struct midcomms_node *node;
342
343 ret = dlm_lowcomms_addr(nodeid, addr, len);
344 if (ret)
345 return ret;
346
347 idx = srcu_read_lock(&nodes_srcu);
348 node = __find_node(nodeid, r);
349 if (node) {
350 srcu_read_unlock(&nodes_srcu, idx);
351 return 0;
352 }
353 srcu_read_unlock(&nodes_srcu, idx);
354
355 node = kmalloc(sizeof(*node), GFP_NOFS);
356 if (!node)
357 return -ENOMEM;
358
359 node->nodeid = nodeid;
360 spin_lock_init(&node->state_lock);
361 spin_lock_init(&node->send_queue_lock);
362 atomic_set(&node->send_queue_cnt, 0);
363 INIT_LIST_HEAD(&node->send_queue);
364 init_waitqueue_head(&node->shutdown_wait);
365 node->users = 0;
366 midcomms_node_reset(node);
367
368 spin_lock(&nodes_lock);
369 hlist_add_head_rcu(&node->hlist, &node_hash[r]);
370 spin_unlock(&nodes_lock);
371
372 node->debugfs = dlm_create_debug_comms_file(nodeid, node);
373 return 0;
374}
375
376static int dlm_send_ack(int nodeid, uint32_t seq)
377{
378 int mb_len = sizeof(struct dlm_header);
379 struct dlm_header *m_header;
380 struct dlm_msg *msg;
381 char *ppc;
382
383 msg = dlm_lowcomms_new_msg(nodeid, mb_len, GFP_ATOMIC, &ppc,
384 NULL, NULL);
385 if (!msg)
386 return -ENOMEM;
387
388 m_header = (struct dlm_header *)ppc;
389
390 m_header->h_version = cpu_to_le32(DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
391 m_header->h_nodeid = cpu_to_le32(dlm_our_nodeid());
392 m_header->h_length = cpu_to_le16(mb_len);
393 m_header->h_cmd = DLM_ACK;
394 m_header->u.h_seq = cpu_to_le32(seq);
395
396 dlm_lowcomms_commit_msg(msg);
397 dlm_lowcomms_put_msg(msg);
398
399 return 0;
400}
401
402static void dlm_send_ack_threshold(struct midcomms_node *node,
403 uint32_t threshold)
404{
405 uint32_t oval, nval;
406 bool send_ack;
407
408 /* let only send one user trigger threshold to send ack back */
409 do {
410 oval = atomic_read(&node->ulp_delivered);
411 send_ack = (oval > threshold);
412 /* abort if threshold is not reached */
413 if (!send_ack)
414 break;
415
416 nval = 0;
417 /* try to reset ulp_delivered counter */
418 } while (atomic_cmpxchg(&node->ulp_delivered, oval, nval) != oval);
419
420 if (send_ack)
421 dlm_send_ack(node->nodeid, atomic_read(&node->seq_next));
422}
423
424static int dlm_send_fin(struct midcomms_node *node,
425 void (*ack_rcv)(struct midcomms_node *node))
426{
427 int mb_len = sizeof(struct dlm_header);
428 struct dlm_header *m_header;
429 struct dlm_mhandle *mh;
430 char *ppc;
431
432 mh = dlm_midcomms_get_mhandle(node->nodeid, mb_len, GFP_ATOMIC, &ppc);
433 if (!mh)
434 return -ENOMEM;
435
436 set_bit(DLM_NODE_FLAG_STOP_TX, &node->flags);
437 mh->ack_rcv = ack_rcv;
438
439 m_header = (struct dlm_header *)ppc;
440
441 m_header->h_version = cpu_to_le32(DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
442 m_header->h_nodeid = cpu_to_le32(dlm_our_nodeid());
443 m_header->h_length = cpu_to_le16(mb_len);
444 m_header->h_cmd = DLM_FIN;
445
446 pr_debug("sending fin msg to node %d\n", node->nodeid);
447 dlm_midcomms_commit_mhandle(mh, NULL, 0);
448
449 return 0;
450}
451
452static void dlm_receive_ack(struct midcomms_node *node, uint32_t seq)
453{
454 struct dlm_mhandle *mh;
455
456 rcu_read_lock();
457 list_for_each_entry_rcu(mh, &node->send_queue, list) {
458 if (before(mh->seq, seq)) {
459 if (mh->ack_rcv)
460 mh->ack_rcv(node);
461 } else {
462 /* send queue should be ordered */
463 break;
464 }
465 }
466
467 spin_lock_bh(&node->send_queue_lock);
468 list_for_each_entry_rcu(mh, &node->send_queue, list) {
469 if (before(mh->seq, seq)) {
470 dlm_mhandle_delete(node, mh);
471 } else {
472 /* send queue should be ordered */
473 break;
474 }
475 }
476 spin_unlock_bh(&node->send_queue_lock);
477 rcu_read_unlock();
478}
479
480static void dlm_pas_fin_ack_rcv(struct midcomms_node *node)
481{
482 spin_lock(&node->state_lock);
483 pr_debug("receive passive fin ack from node %d with state %s\n",
484 node->nodeid, dlm_state_str(node->state));
485
486 switch (node->state) {
487 case DLM_LAST_ACK:
488 /* DLM_CLOSED */
489 midcomms_node_reset(node);
490 break;
491 case DLM_CLOSED:
492 /* not valid but somehow we got what we want */
493 wake_up(&node->shutdown_wait);
494 break;
495 default:
496 spin_unlock(&node->state_lock);
497 log_print("%s: unexpected state: %d",
498 __func__, node->state);
499 WARN_ON_ONCE(1);
500 return;
501 }
502 spin_unlock(&node->state_lock);
503}
504
505static void dlm_receive_buffer_3_2_trace(uint32_t seq,
506 const union dlm_packet *p)
507{
508 switch (p->header.h_cmd) {
509 case DLM_MSG:
510 trace_dlm_recv_message(dlm_our_nodeid(), seq, &p->message);
511 break;
512 case DLM_RCOM:
513 trace_dlm_recv_rcom(dlm_our_nodeid(), seq, &p->rcom);
514 break;
515 default:
516 break;
517 }
518}
519
520static void dlm_midcomms_receive_buffer(const union dlm_packet *p,
521 struct midcomms_node *node,
522 uint32_t seq)
523{
524 bool is_expected_seq;
525 uint32_t oval, nval;
526
527 do {
528 oval = atomic_read(&node->seq_next);
529 is_expected_seq = (oval == seq);
530 if (!is_expected_seq)
531 break;
532
533 nval = oval + 1;
534 } while (atomic_cmpxchg(&node->seq_next, oval, nval) != oval);
535
536 if (is_expected_seq) {
537 switch (p->header.h_cmd) {
538 case DLM_FIN:
539 spin_lock(&node->state_lock);
540 pr_debug("receive fin msg from node %d with state %s\n",
541 node->nodeid, dlm_state_str(node->state));
542
543 switch (node->state) {
544 case DLM_ESTABLISHED:
545 dlm_send_ack(node->nodeid, nval);
546
547 /* passive shutdown DLM_LAST_ACK case 1
548 * additional we check if the node is used by
549 * cluster manager events at all.
550 */
551 if (node->users == 0) {
552 node->state = DLM_LAST_ACK;
553 pr_debug("switch node %d to state %s case 1\n",
554 node->nodeid, dlm_state_str(node->state));
555 set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
556 dlm_send_fin(node, dlm_pas_fin_ack_rcv);
557 } else {
558 node->state = DLM_CLOSE_WAIT;
559 pr_debug("switch node %d to state %s\n",
560 node->nodeid, dlm_state_str(node->state));
561 }
562 break;
563 case DLM_FIN_WAIT1:
564 dlm_send_ack(node->nodeid, nval);
565 node->state = DLM_CLOSING;
566 set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
567 pr_debug("switch node %d to state %s\n",
568 node->nodeid, dlm_state_str(node->state));
569 break;
570 case DLM_FIN_WAIT2:
571 dlm_send_ack(node->nodeid, nval);
572 midcomms_node_reset(node);
573 pr_debug("switch node %d to state %s\n",
574 node->nodeid, dlm_state_str(node->state));
575 break;
576 case DLM_LAST_ACK:
577 /* probably remove_member caught it, do nothing */
578 break;
579 default:
580 spin_unlock(&node->state_lock);
581 log_print("%s: unexpected state: %d",
582 __func__, node->state);
583 WARN_ON_ONCE(1);
584 return;
585 }
586 spin_unlock(&node->state_lock);
587 break;
588 default:
589 WARN_ON_ONCE(test_bit(DLM_NODE_FLAG_STOP_RX, &node->flags));
590 dlm_receive_buffer_3_2_trace(seq, p);
591 dlm_receive_buffer(p, node->nodeid);
592 atomic_inc(&node->ulp_delivered);
593 /* unlikely case to send ack back when we don't transmit */
594 dlm_send_ack_threshold(node, DLM_RECV_ACK_BACK_MSG_THRESHOLD);
595 break;
596 }
597 } else {
598 /* retry to ack message which we already have by sending back
599 * current node->seq_next number as ack.
600 */
601 if (seq < oval)
602 dlm_send_ack(node->nodeid, oval);
603
604 log_print_ratelimited("ignore dlm msg because seq mismatch, seq: %u, expected: %u, nodeid: %d",
605 seq, oval, node->nodeid);
606 }
607}
608
609static int dlm_opts_check_msglen(const union dlm_packet *p, uint16_t msglen,
610 int nodeid)
611{
612 int len = msglen;
613
614 /* we only trust outer header msglen because
615 * it's checked against receive buffer length.
616 */
617 if (len < sizeof(struct dlm_opts))
618 return -1;
619 len -= sizeof(struct dlm_opts);
620
621 if (len < le16_to_cpu(p->opts.o_optlen))
622 return -1;
623 len -= le16_to_cpu(p->opts.o_optlen);
624
625 switch (p->opts.o_nextcmd) {
626 case DLM_FIN:
627 if (len < sizeof(struct dlm_header)) {
628 log_print("fin too small: %d, will skip this message from node %d",
629 len, nodeid);
630 return -1;
631 }
632
633 break;
634 case DLM_MSG:
635 if (len < sizeof(struct dlm_message)) {
636 log_print("msg too small: %d, will skip this message from node %d",
637 msglen, nodeid);
638 return -1;
639 }
640
641 break;
642 case DLM_RCOM:
643 if (len < sizeof(struct dlm_rcom)) {
644 log_print("rcom msg too small: %d, will skip this message from node %d",
645 len, nodeid);
646 return -1;
647 }
648
649 break;
650 default:
651 log_print("unsupported o_nextcmd received: %u, will skip this message from node %d",
652 p->opts.o_nextcmd, nodeid);
653 return -1;
654 }
655
656 return 0;
657}
658
659static void dlm_midcomms_receive_buffer_3_2(const union dlm_packet *p, int nodeid)
660{
661 uint16_t msglen = le16_to_cpu(p->header.h_length);
662 struct midcomms_node *node;
663 uint32_t seq;
664 int ret, idx;
665
666 idx = srcu_read_lock(&nodes_srcu);
667 node = nodeid2node(nodeid);
668 if (WARN_ON_ONCE(!node))
669 goto out;
670
671 switch (node->version) {
672 case DLM_VERSION_NOT_SET:
673 node->version = DLM_VERSION_3_2;
674 wake_up(&node->shutdown_wait);
675 log_print("version 0x%08x for node %d detected", DLM_VERSION_3_2,
676 node->nodeid);
677
678 spin_lock(&node->state_lock);
679 switch (node->state) {
680 case DLM_CLOSED:
681 node->state = DLM_ESTABLISHED;
682 pr_debug("switch node %d to state %s\n",
683 node->nodeid, dlm_state_str(node->state));
684 break;
685 default:
686 break;
687 }
688 spin_unlock(&node->state_lock);
689
690 break;
691 case DLM_VERSION_3_2:
692 break;
693 default:
694 log_print_ratelimited("version mismatch detected, assumed 0x%08x but node %d has 0x%08x",
695 DLM_VERSION_3_2, node->nodeid, node->version);
696 goto out;
697 }
698
699 switch (p->header.h_cmd) {
700 case DLM_RCOM:
701 /* these rcom message we use to determine version.
702 * they have their own retransmission handling and
703 * are the first messages of dlm.
704 *
705 * length already checked.
706 */
707 switch (p->rcom.rc_type) {
708 case cpu_to_le32(DLM_RCOM_NAMES):
709 fallthrough;
710 case cpu_to_le32(DLM_RCOM_NAMES_REPLY):
711 fallthrough;
712 case cpu_to_le32(DLM_RCOM_STATUS):
713 fallthrough;
714 case cpu_to_le32(DLM_RCOM_STATUS_REPLY):
715 break;
716 default:
717 log_print("unsupported rcom type received: %u, will skip this message from node %d",
718 le32_to_cpu(p->rcom.rc_type), nodeid);
719 goto out;
720 }
721
722 WARN_ON_ONCE(test_bit(DLM_NODE_FLAG_STOP_RX, &node->flags));
723 dlm_receive_buffer(p, nodeid);
724 break;
725 case DLM_OPTS:
726 seq = le32_to_cpu(p->header.u.h_seq);
727
728 ret = dlm_opts_check_msglen(p, msglen, nodeid);
729 if (ret < 0) {
730 log_print("opts msg too small: %u, will skip this message from node %d",
731 msglen, nodeid);
732 goto out;
733 }
734
735 p = (union dlm_packet *)((unsigned char *)p->opts.o_opts +
736 le16_to_cpu(p->opts.o_optlen));
737
738 /* recheck inner msglen just if it's not garbage */
739 msglen = le16_to_cpu(p->header.h_length);
740 switch (p->header.h_cmd) {
741 case DLM_RCOM:
742 if (msglen < sizeof(struct dlm_rcom)) {
743 log_print("inner rcom msg too small: %u, will skip this message from node %d",
744 msglen, nodeid);
745 goto out;
746 }
747
748 break;
749 case DLM_MSG:
750 if (msglen < sizeof(struct dlm_message)) {
751 log_print("inner msg too small: %u, will skip this message from node %d",
752 msglen, nodeid);
753 goto out;
754 }
755
756 break;
757 case DLM_FIN:
758 if (msglen < sizeof(struct dlm_header)) {
759 log_print("inner fin too small: %u, will skip this message from node %d",
760 msglen, nodeid);
761 goto out;
762 }
763
764 break;
765 default:
766 log_print("unsupported inner h_cmd received: %u, will skip this message from node %d",
767 msglen, nodeid);
768 goto out;
769 }
770
771 dlm_midcomms_receive_buffer(p, node, seq);
772 break;
773 case DLM_ACK:
774 seq = le32_to_cpu(p->header.u.h_seq);
775 dlm_receive_ack(node, seq);
776 break;
777 default:
778 log_print("unsupported h_cmd received: %u, will skip this message from node %d",
779 p->header.h_cmd, nodeid);
780 break;
781 }
782
783out:
784 srcu_read_unlock(&nodes_srcu, idx);
785}
786
787static void dlm_midcomms_receive_buffer_3_1(const union dlm_packet *p, int nodeid)
788{
789 uint16_t msglen = le16_to_cpu(p->header.h_length);
790 struct midcomms_node *node;
791 int idx;
792
793 idx = srcu_read_lock(&nodes_srcu);
794 node = nodeid2node(nodeid);
795 if (WARN_ON_ONCE(!node)) {
796 srcu_read_unlock(&nodes_srcu, idx);
797 return;
798 }
799
800 switch (node->version) {
801 case DLM_VERSION_NOT_SET:
802 node->version = DLM_VERSION_3_1;
803 wake_up(&node->shutdown_wait);
804 log_print("version 0x%08x for node %d detected", DLM_VERSION_3_1,
805 node->nodeid);
806 break;
807 case DLM_VERSION_3_1:
808 break;
809 default:
810 log_print_ratelimited("version mismatch detected, assumed 0x%08x but node %d has 0x%08x",
811 DLM_VERSION_3_1, node->nodeid, node->version);
812 srcu_read_unlock(&nodes_srcu, idx);
813 return;
814 }
815 srcu_read_unlock(&nodes_srcu, idx);
816
817 switch (p->header.h_cmd) {
818 case DLM_RCOM:
819 /* length already checked */
820 break;
821 case DLM_MSG:
822 if (msglen < sizeof(struct dlm_message)) {
823 log_print("msg too small: %u, will skip this message from node %d",
824 msglen, nodeid);
825 return;
826 }
827
828 break;
829 default:
830 log_print("unsupported h_cmd received: %u, will skip this message from node %d",
831 p->header.h_cmd, nodeid);
832 return;
833 }
834
835 dlm_receive_buffer(p, nodeid);
836}
837
838int dlm_validate_incoming_buffer(int nodeid, unsigned char *buf, int len)
839{
840 const unsigned char *ptr = buf;
841 const struct dlm_header *hd;
842 uint16_t msglen;
843 int ret = 0;
844
845 while (len >= sizeof(struct dlm_header)) {
846 hd = (struct dlm_header *)ptr;
847
848 /* no message should be more than DLM_MAX_SOCKET_BUFSIZE or
849 * less than dlm_header size.
850 *
851 * Some messages does not have a 8 byte length boundary yet
852 * which can occur in a unaligned memory access of some dlm
853 * messages. However this problem need to be fixed at the
854 * sending side, for now it seems nobody run into architecture
855 * related issues yet but it slows down some processing.
856 * Fixing this issue should be scheduled in future by doing
857 * the next major version bump.
858 */
859 msglen = le16_to_cpu(hd->h_length);
860 if (msglen > DLM_MAX_SOCKET_BUFSIZE ||
861 msglen < sizeof(struct dlm_header)) {
862 log_print("received invalid length header: %u from node %d, will abort message parsing",
863 msglen, nodeid);
864 return -EBADMSG;
865 }
866
867 /* caller will take care that leftover
868 * will be parsed next call with more data
869 */
870 if (msglen > len)
871 break;
872
873 ret += msglen;
874 len -= msglen;
875 ptr += msglen;
876 }
877
878 return ret;
879}
880
881/*
882 * Called from the low-level comms layer to process a buffer of
883 * commands.
884 */
885int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
886{
887 const unsigned char *ptr = buf;
888 const struct dlm_header *hd;
889 uint16_t msglen;
890 int ret = 0;
891
892 while (len >= sizeof(struct dlm_header)) {
893 hd = (struct dlm_header *)ptr;
894
895 msglen = le16_to_cpu(hd->h_length);
896 if (msglen > len)
897 break;
898
899 switch (hd->h_version) {
900 case cpu_to_le32(DLM_VERSION_3_1):
901 dlm_midcomms_receive_buffer_3_1((const union dlm_packet *)ptr, nodeid);
902 break;
903 case cpu_to_le32(DLM_VERSION_3_2):
904 dlm_midcomms_receive_buffer_3_2((const union dlm_packet *)ptr, nodeid);
905 break;
906 default:
907 log_print("received invalid version header: %u from node %d, will skip this message",
908 le32_to_cpu(hd->h_version), nodeid);
909 break;
910 }
911
912 ret += msglen;
913 len -= msglen;
914 ptr += msglen;
915 }
916
917 return ret;
918}
919
920void dlm_midcomms_unack_msg_resend(int nodeid)
921{
922 struct midcomms_node *node;
923 struct dlm_mhandle *mh;
924 int idx, ret;
925
926 idx = srcu_read_lock(&nodes_srcu);
927 node = nodeid2node(nodeid);
928 if (WARN_ON_ONCE(!node)) {
929 srcu_read_unlock(&nodes_srcu, idx);
930 return;
931 }
932
933 /* old protocol, we don't support to retransmit on failure */
934 switch (node->version) {
935 case DLM_VERSION_3_2:
936 break;
937 default:
938 srcu_read_unlock(&nodes_srcu, idx);
939 return;
940 }
941
942 rcu_read_lock();
943 list_for_each_entry_rcu(mh, &node->send_queue, list) {
944 if (!mh->committed)
945 continue;
946
947 ret = dlm_lowcomms_resend_msg(mh->msg);
948 if (!ret)
949 log_print_ratelimited("retransmit dlm msg, seq %u, nodeid %d",
950 mh->seq, node->nodeid);
951 }
952 rcu_read_unlock();
953 srcu_read_unlock(&nodes_srcu, idx);
954}
955
956static void dlm_fill_opts_header(struct dlm_opts *opts, uint16_t inner_len,
957 uint32_t seq)
958{
959 opts->o_header.h_cmd = DLM_OPTS;
960 opts->o_header.h_version = cpu_to_le32(DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
961 opts->o_header.h_nodeid = cpu_to_le32(dlm_our_nodeid());
962 opts->o_header.h_length = cpu_to_le16(DLM_MIDCOMMS_OPT_LEN + inner_len);
963 opts->o_header.u.h_seq = cpu_to_le32(seq);
964}
965
966static void midcomms_new_msg_cb(void *data)
967{
968 struct dlm_mhandle *mh = data;
969
970 atomic_inc(&mh->node->send_queue_cnt);
971
972 spin_lock_bh(&mh->node->send_queue_lock);
973 list_add_tail_rcu(&mh->list, &mh->node->send_queue);
974 spin_unlock_bh(&mh->node->send_queue_lock);
975
976 mh->seq = atomic_fetch_inc(&mh->node->seq_send);
977}
978
979static struct dlm_msg *dlm_midcomms_get_msg_3_2(struct dlm_mhandle *mh, int nodeid,
980 int len, gfp_t allocation, char **ppc)
981{
982 struct dlm_opts *opts;
983 struct dlm_msg *msg;
984
985 msg = dlm_lowcomms_new_msg(nodeid, len + DLM_MIDCOMMS_OPT_LEN,
986 allocation, ppc, midcomms_new_msg_cb, mh);
987 if (!msg)
988 return NULL;
989
990 opts = (struct dlm_opts *)*ppc;
991 mh->opts = opts;
992
993 /* add possible options here */
994 dlm_fill_opts_header(opts, len, mh->seq);
995
996 *ppc += sizeof(*opts);
997 mh->inner_p = (const union dlm_packet *)*ppc;
998 return msg;
999}
1000
1001/* avoid false positive for nodes_srcu, unlock happens in
1002 * dlm_midcomms_commit_mhandle which is a must call if success
1003 */
1004#ifndef __CHECKER__
1005struct dlm_mhandle *dlm_midcomms_get_mhandle(int nodeid, int len,
1006 gfp_t allocation, char **ppc)
1007{
1008 struct midcomms_node *node;
1009 struct dlm_mhandle *mh;
1010 struct dlm_msg *msg;
1011 int idx;
1012
1013 idx = srcu_read_lock(&nodes_srcu);
1014 node = nodeid2node(nodeid);
1015 if (WARN_ON_ONCE(!node))
1016 goto err;
1017
1018 /* this is a bug, however we going on and hope it will be resolved */
1019 WARN_ON_ONCE(test_bit(DLM_NODE_FLAG_STOP_TX, &node->flags));
1020
1021 mh = dlm_allocate_mhandle(allocation);
1022 if (!mh)
1023 goto err;
1024
1025 mh->committed = false;
1026 mh->ack_rcv = NULL;
1027 mh->idx = idx;
1028 mh->node = node;
1029
1030 switch (node->version) {
1031 case DLM_VERSION_3_1:
1032 msg = dlm_lowcomms_new_msg(nodeid, len, allocation, ppc,
1033 NULL, NULL);
1034 if (!msg) {
1035 dlm_free_mhandle(mh);
1036 goto err;
1037 }
1038
1039 break;
1040 case DLM_VERSION_3_2:
1041 /* send ack back if necessary */
1042 dlm_send_ack_threshold(node, DLM_SEND_ACK_BACK_MSG_THRESHOLD);
1043
1044 msg = dlm_midcomms_get_msg_3_2(mh, nodeid, len, allocation,
1045 ppc);
1046 if (!msg) {
1047 dlm_free_mhandle(mh);
1048 goto err;
1049 }
1050 break;
1051 default:
1052 dlm_free_mhandle(mh);
1053 WARN_ON_ONCE(1);
1054 goto err;
1055 }
1056
1057 mh->msg = msg;
1058
1059 /* keep in mind that is a must to call
1060 * dlm_midcomms_commit_msg() which releases
1061 * nodes_srcu using mh->idx which is assumed
1062 * here that the application will call it.
1063 */
1064 return mh;
1065
1066err:
1067 srcu_read_unlock(&nodes_srcu, idx);
1068 return NULL;
1069}
1070#endif
1071
1072static void dlm_midcomms_commit_msg_3_2_trace(const struct dlm_mhandle *mh,
1073 const void *name, int namelen)
1074{
1075 switch (mh->inner_p->header.h_cmd) {
1076 case DLM_MSG:
1077 trace_dlm_send_message(mh->node->nodeid, mh->seq,
1078 &mh->inner_p->message,
1079 name, namelen);
1080 break;
1081 case DLM_RCOM:
1082 trace_dlm_send_rcom(mh->node->nodeid, mh->seq,
1083 &mh->inner_p->rcom);
1084 break;
1085 default:
1086 /* nothing to trace */
1087 break;
1088 }
1089}
1090
1091static void dlm_midcomms_commit_msg_3_2(struct dlm_mhandle *mh,
1092 const void *name, int namelen)
1093{
1094 /* nexthdr chain for fast lookup */
1095 mh->opts->o_nextcmd = mh->inner_p->header.h_cmd;
1096 mh->committed = true;
1097 dlm_midcomms_commit_msg_3_2_trace(mh, name, namelen);
1098 dlm_lowcomms_commit_msg(mh->msg);
1099}
1100
1101/* avoid false positive for nodes_srcu, lock was happen in
1102 * dlm_midcomms_get_mhandle
1103 */
1104#ifndef __CHECKER__
1105void dlm_midcomms_commit_mhandle(struct dlm_mhandle *mh,
1106 const void *name, int namelen)
1107{
1108
1109 switch (mh->node->version) {
1110 case DLM_VERSION_3_1:
1111 srcu_read_unlock(&nodes_srcu, mh->idx);
1112
1113 dlm_lowcomms_commit_msg(mh->msg);
1114 dlm_lowcomms_put_msg(mh->msg);
1115 /* mh is not part of rcu list in this case */
1116 dlm_free_mhandle(mh);
1117 break;
1118 case DLM_VERSION_3_2:
1119 /* held rcu read lock here, because we sending the
1120 * dlm message out, when we do that we could receive
1121 * an ack back which releases the mhandle and we
1122 * get a use after free.
1123 */
1124 rcu_read_lock();
1125 dlm_midcomms_commit_msg_3_2(mh, name, namelen);
1126 srcu_read_unlock(&nodes_srcu, mh->idx);
1127 rcu_read_unlock();
1128 break;
1129 default:
1130 srcu_read_unlock(&nodes_srcu, mh->idx);
1131 WARN_ON_ONCE(1);
1132 break;
1133 }
1134}
1135#endif
1136
1137int dlm_midcomms_start(void)
1138{
1139 return dlm_lowcomms_start();
1140}
1141
1142void dlm_midcomms_stop(void)
1143{
1144 dlm_lowcomms_stop();
1145}
1146
1147void dlm_midcomms_init(void)
1148{
1149 int i;
1150
1151 for (i = 0; i < CONN_HASH_SIZE; i++)
1152 INIT_HLIST_HEAD(&node_hash[i]);
1153
1154 dlm_lowcomms_init();
1155}
1156
1157static void midcomms_node_release(struct rcu_head *rcu)
1158{
1159 struct midcomms_node *node = container_of(rcu, struct midcomms_node, rcu);
1160
1161 WARN_ON_ONCE(atomic_read(&node->send_queue_cnt));
1162 dlm_send_queue_flush(node);
1163 kfree(node);
1164}
1165
1166void dlm_midcomms_exit(void)
1167{
1168 struct midcomms_node *node;
1169 int i, idx;
1170
1171 idx = srcu_read_lock(&nodes_srcu);
1172 for (i = 0; i < CONN_HASH_SIZE; i++) {
1173 hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
1174 dlm_delete_debug_comms_file(node->debugfs);
1175
1176 spin_lock(&nodes_lock);
1177 hlist_del_rcu(&node->hlist);
1178 spin_unlock(&nodes_lock);
1179
1180 call_srcu(&nodes_srcu, &node->rcu, midcomms_node_release);
1181 }
1182 }
1183 srcu_read_unlock(&nodes_srcu, idx);
1184
1185 dlm_lowcomms_exit();
1186}
1187
1188static void dlm_act_fin_ack_rcv(struct midcomms_node *node)
1189{
1190 spin_lock(&node->state_lock);
1191 pr_debug("receive active fin ack from node %d with state %s\n",
1192 node->nodeid, dlm_state_str(node->state));
1193
1194 switch (node->state) {
1195 case DLM_FIN_WAIT1:
1196 node->state = DLM_FIN_WAIT2;
1197 pr_debug("switch node %d to state %s\n",
1198 node->nodeid, dlm_state_str(node->state));
1199 break;
1200 case DLM_CLOSING:
1201 midcomms_node_reset(node);
1202 pr_debug("switch node %d to state %s\n",
1203 node->nodeid, dlm_state_str(node->state));
1204 break;
1205 case DLM_CLOSED:
1206 /* not valid but somehow we got what we want */
1207 wake_up(&node->shutdown_wait);
1208 break;
1209 default:
1210 spin_unlock(&node->state_lock);
1211 log_print("%s: unexpected state: %d",
1212 __func__, node->state);
1213 WARN_ON_ONCE(1);
1214 return;
1215 }
1216 spin_unlock(&node->state_lock);
1217}
1218
1219void dlm_midcomms_add_member(int nodeid)
1220{
1221 struct midcomms_node *node;
1222 int idx;
1223
1224 idx = srcu_read_lock(&nodes_srcu);
1225 node = nodeid2node(nodeid);
1226 if (WARN_ON_ONCE(!node)) {
1227 srcu_read_unlock(&nodes_srcu, idx);
1228 return;
1229 }
1230
1231 spin_lock(&node->state_lock);
1232 if (!node->users) {
1233 pr_debug("receive add member from node %d with state %s\n",
1234 node->nodeid, dlm_state_str(node->state));
1235 switch (node->state) {
1236 case DLM_ESTABLISHED:
1237 break;
1238 case DLM_CLOSED:
1239 node->state = DLM_ESTABLISHED;
1240 pr_debug("switch node %d to state %s\n",
1241 node->nodeid, dlm_state_str(node->state));
1242 break;
1243 default:
1244 /* some invalid state passive shutdown
1245 * was failed, we try to reset and
1246 * hope it will go on.
1247 */
1248 log_print("reset node %d because shutdown stuck",
1249 node->nodeid);
1250
1251 midcomms_node_reset(node);
1252 node->state = DLM_ESTABLISHED;
1253 break;
1254 }
1255 }
1256
1257 node->users++;
1258 pr_debug("node %d users inc count %d\n", nodeid, node->users);
1259 spin_unlock(&node->state_lock);
1260
1261 srcu_read_unlock(&nodes_srcu, idx);
1262}
1263
1264void dlm_midcomms_remove_member(int nodeid)
1265{
1266 struct midcomms_node *node;
1267 int idx;
1268
1269 idx = srcu_read_lock(&nodes_srcu);
1270 node = nodeid2node(nodeid);
1271 /* in case of dlm_midcomms_close() removes node */
1272 if (!node) {
1273 srcu_read_unlock(&nodes_srcu, idx);
1274 return;
1275 }
1276
1277 spin_lock(&node->state_lock);
1278 /* case of dlm_midcomms_addr() created node but
1279 * was not added before because dlm_midcomms_close()
1280 * removed the node
1281 */
1282 if (!node->users) {
1283 spin_unlock(&node->state_lock);
1284 srcu_read_unlock(&nodes_srcu, idx);
1285 return;
1286 }
1287
1288 node->users--;
1289 pr_debug("node %d users dec count %d\n", nodeid, node->users);
1290
1291 /* hitting users count to zero means the
1292 * other side is running dlm_midcomms_stop()
1293 * we meet us to have a clean disconnect.
1294 */
1295 if (node->users == 0) {
1296 pr_debug("receive remove member from node %d with state %s\n",
1297 node->nodeid, dlm_state_str(node->state));
1298 switch (node->state) {
1299 case DLM_ESTABLISHED:
1300 break;
1301 case DLM_CLOSE_WAIT:
1302 /* passive shutdown DLM_LAST_ACK case 2 */
1303 node->state = DLM_LAST_ACK;
1304 pr_debug("switch node %d to state %s case 2\n",
1305 node->nodeid, dlm_state_str(node->state));
1306 set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
1307 dlm_send_fin(node, dlm_pas_fin_ack_rcv);
1308 break;
1309 case DLM_LAST_ACK:
1310 /* probably receive fin caught it, do nothing */
1311 break;
1312 case DLM_CLOSED:
1313 /* already gone, do nothing */
1314 break;
1315 default:
1316 log_print("%s: unexpected state: %d",
1317 __func__, node->state);
1318 break;
1319 }
1320 }
1321 spin_unlock(&node->state_lock);
1322
1323 srcu_read_unlock(&nodes_srcu, idx);
1324}
1325
1326void dlm_midcomms_version_wait(void)
1327{
1328 struct midcomms_node *node;
1329 int i, idx, ret;
1330
1331 idx = srcu_read_lock(&nodes_srcu);
1332 for (i = 0; i < CONN_HASH_SIZE; i++) {
1333 hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
1334 ret = wait_event_timeout(node->shutdown_wait,
1335 node->version != DLM_VERSION_NOT_SET ||
1336 node->state == DLM_CLOSED ||
1337 test_bit(DLM_NODE_FLAG_CLOSE, &node->flags),
1338 DLM_SHUTDOWN_TIMEOUT);
1339 if (!ret || test_bit(DLM_NODE_FLAG_CLOSE, &node->flags))
1340 pr_debug("version wait timed out for node %d with state %s\n",
1341 node->nodeid, dlm_state_str(node->state));
1342 }
1343 }
1344 srcu_read_unlock(&nodes_srcu, idx);
1345}
1346
1347static void midcomms_shutdown(struct midcomms_node *node)
1348{
1349 int ret;
1350
1351 /* old protocol, we don't wait for pending operations */
1352 switch (node->version) {
1353 case DLM_VERSION_3_2:
1354 break;
1355 default:
1356 return;
1357 }
1358
1359 spin_lock(&node->state_lock);
1360 pr_debug("receive active shutdown for node %d with state %s\n",
1361 node->nodeid, dlm_state_str(node->state));
1362 switch (node->state) {
1363 case DLM_ESTABLISHED:
1364 node->state = DLM_FIN_WAIT1;
1365 pr_debug("switch node %d to state %s case 2\n",
1366 node->nodeid, dlm_state_str(node->state));
1367 dlm_send_fin(node, dlm_act_fin_ack_rcv);
1368 break;
1369 case DLM_CLOSED:
1370 /* we have what we want */
1371 break;
1372 default:
1373 /* busy to enter DLM_FIN_WAIT1, wait until passive
1374 * done in shutdown_wait to enter DLM_CLOSED.
1375 */
1376 break;
1377 }
1378 spin_unlock(&node->state_lock);
1379
1380 if (DLM_DEBUG_FENCE_TERMINATION)
1381 msleep(5000);
1382
1383 /* wait for other side dlm + fin */
1384 ret = wait_event_timeout(node->shutdown_wait,
1385 node->state == DLM_CLOSED ||
1386 test_bit(DLM_NODE_FLAG_CLOSE, &node->flags),
1387 DLM_SHUTDOWN_TIMEOUT);
1388 if (!ret)
1389 pr_debug("active shutdown timed out for node %d with state %s\n",
1390 node->nodeid, dlm_state_str(node->state));
1391 else
1392 pr_debug("active shutdown done for node %d with state %s\n",
1393 node->nodeid, dlm_state_str(node->state));
1394}
1395
1396void dlm_midcomms_shutdown(void)
1397{
1398 struct midcomms_node *node;
1399 int i, idx;
1400
1401 mutex_lock(&close_lock);
1402 idx = srcu_read_lock(&nodes_srcu);
1403 for (i = 0; i < CONN_HASH_SIZE; i++) {
1404 hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
1405 midcomms_shutdown(node);
1406 }
1407 }
1408
1409 dlm_lowcomms_shutdown();
1410
1411 for (i = 0; i < CONN_HASH_SIZE; i++) {
1412 hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
1413 midcomms_node_reset(node);
1414 }
1415 }
1416 srcu_read_unlock(&nodes_srcu, idx);
1417 mutex_unlock(&close_lock);
1418}
1419
1420int dlm_midcomms_close(int nodeid)
1421{
1422 struct midcomms_node *node;
1423 int idx, ret;
1424
1425 idx = srcu_read_lock(&nodes_srcu);
1426 /* Abort pending close/remove operation */
1427 node = nodeid2node(nodeid);
1428 if (node) {
1429 /* let shutdown waiters leave */
1430 set_bit(DLM_NODE_FLAG_CLOSE, &node->flags);
1431 wake_up(&node->shutdown_wait);
1432 }
1433 srcu_read_unlock(&nodes_srcu, idx);
1434
1435 synchronize_srcu(&nodes_srcu);
1436
1437 mutex_lock(&close_lock);
1438 idx = srcu_read_lock(&nodes_srcu);
1439 node = nodeid2node(nodeid);
1440 if (!node) {
1441 srcu_read_unlock(&nodes_srcu, idx);
1442 mutex_unlock(&close_lock);
1443 return dlm_lowcomms_close(nodeid);
1444 }
1445
1446 ret = dlm_lowcomms_close(nodeid);
1447 dlm_delete_debug_comms_file(node->debugfs);
1448
1449 spin_lock(&nodes_lock);
1450 hlist_del_rcu(&node->hlist);
1451 spin_unlock(&nodes_lock);
1452 srcu_read_unlock(&nodes_srcu, idx);
1453
1454 /* wait that all readers left until flush send queue */
1455 synchronize_srcu(&nodes_srcu);
1456
1457 /* drop all pending dlm messages, this is fine as
1458 * this function get called when the node is fenced
1459 */
1460 dlm_send_queue_flush(node);
1461
1462 call_srcu(&nodes_srcu, &node->rcu, midcomms_node_release);
1463 mutex_unlock(&close_lock);
1464
1465 return ret;
1466}
1467
1468/* debug functionality to send raw dlm msg from user space */
1469struct dlm_rawmsg_data {
1470 struct midcomms_node *node;
1471 void *buf;
1472};
1473
1474static void midcomms_new_rawmsg_cb(void *data)
1475{
1476 struct dlm_rawmsg_data *rd = data;
1477 struct dlm_header *h = rd->buf;
1478
1479 switch (h->h_version) {
1480 case cpu_to_le32(DLM_VERSION_3_1):
1481 break;
1482 default:
1483 switch (h->h_cmd) {
1484 case DLM_OPTS:
1485 if (!h->u.h_seq)
1486 h->u.h_seq = cpu_to_le32(atomic_fetch_inc(&rd->node->seq_send));
1487 break;
1488 default:
1489 break;
1490 }
1491 break;
1492 }
1493}
1494
1495int dlm_midcomms_rawmsg_send(struct midcomms_node *node, void *buf,
1496 int buflen)
1497{
1498 struct dlm_rawmsg_data rd;
1499 struct dlm_msg *msg;
1500 char *msgbuf;
1501
1502 rd.node = node;
1503 rd.buf = buf;
1504
1505 msg = dlm_lowcomms_new_msg(node->nodeid, buflen, GFP_NOFS,
1506 &msgbuf, midcomms_new_rawmsg_cb, &rd);
1507 if (!msg)
1508 return -ENOMEM;
1509
1510 memcpy(msgbuf, buf, buflen);
1511 dlm_lowcomms_commit_msg(msg);
1512 return 0;
1513}
1514