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1/******************************************************************************
2*******************************************************************************
3**
4** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
5** Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
6**
7** This copyrighted material is made available to anyone wishing to use,
8** modify, copy, or redistribute it subject to the terms and conditions
9** of the GNU General Public License v.2.
10**
11*******************************************************************************
12******************************************************************************/
13
14/*
15 * midcomms.c
16 *
17 * This is the appallingly named "mid-level" comms layer.
18 *
19 * Its purpose is to take packets from the "real" comms layer,
20 * split them up into packets and pass them to the interested
21 * part of the locking mechanism.
22 *
23 * It also takes messages from the locking layer, formats them
24 * into packets and sends them to the comms layer.
25 */
26
27#include "dlm_internal.h"
28#include "lowcomms.h"
29#include "config.h"
30#include "lock.h"
31#include "midcomms.h"
32
33
34static void copy_from_cb(void *dst, const void *base, unsigned offset,
35 unsigned len, unsigned limit)
36{
37 unsigned copy = len;
38
39 if ((copy + offset) > limit)
40 copy = limit - offset;
41 memcpy(dst, base + offset, copy);
42 len -= copy;
43 if (len)
44 memcpy(dst + copy, base, len);
45}
46
47/*
48 * Called from the low-level comms layer to process a buffer of
49 * commands.
50 *
51 * Only complete messages are processed here, any "spare" bytes from
52 * the end of a buffer are saved and tacked onto the front of the next
53 * message that comes in. I doubt this will happen very often but we
54 * need to be able to cope with it and I don't want the task to be waiting
55 * for packets to come in when there is useful work to be done.
56 */
57
58int dlm_process_incoming_buffer(int nodeid, const void *base,
59 unsigned offset, unsigned len, unsigned limit)
60{
61 union {
62 unsigned char __buf[DLM_INBUF_LEN];
63 /* this is to force proper alignment on some arches */
64 union dlm_packet p;
65 } __tmp;
66 union dlm_packet *p = &__tmp.p;
67 int ret = 0;
68 int err = 0;
69 uint16_t msglen;
70 uint32_t lockspace;
71
72 while (len > sizeof(struct dlm_header)) {
73
74 /* Copy just the header to check the total length. The
75 message may wrap around the end of the buffer back to the
76 start, so we need to use a temp buffer and copy_from_cb. */
77
78 copy_from_cb(p, base, offset, sizeof(struct dlm_header),
79 limit);
80
81 msglen = le16_to_cpu(p->header.h_length);
82 lockspace = p->header.h_lockspace;
83
84 err = -EINVAL;
85 if (msglen < sizeof(struct dlm_header))
86 break;
87 if (p->header.h_cmd == DLM_MSG) {
88 if (msglen < sizeof(struct dlm_message))
89 break;
90 } else {
91 if (msglen < sizeof(struct dlm_rcom))
92 break;
93 }
94 err = -E2BIG;
95 if (msglen > dlm_config.ci_buffer_size) {
96 log_print("message size %d from %d too big, buf len %d",
97 msglen, nodeid, len);
98 break;
99 }
100 err = 0;
101
102 /* If only part of the full message is contained in this
103 buffer, then do nothing and wait for lowcomms to call
104 us again later with more data. We return 0 meaning
105 we've consumed none of the input buffer. */
106
107 if (msglen > len)
108 break;
109
110 /* Allocate a larger temp buffer if the full message won't fit
111 in the buffer on the stack (which should work for most
112 ordinary messages). */
113
114 if (msglen > sizeof(__tmp) && p == &__tmp.p) {
115 p = kmalloc(dlm_config.ci_buffer_size, GFP_NOFS);
116 if (p == NULL)
117 return ret;
118 }
119
120 copy_from_cb(p, base, offset, msglen, limit);
121
122 BUG_ON(lockspace != p->header.h_lockspace);
123
124 ret += msglen;
125 offset += msglen;
126 offset &= (limit - 1);
127 len -= msglen;
128
129 dlm_receive_buffer(p, nodeid);
130 }
131
132 if (p != &__tmp.p)
133 kfree(p);
134
135 return err ? err : ret;
136}
137
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}