xref: /linux/fs/dlm/midcomms.c (revision 578acf9a)
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 
154 struct 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 
198 struct 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 
215 static struct hlist_head node_hash[CONN_HASH_SIZE];
216 static DEFINE_SPINLOCK(nodes_lock);
217 DEFINE_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  */
225 static DEFINE_MUTEX(close_lock);
226 
dlm_midcomms_cache_create(void)227 struct kmem_cache *dlm_midcomms_cache_create(void)
228 {
229 	return KMEM_CACHE(dlm_mhandle, 0);
230 }
231 
dlm_state_str(int state)232 static inline const char *dlm_state_str(int state)
233 {
234 	switch (state) {
235 	case DLM_CLOSED:
236 		return "CLOSED";
237 	case DLM_ESTABLISHED:
238 		return "ESTABLISHED";
239 	case DLM_FIN_WAIT1:
240 		return "FIN_WAIT1";
241 	case DLM_FIN_WAIT2:
242 		return "FIN_WAIT2";
243 	case DLM_CLOSE_WAIT:
244 		return "CLOSE_WAIT";
245 	case DLM_LAST_ACK:
246 		return "LAST_ACK";
247 	case DLM_CLOSING:
248 		return "CLOSING";
249 	default:
250 		return "UNKNOWN";
251 	}
252 }
253 
dlm_midcomms_state(struct midcomms_node * node)254 const char *dlm_midcomms_state(struct midcomms_node *node)
255 {
256 	return dlm_state_str(node->state);
257 }
258 
dlm_midcomms_flags(struct midcomms_node * node)259 unsigned long dlm_midcomms_flags(struct midcomms_node *node)
260 {
261 	return node->flags;
262 }
263 
dlm_midcomms_send_queue_cnt(struct midcomms_node * node)264 int dlm_midcomms_send_queue_cnt(struct midcomms_node *node)
265 {
266 	return atomic_read(&node->send_queue_cnt);
267 }
268 
dlm_midcomms_version(struct midcomms_node * node)269 uint32_t dlm_midcomms_version(struct midcomms_node *node)
270 {
271 	return node->version;
272 }
273 
__find_node(int nodeid,int r)274 static struct midcomms_node *__find_node(int nodeid, int r)
275 {
276 	struct midcomms_node *node;
277 
278 	hlist_for_each_entry_rcu(node, &node_hash[r], hlist) {
279 		if (node->nodeid == nodeid)
280 			return node;
281 	}
282 
283 	return NULL;
284 }
285 
dlm_mhandle_release(struct rcu_head * rcu)286 static void dlm_mhandle_release(struct rcu_head *rcu)
287 {
288 	struct dlm_mhandle *mh = container_of(rcu, struct dlm_mhandle, rcu);
289 
290 	dlm_lowcomms_put_msg(mh->msg);
291 	dlm_free_mhandle(mh);
292 }
293 
dlm_mhandle_delete(struct midcomms_node * node,struct dlm_mhandle * mh)294 static void dlm_mhandle_delete(struct midcomms_node *node,
295 			       struct dlm_mhandle *mh)
296 {
297 	list_del_rcu(&mh->list);
298 	atomic_dec(&node->send_queue_cnt);
299 	call_rcu(&mh->rcu, dlm_mhandle_release);
300 }
301 
dlm_send_queue_flush(struct midcomms_node * node)302 static void dlm_send_queue_flush(struct midcomms_node *node)
303 {
304 	struct dlm_mhandle *mh;
305 
306 	pr_debug("flush midcomms send queue of node %d\n", node->nodeid);
307 
308 	rcu_read_lock();
309 	spin_lock_bh(&node->send_queue_lock);
310 	list_for_each_entry_rcu(mh, &node->send_queue, list) {
311 		dlm_mhandle_delete(node, mh);
312 	}
313 	spin_unlock_bh(&node->send_queue_lock);
314 	rcu_read_unlock();
315 }
316 
midcomms_node_reset(struct midcomms_node * node)317 static void midcomms_node_reset(struct midcomms_node *node)
318 {
319 	pr_debug("reset node %d\n", node->nodeid);
320 
321 	atomic_set(&node->seq_next, DLM_SEQ_INIT);
322 	atomic_set(&node->seq_send, DLM_SEQ_INIT);
323 	atomic_set(&node->ulp_delivered, 0);
324 	node->version = DLM_VERSION_NOT_SET;
325 	node->flags = 0;
326 
327 	dlm_send_queue_flush(node);
328 	node->state = DLM_CLOSED;
329 	wake_up(&node->shutdown_wait);
330 }
331 
nodeid2node(int nodeid)332 static struct midcomms_node *nodeid2node(int nodeid)
333 {
334 	return __find_node(nodeid, nodeid_hash(nodeid));
335 }
336 
dlm_midcomms_addr(int nodeid,struct sockaddr_storage * addr,int len)337 int dlm_midcomms_addr(int nodeid, struct sockaddr_storage *addr, int len)
338 {
339 	int ret, idx, r = nodeid_hash(nodeid);
340 	struct midcomms_node *node;
341 
342 	ret = dlm_lowcomms_addr(nodeid, addr, len);
343 	if (ret)
344 		return ret;
345 
346 	idx = srcu_read_lock(&nodes_srcu);
347 	node = __find_node(nodeid, r);
348 	if (node) {
349 		srcu_read_unlock(&nodes_srcu, idx);
350 		return 0;
351 	}
352 	srcu_read_unlock(&nodes_srcu, idx);
353 
354 	node = kmalloc(sizeof(*node), GFP_NOFS);
355 	if (!node)
356 		return -ENOMEM;
357 
358 	node->nodeid = nodeid;
359 	spin_lock_init(&node->state_lock);
360 	spin_lock_init(&node->send_queue_lock);
361 	atomic_set(&node->send_queue_cnt, 0);
362 	INIT_LIST_HEAD(&node->send_queue);
363 	init_waitqueue_head(&node->shutdown_wait);
364 	node->users = 0;
365 	midcomms_node_reset(node);
366 
367 	spin_lock_bh(&nodes_lock);
368 	hlist_add_head_rcu(&node->hlist, &node_hash[r]);
369 	spin_unlock_bh(&nodes_lock);
370 
371 	node->debugfs = dlm_create_debug_comms_file(nodeid, node);
372 	return 0;
373 }
374 
dlm_send_ack(int nodeid,uint32_t seq)375 static int dlm_send_ack(int nodeid, uint32_t seq)
376 {
377 	int mb_len = sizeof(struct dlm_header);
378 	struct dlm_header *m_header;
379 	struct dlm_msg *msg;
380 	char *ppc;
381 
382 	msg = dlm_lowcomms_new_msg(nodeid, mb_len, &ppc, NULL, NULL);
383 	if (!msg)
384 		return -ENOMEM;
385 
386 	m_header = (struct dlm_header *)ppc;
387 
388 	m_header->h_version = cpu_to_le32(DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
389 	m_header->h_nodeid = cpu_to_le32(dlm_our_nodeid());
390 	m_header->h_length = cpu_to_le16(mb_len);
391 	m_header->h_cmd = DLM_ACK;
392 	m_header->u.h_seq = cpu_to_le32(seq);
393 
394 	dlm_lowcomms_commit_msg(msg);
395 	dlm_lowcomms_put_msg(msg);
396 
397 	return 0;
398 }
399 
dlm_send_ack_threshold(struct midcomms_node * node,uint32_t threshold)400 static void dlm_send_ack_threshold(struct midcomms_node *node,
401 				   uint32_t threshold)
402 {
403 	uint32_t oval, nval;
404 	bool send_ack;
405 
406 	/* let only send one user trigger threshold to send ack back */
407 	do {
408 		oval = atomic_read(&node->ulp_delivered);
409 		send_ack = (oval > threshold);
410 		/* abort if threshold is not reached */
411 		if (!send_ack)
412 			break;
413 
414 		nval = 0;
415 		/* try to reset ulp_delivered counter */
416 	} while (atomic_cmpxchg(&node->ulp_delivered, oval, nval) != oval);
417 
418 	if (send_ack)
419 		dlm_send_ack(node->nodeid, atomic_read(&node->seq_next));
420 }
421 
dlm_send_fin(struct midcomms_node * node,void (* ack_rcv)(struct midcomms_node * node))422 static int dlm_send_fin(struct midcomms_node *node,
423 			void (*ack_rcv)(struct midcomms_node *node))
424 {
425 	int mb_len = sizeof(struct dlm_header);
426 	struct dlm_header *m_header;
427 	struct dlm_mhandle *mh;
428 	char *ppc;
429 
430 	mh = dlm_midcomms_get_mhandle(node->nodeid, mb_len, &ppc);
431 	if (!mh)
432 		return -ENOMEM;
433 
434 	set_bit(DLM_NODE_FLAG_STOP_TX, &node->flags);
435 	mh->ack_rcv = ack_rcv;
436 
437 	m_header = (struct dlm_header *)ppc;
438 
439 	m_header->h_version = cpu_to_le32(DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
440 	m_header->h_nodeid = cpu_to_le32(dlm_our_nodeid());
441 	m_header->h_length = cpu_to_le16(mb_len);
442 	m_header->h_cmd = DLM_FIN;
443 
444 	pr_debug("sending fin msg to node %d\n", node->nodeid);
445 	dlm_midcomms_commit_mhandle(mh, NULL, 0);
446 
447 	return 0;
448 }
449 
dlm_receive_ack(struct midcomms_node * node,uint32_t seq)450 static void dlm_receive_ack(struct midcomms_node *node, uint32_t seq)
451 {
452 	struct dlm_mhandle *mh;
453 
454 	rcu_read_lock();
455 	list_for_each_entry_rcu(mh, &node->send_queue, list) {
456 		if (before(mh->seq, seq)) {
457 			if (mh->ack_rcv)
458 				mh->ack_rcv(node);
459 		} else {
460 			/* send queue should be ordered */
461 			break;
462 		}
463 	}
464 
465 	spin_lock_bh(&node->send_queue_lock);
466 	list_for_each_entry_rcu(mh, &node->send_queue, list) {
467 		if (before(mh->seq, seq)) {
468 			dlm_mhandle_delete(node, mh);
469 		} else {
470 			/* send queue should be ordered */
471 			break;
472 		}
473 	}
474 	spin_unlock_bh(&node->send_queue_lock);
475 	rcu_read_unlock();
476 }
477 
dlm_pas_fin_ack_rcv(struct midcomms_node * node)478 static void dlm_pas_fin_ack_rcv(struct midcomms_node *node)
479 {
480 	spin_lock_bh(&node->state_lock);
481 	pr_debug("receive passive fin ack from node %d with state %s\n",
482 		 node->nodeid, dlm_state_str(node->state));
483 
484 	switch (node->state) {
485 	case DLM_LAST_ACK:
486 		/* DLM_CLOSED */
487 		midcomms_node_reset(node);
488 		break;
489 	case DLM_CLOSED:
490 		/* not valid but somehow we got what we want */
491 		wake_up(&node->shutdown_wait);
492 		break;
493 	default:
494 		spin_unlock_bh(&node->state_lock);
495 		log_print("%s: unexpected state: %d",
496 			  __func__, node->state);
497 		WARN_ON_ONCE(1);
498 		return;
499 	}
500 	spin_unlock_bh(&node->state_lock);
501 }
502 
dlm_receive_buffer_3_2_trace(uint32_t seq,const union dlm_packet * p)503 static void dlm_receive_buffer_3_2_trace(uint32_t seq,
504 					 const union dlm_packet *p)
505 {
506 	switch (p->header.h_cmd) {
507 	case DLM_MSG:
508 		trace_dlm_recv_message(dlm_our_nodeid(), seq, &p->message);
509 		break;
510 	case DLM_RCOM:
511 		trace_dlm_recv_rcom(dlm_our_nodeid(), seq, &p->rcom);
512 		break;
513 	default:
514 		break;
515 	}
516 }
517 
dlm_midcomms_receive_buffer(const union dlm_packet * p,struct midcomms_node * node,uint32_t seq)518 static void dlm_midcomms_receive_buffer(const union dlm_packet *p,
519 					struct midcomms_node *node,
520 					uint32_t seq)
521 {
522 	bool is_expected_seq;
523 	uint32_t oval, nval;
524 
525 	do {
526 		oval = atomic_read(&node->seq_next);
527 		is_expected_seq = (oval == seq);
528 		if (!is_expected_seq)
529 			break;
530 
531 		nval = oval + 1;
532 	} while (atomic_cmpxchg(&node->seq_next, oval, nval) != oval);
533 
534 	if (is_expected_seq) {
535 		switch (p->header.h_cmd) {
536 		case DLM_FIN:
537 			spin_lock_bh(&node->state_lock);
538 			pr_debug("receive fin msg from node %d with state %s\n",
539 				 node->nodeid, dlm_state_str(node->state));
540 
541 			switch (node->state) {
542 			case DLM_ESTABLISHED:
543 				dlm_send_ack(node->nodeid, nval);
544 
545 				/* passive shutdown DLM_LAST_ACK case 1
546 				 * additional we check if the node is used by
547 				 * cluster manager events at all.
548 				 */
549 				if (node->users == 0) {
550 					node->state = DLM_LAST_ACK;
551 					pr_debug("switch node %d to state %s case 1\n",
552 						 node->nodeid, dlm_state_str(node->state));
553 					set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
554 					dlm_send_fin(node, dlm_pas_fin_ack_rcv);
555 				} else {
556 					node->state = DLM_CLOSE_WAIT;
557 					pr_debug("switch node %d to state %s\n",
558 						 node->nodeid, dlm_state_str(node->state));
559 				}
560 				break;
561 			case DLM_FIN_WAIT1:
562 				dlm_send_ack(node->nodeid, nval);
563 				node->state = DLM_CLOSING;
564 				set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
565 				pr_debug("switch node %d to state %s\n",
566 					 node->nodeid, dlm_state_str(node->state));
567 				break;
568 			case DLM_FIN_WAIT2:
569 				dlm_send_ack(node->nodeid, nval);
570 				midcomms_node_reset(node);
571 				pr_debug("switch node %d to state %s\n",
572 					 node->nodeid, dlm_state_str(node->state));
573 				break;
574 			case DLM_LAST_ACK:
575 				/* probably remove_member caught it, do nothing */
576 				break;
577 			default:
578 				spin_unlock_bh(&node->state_lock);
579 				log_print("%s: unexpected state: %d",
580 					  __func__, node->state);
581 				WARN_ON_ONCE(1);
582 				return;
583 			}
584 			spin_unlock_bh(&node->state_lock);
585 			break;
586 		default:
587 			WARN_ON_ONCE(test_bit(DLM_NODE_FLAG_STOP_RX, &node->flags));
588 			dlm_receive_buffer_3_2_trace(seq, p);
589 			dlm_receive_buffer(p, node->nodeid);
590 			atomic_inc(&node->ulp_delivered);
591 			/* unlikely case to send ack back when we don't transmit */
592 			dlm_send_ack_threshold(node, DLM_RECV_ACK_BACK_MSG_THRESHOLD);
593 			break;
594 		}
595 	} else {
596 		/* retry to ack message which we already have by sending back
597 		 * current node->seq_next number as ack.
598 		 */
599 		if (seq < oval)
600 			dlm_send_ack(node->nodeid, oval);
601 
602 		log_print_ratelimited("ignore dlm msg because seq mismatch, seq: %u, expected: %u, nodeid: %d",
603 				      seq, oval, node->nodeid);
604 	}
605 }
606 
dlm_opts_check_msglen(const union dlm_packet * p,uint16_t msglen,int nodeid)607 static int dlm_opts_check_msglen(const union dlm_packet *p, uint16_t msglen,
608 				 int nodeid)
609 {
610 	int len = msglen;
611 
612 	/* we only trust outer header msglen because
613 	 * it's checked against receive buffer length.
614 	 */
615 	if (len < sizeof(struct dlm_opts))
616 		return -1;
617 	len -= sizeof(struct dlm_opts);
618 
619 	if (len < le16_to_cpu(p->opts.o_optlen))
620 		return -1;
621 	len -= le16_to_cpu(p->opts.o_optlen);
622 
623 	switch (p->opts.o_nextcmd) {
624 	case DLM_FIN:
625 		if (len < sizeof(struct dlm_header)) {
626 			log_print("fin too small: %d, will skip this message from node %d",
627 				  len, nodeid);
628 			return -1;
629 		}
630 
631 		break;
632 	case DLM_MSG:
633 		if (len < sizeof(struct dlm_message)) {
634 			log_print("msg too small: %d, will skip this message from node %d",
635 				  msglen, nodeid);
636 			return -1;
637 		}
638 
639 		break;
640 	case DLM_RCOM:
641 		if (len < sizeof(struct dlm_rcom)) {
642 			log_print("rcom msg too small: %d, will skip this message from node %d",
643 				  len, nodeid);
644 			return -1;
645 		}
646 
647 		break;
648 	default:
649 		log_print("unsupported o_nextcmd received: %u, will skip this message from node %d",
650 			  p->opts.o_nextcmd, nodeid);
651 		return -1;
652 	}
653 
654 	return 0;
655 }
656 
dlm_midcomms_receive_buffer_3_2(const union dlm_packet * p,int nodeid)657 static void dlm_midcomms_receive_buffer_3_2(const union dlm_packet *p, int nodeid)
658 {
659 	uint16_t msglen = le16_to_cpu(p->header.h_length);
660 	struct midcomms_node *node;
661 	uint32_t seq;
662 	int ret, idx;
663 
664 	idx = srcu_read_lock(&nodes_srcu);
665 	node = nodeid2node(nodeid);
666 	if (WARN_ON_ONCE(!node))
667 		goto out;
668 
669 	switch (node->version) {
670 	case DLM_VERSION_NOT_SET:
671 		node->version = DLM_VERSION_3_2;
672 		wake_up(&node->shutdown_wait);
673 		log_print("version 0x%08x for node %d detected", DLM_VERSION_3_2,
674 			  node->nodeid);
675 
676 		spin_lock(&node->state_lock);
677 		switch (node->state) {
678 		case DLM_CLOSED:
679 			node->state = DLM_ESTABLISHED;
680 			pr_debug("switch node %d to state %s\n",
681 				 node->nodeid, dlm_state_str(node->state));
682 			break;
683 		default:
684 			break;
685 		}
686 		spin_unlock(&node->state_lock);
687 
688 		break;
689 	case DLM_VERSION_3_2:
690 		break;
691 	default:
692 		log_print_ratelimited("version mismatch detected, assumed 0x%08x but node %d has 0x%08x",
693 				      DLM_VERSION_3_2, node->nodeid, node->version);
694 		goto out;
695 	}
696 
697 	switch (p->header.h_cmd) {
698 	case DLM_RCOM:
699 		/* these rcom message we use to determine version.
700 		 * they have their own retransmission handling and
701 		 * are the first messages of dlm.
702 		 *
703 		 * length already checked.
704 		 */
705 		switch (p->rcom.rc_type) {
706 		case cpu_to_le32(DLM_RCOM_NAMES):
707 			fallthrough;
708 		case cpu_to_le32(DLM_RCOM_NAMES_REPLY):
709 			fallthrough;
710 		case cpu_to_le32(DLM_RCOM_STATUS):
711 			fallthrough;
712 		case cpu_to_le32(DLM_RCOM_STATUS_REPLY):
713 			break;
714 		default:
715 			log_print("unsupported rcom type received: %u, will skip this message from node %d",
716 				  le32_to_cpu(p->rcom.rc_type), nodeid);
717 			goto out;
718 		}
719 
720 		WARN_ON_ONCE(test_bit(DLM_NODE_FLAG_STOP_RX, &node->flags));
721 		dlm_receive_buffer(p, nodeid);
722 		break;
723 	case DLM_OPTS:
724 		seq = le32_to_cpu(p->header.u.h_seq);
725 
726 		ret = dlm_opts_check_msglen(p, msglen, nodeid);
727 		if (ret < 0) {
728 			log_print("opts msg too small: %u, will skip this message from node %d",
729 				  msglen, nodeid);
730 			goto out;
731 		}
732 
733 		p = (union dlm_packet *)((unsigned char *)p->opts.o_opts +
734 					 le16_to_cpu(p->opts.o_optlen));
735 
736 		/* recheck inner msglen just if it's not garbage */
737 		msglen = le16_to_cpu(p->header.h_length);
738 		switch (p->header.h_cmd) {
739 		case DLM_RCOM:
740 			if (msglen < sizeof(struct dlm_rcom)) {
741 				log_print("inner rcom msg too small: %u, will skip this message from node %d",
742 					  msglen, nodeid);
743 				goto out;
744 			}
745 
746 			break;
747 		case DLM_MSG:
748 			if (msglen < sizeof(struct dlm_message)) {
749 				log_print("inner msg too small: %u, will skip this message from node %d",
750 					  msglen, nodeid);
751 				goto out;
752 			}
753 
754 			break;
755 		case DLM_FIN:
756 			if (msglen < sizeof(struct dlm_header)) {
757 				log_print("inner fin too small: %u, will skip this message from node %d",
758 					  msglen, nodeid);
759 				goto out;
760 			}
761 
762 			break;
763 		default:
764 			log_print("unsupported inner h_cmd received: %u, will skip this message from node %d",
765 				  msglen, nodeid);
766 			goto out;
767 		}
768 
769 		dlm_midcomms_receive_buffer(p, node, seq);
770 		break;
771 	case DLM_ACK:
772 		seq = le32_to_cpu(p->header.u.h_seq);
773 		dlm_receive_ack(node, seq);
774 		break;
775 	default:
776 		log_print("unsupported h_cmd received: %u, will skip this message from node %d",
777 			  p->header.h_cmd, nodeid);
778 		break;
779 	}
780 
781 out:
782 	srcu_read_unlock(&nodes_srcu, idx);
783 }
784 
dlm_midcomms_receive_buffer_3_1(const union dlm_packet * p,int nodeid)785 static void dlm_midcomms_receive_buffer_3_1(const union dlm_packet *p, int nodeid)
786 {
787 	uint16_t msglen = le16_to_cpu(p->header.h_length);
788 	struct midcomms_node *node;
789 	int idx;
790 
791 	idx = srcu_read_lock(&nodes_srcu);
792 	node = nodeid2node(nodeid);
793 	if (WARN_ON_ONCE(!node)) {
794 		srcu_read_unlock(&nodes_srcu, idx);
795 		return;
796 	}
797 
798 	switch (node->version) {
799 	case DLM_VERSION_NOT_SET:
800 		node->version = DLM_VERSION_3_1;
801 		wake_up(&node->shutdown_wait);
802 		log_print("version 0x%08x for node %d detected", DLM_VERSION_3_1,
803 			  node->nodeid);
804 		break;
805 	case DLM_VERSION_3_1:
806 		break;
807 	default:
808 		log_print_ratelimited("version mismatch detected, assumed 0x%08x but node %d has 0x%08x",
809 				      DLM_VERSION_3_1, node->nodeid, node->version);
810 		srcu_read_unlock(&nodes_srcu, idx);
811 		return;
812 	}
813 	srcu_read_unlock(&nodes_srcu, idx);
814 
815 	switch (p->header.h_cmd) {
816 	case DLM_RCOM:
817 		/* length already checked */
818 		break;
819 	case DLM_MSG:
820 		if (msglen < sizeof(struct dlm_message)) {
821 			log_print("msg too small: %u, will skip this message from node %d",
822 				  msglen, nodeid);
823 			return;
824 		}
825 
826 		break;
827 	default:
828 		log_print("unsupported h_cmd received: %u, will skip this message from node %d",
829 			  p->header.h_cmd, nodeid);
830 		return;
831 	}
832 
833 	dlm_receive_buffer(p, nodeid);
834 }
835 
dlm_validate_incoming_buffer(int nodeid,unsigned char * buf,int len)836 int dlm_validate_incoming_buffer(int nodeid, unsigned char *buf, int len)
837 {
838 	const unsigned char *ptr = buf;
839 	const struct dlm_header *hd;
840 	uint16_t msglen;
841 	int ret = 0;
842 
843 	while (len >= sizeof(struct dlm_header)) {
844 		hd = (struct dlm_header *)ptr;
845 
846 		/* no message should be more than DLM_MAX_SOCKET_BUFSIZE or
847 		 * less than dlm_header size.
848 		 *
849 		 * Some messages does not have a 8 byte length boundary yet
850 		 * which can occur in a unaligned memory access of some dlm
851 		 * messages. However this problem need to be fixed at the
852 		 * sending side, for now it seems nobody run into architecture
853 		 * related issues yet but it slows down some processing.
854 		 * Fixing this issue should be scheduled in future by doing
855 		 * the next major version bump.
856 		 */
857 		msglen = le16_to_cpu(hd->h_length);
858 		if (msglen > DLM_MAX_SOCKET_BUFSIZE ||
859 		    msglen < sizeof(struct dlm_header)) {
860 			log_print("received invalid length header: %u from node %d, will abort message parsing",
861 				  msglen, nodeid);
862 			return -EBADMSG;
863 		}
864 
865 		/* caller will take care that leftover
866 		 * will be parsed next call with more data
867 		 */
868 		if (msglen > len)
869 			break;
870 
871 		ret += msglen;
872 		len -= msglen;
873 		ptr += msglen;
874 	}
875 
876 	return ret;
877 }
878 
879 /*
880  * Called from the low-level comms layer to process a buffer of
881  * commands.
882  */
dlm_process_incoming_buffer(int nodeid,unsigned char * buf,int len)883 int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
884 {
885 	const unsigned char *ptr = buf;
886 	const struct dlm_header *hd;
887 	uint16_t msglen;
888 	int ret = 0;
889 
890 	while (len >= sizeof(struct dlm_header)) {
891 		hd = (struct dlm_header *)ptr;
892 
893 		msglen = le16_to_cpu(hd->h_length);
894 		if (msglen > len)
895 			break;
896 
897 		switch (hd->h_version) {
898 		case cpu_to_le32(DLM_VERSION_3_1):
899 			dlm_midcomms_receive_buffer_3_1((const union dlm_packet *)ptr, nodeid);
900 			break;
901 		case cpu_to_le32(DLM_VERSION_3_2):
902 			dlm_midcomms_receive_buffer_3_2((const union dlm_packet *)ptr, nodeid);
903 			break;
904 		default:
905 			log_print("received invalid version header: %u from node %d, will skip this message",
906 				  le32_to_cpu(hd->h_version), nodeid);
907 			break;
908 		}
909 
910 		ret += msglen;
911 		len -= msglen;
912 		ptr += msglen;
913 	}
914 
915 	return ret;
916 }
917 
dlm_midcomms_unack_msg_resend(int nodeid)918 void dlm_midcomms_unack_msg_resend(int nodeid)
919 {
920 	struct midcomms_node *node;
921 	struct dlm_mhandle *mh;
922 	int idx, ret;
923 
924 	idx = srcu_read_lock(&nodes_srcu);
925 	node = nodeid2node(nodeid);
926 	if (WARN_ON_ONCE(!node)) {
927 		srcu_read_unlock(&nodes_srcu, idx);
928 		return;
929 	}
930 
931 	/* old protocol, we don't support to retransmit on failure */
932 	switch (node->version) {
933 	case DLM_VERSION_3_2:
934 		break;
935 	default:
936 		srcu_read_unlock(&nodes_srcu, idx);
937 		return;
938 	}
939 
940 	rcu_read_lock();
941 	list_for_each_entry_rcu(mh, &node->send_queue, list) {
942 		if (!mh->committed)
943 			continue;
944 
945 		ret = dlm_lowcomms_resend_msg(mh->msg);
946 		if (!ret)
947 			log_print_ratelimited("retransmit dlm msg, seq %u, nodeid %d",
948 					      mh->seq, node->nodeid);
949 	}
950 	rcu_read_unlock();
951 	srcu_read_unlock(&nodes_srcu, idx);
952 }
953 
dlm_fill_opts_header(struct dlm_opts * opts,uint16_t inner_len,uint32_t seq)954 static void dlm_fill_opts_header(struct dlm_opts *opts, uint16_t inner_len,
955 				 uint32_t seq)
956 {
957 	opts->o_header.h_cmd = DLM_OPTS;
958 	opts->o_header.h_version = cpu_to_le32(DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
959 	opts->o_header.h_nodeid = cpu_to_le32(dlm_our_nodeid());
960 	opts->o_header.h_length = cpu_to_le16(DLM_MIDCOMMS_OPT_LEN + inner_len);
961 	opts->o_header.u.h_seq = cpu_to_le32(seq);
962 }
963 
midcomms_new_msg_cb(void * data)964 static void midcomms_new_msg_cb(void *data)
965 {
966 	struct dlm_mhandle *mh = data;
967 
968 	atomic_inc(&mh->node->send_queue_cnt);
969 
970 	spin_lock_bh(&mh->node->send_queue_lock);
971 	list_add_tail_rcu(&mh->list, &mh->node->send_queue);
972 	spin_unlock_bh(&mh->node->send_queue_lock);
973 
974 	mh->seq = atomic_fetch_inc(&mh->node->seq_send);
975 }
976 
dlm_midcomms_get_msg_3_2(struct dlm_mhandle * mh,int nodeid,int len,char ** ppc)977 static struct dlm_msg *dlm_midcomms_get_msg_3_2(struct dlm_mhandle *mh, int nodeid,
978 						int len, char **ppc)
979 {
980 	struct dlm_opts *opts;
981 	struct dlm_msg *msg;
982 
983 	msg = dlm_lowcomms_new_msg(nodeid, len + DLM_MIDCOMMS_OPT_LEN,
984 				   ppc, midcomms_new_msg_cb, mh);
985 	if (!msg)
986 		return NULL;
987 
988 	opts = (struct dlm_opts *)*ppc;
989 	mh->opts = opts;
990 
991 	/* add possible options here */
992 	dlm_fill_opts_header(opts, len, mh->seq);
993 
994 	*ppc += sizeof(*opts);
995 	mh->inner_p = (const union dlm_packet *)*ppc;
996 	return msg;
997 }
998 
999 /* avoid false positive for nodes_srcu, unlock happens in
1000  * dlm_midcomms_commit_mhandle which is a must call if success
1001  */
1002 #ifndef __CHECKER__
dlm_midcomms_get_mhandle(int nodeid,int len,char ** ppc)1003 struct dlm_mhandle *dlm_midcomms_get_mhandle(int nodeid, int len, char **ppc)
1004 {
1005 	struct midcomms_node *node;
1006 	struct dlm_mhandle *mh;
1007 	struct dlm_msg *msg;
1008 	int idx;
1009 
1010 	idx = srcu_read_lock(&nodes_srcu);
1011 	node = nodeid2node(nodeid);
1012 	if (WARN_ON_ONCE(!node))
1013 		goto err;
1014 
1015 	/* this is a bug, however we going on and hope it will be resolved */
1016 	WARN_ON_ONCE(test_bit(DLM_NODE_FLAG_STOP_TX, &node->flags));
1017 
1018 	mh = dlm_allocate_mhandle();
1019 	if (!mh)
1020 		goto err;
1021 
1022 	mh->committed = false;
1023 	mh->ack_rcv = NULL;
1024 	mh->idx = idx;
1025 	mh->node = node;
1026 
1027 	switch (node->version) {
1028 	case DLM_VERSION_3_1:
1029 		msg = dlm_lowcomms_new_msg(nodeid, len, ppc, NULL, NULL);
1030 		if (!msg) {
1031 			dlm_free_mhandle(mh);
1032 			goto err;
1033 		}
1034 
1035 		break;
1036 	case DLM_VERSION_3_2:
1037 		/* send ack back if necessary */
1038 		dlm_send_ack_threshold(node, DLM_SEND_ACK_BACK_MSG_THRESHOLD);
1039 
1040 		msg = dlm_midcomms_get_msg_3_2(mh, nodeid, len, ppc);
1041 		if (!msg) {
1042 			dlm_free_mhandle(mh);
1043 			goto err;
1044 		}
1045 		break;
1046 	default:
1047 		dlm_free_mhandle(mh);
1048 		WARN_ON_ONCE(1);
1049 		goto err;
1050 	}
1051 
1052 	mh->msg = msg;
1053 
1054 	/* keep in mind that is a must to call
1055 	 * dlm_midcomms_commit_msg() which releases
1056 	 * nodes_srcu using mh->idx which is assumed
1057 	 * here that the application will call it.
1058 	 */
1059 	return mh;
1060 
1061 err:
1062 	srcu_read_unlock(&nodes_srcu, idx);
1063 	return NULL;
1064 }
1065 #endif
1066 
dlm_midcomms_commit_msg_3_2_trace(const struct dlm_mhandle * mh,const void * name,int namelen)1067 static void dlm_midcomms_commit_msg_3_2_trace(const struct dlm_mhandle *mh,
1068 					      const void *name, int namelen)
1069 {
1070 	switch (mh->inner_p->header.h_cmd) {
1071 	case DLM_MSG:
1072 		trace_dlm_send_message(mh->node->nodeid, mh->seq,
1073 				       &mh->inner_p->message,
1074 				       name, namelen);
1075 		break;
1076 	case DLM_RCOM:
1077 		trace_dlm_send_rcom(mh->node->nodeid, mh->seq,
1078 				    &mh->inner_p->rcom);
1079 		break;
1080 	default:
1081 		/* nothing to trace */
1082 		break;
1083 	}
1084 }
1085 
dlm_midcomms_commit_msg_3_2(struct dlm_mhandle * mh,const void * name,int namelen)1086 static void dlm_midcomms_commit_msg_3_2(struct dlm_mhandle *mh,
1087 					const void *name, int namelen)
1088 {
1089 	/* nexthdr chain for fast lookup */
1090 	mh->opts->o_nextcmd = mh->inner_p->header.h_cmd;
1091 	mh->committed = true;
1092 	dlm_midcomms_commit_msg_3_2_trace(mh, name, namelen);
1093 	dlm_lowcomms_commit_msg(mh->msg);
1094 }
1095 
1096 /* avoid false positive for nodes_srcu, lock was happen in
1097  * dlm_midcomms_get_mhandle
1098  */
1099 #ifndef __CHECKER__
dlm_midcomms_commit_mhandle(struct dlm_mhandle * mh,const void * name,int namelen)1100 void dlm_midcomms_commit_mhandle(struct dlm_mhandle *mh,
1101 				 const void *name, int namelen)
1102 {
1103 
1104 	switch (mh->node->version) {
1105 	case DLM_VERSION_3_1:
1106 		srcu_read_unlock(&nodes_srcu, mh->idx);
1107 
1108 		dlm_lowcomms_commit_msg(mh->msg);
1109 		dlm_lowcomms_put_msg(mh->msg);
1110 		/* mh is not part of rcu list in this case */
1111 		dlm_free_mhandle(mh);
1112 		break;
1113 	case DLM_VERSION_3_2:
1114 		/* held rcu read lock here, because we sending the
1115 		 * dlm message out, when we do that we could receive
1116 		 * an ack back which releases the mhandle and we
1117 		 * get a use after free.
1118 		 */
1119 		rcu_read_lock();
1120 		dlm_midcomms_commit_msg_3_2(mh, name, namelen);
1121 		srcu_read_unlock(&nodes_srcu, mh->idx);
1122 		rcu_read_unlock();
1123 		break;
1124 	default:
1125 		srcu_read_unlock(&nodes_srcu, mh->idx);
1126 		WARN_ON_ONCE(1);
1127 		break;
1128 	}
1129 }
1130 #endif
1131 
dlm_midcomms_start(void)1132 int dlm_midcomms_start(void)
1133 {
1134 	return dlm_lowcomms_start();
1135 }
1136 
dlm_midcomms_stop(void)1137 void dlm_midcomms_stop(void)
1138 {
1139 	dlm_lowcomms_stop();
1140 }
1141 
dlm_midcomms_init(void)1142 void dlm_midcomms_init(void)
1143 {
1144 	int i;
1145 
1146 	for (i = 0; i < CONN_HASH_SIZE; i++)
1147 		INIT_HLIST_HEAD(&node_hash[i]);
1148 
1149 	dlm_lowcomms_init();
1150 }
1151 
midcomms_node_release(struct rcu_head * rcu)1152 static void midcomms_node_release(struct rcu_head *rcu)
1153 {
1154 	struct midcomms_node *node = container_of(rcu, struct midcomms_node, rcu);
1155 
1156 	WARN_ON_ONCE(atomic_read(&node->send_queue_cnt));
1157 	dlm_send_queue_flush(node);
1158 	kfree(node);
1159 }
1160 
dlm_midcomms_exit(void)1161 void dlm_midcomms_exit(void)
1162 {
1163 	struct midcomms_node *node;
1164 	int i, idx;
1165 
1166 	idx = srcu_read_lock(&nodes_srcu);
1167 	for (i = 0; i < CONN_HASH_SIZE; i++) {
1168 		hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
1169 			dlm_delete_debug_comms_file(node->debugfs);
1170 
1171 			spin_lock(&nodes_lock);
1172 			hlist_del_rcu(&node->hlist);
1173 			spin_unlock(&nodes_lock);
1174 
1175 			call_srcu(&nodes_srcu, &node->rcu, midcomms_node_release);
1176 		}
1177 	}
1178 	srcu_read_unlock(&nodes_srcu, idx);
1179 
1180 	dlm_lowcomms_exit();
1181 }
1182 
dlm_act_fin_ack_rcv(struct midcomms_node * node)1183 static void dlm_act_fin_ack_rcv(struct midcomms_node *node)
1184 {
1185 	spin_lock_bh(&node->state_lock);
1186 	pr_debug("receive active fin ack from node %d with state %s\n",
1187 		 node->nodeid, dlm_state_str(node->state));
1188 
1189 	switch (node->state) {
1190 	case DLM_FIN_WAIT1:
1191 		node->state = DLM_FIN_WAIT2;
1192 		pr_debug("switch node %d to state %s\n",
1193 			 node->nodeid, dlm_state_str(node->state));
1194 		break;
1195 	case DLM_CLOSING:
1196 		midcomms_node_reset(node);
1197 		pr_debug("switch node %d to state %s\n",
1198 			 node->nodeid, dlm_state_str(node->state));
1199 		break;
1200 	case DLM_CLOSED:
1201 		/* not valid but somehow we got what we want */
1202 		wake_up(&node->shutdown_wait);
1203 		break;
1204 	default:
1205 		spin_unlock_bh(&node->state_lock);
1206 		log_print("%s: unexpected state: %d",
1207 			  __func__, node->state);
1208 		WARN_ON_ONCE(1);
1209 		return;
1210 	}
1211 	spin_unlock_bh(&node->state_lock);
1212 }
1213 
dlm_midcomms_add_member(int nodeid)1214 void dlm_midcomms_add_member(int nodeid)
1215 {
1216 	struct midcomms_node *node;
1217 	int idx;
1218 
1219 	idx = srcu_read_lock(&nodes_srcu);
1220 	node = nodeid2node(nodeid);
1221 	if (WARN_ON_ONCE(!node)) {
1222 		srcu_read_unlock(&nodes_srcu, idx);
1223 		return;
1224 	}
1225 
1226 	spin_lock_bh(&node->state_lock);
1227 	if (!node->users) {
1228 		pr_debug("receive add member from node %d with state %s\n",
1229 			 node->nodeid, dlm_state_str(node->state));
1230 		switch (node->state) {
1231 		case DLM_ESTABLISHED:
1232 			break;
1233 		case DLM_CLOSED:
1234 			node->state = DLM_ESTABLISHED;
1235 			pr_debug("switch node %d to state %s\n",
1236 				 node->nodeid, dlm_state_str(node->state));
1237 			break;
1238 		default:
1239 			/* some invalid state passive shutdown
1240 			 * was failed, we try to reset and
1241 			 * hope it will go on.
1242 			 */
1243 			log_print("reset node %d because shutdown stuck",
1244 				  node->nodeid);
1245 
1246 			midcomms_node_reset(node);
1247 			node->state = DLM_ESTABLISHED;
1248 			break;
1249 		}
1250 	}
1251 
1252 	node->users++;
1253 	pr_debug("node %d users inc count %d\n", nodeid, node->users);
1254 	spin_unlock_bh(&node->state_lock);
1255 
1256 	srcu_read_unlock(&nodes_srcu, idx);
1257 }
1258 
dlm_midcomms_remove_member(int nodeid)1259 void dlm_midcomms_remove_member(int nodeid)
1260 {
1261 	struct midcomms_node *node;
1262 	int idx;
1263 
1264 	idx = srcu_read_lock(&nodes_srcu);
1265 	node = nodeid2node(nodeid);
1266 	/* in case of dlm_midcomms_close() removes node */
1267 	if (!node) {
1268 		srcu_read_unlock(&nodes_srcu, idx);
1269 		return;
1270 	}
1271 
1272 	spin_lock_bh(&node->state_lock);
1273 	/* case of dlm_midcomms_addr() created node but
1274 	 * was not added before because dlm_midcomms_close()
1275 	 * removed the node
1276 	 */
1277 	if (!node->users) {
1278 		spin_unlock_bh(&node->state_lock);
1279 		srcu_read_unlock(&nodes_srcu, idx);
1280 		return;
1281 	}
1282 
1283 	node->users--;
1284 	pr_debug("node %d users dec count %d\n", nodeid, node->users);
1285 
1286 	/* hitting users count to zero means the
1287 	 * other side is running dlm_midcomms_stop()
1288 	 * we meet us to have a clean disconnect.
1289 	 */
1290 	if (node->users == 0) {
1291 		pr_debug("receive remove member from node %d with state %s\n",
1292 			 node->nodeid, dlm_state_str(node->state));
1293 		switch (node->state) {
1294 		case DLM_ESTABLISHED:
1295 			break;
1296 		case DLM_CLOSE_WAIT:
1297 			/* passive shutdown DLM_LAST_ACK case 2 */
1298 			node->state = DLM_LAST_ACK;
1299 			pr_debug("switch node %d to state %s case 2\n",
1300 				 node->nodeid, dlm_state_str(node->state));
1301 			set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
1302 			dlm_send_fin(node, dlm_pas_fin_ack_rcv);
1303 			break;
1304 		case DLM_LAST_ACK:
1305 			/* probably receive fin caught it, do nothing */
1306 			break;
1307 		case DLM_CLOSED:
1308 			/* already gone, do nothing */
1309 			break;
1310 		default:
1311 			log_print("%s: unexpected state: %d",
1312 				  __func__, node->state);
1313 			break;
1314 		}
1315 	}
1316 	spin_unlock_bh(&node->state_lock);
1317 
1318 	srcu_read_unlock(&nodes_srcu, idx);
1319 }
1320 
dlm_midcomms_version_wait(void)1321 void dlm_midcomms_version_wait(void)
1322 {
1323 	struct midcomms_node *node;
1324 	int i, idx, ret;
1325 
1326 	idx = srcu_read_lock(&nodes_srcu);
1327 	for (i = 0; i < CONN_HASH_SIZE; i++) {
1328 		hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
1329 			ret = wait_event_timeout(node->shutdown_wait,
1330 						 node->version != DLM_VERSION_NOT_SET ||
1331 						 node->state == DLM_CLOSED ||
1332 						 test_bit(DLM_NODE_FLAG_CLOSE, &node->flags),
1333 						 DLM_SHUTDOWN_TIMEOUT);
1334 			if (!ret || test_bit(DLM_NODE_FLAG_CLOSE, &node->flags))
1335 				pr_debug("version wait timed out for node %d with state %s\n",
1336 					 node->nodeid, dlm_state_str(node->state));
1337 		}
1338 	}
1339 	srcu_read_unlock(&nodes_srcu, idx);
1340 }
1341 
midcomms_shutdown(struct midcomms_node * node)1342 static void midcomms_shutdown(struct midcomms_node *node)
1343 {
1344 	int ret;
1345 
1346 	/* old protocol, we don't wait for pending operations */
1347 	switch (node->version) {
1348 	case DLM_VERSION_3_2:
1349 		break;
1350 	default:
1351 		return;
1352 	}
1353 
1354 	spin_lock_bh(&node->state_lock);
1355 	pr_debug("receive active shutdown for node %d with state %s\n",
1356 		 node->nodeid, dlm_state_str(node->state));
1357 	switch (node->state) {
1358 	case DLM_ESTABLISHED:
1359 		node->state = DLM_FIN_WAIT1;
1360 		pr_debug("switch node %d to state %s case 2\n",
1361 			 node->nodeid, dlm_state_str(node->state));
1362 		dlm_send_fin(node, dlm_act_fin_ack_rcv);
1363 		break;
1364 	case DLM_CLOSED:
1365 		/* we have what we want */
1366 		break;
1367 	default:
1368 		/* busy to enter DLM_FIN_WAIT1, wait until passive
1369 		 * done in shutdown_wait to enter DLM_CLOSED.
1370 		 */
1371 		break;
1372 	}
1373 	spin_unlock_bh(&node->state_lock);
1374 
1375 	if (DLM_DEBUG_FENCE_TERMINATION)
1376 		msleep(5000);
1377 
1378 	/* wait for other side dlm + fin */
1379 	ret = wait_event_timeout(node->shutdown_wait,
1380 				 node->state == DLM_CLOSED ||
1381 				 test_bit(DLM_NODE_FLAG_CLOSE, &node->flags),
1382 				 DLM_SHUTDOWN_TIMEOUT);
1383 	if (!ret)
1384 		pr_debug("active shutdown timed out for node %d with state %s\n",
1385 			 node->nodeid, dlm_state_str(node->state));
1386 	else
1387 		pr_debug("active shutdown done for node %d with state %s\n",
1388 			 node->nodeid, dlm_state_str(node->state));
1389 }
1390 
dlm_midcomms_shutdown(void)1391 void dlm_midcomms_shutdown(void)
1392 {
1393 	struct midcomms_node *node;
1394 	int i, idx;
1395 
1396 	mutex_lock(&close_lock);
1397 	idx = srcu_read_lock(&nodes_srcu);
1398 	for (i = 0; i < CONN_HASH_SIZE; i++) {
1399 		hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
1400 			midcomms_shutdown(node);
1401 		}
1402 	}
1403 
1404 	dlm_lowcomms_shutdown();
1405 
1406 	for (i = 0; i < CONN_HASH_SIZE; i++) {
1407 		hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
1408 			midcomms_node_reset(node);
1409 		}
1410 	}
1411 	srcu_read_unlock(&nodes_srcu, idx);
1412 	mutex_unlock(&close_lock);
1413 }
1414 
dlm_midcomms_close(int nodeid)1415 int dlm_midcomms_close(int nodeid)
1416 {
1417 	struct midcomms_node *node;
1418 	int idx, ret;
1419 
1420 	idx = srcu_read_lock(&nodes_srcu);
1421 	/* Abort pending close/remove operation */
1422 	node = nodeid2node(nodeid);
1423 	if (node) {
1424 		/* let shutdown waiters leave */
1425 		set_bit(DLM_NODE_FLAG_CLOSE, &node->flags);
1426 		wake_up(&node->shutdown_wait);
1427 	}
1428 	srcu_read_unlock(&nodes_srcu, idx);
1429 
1430 	synchronize_srcu(&nodes_srcu);
1431 
1432 	mutex_lock(&close_lock);
1433 	idx = srcu_read_lock(&nodes_srcu);
1434 	node = nodeid2node(nodeid);
1435 	if (!node) {
1436 		srcu_read_unlock(&nodes_srcu, idx);
1437 		mutex_unlock(&close_lock);
1438 		return dlm_lowcomms_close(nodeid);
1439 	}
1440 
1441 	ret = dlm_lowcomms_close(nodeid);
1442 	dlm_delete_debug_comms_file(node->debugfs);
1443 
1444 	spin_lock_bh(&nodes_lock);
1445 	hlist_del_rcu(&node->hlist);
1446 	spin_unlock_bh(&nodes_lock);
1447 	srcu_read_unlock(&nodes_srcu, idx);
1448 
1449 	/* wait that all readers left until flush send queue */
1450 	synchronize_srcu(&nodes_srcu);
1451 
1452 	/* drop all pending dlm messages, this is fine as
1453 	 * this function get called when the node is fenced
1454 	 */
1455 	dlm_send_queue_flush(node);
1456 
1457 	call_srcu(&nodes_srcu, &node->rcu, midcomms_node_release);
1458 	mutex_unlock(&close_lock);
1459 
1460 	return ret;
1461 }
1462 
1463 /* debug functionality to send raw dlm msg from user space */
1464 struct dlm_rawmsg_data {
1465 	struct midcomms_node *node;
1466 	void *buf;
1467 };
1468 
midcomms_new_rawmsg_cb(void * data)1469 static void midcomms_new_rawmsg_cb(void *data)
1470 {
1471 	struct dlm_rawmsg_data *rd = data;
1472 	struct dlm_header *h = rd->buf;
1473 
1474 	switch (h->h_version) {
1475 	case cpu_to_le32(DLM_VERSION_3_1):
1476 		break;
1477 	default:
1478 		switch (h->h_cmd) {
1479 		case DLM_OPTS:
1480 			if (!h->u.h_seq)
1481 				h->u.h_seq = cpu_to_le32(atomic_fetch_inc(&rd->node->seq_send));
1482 			break;
1483 		default:
1484 			break;
1485 		}
1486 		break;
1487 	}
1488 }
1489 
dlm_midcomms_rawmsg_send(struct midcomms_node * node,void * buf,int buflen)1490 int dlm_midcomms_rawmsg_send(struct midcomms_node *node, void *buf,
1491 			     int buflen)
1492 {
1493 	struct dlm_rawmsg_data rd;
1494 	struct dlm_msg *msg;
1495 	char *msgbuf;
1496 
1497 	rd.node = node;
1498 	rd.buf = buf;
1499 
1500 	msg = dlm_lowcomms_new_msg(node->nodeid, buflen, &msgbuf,
1501 				   midcomms_new_rawmsg_cb, &rd);
1502 	if (!msg)
1503 		return -ENOMEM;
1504 
1505 	memcpy(msgbuf, buf, buflen);
1506 	dlm_lowcomms_commit_msg(msg);
1507 	return 0;
1508 }
1509 
1510