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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Client connection-specific management code.
3 *
4 * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 *
7 * Client connections need to be cached for a little while after they've made a
8 * call so as to handle retransmitted DATA packets in case the server didn't
9 * receive the final ACK or terminating ABORT we sent it.
10 *
11 * Client connections can be in one of a number of cache states:
12 *
13 * (1) INACTIVE - The connection is not held in any list and may not have been
14 * exposed to the world. If it has been previously exposed, it was
15 * discarded from the idle list after expiring.
16 *
17 * (2) WAITING - The connection is waiting for the number of client conns to
18 * drop below the maximum capacity. Calls may be in progress upon it from
19 * when it was active and got culled.
20 *
21 * The connection is on the rxrpc_waiting_client_conns list which is kept
22 * in to-be-granted order. Culled conns with waiters go to the back of
23 * the queue just like new conns.
24 *
25 * (3) ACTIVE - The connection has at least one call in progress upon it, it
26 * may freely grant available channels to new calls and calls may be
27 * waiting on it for channels to become available.
28 *
29 * The connection is on the rxnet->active_client_conns list which is kept
30 * in activation order for culling purposes.
31 *
32 * rxrpc_nr_active_client_conns is held incremented also.
33 *
34 * (4) UPGRADE - As for ACTIVE, but only one call may be in progress and is
35 * being used to probe for service upgrade.
36 *
37 * (5) CULLED - The connection got summarily culled to try and free up
38 * capacity. Calls currently in progress on the connection are allowed to
39 * continue, but new calls will have to wait. There can be no waiters in
40 * this state - the conn would have to go to the WAITING state instead.
41 *
42 * (6) IDLE - The connection has no calls in progress upon it and must have
43 * been exposed to the world (ie. the EXPOSED flag must be set). When it
44 * expires, the EXPOSED flag is cleared and the connection transitions to
45 * the INACTIVE state.
46 *
47 * The connection is on the rxnet->idle_client_conns list which is kept in
48 * order of how soon they'll expire.
49 *
50 * There are flags of relevance to the cache:
51 *
52 * (1) EXPOSED - The connection ID got exposed to the world. If this flag is
53 * set, an extra ref is added to the connection preventing it from being
54 * reaped when it has no calls outstanding. This flag is cleared and the
55 * ref dropped when a conn is discarded from the idle list.
56 *
57 * This allows us to move terminal call state retransmission to the
58 * connection and to discard the call immediately we think it is done
59 * with. It also give us a chance to reuse the connection.
60 *
61 * (2) DONT_REUSE - The connection should be discarded as soon as possible and
62 * should not be reused. This is set when an exclusive connection is used
63 * or a call ID counter overflows.
64 *
65 * The caching state may only be changed if the cache lock is held.
66 *
67 * There are two idle client connection expiry durations. If the total number
68 * of connections is below the reap threshold, we use the normal duration; if
69 * it's above, we use the fast duration.
70 */
71
72#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
73
74#include <linux/slab.h>
75#include <linux/idr.h>
76#include <linux/timer.h>
77#include <linux/sched/signal.h>
78
79#include "ar-internal.h"
80
81__read_mostly unsigned int rxrpc_max_client_connections = 1000;
82__read_mostly unsigned int rxrpc_reap_client_connections = 900;
83__read_mostly unsigned long rxrpc_conn_idle_client_expiry = 2 * 60 * HZ;
84__read_mostly unsigned long rxrpc_conn_idle_client_fast_expiry = 2 * HZ;
85
86/*
87 * We use machine-unique IDs for our client connections.
88 */
89DEFINE_IDR(rxrpc_client_conn_ids);
90static DEFINE_SPINLOCK(rxrpc_conn_id_lock);
91
92static void rxrpc_cull_active_client_conns(struct rxrpc_net *);
93
94/*
95 * Get a connection ID and epoch for a client connection from the global pool.
96 * The connection struct pointer is then recorded in the idr radix tree. The
97 * epoch doesn't change until the client is rebooted (or, at least, unless the
98 * module is unloaded).
99 */
100static int rxrpc_get_client_connection_id(struct rxrpc_connection *conn,
101 gfp_t gfp)
102{
103 struct rxrpc_net *rxnet = conn->params.local->rxnet;
104 int id;
105
106 _enter("");
107
108 idr_preload(gfp);
109 spin_lock(&rxrpc_conn_id_lock);
110
111 id = idr_alloc_cyclic(&rxrpc_client_conn_ids, conn,
112 1, 0x40000000, GFP_NOWAIT);
113 if (id < 0)
114 goto error;
115
116 spin_unlock(&rxrpc_conn_id_lock);
117 idr_preload_end();
118
119 conn->proto.epoch = rxnet->epoch;
120 conn->proto.cid = id << RXRPC_CIDSHIFT;
121 set_bit(RXRPC_CONN_HAS_IDR, &conn->flags);
122 _leave(" [CID %x]", conn->proto.cid);
123 return 0;
124
125error:
126 spin_unlock(&rxrpc_conn_id_lock);
127 idr_preload_end();
128 _leave(" = %d", id);
129 return id;
130}
131
132/*
133 * Release a connection ID for a client connection from the global pool.
134 */
135static void rxrpc_put_client_connection_id(struct rxrpc_connection *conn)
136{
137 if (test_bit(RXRPC_CONN_HAS_IDR, &conn->flags)) {
138 spin_lock(&rxrpc_conn_id_lock);
139 idr_remove(&rxrpc_client_conn_ids,
140 conn->proto.cid >> RXRPC_CIDSHIFT);
141 spin_unlock(&rxrpc_conn_id_lock);
142 }
143}
144
145/*
146 * Destroy the client connection ID tree.
147 */
148void rxrpc_destroy_client_conn_ids(void)
149{
150 struct rxrpc_connection *conn;
151 int id;
152
153 if (!idr_is_empty(&rxrpc_client_conn_ids)) {
154 idr_for_each_entry(&rxrpc_client_conn_ids, conn, id) {
155 pr_err("AF_RXRPC: Leaked client conn %p {%d}\n",
156 conn, atomic_read(&conn->usage));
157 }
158 BUG();
159 }
160
161 idr_destroy(&rxrpc_client_conn_ids);
162}
163
164/*
165 * Allocate a client connection.
166 */
167static struct rxrpc_connection *
168rxrpc_alloc_client_connection(struct rxrpc_conn_parameters *cp, gfp_t gfp)
169{
170 struct rxrpc_connection *conn;
171 struct rxrpc_net *rxnet = cp->local->rxnet;
172 int ret;
173
174 _enter("");
175
176 conn = rxrpc_alloc_connection(gfp);
177 if (!conn) {
178 _leave(" = -ENOMEM");
179 return ERR_PTR(-ENOMEM);
180 }
181
182 atomic_set(&conn->usage, 1);
183 if (cp->exclusive)
184 __set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
185 if (cp->upgrade)
186 __set_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags);
187
188 conn->params = *cp;
189 conn->out_clientflag = RXRPC_CLIENT_INITIATED;
190 conn->state = RXRPC_CONN_CLIENT;
191 conn->service_id = cp->service_id;
192
193 ret = rxrpc_get_client_connection_id(conn, gfp);
194 if (ret < 0)
195 goto error_0;
196
197 ret = rxrpc_init_client_conn_security(conn);
198 if (ret < 0)
199 goto error_1;
200
201 ret = conn->security->prime_packet_security(conn);
202 if (ret < 0)
203 goto error_2;
204
205 atomic_inc(&rxnet->nr_conns);
206 write_lock(&rxnet->conn_lock);
207 list_add_tail(&conn->proc_link, &rxnet->conn_proc_list);
208 write_unlock(&rxnet->conn_lock);
209
210 /* We steal the caller's peer ref. */
211 cp->peer = NULL;
212 rxrpc_get_local(conn->params.local);
213 key_get(conn->params.key);
214
215 trace_rxrpc_conn(conn->debug_id, rxrpc_conn_new_client,
216 atomic_read(&conn->usage),
217 __builtin_return_address(0));
218 trace_rxrpc_client(conn, -1, rxrpc_client_alloc);
219 _leave(" = %p", conn);
220 return conn;
221
222error_2:
223 conn->security->clear(conn);
224error_1:
225 rxrpc_put_client_connection_id(conn);
226error_0:
227 kfree(conn);
228 _leave(" = %d", ret);
229 return ERR_PTR(ret);
230}
231
232/*
233 * Determine if a connection may be reused.
234 */
235static bool rxrpc_may_reuse_conn(struct rxrpc_connection *conn)
236{
237 struct rxrpc_net *rxnet = conn->params.local->rxnet;
238 int id_cursor, id, distance, limit;
239
240 if (test_bit(RXRPC_CONN_DONT_REUSE, &conn->flags))
241 goto dont_reuse;
242
243 if (conn->proto.epoch != rxnet->epoch)
244 goto mark_dont_reuse;
245
246 /* The IDR tree gets very expensive on memory if the connection IDs are
247 * widely scattered throughout the number space, so we shall want to
248 * kill off connections that, say, have an ID more than about four
249 * times the maximum number of client conns away from the current
250 * allocation point to try and keep the IDs concentrated.
251 */
252 id_cursor = idr_get_cursor(&rxrpc_client_conn_ids);
253 id = conn->proto.cid >> RXRPC_CIDSHIFT;
254 distance = id - id_cursor;
255 if (distance < 0)
256 distance = -distance;
257 limit = max(rxrpc_max_client_connections * 4, 1024U);
258 if (distance > limit)
259 goto mark_dont_reuse;
260
261 return true;
262
263mark_dont_reuse:
264 set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
265dont_reuse:
266 return false;
267}
268
269/*
270 * Create or find a client connection to use for a call.
271 *
272 * If we return with a connection, the call will be on its waiting list. It's
273 * left to the caller to assign a channel and wake up the call.
274 */
275static int rxrpc_get_client_conn(struct rxrpc_sock *rx,
276 struct rxrpc_call *call,
277 struct rxrpc_conn_parameters *cp,
278 struct sockaddr_rxrpc *srx,
279 gfp_t gfp)
280{
281 struct rxrpc_connection *conn, *candidate = NULL;
282 struct rxrpc_local *local = cp->local;
283 struct rb_node *p, **pp, *parent;
284 long diff;
285 int ret = -ENOMEM;
286
287 _enter("{%d,%lx},", call->debug_id, call->user_call_ID);
288
289 cp->peer = rxrpc_lookup_peer(rx, cp->local, srx, gfp);
290 if (!cp->peer)
291 goto error;
292
293 call->cong_cwnd = cp->peer->cong_cwnd;
294 if (call->cong_cwnd >= call->cong_ssthresh)
295 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
296 else
297 call->cong_mode = RXRPC_CALL_SLOW_START;
298
299 /* If the connection is not meant to be exclusive, search the available
300 * connections to see if the connection we want to use already exists.
301 */
302 if (!cp->exclusive) {
303 _debug("search 1");
304 spin_lock(&local->client_conns_lock);
305 p = local->client_conns.rb_node;
306 while (p) {
307 conn = rb_entry(p, struct rxrpc_connection, client_node);
308
309#define cmp(X) ((long)conn->params.X - (long)cp->X)
310 diff = (cmp(peer) ?:
311 cmp(key) ?:
312 cmp(security_level) ?:
313 cmp(upgrade));
314#undef cmp
315 if (diff < 0) {
316 p = p->rb_left;
317 } else if (diff > 0) {
318 p = p->rb_right;
319 } else {
320 if (rxrpc_may_reuse_conn(conn) &&
321 rxrpc_get_connection_maybe(conn))
322 goto found_extant_conn;
323 /* The connection needs replacing. It's better
324 * to effect that when we have something to
325 * replace it with so that we don't have to
326 * rebalance the tree twice.
327 */
328 break;
329 }
330 }
331 spin_unlock(&local->client_conns_lock);
332 }
333
334 /* There wasn't a connection yet or we need an exclusive connection.
335 * We need to create a candidate and then potentially redo the search
336 * in case we're racing with another thread also trying to connect on a
337 * shareable connection.
338 */
339 _debug("new conn");
340 candidate = rxrpc_alloc_client_connection(cp, gfp);
341 if (IS_ERR(candidate)) {
342 ret = PTR_ERR(candidate);
343 goto error_peer;
344 }
345
346 /* Add the call to the new connection's waiting list in case we're
347 * going to have to wait for the connection to come live. It's our
348 * connection, so we want first dibs on the channel slots. We would
349 * normally have to take channel_lock but we do this before anyone else
350 * can see the connection.
351 */
352 list_add(&call->chan_wait_link, &candidate->waiting_calls);
353
354 if (cp->exclusive) {
355 call->conn = candidate;
356 call->security = candidate->security;
357 call->security_ix = candidate->security_ix;
358 call->service_id = candidate->service_id;
359 _leave(" = 0 [exclusive %d]", candidate->debug_id);
360 return 0;
361 }
362
363 /* Publish the new connection for userspace to find. We need to redo
364 * the search before doing this lest we race with someone else adding a
365 * conflicting instance.
366 */
367 _debug("search 2");
368 spin_lock(&local->client_conns_lock);
369
370 pp = &local->client_conns.rb_node;
371 parent = NULL;
372 while (*pp) {
373 parent = *pp;
374 conn = rb_entry(parent, struct rxrpc_connection, client_node);
375
376#define cmp(X) ((long)conn->params.X - (long)candidate->params.X)
377 diff = (cmp(peer) ?:
378 cmp(key) ?:
379 cmp(security_level) ?:
380 cmp(upgrade));
381#undef cmp
382 if (diff < 0) {
383 pp = &(*pp)->rb_left;
384 } else if (diff > 0) {
385 pp = &(*pp)->rb_right;
386 } else {
387 if (rxrpc_may_reuse_conn(conn) &&
388 rxrpc_get_connection_maybe(conn))
389 goto found_extant_conn;
390 /* The old connection is from an outdated epoch. */
391 _debug("replace conn");
392 clear_bit(RXRPC_CONN_IN_CLIENT_CONNS, &conn->flags);
393 rb_replace_node(&conn->client_node,
394 &candidate->client_node,
395 &local->client_conns);
396 trace_rxrpc_client(conn, -1, rxrpc_client_replace);
397 goto candidate_published;
398 }
399 }
400
401 _debug("new conn");
402 rb_link_node(&candidate->client_node, parent, pp);
403 rb_insert_color(&candidate->client_node, &local->client_conns);
404
405candidate_published:
406 set_bit(RXRPC_CONN_IN_CLIENT_CONNS, &candidate->flags);
407 call->conn = candidate;
408 call->security = candidate->security;
409 call->security_ix = candidate->security_ix;
410 call->service_id = candidate->service_id;
411 spin_unlock(&local->client_conns_lock);
412 _leave(" = 0 [new %d]", candidate->debug_id);
413 return 0;
414
415 /* We come here if we found a suitable connection already in existence.
416 * Discard any candidate we may have allocated, and try to get a
417 * channel on this one.
418 */
419found_extant_conn:
420 _debug("found conn");
421 spin_unlock(&local->client_conns_lock);
422
423 if (candidate) {
424 trace_rxrpc_client(candidate, -1, rxrpc_client_duplicate);
425 rxrpc_put_connection(candidate);
426 candidate = NULL;
427 }
428
429 spin_lock(&conn->channel_lock);
430 call->conn = conn;
431 call->security = conn->security;
432 call->security_ix = conn->security_ix;
433 call->service_id = conn->service_id;
434 list_add_tail(&call->chan_wait_link, &conn->waiting_calls);
435 spin_unlock(&conn->channel_lock);
436 _leave(" = 0 [extant %d]", conn->debug_id);
437 return 0;
438
439error_peer:
440 rxrpc_put_peer(cp->peer);
441 cp->peer = NULL;
442error:
443 _leave(" = %d", ret);
444 return ret;
445}
446
447/*
448 * Activate a connection.
449 */
450static void rxrpc_activate_conn(struct rxrpc_net *rxnet,
451 struct rxrpc_connection *conn)
452{
453 if (test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags)) {
454 trace_rxrpc_client(conn, -1, rxrpc_client_to_upgrade);
455 conn->cache_state = RXRPC_CONN_CLIENT_UPGRADE;
456 } else {
457 trace_rxrpc_client(conn, -1, rxrpc_client_to_active);
458 conn->cache_state = RXRPC_CONN_CLIENT_ACTIVE;
459 }
460 rxnet->nr_active_client_conns++;
461 list_move_tail(&conn->cache_link, &rxnet->active_client_conns);
462}
463
464/*
465 * Attempt to animate a connection for a new call.
466 *
467 * If it's not exclusive, the connection is in the endpoint tree, and we're in
468 * the conn's list of those waiting to grab a channel. There is, however, a
469 * limit on the number of live connections allowed at any one time, so we may
470 * have to wait for capacity to become available.
471 *
472 * Note that a connection on the waiting queue might *also* have active
473 * channels if it has been culled to make space and then re-requested by a new
474 * call.
475 */
476static void rxrpc_animate_client_conn(struct rxrpc_net *rxnet,
477 struct rxrpc_connection *conn)
478{
479 unsigned int nr_conns;
480
481 _enter("%d,%d", conn->debug_id, conn->cache_state);
482
483 if (conn->cache_state == RXRPC_CONN_CLIENT_ACTIVE ||
484 conn->cache_state == RXRPC_CONN_CLIENT_UPGRADE)
485 goto out;
486
487 spin_lock(&rxnet->client_conn_cache_lock);
488
489 nr_conns = rxnet->nr_client_conns;
490 if (!test_and_set_bit(RXRPC_CONN_COUNTED, &conn->flags)) {
491 trace_rxrpc_client(conn, -1, rxrpc_client_count);
492 rxnet->nr_client_conns = nr_conns + 1;
493 }
494
495 switch (conn->cache_state) {
496 case RXRPC_CONN_CLIENT_ACTIVE:
497 case RXRPC_CONN_CLIENT_UPGRADE:
498 case RXRPC_CONN_CLIENT_WAITING:
499 break;
500
501 case RXRPC_CONN_CLIENT_INACTIVE:
502 case RXRPC_CONN_CLIENT_CULLED:
503 case RXRPC_CONN_CLIENT_IDLE:
504 if (nr_conns >= rxrpc_max_client_connections)
505 goto wait_for_capacity;
506 goto activate_conn;
507
508 default:
509 BUG();
510 }
511
512out_unlock:
513 spin_unlock(&rxnet->client_conn_cache_lock);
514out:
515 _leave(" [%d]", conn->cache_state);
516 return;
517
518activate_conn:
519 _debug("activate");
520 rxrpc_activate_conn(rxnet, conn);
521 goto out_unlock;
522
523wait_for_capacity:
524 _debug("wait");
525 trace_rxrpc_client(conn, -1, rxrpc_client_to_waiting);
526 conn->cache_state = RXRPC_CONN_CLIENT_WAITING;
527 list_move_tail(&conn->cache_link, &rxnet->waiting_client_conns);
528 goto out_unlock;
529}
530
531/*
532 * Deactivate a channel.
533 */
534static void rxrpc_deactivate_one_channel(struct rxrpc_connection *conn,
535 unsigned int channel)
536{
537 struct rxrpc_channel *chan = &conn->channels[channel];
538
539 rcu_assign_pointer(chan->call, NULL);
540 conn->active_chans &= ~(1 << channel);
541}
542
543/*
544 * Assign a channel to the call at the front of the queue and wake the call up.
545 * We don't increment the callNumber counter until this number has been exposed
546 * to the world.
547 */
548static void rxrpc_activate_one_channel(struct rxrpc_connection *conn,
549 unsigned int channel)
550{
551 struct rxrpc_channel *chan = &conn->channels[channel];
552 struct rxrpc_call *call = list_entry(conn->waiting_calls.next,
553 struct rxrpc_call, chan_wait_link);
554 u32 call_id = chan->call_counter + 1;
555
556 trace_rxrpc_client(conn, channel, rxrpc_client_chan_activate);
557
558 /* Cancel the final ACK on the previous call if it hasn't been sent yet
559 * as the DATA packet will implicitly ACK it.
560 */
561 clear_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
562
563 write_lock_bh(&call->state_lock);
564 call->state = RXRPC_CALL_CLIENT_SEND_REQUEST;
565 write_unlock_bh(&call->state_lock);
566
567 rxrpc_see_call(call);
568 list_del_init(&call->chan_wait_link);
569 conn->active_chans |= 1 << channel;
570 call->peer = rxrpc_get_peer(conn->params.peer);
571 call->cid = conn->proto.cid | channel;
572 call->call_id = call_id;
573
574 trace_rxrpc_connect_call(call);
575 _net("CONNECT call %08x:%08x as call %d on conn %d",
576 call->cid, call->call_id, call->debug_id, conn->debug_id);
577
578 /* Paired with the read barrier in rxrpc_wait_for_channel(). This
579 * orders cid and epoch in the connection wrt to call_id without the
580 * need to take the channel_lock.
581 *
582 * We provisionally assign a callNumber at this point, but we don't
583 * confirm it until the call is about to be exposed.
584 *
585 * TODO: Pair with a barrier in the data_ready handler when that looks
586 * at the call ID through a connection channel.
587 */
588 smp_wmb();
589 chan->call_id = call_id;
590 chan->call_debug_id = call->debug_id;
591 rcu_assign_pointer(chan->call, call);
592 wake_up(&call->waitq);
593}
594
595/*
596 * Assign channels and callNumbers to waiting calls with channel_lock
597 * held by caller.
598 */
599static void rxrpc_activate_channels_locked(struct rxrpc_connection *conn)
600{
601 u8 avail, mask;
602
603 switch (conn->cache_state) {
604 case RXRPC_CONN_CLIENT_ACTIVE:
605 mask = RXRPC_ACTIVE_CHANS_MASK;
606 break;
607 case RXRPC_CONN_CLIENT_UPGRADE:
608 mask = 0x01;
609 break;
610 default:
611 return;
612 }
613
614 while (!list_empty(&conn->waiting_calls) &&
615 (avail = ~conn->active_chans,
616 avail &= mask,
617 avail != 0))
618 rxrpc_activate_one_channel(conn, __ffs(avail));
619}
620
621/*
622 * Assign channels and callNumbers to waiting calls.
623 */
624static void rxrpc_activate_channels(struct rxrpc_connection *conn)
625{
626 _enter("%d", conn->debug_id);
627
628 trace_rxrpc_client(conn, -1, rxrpc_client_activate_chans);
629
630 if (conn->active_chans == RXRPC_ACTIVE_CHANS_MASK)
631 return;
632
633 spin_lock(&conn->channel_lock);
634 rxrpc_activate_channels_locked(conn);
635 spin_unlock(&conn->channel_lock);
636 _leave("");
637}
638
639/*
640 * Wait for a callNumber and a channel to be granted to a call.
641 */
642static int rxrpc_wait_for_channel(struct rxrpc_call *call, gfp_t gfp)
643{
644 int ret = 0;
645
646 _enter("%d", call->debug_id);
647
648 if (!call->call_id) {
649 DECLARE_WAITQUEUE(myself, current);
650
651 if (!gfpflags_allow_blocking(gfp)) {
652 ret = -EAGAIN;
653 goto out;
654 }
655
656 add_wait_queue_exclusive(&call->waitq, &myself);
657 for (;;) {
658 switch (call->interruptibility) {
659 case RXRPC_INTERRUPTIBLE:
660 case RXRPC_PREINTERRUPTIBLE:
661 set_current_state(TASK_INTERRUPTIBLE);
662 break;
663 case RXRPC_UNINTERRUPTIBLE:
664 default:
665 set_current_state(TASK_UNINTERRUPTIBLE);
666 break;
667 }
668 if (call->call_id)
669 break;
670 if ((call->interruptibility == RXRPC_INTERRUPTIBLE ||
671 call->interruptibility == RXRPC_PREINTERRUPTIBLE) &&
672 signal_pending(current)) {
673 ret = -ERESTARTSYS;
674 break;
675 }
676 schedule();
677 }
678 remove_wait_queue(&call->waitq, &myself);
679 __set_current_state(TASK_RUNNING);
680 }
681
682 /* Paired with the write barrier in rxrpc_activate_one_channel(). */
683 smp_rmb();
684
685out:
686 _leave(" = %d", ret);
687 return ret;
688}
689
690/*
691 * find a connection for a call
692 * - called in process context with IRQs enabled
693 */
694int rxrpc_connect_call(struct rxrpc_sock *rx,
695 struct rxrpc_call *call,
696 struct rxrpc_conn_parameters *cp,
697 struct sockaddr_rxrpc *srx,
698 gfp_t gfp)
699{
700 struct rxrpc_net *rxnet = cp->local->rxnet;
701 int ret;
702
703 _enter("{%d,%lx},", call->debug_id, call->user_call_ID);
704
705 rxrpc_discard_expired_client_conns(&rxnet->client_conn_reaper);
706 rxrpc_cull_active_client_conns(rxnet);
707
708 ret = rxrpc_get_client_conn(rx, call, cp, srx, gfp);
709 if (ret < 0)
710 goto out;
711
712 rxrpc_animate_client_conn(rxnet, call->conn);
713 rxrpc_activate_channels(call->conn);
714
715 ret = rxrpc_wait_for_channel(call, gfp);
716 if (ret < 0) {
717 trace_rxrpc_client(call->conn, ret, rxrpc_client_chan_wait_failed);
718 rxrpc_disconnect_client_call(call);
719 goto out;
720 }
721
722 spin_lock_bh(&call->conn->params.peer->lock);
723 hlist_add_head_rcu(&call->error_link,
724 &call->conn->params.peer->error_targets);
725 spin_unlock_bh(&call->conn->params.peer->lock);
726
727out:
728 _leave(" = %d", ret);
729 return ret;
730}
731
732/*
733 * Note that a connection is about to be exposed to the world. Once it is
734 * exposed, we maintain an extra ref on it that stops it from being summarily
735 * discarded before it's (a) had a chance to deal with retransmission and (b)
736 * had a chance at re-use (the per-connection security negotiation is
737 * expensive).
738 */
739static void rxrpc_expose_client_conn(struct rxrpc_connection *conn,
740 unsigned int channel)
741{
742 if (!test_and_set_bit(RXRPC_CONN_EXPOSED, &conn->flags)) {
743 trace_rxrpc_client(conn, channel, rxrpc_client_exposed);
744 rxrpc_get_connection(conn);
745 }
746}
747
748/*
749 * Note that a call, and thus a connection, is about to be exposed to the
750 * world.
751 */
752void rxrpc_expose_client_call(struct rxrpc_call *call)
753{
754 unsigned int channel = call->cid & RXRPC_CHANNELMASK;
755 struct rxrpc_connection *conn = call->conn;
756 struct rxrpc_channel *chan = &conn->channels[channel];
757
758 if (!test_and_set_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
759 /* Mark the call ID as being used. If the callNumber counter
760 * exceeds ~2 billion, we kill the connection after its
761 * outstanding calls have finished so that the counter doesn't
762 * wrap.
763 */
764 chan->call_counter++;
765 if (chan->call_counter >= INT_MAX)
766 set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
767 rxrpc_expose_client_conn(conn, channel);
768 }
769}
770
771/*
772 * Set the reap timer.
773 */
774static void rxrpc_set_client_reap_timer(struct rxrpc_net *rxnet)
775{
776 unsigned long now = jiffies;
777 unsigned long reap_at = now + rxrpc_conn_idle_client_expiry;
778
779 if (rxnet->live)
780 timer_reduce(&rxnet->client_conn_reap_timer, reap_at);
781}
782
783/*
784 * Disconnect a client call.
785 */
786void rxrpc_disconnect_client_call(struct rxrpc_call *call)
787{
788 struct rxrpc_connection *conn = call->conn;
789 struct rxrpc_channel *chan = NULL;
790 struct rxrpc_net *rxnet = conn->params.local->rxnet;
791 unsigned int channel = -1;
792 u32 cid;
793
794 spin_lock(&conn->channel_lock);
795 set_bit(RXRPC_CALL_DISCONNECTED, &call->flags);
796
797 cid = call->cid;
798 if (cid) {
799 channel = cid & RXRPC_CHANNELMASK;
800 chan = &conn->channels[channel];
801 }
802 trace_rxrpc_client(conn, channel, rxrpc_client_chan_disconnect);
803
804 /* Calls that have never actually been assigned a channel can simply be
805 * discarded. If the conn didn't get used either, it will follow
806 * immediately unless someone else grabs it in the meantime.
807 */
808 if (!list_empty(&call->chan_wait_link)) {
809 _debug("call is waiting");
810 ASSERTCMP(call->call_id, ==, 0);
811 ASSERT(!test_bit(RXRPC_CALL_EXPOSED, &call->flags));
812 list_del_init(&call->chan_wait_link);
813
814 trace_rxrpc_client(conn, channel, rxrpc_client_chan_unstarted);
815
816 /* We must deactivate or idle the connection if it's now
817 * waiting for nothing.
818 */
819 spin_lock(&rxnet->client_conn_cache_lock);
820 if (conn->cache_state == RXRPC_CONN_CLIENT_WAITING &&
821 list_empty(&conn->waiting_calls) &&
822 !conn->active_chans)
823 goto idle_connection;
824 goto out;
825 }
826
827 if (rcu_access_pointer(chan->call) != call) {
828 spin_unlock(&conn->channel_lock);
829 BUG();
830 }
831
832 /* If a client call was exposed to the world, we save the result for
833 * retransmission.
834 *
835 * We use a barrier here so that the call number and abort code can be
836 * read without needing to take a lock.
837 *
838 * TODO: Make the incoming packet handler check this and handle
839 * terminal retransmission without requiring access to the call.
840 */
841 if (test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
842 _debug("exposed %u,%u", call->call_id, call->abort_code);
843 __rxrpc_disconnect_call(conn, call);
844 }
845
846 /* See if we can pass the channel directly to another call. */
847 if (conn->cache_state == RXRPC_CONN_CLIENT_ACTIVE &&
848 !list_empty(&conn->waiting_calls)) {
849 trace_rxrpc_client(conn, channel, rxrpc_client_chan_pass);
850 rxrpc_activate_one_channel(conn, channel);
851 goto out_2;
852 }
853
854 /* Schedule the final ACK to be transmitted in a short while so that it
855 * can be skipped if we find a follow-on call. The first DATA packet
856 * of the follow on call will implicitly ACK this call.
857 */
858 if (call->completion == RXRPC_CALL_SUCCEEDED &&
859 test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
860 unsigned long final_ack_at = jiffies + 2;
861
862 WRITE_ONCE(chan->final_ack_at, final_ack_at);
863 smp_wmb(); /* vs rxrpc_process_delayed_final_acks() */
864 set_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
865 rxrpc_reduce_conn_timer(conn, final_ack_at);
866 }
867
868 /* Things are more complex and we need the cache lock. We might be
869 * able to simply idle the conn or it might now be lurking on the wait
870 * list. It might even get moved back to the active list whilst we're
871 * waiting for the lock.
872 */
873 spin_lock(&rxnet->client_conn_cache_lock);
874
875 switch (conn->cache_state) {
876 case RXRPC_CONN_CLIENT_UPGRADE:
877 /* Deal with termination of a service upgrade probe. */
878 if (test_bit(RXRPC_CONN_EXPOSED, &conn->flags)) {
879 clear_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags);
880 trace_rxrpc_client(conn, channel, rxrpc_client_to_active);
881 conn->cache_state = RXRPC_CONN_CLIENT_ACTIVE;
882 rxrpc_activate_channels_locked(conn);
883 }
884 fallthrough;
885 case RXRPC_CONN_CLIENT_ACTIVE:
886 if (list_empty(&conn->waiting_calls)) {
887 rxrpc_deactivate_one_channel(conn, channel);
888 if (!conn->active_chans) {
889 rxnet->nr_active_client_conns--;
890 goto idle_connection;
891 }
892 goto out;
893 }
894
895 trace_rxrpc_client(conn, channel, rxrpc_client_chan_pass);
896 rxrpc_activate_one_channel(conn, channel);
897 goto out;
898
899 case RXRPC_CONN_CLIENT_CULLED:
900 rxrpc_deactivate_one_channel(conn, channel);
901 ASSERT(list_empty(&conn->waiting_calls));
902 if (!conn->active_chans)
903 goto idle_connection;
904 goto out;
905
906 case RXRPC_CONN_CLIENT_WAITING:
907 rxrpc_deactivate_one_channel(conn, channel);
908 goto out;
909
910 default:
911 BUG();
912 }
913
914out:
915 spin_unlock(&rxnet->client_conn_cache_lock);
916out_2:
917 spin_unlock(&conn->channel_lock);
918 _leave("");
919 return;
920
921idle_connection:
922 /* As no channels remain active, the connection gets deactivated
923 * immediately or moved to the idle list for a short while.
924 */
925 if (test_bit(RXRPC_CONN_EXPOSED, &conn->flags)) {
926 trace_rxrpc_client(conn, channel, rxrpc_client_to_idle);
927 conn->idle_timestamp = jiffies;
928 conn->cache_state = RXRPC_CONN_CLIENT_IDLE;
929 list_move_tail(&conn->cache_link, &rxnet->idle_client_conns);
930 if (rxnet->idle_client_conns.next == &conn->cache_link &&
931 !rxnet->kill_all_client_conns)
932 rxrpc_set_client_reap_timer(rxnet);
933 } else {
934 trace_rxrpc_client(conn, channel, rxrpc_client_to_inactive);
935 conn->cache_state = RXRPC_CONN_CLIENT_INACTIVE;
936 list_del_init(&conn->cache_link);
937 }
938 goto out;
939}
940
941/*
942 * Clean up a dead client connection.
943 */
944static struct rxrpc_connection *
945rxrpc_put_one_client_conn(struct rxrpc_connection *conn)
946{
947 struct rxrpc_connection *next = NULL;
948 struct rxrpc_local *local = conn->params.local;
949 struct rxrpc_net *rxnet = local->rxnet;
950 unsigned int nr_conns;
951
952 trace_rxrpc_client(conn, -1, rxrpc_client_cleanup);
953
954 if (test_bit(RXRPC_CONN_IN_CLIENT_CONNS, &conn->flags)) {
955 spin_lock(&local->client_conns_lock);
956 if (test_and_clear_bit(RXRPC_CONN_IN_CLIENT_CONNS,
957 &conn->flags))
958 rb_erase(&conn->client_node, &local->client_conns);
959 spin_unlock(&local->client_conns_lock);
960 }
961
962 rxrpc_put_client_connection_id(conn);
963
964 ASSERTCMP(conn->cache_state, ==, RXRPC_CONN_CLIENT_INACTIVE);
965
966 if (test_bit(RXRPC_CONN_COUNTED, &conn->flags)) {
967 trace_rxrpc_client(conn, -1, rxrpc_client_uncount);
968 spin_lock(&rxnet->client_conn_cache_lock);
969 nr_conns = --rxnet->nr_client_conns;
970
971 if (nr_conns < rxrpc_max_client_connections &&
972 !list_empty(&rxnet->waiting_client_conns)) {
973 next = list_entry(rxnet->waiting_client_conns.next,
974 struct rxrpc_connection, cache_link);
975 rxrpc_get_connection(next);
976 rxrpc_activate_conn(rxnet, next);
977 }
978
979 spin_unlock(&rxnet->client_conn_cache_lock);
980 }
981
982 rxrpc_kill_connection(conn);
983 if (next)
984 rxrpc_activate_channels(next);
985
986 /* We need to get rid of the temporary ref we took upon next, but we
987 * can't call rxrpc_put_connection() recursively.
988 */
989 return next;
990}
991
992/*
993 * Clean up a dead client connections.
994 */
995void rxrpc_put_client_conn(struct rxrpc_connection *conn)
996{
997 const void *here = __builtin_return_address(0);
998 unsigned int debug_id = conn->debug_id;
999 int n;
1000
1001 do {
1002 n = atomic_dec_return(&conn->usage);
1003 trace_rxrpc_conn(debug_id, rxrpc_conn_put_client, n, here);
1004 if (n > 0)
1005 return;
1006 ASSERTCMP(n, >=, 0);
1007
1008 conn = rxrpc_put_one_client_conn(conn);
1009 } while (conn);
1010}
1011
1012/*
1013 * Kill the longest-active client connections to make room for new ones.
1014 */
1015static void rxrpc_cull_active_client_conns(struct rxrpc_net *rxnet)
1016{
1017 struct rxrpc_connection *conn;
1018 unsigned int nr_conns = rxnet->nr_client_conns;
1019 unsigned int nr_active, limit;
1020
1021 _enter("");
1022
1023 ASSERTCMP(nr_conns, >=, 0);
1024 if (nr_conns < rxrpc_max_client_connections) {
1025 _leave(" [ok]");
1026 return;
1027 }
1028 limit = rxrpc_reap_client_connections;
1029
1030 spin_lock(&rxnet->client_conn_cache_lock);
1031 nr_active = rxnet->nr_active_client_conns;
1032
1033 while (nr_active > limit) {
1034 ASSERT(!list_empty(&rxnet->active_client_conns));
1035 conn = list_entry(rxnet->active_client_conns.next,
1036 struct rxrpc_connection, cache_link);
1037 ASSERTIFCMP(conn->cache_state != RXRPC_CONN_CLIENT_ACTIVE,
1038 conn->cache_state, ==, RXRPC_CONN_CLIENT_UPGRADE);
1039
1040 if (list_empty(&conn->waiting_calls)) {
1041 trace_rxrpc_client(conn, -1, rxrpc_client_to_culled);
1042 conn->cache_state = RXRPC_CONN_CLIENT_CULLED;
1043 list_del_init(&conn->cache_link);
1044 } else {
1045 trace_rxrpc_client(conn, -1, rxrpc_client_to_waiting);
1046 conn->cache_state = RXRPC_CONN_CLIENT_WAITING;
1047 list_move_tail(&conn->cache_link,
1048 &rxnet->waiting_client_conns);
1049 }
1050
1051 nr_active--;
1052 }
1053
1054 rxnet->nr_active_client_conns = nr_active;
1055 spin_unlock(&rxnet->client_conn_cache_lock);
1056 ASSERTCMP(nr_active, >=, 0);
1057 _leave(" [culled]");
1058}
1059
1060/*
1061 * Discard expired client connections from the idle list. Each conn in the
1062 * idle list has been exposed and holds an extra ref because of that.
1063 *
1064 * This may be called from conn setup or from a work item so cannot be
1065 * considered non-reentrant.
1066 */
1067void rxrpc_discard_expired_client_conns(struct work_struct *work)
1068{
1069 struct rxrpc_connection *conn;
1070 struct rxrpc_net *rxnet =
1071 container_of(work, struct rxrpc_net, client_conn_reaper);
1072 unsigned long expiry, conn_expires_at, now;
1073 unsigned int nr_conns;
1074
1075 _enter("");
1076
1077 if (list_empty(&rxnet->idle_client_conns)) {
1078 _leave(" [empty]");
1079 return;
1080 }
1081
1082 /* Don't double up on the discarding */
1083 if (!spin_trylock(&rxnet->client_conn_discard_lock)) {
1084 _leave(" [already]");
1085 return;
1086 }
1087
1088 /* We keep an estimate of what the number of conns ought to be after
1089 * we've discarded some so that we don't overdo the discarding.
1090 */
1091 nr_conns = rxnet->nr_client_conns;
1092
1093next:
1094 spin_lock(&rxnet->client_conn_cache_lock);
1095
1096 if (list_empty(&rxnet->idle_client_conns))
1097 goto out;
1098
1099 conn = list_entry(rxnet->idle_client_conns.next,
1100 struct rxrpc_connection, cache_link);
1101 ASSERT(test_bit(RXRPC_CONN_EXPOSED, &conn->flags));
1102
1103 if (!rxnet->kill_all_client_conns) {
1104 /* If the number of connections is over the reap limit, we
1105 * expedite discard by reducing the expiry timeout. We must,
1106 * however, have at least a short grace period to be able to do
1107 * final-ACK or ABORT retransmission.
1108 */
1109 expiry = rxrpc_conn_idle_client_expiry;
1110 if (nr_conns > rxrpc_reap_client_connections)
1111 expiry = rxrpc_conn_idle_client_fast_expiry;
1112 if (conn->params.local->service_closed)
1113 expiry = rxrpc_closed_conn_expiry * HZ;
1114
1115 conn_expires_at = conn->idle_timestamp + expiry;
1116
1117 now = READ_ONCE(jiffies);
1118 if (time_after(conn_expires_at, now))
1119 goto not_yet_expired;
1120 }
1121
1122 trace_rxrpc_client(conn, -1, rxrpc_client_discard);
1123 if (!test_and_clear_bit(RXRPC_CONN_EXPOSED, &conn->flags))
1124 BUG();
1125 conn->cache_state = RXRPC_CONN_CLIENT_INACTIVE;
1126 list_del_init(&conn->cache_link);
1127
1128 spin_unlock(&rxnet->client_conn_cache_lock);
1129
1130 /* When we cleared the EXPOSED flag, we took on responsibility for the
1131 * reference that that had on the usage count. We deal with that here.
1132 * If someone re-sets the flag and re-gets the ref, that's fine.
1133 */
1134 rxrpc_put_connection(conn);
1135 nr_conns--;
1136 goto next;
1137
1138not_yet_expired:
1139 /* The connection at the front of the queue hasn't yet expired, so
1140 * schedule the work item for that point if we discarded something.
1141 *
1142 * We don't worry if the work item is already scheduled - it can look
1143 * after rescheduling itself at a later time. We could cancel it, but
1144 * then things get messier.
1145 */
1146 _debug("not yet");
1147 if (!rxnet->kill_all_client_conns)
1148 timer_reduce(&rxnet->client_conn_reap_timer,
1149 conn_expires_at);
1150
1151out:
1152 spin_unlock(&rxnet->client_conn_cache_lock);
1153 spin_unlock(&rxnet->client_conn_discard_lock);
1154 _leave("");
1155}
1156
1157/*
1158 * Preemptively destroy all the client connection records rather than waiting
1159 * for them to time out
1160 */
1161void rxrpc_destroy_all_client_connections(struct rxrpc_net *rxnet)
1162{
1163 _enter("");
1164
1165 spin_lock(&rxnet->client_conn_cache_lock);
1166 rxnet->kill_all_client_conns = true;
1167 spin_unlock(&rxnet->client_conn_cache_lock);
1168
1169 del_timer_sync(&rxnet->client_conn_reap_timer);
1170
1171 if (!rxrpc_queue_work(&rxnet->client_conn_reaper))
1172 _debug("destroy: queue failed");
1173
1174 _leave("");
1175}
1176
1177/*
1178 * Clean up the client connections on a local endpoint.
1179 */
1180void rxrpc_clean_up_local_conns(struct rxrpc_local *local)
1181{
1182 struct rxrpc_connection *conn, *tmp;
1183 struct rxrpc_net *rxnet = local->rxnet;
1184 unsigned int nr_active;
1185 LIST_HEAD(graveyard);
1186
1187 _enter("");
1188
1189 spin_lock(&rxnet->client_conn_cache_lock);
1190 nr_active = rxnet->nr_active_client_conns;
1191
1192 list_for_each_entry_safe(conn, tmp, &rxnet->idle_client_conns,
1193 cache_link) {
1194 if (conn->params.local == local) {
1195 ASSERTCMP(conn->cache_state, ==, RXRPC_CONN_CLIENT_IDLE);
1196
1197 trace_rxrpc_client(conn, -1, rxrpc_client_discard);
1198 if (!test_and_clear_bit(RXRPC_CONN_EXPOSED, &conn->flags))
1199 BUG();
1200 conn->cache_state = RXRPC_CONN_CLIENT_INACTIVE;
1201 list_move(&conn->cache_link, &graveyard);
1202 nr_active--;
1203 }
1204 }
1205
1206 rxnet->nr_active_client_conns = nr_active;
1207 spin_unlock(&rxnet->client_conn_cache_lock);
1208 ASSERTCMP(nr_active, >=, 0);
1209
1210 while (!list_empty(&graveyard)) {
1211 conn = list_entry(graveyard.next,
1212 struct rxrpc_connection, cache_link);
1213 list_del_init(&conn->cache_link);
1214
1215 rxrpc_put_connection(conn);
1216 }
1217
1218 _leave(" [culled]");
1219}