aboutsummaryrefslogtreecommitdiffstats
path: root/fs/afs/rxrpc.c
blob: e45a323aebb4468711de395fd06e5f0f9d2833d0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
/* Maintain an RxRPC server socket to do AFS communications through
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/slab.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <rxrpc/packet.h>
#include "internal.h"
#include "afs_cm.h"

static struct socket *afs_socket; /* my RxRPC socket */
static struct workqueue_struct *afs_async_calls;
static atomic_t afs_outstanding_calls;
static atomic_t afs_outstanding_skbs;

static void afs_wake_up_call_waiter(struct afs_call *);
static int afs_wait_for_call_to_complete(struct afs_call *);
static void afs_wake_up_async_call(struct afs_call *);
static int afs_dont_wait_for_call_to_complete(struct afs_call *);
static void afs_process_async_call(struct work_struct *);
static void afs_rx_interceptor(struct sock *, unsigned long, struct sk_buff *);
static int afs_deliver_cm_op_id(struct afs_call *, struct sk_buff *, bool);

/* synchronous call management */
const struct afs_wait_mode afs_sync_call = {
	.rx_wakeup	= afs_wake_up_call_waiter,
	.wait		= afs_wait_for_call_to_complete,
};

/* asynchronous call management */
const struct afs_wait_mode afs_async_call = {
	.rx_wakeup	= afs_wake_up_async_call,
	.wait		= afs_dont_wait_for_call_to_complete,
};

/* asynchronous incoming call management */
static const struct afs_wait_mode afs_async_incoming_call = {
	.rx_wakeup	= afs_wake_up_async_call,
};

/* asynchronous incoming call initial processing */
static const struct afs_call_type afs_RXCMxxxx = {
	.name		= "CB.xxxx",
	.deliver	= afs_deliver_cm_op_id,
	.abort_to_error	= afs_abort_to_error,
};

static void afs_collect_incoming_call(struct work_struct *);

static struct sk_buff_head afs_incoming_calls;
static DECLARE_WORK(afs_collect_incoming_call_work, afs_collect_incoming_call);

/*
 * open an RxRPC socket and bind it to be a server for callback notifications
 * - the socket is left in blocking mode and non-blocking ops use MSG_DONTWAIT
 */
int afs_open_socket(void)
{
	struct sockaddr_rxrpc srx;
	struct socket *socket;
	int ret;

	_enter("");

	skb_queue_head_init(&afs_incoming_calls);

	afs_async_calls = create_singlethread_workqueue("kafsd");
	if (!afs_async_calls) {
		_leave(" = -ENOMEM [wq]");
		return -ENOMEM;
	}

	ret = sock_create_kern(AF_RXRPC, SOCK_DGRAM, PF_INET, &socket);
	if (ret < 0) {
		destroy_workqueue(afs_async_calls);
		_leave(" = %d [socket]", ret);
		return ret;
	}

	socket->sk->sk_allocation = GFP_NOFS;

	/* bind the callback manager's address to make this a server socket */
	srx.srx_family			= AF_RXRPC;
	srx.srx_service			= CM_SERVICE;
	srx.transport_type		= SOCK_DGRAM;
	srx.transport_len		= sizeof(srx.transport.sin);
	srx.transport.sin.sin_family	= AF_INET;
	srx.transport.sin.sin_port	= htons(AFS_CM_PORT);
	memset(&srx.transport.sin.sin_addr, 0,
	       sizeof(srx.transport.sin.sin_addr));

	ret = kernel_bind(socket, (struct sockaddr *) &srx, sizeof(srx));
	if (ret < 0) {
		sock_release(socket);
		destroy_workqueue(afs_async_calls);
		_leave(" = %d [bind]", ret);
		return ret;
	}

	rxrpc_kernel_intercept_rx_messages(socket, afs_rx_interceptor);

	afs_socket = socket;
	_leave(" = 0");
	return 0;
}

/*
 * close the RxRPC socket AFS was using
 */
void afs_close_socket(void)
{
	_enter("");

	sock_release(afs_socket);

	_debug("dework");
	destroy_workqueue(afs_async_calls);

	ASSERTCMP(atomic_read(&afs_outstanding_skbs), ==, 0);
	ASSERTCMP(atomic_read(&afs_outstanding_calls), ==, 0);
	_leave("");
}

/*
 * note that the data in a socket buffer is now delivered and that the buffer
 * should be freed
 */
static void afs_data_delivered(struct sk_buff *skb)
{
	if (!skb) {
		_debug("DLVR NULL [%d]", atomic_read(&afs_outstanding_skbs));
		dump_stack();
	} else {
		_debug("DLVR %p{%u} [%d]",
		       skb, skb->mark, atomic_read(&afs_outstanding_skbs));
		if (atomic_dec_return(&afs_outstanding_skbs) == -1)
			BUG();
		rxrpc_kernel_data_delivered(skb);
	}
}

/*
 * free a socket buffer
 */
static void afs_free_skb(struct sk_buff *skb)
{
	if (!skb) {
		_debug("FREE NULL [%d]", atomic_read(&afs_outstanding_skbs));
		dump_stack();
	} else {
		_debug("FREE %p{%u} [%d]",
		       skb, skb->mark, atomic_read(&afs_outstanding_skbs));
		if (atomic_dec_return(&afs_outstanding_skbs) == -1)
			BUG();
		rxrpc_kernel_free_skb(skb);
	}
}

/*
 * free a call
 */
static void afs_free_call(struct afs_call *call)
{
	_debug("DONE %p{%s} [%d]",
	       call, call->type->name, atomic_read(&afs_outstanding_calls));
	if (atomic_dec_return(&afs_outstanding_calls) == -1)
		BUG();

	ASSERTCMP(call->rxcall, ==, NULL);
	ASSERT(!work_pending(&call->async_work));
	ASSERT(skb_queue_empty(&call->rx_queue));
	ASSERT(call->type->name != NULL);

	kfree(call->request);
	kfree(call);
}

/*
 * allocate a call with flat request and reply buffers
 */
struct afs_call *afs_alloc_flat_call(const struct afs_call_type *type,
				     size_t request_size, size_t reply_size)
{
	struct afs_call *call;

	call = kzalloc(sizeof(*call), GFP_NOFS);
	if (!call)
		goto nomem_call;

	_debug("CALL %p{%s} [%d]",
	       call, type->name, atomic_read(&afs_outstanding_calls));
	atomic_inc(&afs_outstanding_calls);

	call->type = type;
	call->request_size = request_size;
	call->reply_max = reply_size;

	if (request_size) {
		call->request = kmalloc(request_size, GFP_NOFS);
		if (!call->request)
			goto nomem_free;
	}

	if (reply_size) {
		call->buffer = kmalloc(reply_size, GFP_NOFS);
		if (!call->buffer)
			goto nomem_free;
	}

	init_waitqueue_head(&call->waitq);
	skb_queue_head_init(&call->rx_queue);
	return call;

nomem_free:
	afs_free_call(call);
nomem_call:
	return NULL;
}

/*
 * clean up a call with flat buffer
 */
void afs_flat_call_destructor(struct afs_call *call)
{
	_enter("");

	kfree(call->request);
	call->request = NULL;
	kfree(call->buffer);
	call->buffer = NULL;
}

/*
 * attach the data from a bunch of pages on an inode to a call
 */
static int afs_send_pages(struct afs_call *call, struct msghdr *msg,
			  struct kvec *iov)
{
	struct page *pages[8];
	unsigned count, n, loop, offset, to;
	pgoff_t first = call->first, last = call->last;
	int ret;

	_enter("");

	offset = call->first_offset;
	call->first_offset = 0;

	do {
		_debug("attach %lx-%lx", first, last);

		count = last - first + 1;
		if (count > ARRAY_SIZE(pages))
			count = ARRAY_SIZE(pages);
		n = find_get_pages_contig(call->mapping, first, count, pages);
		ASSERTCMP(n, ==, count);

		loop = 0;
		do {
			msg->msg_flags = 0;
			to = PAGE_SIZE;
			if (first + loop >= last)
				to = call->last_to;
			else
				msg->msg_flags = MSG_MORE;
			iov->iov_base = kmap(pages[loop]) + offset;
			iov->iov_len = to - offset;
			offset = 0;

			_debug("- range %u-%u%s",
			       offset, to, msg->msg_flags ? " [more]" : "");
			msg->msg_iov = (struct iovec *) iov;
			msg->msg_iovlen = 1;

			/* have to change the state *before* sending the last
			 * packet as RxRPC might give us the reply before it
			 * returns from sending the request */
			if (first + loop >= last)
				call->state = AFS_CALL_AWAIT_REPLY;
			ret = rxrpc_kernel_send_data(call->rxcall, msg,
						     to - offset);
			kunmap(pages[loop]);
			if (ret < 0)
				break;
		} while (++loop < count);
		first += count;

		for (loop = 0; loop < count; loop++)
			put_page(pages[loop]);
		if (ret < 0)
			break;
	} while (first <= last);

	_leave(" = %d", ret);
	return ret;
}

/*
 * initiate a call
 */
int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
		  const struct afs_wait_mode *wait_mode)
{
	struct sockaddr_rxrpc srx;
	struct rxrpc_call *rxcall;
	struct msghdr msg;
	struct kvec iov[1];
	int ret;

	_enter("%x,{%d},", addr->s_addr, ntohs(call->port));

	ASSERT(call->type != NULL);
	ASSERT(call->type->name != NULL);

	_debug("____MAKE %p{%s,%x} [%d]____",
	       call, call->type->name, key_serial(call->key),
	       atomic_read(&afs_outstanding_calls));

	call->wait_mode = wait_mode;
	INIT_WORK(&call->async_work, afs_process_async_call);

	memset(&srx, 0, sizeof(srx));
	srx.srx_family = AF_RXRPC;
	srx.srx_service = call->service_id;
	srx.transport_type = SOCK_DGRAM;
	srx.transport_len = sizeof(srx.transport.sin);
	srx.transport.sin.sin_family = AF_INET;
	srx.transport.sin.sin_port = call->port;
	memcpy(&srx.transport.sin.sin_addr, addr, 4);

	/* create a call */
	rxcall = rxrpc_kernel_begin_call(afs_socket, &srx, call->key,
					 (unsigned long) call, gfp);
	call->key = NULL;
	if (IS_ERR(rxcall)) {
		ret = PTR_ERR(rxcall);
		goto error_kill_call;
	}

	call->rxcall = rxcall;

	/* send the request */
	iov[0].iov_base	= call->request;
	iov[0].iov_len	= call->request_size;

	msg.msg_name		= NULL;
	msg.msg_namelen		= 0;
	msg.msg_iov		= (struct iovec *) iov;
	msg.msg_iovlen		= 1;
	msg.msg_control		= NULL;
	msg.msg_controllen	= 0;
	msg.msg_flags		= (call->send_pages ? MSG_MORE : 0);

	/* have to change the state *before* sending the last packet as RxRPC
	 * might give us the reply before it returns from sending the
	 * request */
	if (!call->send_pages)
		call->state = AFS_CALL_AWAIT_REPLY;
	ret = rxrpc_kernel_send_data(rxcall, &msg, call->request_size);
	if (ret < 0)
		goto error_do_abort;

	if (call->send_pages) {
		ret = afs_send_pages(call, &msg, iov);
		if (ret < 0)
			goto error_do_abort;
	}

	/* at this point, an async call may no longer exist as it may have
	 * already completed */
	return wait_mode->wait(call);

error_do_abort:
	rxrpc_kernel_abort_call(rxcall, RX_USER_ABORT);
	rxrpc_kernel_end_call(rxcall);
	call->rxcall = NULL;
error_kill_call:
	call->type->destructor(call);
	afs_free_call(call);
	_leave(" = %d", ret);
	return ret;
}

/*
 * handles intercepted messages that were arriving in the socket's Rx queue
 * - called with the socket receive queue lock held to ensure message ordering
 * - called with softirqs disabled
 */
static void afs_rx_interceptor(struct sock *sk, unsigned long user_call_ID,
			       struct sk_buff *skb)
{
	struct afs_call *call = (struct afs_call *) user_call_ID;

	_enter("%p,,%u", call, skb->mark);

	_debug("ICPT %p{%u} [%d]",
	       skb, skb->mark, atomic_read(&afs_outstanding_skbs));

	ASSERTCMP(sk, ==, afs_socket->sk);
	atomic_inc(&afs_outstanding_skbs);

	if (!call) {
		/* its an incoming call for our callback service */
		skb_queue_tail(&afs_incoming_calls, skb);
		queue_work(afs_wq, &afs_collect_incoming_call_work);
	} else {
		/* route the messages directly to the appropriate call */
		skb_queue_tail(&call->rx_queue, skb);
		call->wait_mode->rx_wakeup(call);
	}

	_leave("");
}

/*
 * deliver messages to a call
 */
static void afs_deliver_to_call(struct afs_call *call)
{
	struct sk_buff *skb;
	bool last;
	u32 abort_code;
	int ret;

	_enter("");

	while ((call->state == AFS_CALL_AWAIT_REPLY ||
		call->state == AFS_CALL_AWAIT_OP_ID ||
		call->state == AFS_CALL_AWAIT_REQUEST ||
		call->state == AFS_CALL_AWAIT_ACK) &&
	       (skb = skb_dequeue(&call->rx_queue))) {
		switch (skb->mark) {
		case RXRPC_SKB_MARK_DATA:
			_debug("Rcv DATA");
			last = rxrpc_kernel_is_data_last(skb);
			ret = call->type->deliver(call, skb, last);
			switch (ret) {
			case 0:
				if (last &&
				    call->state == AFS_CALL_AWAIT_REPLY)
					call->state = AFS_CALL_COMPLETE;
				break;
			case -ENOTCONN:
				abort_code = RX_CALL_DEAD;
				goto do_abort;
			case -ENOTSUPP:
				abort_code = RX_INVALID_OPERATION;
				goto do_abort;
			default:
				abort_code = RXGEN_CC_UNMARSHAL;
				if (call->state != AFS_CALL_AWAIT_REPLY)
					abort_code = RXGEN_SS_UNMARSHAL;
			do_abort:
				rxrpc_kernel_abort_call(call->rxcall,
							abort_code);
				call->error = ret;
				call->state = AFS_CALL_ERROR;
				break;
			}
			afs_data_delivered(skb);
			skb = NULL;
			continue;
		case RXRPC_SKB_MARK_FINAL_ACK:
			_debug("Rcv ACK");
			call->state = AFS_CALL_COMPLETE;
			break;
		case RXRPC_SKB_MARK_BUSY:
			_debug("Rcv BUSY");
			call->error = -EBUSY;
			call->state = AFS_CALL_BUSY;
			break;
		case RXRPC_SKB_MARK_REMOTE_ABORT:
			abort_code = rxrpc_kernel_get_abort_code(skb);
			call->error = call->type->abort_to_error(abort_code);
			call->state = AFS_CALL_ABORTED;
			_debug("Rcv ABORT %u -> %d", abort_code, call->error);
			break;
		case RXRPC_SKB_MARK_NET_ERROR:
			call->error = -rxrpc_kernel_get_error_number(skb);
			call->state = AFS_CALL_ERROR;
			_debug("Rcv NET ERROR %d", call->error);
			break;
		case RXRPC_SKB_MARK_LOCAL_ERROR:
			call->error = -rxrpc_kernel_get_error_number(skb);
			call->state = AFS_CALL_ERROR;
			_debug("Rcv LOCAL ERROR %d", call->error);
			break;
		default:
			BUG();
			break;
		}

		afs_free_skb(skb);
	}

	/* make sure the queue is empty if the call is done with (we might have
	 * aborted the call early because of an unmarshalling error) */
	if (call->state >= AFS_CALL_COMPLETE) {
		while ((skb = skb_dequeue(&call->rx_queue)))
			afs_free_skb(skb);
		if (call->incoming) {
			rxrpc_kernel_end_call(call->rxcall);
			call->rxcall = NULL;
			call->type->destructor(call);
			afs_free_call(call);
		}
	}

	_leave("");
}

/*
 * wait synchronously for a call to complete
 */
static int afs_wait_for_call_to_complete(struct afs_call *call)
{
	struct sk_buff *skb;
	int ret;

	DECLARE_WAITQUEUE(myself, current);

	_enter("");

	add_wait_queue(&call->waitq, &myself);
	for (;;) {
		set_current_state(TASK_INTERRUPTIBLE);

		/* deliver any messages that are in the queue */
		if (!skb_queue_empty(&call->rx_queue)) {
			__set_current_state(TASK_RUNNING);
			afs_deliver_to_call(call);
			continue;
		}

		ret = call->error;
		if (call->state >= AFS_CALL_COMPLETE)
			break;
		ret = -EINTR;
		if (signal_pending(current))
			break;
		schedule();
	}

	remove_wait_queue(&call->waitq, &myself);
	__set_current_state(TASK_RUNNING);

	/* kill the call */
	if (call->state < AFS_CALL_COMPLETE) {
		_debug("call incomplete");
		rxrpc_kernel_abort_call(call->rxcall, RX_CALL_DEAD);
		while ((skb = skb_dequeue(&call->rx_queue)))
			afs_free_skb(skb);
	}

	_debug("call complete");
	rxrpc_kernel_end_call(call->rxcall);
	call->rxcall = NULL;
	call->type->destructor(call);
	afs_free_call(call);
	_leave(" = %d", ret);
	return ret;
}

/*
 * wake up a waiting call
 */
static void afs_wake_up_call_waiter(struct afs_call *call)
{
	wake_up(&call->waitq);
}

/*
 * wake up an asynchronous call
 */
static void afs_wake_up_async_call(struct afs_call *call)
{
	_enter("");
	queue_work(afs_async_calls, &call->async_work);
}

/*
 * put a call into asynchronous mode
 * - mustn't touch the call descriptor as the call my have completed by the
 *   time we get here
 */
static int afs_dont_wait_for_call_to_complete(struct afs_call *call)
{
	_enter("");
	return -EINPROGRESS;
}

/*
 * delete an asynchronous call
 */
static void afs_delete_async_call(struct work_struct *work)
{
	struct afs_call *call =
		container_of(work, struct afs_call, async_work);

	_enter("");

	afs_free_call(call);

	_leave("");
}

/*
 * perform processing on an asynchronous call
 * - on a multiple-thread workqueue this work item may try to run on several
 *   CPUs at the same time
 */
static void afs_process_async_call(struct work_struct *work)
{
	struct afs_call *call =
		container_of(work, struct afs_call, async_work);

	_enter("");

	if (!skb_queue_empty(&call->rx_queue))
		afs_deliver_to_call(call);

	if (call->state >= AFS_CALL_COMPLETE && call->wait_mode) {
		if (call->wait_mode->async_complete)
			call->wait_mode->async_complete(call->reply,
							call->error);
		call->reply = NULL;

		/* kill the call */
		rxrpc_kernel_end_call(call->rxcall);
		call->rxcall = NULL;
		if (call->type->destructor)
			call->type->destructor(call);

		/* we can't just delete the call because the work item may be
		 * queued */
		PREPARE_WORK(&call->async_work, afs_delete_async_call);
		queue_work(afs_async_calls, &call->async_work);
	}

	_leave("");
}

/*
 * empty a socket buffer into a flat reply buffer
 */
void afs_transfer_reply(struct afs_call *call, struct sk_buff *skb)
{
	size_t len = skb->len;

	if (skb_copy_bits(skb, 0, call->buffer + call->reply_size, len) < 0)
		BUG();
	call->reply_size += len;
}

/*
 * accept the backlog of incoming calls
 */
static void afs_collect_incoming_call(struct work_struct *work)
{
	struct rxrpc_call *rxcall;
	struct afs_call *call = NULL;
	struct sk_buff *skb;

	while ((skb = skb_dequeue(&afs_incoming_calls))) {
		_debug("new call");

		/* don't need the notification */
		afs_free_skb(skb);

		if (!call) {
			call = kzalloc(sizeof(struct afs_call), GFP_KERNEL);
			if (!call) {
				rxrpc_kernel_reject_call(afs_socket);
				return;
			}

			INIT_WORK(&call->async_work, afs_process_async_call);
			call->wait_mode = &afs_async_incoming_call;
			call->type = &afs_RXCMxxxx;
			init_waitqueue_head(&call->waitq);
			skb_queue_head_init(&call->rx_queue);
			call->state = AFS_CALL_AWAIT_OP_ID;

			_debug("CALL %p{%s} [%d]",
			       call, call->type->name,
			       atomic_read(&afs_outstanding_calls));
			atomic_inc(&afs_outstanding_calls);
		}

		rxcall = rxrpc_kernel_accept_call(afs_socket,
						  (unsigned long) call);
		if (!IS_ERR(rxcall)) {
			call->rxcall = rxcall;
			call = NULL;
		}
	}

	if (call)
		afs_free_call(call);
}

/*
 * grab the operation ID from an incoming cache manager call
 */
static int afs_deliver_cm_op_id(struct afs_call *call, struct sk_buff *skb,
				bool last)
{
	size_t len = skb->len;
	void *oibuf = (void *) &call->operation_ID;

	_enter("{%u},{%zu},%d", call->offset, len, last);

	ASSERTCMP(call->offset, <, 4);

	/* the operation ID forms the first four bytes of the request data */
	len = min_t(size_t, len, 4 - call->offset);
	if (skb_copy_bits(skb, 0, oibuf + call->offset, len) < 0)
		BUG();
	if (!pskb_pull(skb, len))
		BUG();
	call->offset += len;

	if (call->offset < 4) {
		if (last) {
			_leave(" = -EBADMSG [op ID short]");
			return -EBADMSG;
		}
		_leave(" = 0 [incomplete]");
		return 0;
	}

	call->state = AFS_CALL_AWAIT_REQUEST;

	/* ask the cache manager to route the call (it'll change the call type
	 * if successful) */
	if (!afs_cm_incoming_call(call))
		return -ENOTSUPP;

	/* pass responsibility for the remainer of this message off to the
	 * cache manager op */
	return call->type->deliver(call, skb, last);
}

/*
 * send an empty reply
 */
void afs_send_empty_reply(struct afs_call *call)
{
	struct msghdr msg;
	struct iovec iov[1];

	_enter("");

	iov[0].iov_base		= NULL;
	iov[0].iov_len		= 0;
	msg.msg_name		= NULL;
	msg.msg_namelen		= 0;
	msg.msg_iov		= iov;
	msg.msg_iovlen		= 0;
	msg.msg_control		= NULL;
	msg.msg_controllen	= 0;
	msg.msg_flags		= 0;

	call->state = AFS_CALL_AWAIT_ACK;
	switch (rxrpc_kernel_send_data(call->rxcall, &msg, 0)) {
	case 0:
		_leave(" [replied]");
		return;

	case -ENOMEM:
		_debug("oom");
		rxrpc_kernel_abort_call(call->rxcall, RX_USER_ABORT);
	default:
		rxrpc_kernel_end_call(call->rxcall);
		call->rxcall = NULL;
		call->type->destructor(call);
		afs_free_call(call);
		_leave(" [error]");
		return;
	}
}

/*
 * send a simple reply
 */
void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len)
{
	struct msghdr msg;
	struct iovec iov[1];
	int n;

	_enter("");

	iov[0].iov_base		= (void *) buf;
	iov[0].iov_len		= len;
	msg.msg_name		= NULL;
	msg.msg_namelen		= 0;
	msg.msg_iov		= iov;
	msg.msg_iovlen		= 1;
	msg.msg_control		= NULL;
	msg.msg_controllen	= 0;
	msg.msg_flags		= 0;

	call->state = AFS_CALL_AWAIT_ACK;
	n = rxrpc_kernel_send_data(call->rxcall, &msg, len);
	if (n >= 0) {
		_leave(" [replied]");
		return;
	}
	if (n == -ENOMEM) {
		_debug("oom");
		rxrpc_kernel_abort_call(call->rxcall, RX_USER_ABORT);
	}
	rxrpc_kernel_end_call(call->rxcall);
	call->rxcall = NULL;
	call->type->destructor(call);
	afs_free_call(call);
	_leave(" [error]");
}

/*
 * extract a piece of data from the received data socket buffers
 */
int afs_extract_data(struct afs_call *call, struct sk_buff *skb,
		     bool last, void *buf, size_t count)
{
	size_t len = skb->len;

	_enter("{%u},{%zu},%d,,%zu", call->offset, len, last, count);

	ASSERTCMP(call->offset, <, count);

	len = min_t(size_t, len, count - call->offset);
	if (skb_copy_bits(skb, 0, buf + call->offset, len) < 0 ||
	    !pskb_pull(skb, len))
		BUG();
	call->offset += len;

	if (call->offset < count) {
		if (last) {
			_leave(" = -EBADMSG [%d < %zu]", call->offset, count);
			return -EBADMSG;
		}
		_leave(" = -EAGAIN");
		return -EAGAIN;
	}
	return 0;
}