summaryrefslogtreecommitdiffstats
path: root/net/rxrpc/call_event.c
blob: 20210418904bf61975e5f00ef196c5dce4770cca (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
/* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
 *
 * 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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/circ_buf.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/udp.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"

/*
 * Propose a PING ACK be sent.
 */
static void rxrpc_propose_ping(struct rxrpc_call *call,
			       bool immediate, bool background)
{
	if (immediate) {
		if (background &&
		    !test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
			rxrpc_queue_call(call);
	} else {
		unsigned long now = jiffies;
		unsigned long ping_at = now + rxrpc_idle_ack_delay;

		if (time_before(ping_at, call->ping_at)) {
			WRITE_ONCE(call->ping_at, ping_at);
			rxrpc_reduce_call_timer(call, ping_at, now,
						rxrpc_timer_set_for_ping);
		}
	}
}

/*
 * propose an ACK be sent
 */
static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
				u16 skew, u32 serial, bool immediate,
				bool background,
				enum rxrpc_propose_ack_trace why)
{
	enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
	unsigned long expiry = rxrpc_soft_ack_delay;
	s8 prior = rxrpc_ack_priority[ack_reason];

	/* Pings are handled specially because we don't want to accidentally
	 * lose a ping response by subsuming it into a ping.
	 */
	if (ack_reason == RXRPC_ACK_PING) {
		rxrpc_propose_ping(call, immediate, background);
		goto trace;
	}

	/* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
	 * numbers, but we don't alter the timeout.
	 */
	_debug("prior %u %u vs %u %u",
	       ack_reason, prior,
	       call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]);
	if (ack_reason == call->ackr_reason) {
		if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) {
			outcome = rxrpc_propose_ack_update;
			call->ackr_serial = serial;
			call->ackr_skew = skew;
		}
		if (!immediate)
			goto trace;
	} else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
		call->ackr_reason = ack_reason;
		call->ackr_serial = serial;
		call->ackr_skew = skew;
	} else {
		outcome = rxrpc_propose_ack_subsume;
	}

	switch (ack_reason) {
	case RXRPC_ACK_REQUESTED:
		if (rxrpc_requested_ack_delay < expiry)
			expiry = rxrpc_requested_ack_delay;
		if (serial == 1)
			immediate = false;
		break;

	case RXRPC_ACK_DELAY:
		if (rxrpc_soft_ack_delay < expiry)
			expiry = rxrpc_soft_ack_delay;
		break;

	case RXRPC_ACK_IDLE:
		if (rxrpc_idle_ack_delay < expiry)
			expiry = rxrpc_idle_ack_delay;
		break;

	default:
		immediate = true;
		break;
	}

	if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) {
		_debug("already scheduled");
	} else if (immediate || expiry == 0) {
		_debug("immediate ACK %lx", call->events);
		if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) &&
		    background)
			rxrpc_queue_call(call);
	} else {
		unsigned long now = jiffies, ack_at;

		if (call->peer->rtt_usage > 0)
			ack_at = nsecs_to_jiffies(call->peer->rtt);
		else
			ack_at = expiry;

		ack_at += now;
		if (time_before(ack_at, call->ack_at)) {
			WRITE_ONCE(call->ack_at, ack_at);
			rxrpc_reduce_call_timer(call, ack_at, now,
						rxrpc_timer_set_for_ack);
		}
	}

trace:
	trace_rxrpc_propose_ack(call, why, ack_reason, serial, immediate,
				background, outcome);
}

/*
 * propose an ACK be sent, locking the call structure
 */
void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
		       u16 skew, u32 serial, bool immediate, bool background,
		       enum rxrpc_propose_ack_trace why)
{
	spin_lock_bh(&call->lock);
	__rxrpc_propose_ACK(call, ack_reason, skew, serial,
			    immediate, background, why);
	spin_unlock_bh(&call->lock);
}

/*
 * Handle congestion being detected by the retransmit timeout.
 */
static void rxrpc_congestion_timeout(struct rxrpc_call *call)
{
	set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
}

/*
 * Perform retransmission of NAK'd and unack'd packets.
 */
static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
{
	struct rxrpc_skb_priv *sp;
	struct sk_buff *skb;
	unsigned long resend_at;
	rxrpc_seq_t cursor, seq, top;
	ktime_t now, max_age, oldest, ack_ts, timeout, min_timeo;
	int ix;
	u8 annotation, anno_type, retrans = 0, unacked = 0;

	_enter("{%d,%d}", call->tx_hard_ack, call->tx_top);

	if (call->peer->rtt_usage > 1)
		timeout = ns_to_ktime(call->peer->rtt * 3 / 2);
	else
		timeout = ms_to_ktime(rxrpc_resend_timeout);
	min_timeo = ns_to_ktime((1000000000 / HZ) * 4);
	if (ktime_before(timeout, min_timeo))
		timeout = min_timeo;

	now = ktime_get_real();
	max_age = ktime_sub(now, timeout);

	spin_lock_bh(&call->lock);

	cursor = call->tx_hard_ack;
	top = call->tx_top;
	ASSERT(before_eq(cursor, top));
	if (cursor == top)
		goto out_unlock;

	/* Scan the packet list without dropping the lock and decide which of
	 * the packets in the Tx buffer we're going to resend and what the new
	 * resend timeout will be.
	 */
	trace_rxrpc_resend(call, (cursor + 1) & RXRPC_RXTX_BUFF_MASK);
	oldest = now;
	for (seq = cursor + 1; before_eq(seq, top); seq++) {
		ix = seq & RXRPC_RXTX_BUFF_MASK;
		annotation = call->rxtx_annotations[ix];
		anno_type = annotation & RXRPC_TX_ANNO_MASK;
		annotation &= ~RXRPC_TX_ANNO_MASK;
		if (anno_type == RXRPC_TX_ANNO_ACK)
			continue;

		skb = call->rxtx_buffer[ix];
		rxrpc_see_skb(skb, rxrpc_skb_tx_seen);
		sp = rxrpc_skb(skb);

		if (anno_type == RXRPC_TX_ANNO_UNACK) {
			if (ktime_after(skb->tstamp, max_age)) {
				if (ktime_before(skb->tstamp, oldest))
					oldest = skb->tstamp;
				continue;
			}
			if (!(annotation & RXRPC_TX_ANNO_RESENT))
				unacked++;
		}

		/* Okay, we need to retransmit a packet. */
		call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation;
		retrans++;
		trace_rxrpc_retransmit(call, seq, annotation | anno_type,
				       ktime_to_ns(ktime_sub(skb->tstamp, max_age)));
	}

	resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
	resend_at += jiffies + rxrpc_resend_timeout;
	WRITE_ONCE(call->resend_at, resend_at);

	if (unacked)
		rxrpc_congestion_timeout(call);

	/* If there was nothing that needed retransmission then it's likely
	 * that an ACK got lost somewhere.  Send a ping to find out instead of
	 * retransmitting data.
	 */
	if (!retrans) {
		rxrpc_reduce_call_timer(call, resend_at, now_j,
					rxrpc_timer_set_for_resend);
		spin_unlock_bh(&call->lock);
		ack_ts = ktime_sub(now, call->acks_latest_ts);
		if (ktime_to_ns(ack_ts) < call->peer->rtt)
			goto out;
		rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false,
				  rxrpc_propose_ack_ping_for_lost_ack);
		rxrpc_send_ack_packet(call, true, NULL);
		goto out;
	}

	/* Now go through the Tx window and perform the retransmissions.  We
	 * have to drop the lock for each send.  If an ACK comes in whilst the
	 * lock is dropped, it may clear some of the retransmission markers for
	 * packets that it soft-ACKs.
	 */
	for (seq = cursor + 1; before_eq(seq, top); seq++) {
		ix = seq & RXRPC_RXTX_BUFF_MASK;
		annotation = call->rxtx_annotations[ix];
		anno_type = annotation & RXRPC_TX_ANNO_MASK;
		if (anno_type != RXRPC_TX_ANNO_RETRANS)
			continue;

		skb = call->rxtx_buffer[ix];
		rxrpc_get_skb(skb, rxrpc_skb_tx_got);
		spin_unlock_bh(&call->lock);

		if (rxrpc_send_data_packet(call, skb, true) < 0) {
			rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
			return;
		}

		if (rxrpc_is_client_call(call))
			rxrpc_expose_client_call(call);

		rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
		spin_lock_bh(&call->lock);

		/* We need to clear the retransmit state, but there are two
		 * things we need to be aware of: A new ACK/NAK might have been
		 * received and the packet might have been hard-ACK'd (in which
		 * case it will no longer be in the buffer).
		 */
		if (after(seq, call->tx_hard_ack)) {
			annotation = call->rxtx_annotations[ix];
			anno_type = annotation & RXRPC_TX_ANNO_MASK;
			if (anno_type == RXRPC_TX_ANNO_RETRANS ||
			    anno_type == RXRPC_TX_ANNO_NAK) {
				annotation &= ~RXRPC_TX_ANNO_MASK;
				annotation |= RXRPC_TX_ANNO_UNACK;
			}
			annotation |= RXRPC_TX_ANNO_RESENT;
			call->rxtx_annotations[ix] = annotation;
		}

		if (after(call->tx_hard_ack, seq))
			seq = call->tx_hard_ack;
	}

out_unlock:
	spin_unlock_bh(&call->lock);
out:
	_leave("");
}

/*
 * Handle retransmission and deferred ACK/abort generation.
 */
void rxrpc_process_call(struct work_struct *work)
{
	struct rxrpc_call *call =
		container_of(work, struct rxrpc_call, processor);
	rxrpc_serial_t *send_ack;
	unsigned long now, next, t;

	rxrpc_see_call(call);

	//printk("\n--------------------\n");
	_enter("{%d,%s,%lx}",
	       call->debug_id, rxrpc_call_states[call->state], call->events);

recheck_state:
	if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
		rxrpc_send_abort_packet(call);
		goto recheck_state;
	}

	if (call->state == RXRPC_CALL_COMPLETE) {
		del_timer_sync(&call->timer);
		rxrpc_notify_socket(call);
		goto out_put;
	}

	/* Work out if any timeouts tripped */
	now = jiffies;
	t = READ_ONCE(call->expect_rx_by);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
		set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
	}

	t = READ_ONCE(call->expect_req_by);
	if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST &&
	    time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
		set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
	}

	t = READ_ONCE(call->expect_term_by);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
		set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
	}

	t = READ_ONCE(call->ack_at);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
		cmpxchg(&call->ack_at, t, now + MAX_JIFFY_OFFSET);
		set_bit(RXRPC_CALL_EV_ACK, &call->events);
	}

	t = READ_ONCE(call->ack_lost_at);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now);
		cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET);
		set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
	}

	t = READ_ONCE(call->keepalive_at);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now);
		cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET);
		rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, true,
				  rxrpc_propose_ack_ping_for_keepalive);
		set_bit(RXRPC_CALL_EV_PING, &call->events);
	}

	t = READ_ONCE(call->ping_at);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
		cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
		set_bit(RXRPC_CALL_EV_PING, &call->events);
	}

	t = READ_ONCE(call->resend_at);
	if (time_after_eq(now, t)) {
		trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
		cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
		set_bit(RXRPC_CALL_EV_RESEND, &call->events);
	}

	/* Process events */
	if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED, &call->events)) {
		if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) &&
		    (int)call->conn->hi_serial - (int)call->rx_serial > 0) {
			trace_rxrpc_call_reset(call);
			rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ECONNRESET);
		} else {
			rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ETIME);
		}
		set_bit(RXRPC_CALL_EV_ABORT, &call->events);
		goto recheck_state;
	}

	send_ack = NULL;
	if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events)) {
		call->acks_lost_top = call->tx_top;
		rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false,
				  rxrpc_propose_ack_ping_for_lost_ack);
		send_ack = &call->acks_lost_ping;
	}

	if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) ||
	    send_ack) {
		if (call->ackr_reason) {
			rxrpc_send_ack_packet(call, false, send_ack);
			goto recheck_state;
		}
	}

	if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {
		rxrpc_send_ack_packet(call, true, NULL);
		goto recheck_state;
	}

	if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) {
		rxrpc_resend(call, now);
		goto recheck_state;
	}

	/* Make sure the timer is restarted */
	next = call->expect_rx_by;

#define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }

	set(call->expect_req_by);
	set(call->expect_term_by);
	set(call->ack_at);
	set(call->ack_lost_at);
	set(call->resend_at);
	set(call->keepalive_at);
	set(call->ping_at);

	now = jiffies;
	if (time_after_eq(now, next))
		goto recheck_state;

	rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);

	/* other events may have been raised since we started checking */
	if (call->events && call->state < RXRPC_CALL_COMPLETE) {
		__rxrpc_queue_call(call);
		goto out;
	}

out_put:
	rxrpc_put_call(call, rxrpc_call_put);
out:
	_leave("");
}