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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/module.h>
11#include <linux/circ_buf.h>
12#include <linux/net.h>
13#include <linux/skbuff.h>
14#include <linux/slab.h>
15#include <linux/udp.h>
16#include <net/sock.h>
17#include <net/af_rxrpc.h>
18#include "ar-internal.h"
19
20/*
21 * Propose a PING ACK be sent.
22 */
23void rxrpc_propose_ping(struct rxrpc_call *call, u32 serial,
24 enum rxrpc_propose_ack_trace why)
25{
26 ktime_t delay = ms_to_ktime(READ_ONCE(rxrpc_idle_ack_delay));
27 ktime_t now = ktime_get_real();
28 ktime_t ping_at = ktime_add(now, delay);
29
30 trace_rxrpc_propose_ack(call, why, RXRPC_ACK_PING, serial);
31 if (ktime_before(ping_at, call->ping_at)) {
32 call->ping_at = ping_at;
33 trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_ping);
34 }
35}
36
37/*
38 * Propose a DELAY ACK be sent in the future.
39 */
40void rxrpc_propose_delay_ACK(struct rxrpc_call *call, rxrpc_serial_t serial,
41 enum rxrpc_propose_ack_trace why)
42{
43 ktime_t now = ktime_get_real(), delay;
44
45 trace_rxrpc_propose_ack(call, why, RXRPC_ACK_DELAY, serial);
46
47 if (call->peer->srtt_us)
48 delay = (call->peer->srtt_us >> 3) * NSEC_PER_USEC;
49 else
50 delay = ms_to_ktime(READ_ONCE(rxrpc_soft_ack_delay));
51 ktime_add_ms(delay, call->tx_backoff);
52
53 call->delay_ack_at = ktime_add(now, delay);
54 trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_delayed_ack);
55}
56
57/*
58 * Handle congestion being detected by the retransmit timeout.
59 */
60static void rxrpc_congestion_timeout(struct rxrpc_call *call)
61{
62 set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
63}
64
65/*
66 * Perform retransmission of NAK'd and unack'd packets.
67 */
68void rxrpc_resend(struct rxrpc_call *call, struct sk_buff *ack_skb)
69{
70 struct rxrpc_ackpacket *ack = NULL;
71 struct rxrpc_skb_priv *sp;
72 struct rxrpc_txbuf *txb;
73 rxrpc_seq_t transmitted = call->tx_transmitted;
74 ktime_t next_resend = KTIME_MAX, rto = ns_to_ktime(call->peer->rto_us * NSEC_PER_USEC);
75 ktime_t resend_at = KTIME_MAX, now, delay;
76 bool unacked = false, did_send = false;
77 unsigned int i;
78
79 _enter("{%d,%d}", call->acks_hard_ack, call->tx_top);
80
81 now = ktime_get_real();
82
83 if (list_empty(&call->tx_buffer))
84 goto no_resend;
85
86 trace_rxrpc_resend(call, ack_skb);
87 txb = list_first_entry(&call->tx_buffer, struct rxrpc_txbuf, call_link);
88
89 /* Scan the soft ACK table without dropping the lock and resend any
90 * explicitly NAK'd packets.
91 */
92 if (ack_skb) {
93 sp = rxrpc_skb(ack_skb);
94 ack = (void *)ack_skb->data + sizeof(struct rxrpc_wire_header);
95
96 for (i = 0; i < sp->ack.nr_acks; i++) {
97 rxrpc_seq_t seq;
98
99 if (ack->acks[i] & 1)
100 continue;
101 seq = sp->ack.first_ack + i;
102 if (after(txb->seq, transmitted))
103 break;
104 if (after(txb->seq, seq))
105 continue; /* A new hard ACK probably came in */
106 list_for_each_entry_from(txb, &call->tx_buffer, call_link) {
107 if (txb->seq == seq)
108 goto found_txb;
109 }
110 goto no_further_resend;
111
112 found_txb:
113 resend_at = ktime_add(txb->last_sent, rto);
114 if (after(txb->serial, call->acks_highest_serial)) {
115 if (ktime_after(resend_at, now) &&
116 ktime_before(resend_at, next_resend))
117 next_resend = resend_at;
118 continue; /* Ack point not yet reached */
119 }
120
121 rxrpc_see_txbuf(txb, rxrpc_txbuf_see_unacked);
122
123 trace_rxrpc_retransmit(call, txb->seq, txb->serial,
124 ktime_sub(resend_at, now));
125
126 txb->flags |= RXRPC_TXBUF_RESENT;
127 rxrpc_transmit_one(call, txb);
128 did_send = true;
129 now = ktime_get_real();
130
131 if (list_is_last(&txb->call_link, &call->tx_buffer))
132 goto no_further_resend;
133 txb = list_next_entry(txb, call_link);
134 }
135 }
136
137 /* Fast-forward through the Tx queue to the point the peer says it has
138 * seen. Anything between the soft-ACK table and that point will get
139 * ACK'd or NACK'd in due course, so don't worry about it here; here we
140 * need to consider retransmitting anything beyond that point.
141 */
142 if (after_eq(call->acks_prev_seq, call->tx_transmitted))
143 goto no_further_resend;
144
145 list_for_each_entry_from(txb, &call->tx_buffer, call_link) {
146 resend_at = ktime_add(txb->last_sent, rto);
147
148 if (before_eq(txb->seq, call->acks_prev_seq))
149 continue;
150 if (after(txb->seq, call->tx_transmitted))
151 break; /* Not transmitted yet */
152
153 if (ack && ack->reason == RXRPC_ACK_PING_RESPONSE &&
154 before(txb->serial, ntohl(ack->serial)))
155 goto do_resend; /* Wasn't accounted for by a more recent ping. */
156
157 if (ktime_after(resend_at, now)) {
158 if (ktime_before(resend_at, next_resend))
159 next_resend = resend_at;
160 continue;
161 }
162
163 do_resend:
164 unacked = true;
165
166 txb->flags |= RXRPC_TXBUF_RESENT;
167 rxrpc_transmit_one(call, txb);
168 did_send = true;
169 rxrpc_inc_stat(call->rxnet, stat_tx_data_retrans);
170 now = ktime_get_real();
171 }
172
173no_further_resend:
174no_resend:
175 if (resend_at < KTIME_MAX) {
176 delay = rxrpc_get_rto_backoff(call->peer, did_send);
177 resend_at = ktime_add(resend_at, delay);
178 trace_rxrpc_timer_set(call, resend_at - now, rxrpc_timer_trace_resend_reset);
179 }
180 call->resend_at = resend_at;
181
182 if (unacked)
183 rxrpc_congestion_timeout(call);
184
185 /* If there was nothing that needed retransmission then it's likely
186 * that an ACK got lost somewhere. Send a ping to find out instead of
187 * retransmitting data.
188 */
189 if (!did_send) {
190 ktime_t next_ping = ktime_add_us(call->acks_latest_ts,
191 call->peer->srtt_us >> 3);
192
193 if (ktime_sub(next_ping, now) <= 0)
194 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
195 rxrpc_propose_ack_ping_for_0_retrans);
196 }
197
198 _leave("");
199}
200
201/*
202 * Start transmitting the reply to a service. This cancels the need to ACK the
203 * request if we haven't yet done so.
204 */
205static void rxrpc_begin_service_reply(struct rxrpc_call *call)
206{
207 rxrpc_set_call_state(call, RXRPC_CALL_SERVER_SEND_REPLY);
208 if (call->ackr_reason == RXRPC_ACK_DELAY)
209 call->ackr_reason = 0;
210 call->delay_ack_at = KTIME_MAX;
211 trace_rxrpc_timer_can(call, rxrpc_timer_trace_delayed_ack);
212}
213
214/*
215 * Close the transmission phase. After this point there is no more data to be
216 * transmitted in the call.
217 */
218static void rxrpc_close_tx_phase(struct rxrpc_call *call)
219{
220 _debug("________awaiting reply/ACK__________");
221
222 switch (__rxrpc_call_state(call)) {
223 case RXRPC_CALL_CLIENT_SEND_REQUEST:
224 rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_AWAIT_REPLY);
225 break;
226 case RXRPC_CALL_SERVER_SEND_REPLY:
227 rxrpc_set_call_state(call, RXRPC_CALL_SERVER_AWAIT_ACK);
228 break;
229 default:
230 break;
231 }
232}
233
234static bool rxrpc_tx_window_has_space(struct rxrpc_call *call)
235{
236 unsigned int winsize = min_t(unsigned int, call->tx_winsize,
237 call->cong_cwnd + call->cong_extra);
238 rxrpc_seq_t window = call->acks_hard_ack, wtop = window + winsize;
239 rxrpc_seq_t tx_top = call->tx_top;
240 int space;
241
242 space = wtop - tx_top;
243 return space > 0;
244}
245
246/*
247 * Decant some if the sendmsg prepared queue into the transmission buffer.
248 */
249static void rxrpc_decant_prepared_tx(struct rxrpc_call *call)
250{
251 struct rxrpc_txbuf *txb;
252
253 if (!test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
254 if (list_empty(&call->tx_sendmsg))
255 return;
256 rxrpc_expose_client_call(call);
257 }
258
259 while ((txb = list_first_entry_or_null(&call->tx_sendmsg,
260 struct rxrpc_txbuf, call_link))) {
261 spin_lock(&call->tx_lock);
262 list_del(&txb->call_link);
263 spin_unlock(&call->tx_lock);
264
265 call->tx_top = txb->seq;
266 list_add_tail(&txb->call_link, &call->tx_buffer);
267
268 if (txb->flags & RXRPC_LAST_PACKET)
269 rxrpc_close_tx_phase(call);
270
271 rxrpc_transmit_one(call, txb);
272
273 if (!rxrpc_tx_window_has_space(call))
274 break;
275 }
276}
277
278static void rxrpc_transmit_some_data(struct rxrpc_call *call)
279{
280 switch (__rxrpc_call_state(call)) {
281 case RXRPC_CALL_SERVER_ACK_REQUEST:
282 if (list_empty(&call->tx_sendmsg))
283 return;
284 rxrpc_begin_service_reply(call);
285 fallthrough;
286
287 case RXRPC_CALL_SERVER_SEND_REPLY:
288 case RXRPC_CALL_CLIENT_SEND_REQUEST:
289 if (!rxrpc_tx_window_has_space(call))
290 return;
291 if (list_empty(&call->tx_sendmsg)) {
292 rxrpc_inc_stat(call->rxnet, stat_tx_data_underflow);
293 return;
294 }
295 rxrpc_decant_prepared_tx(call);
296 break;
297 default:
298 return;
299 }
300}
301
302/*
303 * Ping the other end to fill our RTT cache and to retrieve the rwind
304 * and MTU parameters.
305 */
306static void rxrpc_send_initial_ping(struct rxrpc_call *call)
307{
308 if (call->peer->rtt_count < 3 ||
309 ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000),
310 ktime_get_real()))
311 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
312 rxrpc_propose_ack_ping_for_params);
313}
314
315/*
316 * Handle retransmission and deferred ACK/abort generation.
317 */
318bool rxrpc_input_call_event(struct rxrpc_call *call, struct sk_buff *skb)
319{
320 ktime_t now, t;
321 bool resend = false;
322 s32 abort_code;
323
324 rxrpc_see_call(call, rxrpc_call_see_input);
325
326 //printk("\n--------------------\n");
327 _enter("{%d,%s,%lx}",
328 call->debug_id, rxrpc_call_states[__rxrpc_call_state(call)],
329 call->events);
330
331 if (__rxrpc_call_is_complete(call))
332 goto out;
333
334 /* Handle abort request locklessly, vs rxrpc_propose_abort(). */
335 abort_code = smp_load_acquire(&call->send_abort);
336 if (abort_code) {
337 rxrpc_abort_call(call, 0, call->send_abort, call->send_abort_err,
338 call->send_abort_why);
339 goto out;
340 }
341
342 if (skb && skb->mark == RXRPC_SKB_MARK_ERROR)
343 goto out;
344
345 if (skb)
346 rxrpc_input_call_packet(call, skb);
347
348 /* If we see our async-event poke, check for timeout trippage. */
349 now = ktime_get_real();
350 t = ktime_sub(call->expect_rx_by, now);
351 if (t <= 0) {
352 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_expect_rx);
353 goto expired;
354 }
355
356 t = ktime_sub(call->expect_req_by, now);
357 if (t <= 0) {
358 call->expect_req_by = KTIME_MAX;
359 if (__rxrpc_call_state(call) == RXRPC_CALL_SERVER_RECV_REQUEST) {
360 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_idle);
361 goto expired;
362 }
363 }
364
365 t = ktime_sub(READ_ONCE(call->expect_term_by), now);
366 if (t <= 0) {
367 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_hard);
368 goto expired;
369 }
370
371 t = ktime_sub(call->delay_ack_at, now);
372 if (t <= 0) {
373 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_delayed_ack);
374 call->delay_ack_at = KTIME_MAX;
375 rxrpc_send_ACK(call, RXRPC_ACK_DELAY, 0,
376 rxrpc_propose_ack_delayed_ack);
377 }
378
379 t = ktime_sub(call->ack_lost_at, now);
380 if (t <= 0) {
381 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_lost_ack);
382 call->ack_lost_at = KTIME_MAX;
383 set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
384 }
385
386 t = ktime_sub(call->ping_at, now);
387 if (t <= 0) {
388 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_ping);
389 call->ping_at = KTIME_MAX;
390 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
391 rxrpc_propose_ack_ping_for_keepalive);
392 }
393
394 t = ktime_sub(call->resend_at, now);
395 if (t <= 0) {
396 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_resend);
397 call->resend_at = KTIME_MAX;
398 resend = true;
399 }
400
401 rxrpc_transmit_some_data(call);
402
403 now = ktime_get_real();
404 t = ktime_sub(call->keepalive_at, now);
405 if (t <= 0) {
406 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_keepalive);
407 call->keepalive_at = KTIME_MAX;
408 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
409 rxrpc_propose_ack_ping_for_keepalive);
410 }
411
412 if (skb) {
413 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
414
415 if (sp->hdr.type == RXRPC_PACKET_TYPE_ACK)
416 rxrpc_congestion_degrade(call);
417 }
418
419 if (test_and_clear_bit(RXRPC_CALL_EV_INITIAL_PING, &call->events))
420 rxrpc_send_initial_ping(call);
421
422 /* Process events */
423 if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events))
424 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
425 rxrpc_propose_ack_ping_for_lost_ack);
426
427 if (resend &&
428 __rxrpc_call_state(call) != RXRPC_CALL_CLIENT_RECV_REPLY &&
429 !test_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags))
430 rxrpc_resend(call, NULL);
431
432 if (test_and_clear_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags))
433 rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
434 rxrpc_propose_ack_rx_idle);
435
436 if (call->ackr_nr_unacked > 2) {
437 if (call->peer->rtt_count < 3)
438 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
439 rxrpc_propose_ack_ping_for_rtt);
440 else if (ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000),
441 ktime_get_real()))
442 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
443 rxrpc_propose_ack_ping_for_old_rtt);
444 else
445 rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
446 rxrpc_propose_ack_input_data);
447 }
448
449 /* Make sure the timer is restarted */
450 if (!__rxrpc_call_is_complete(call)) {
451 ktime_t next = READ_ONCE(call->expect_term_by), delay;
452
453#define set(T) { ktime_t _t = (T); if (ktime_before(_t, next)) next = _t; }
454
455 set(call->expect_req_by);
456 set(call->expect_rx_by);
457 set(call->delay_ack_at);
458 set(call->ack_lost_at);
459 set(call->resend_at);
460 set(call->keepalive_at);
461 set(call->ping_at);
462
463 now = ktime_get_real();
464 delay = ktime_sub(next, now);
465 if (delay <= 0) {
466 rxrpc_poke_call(call, rxrpc_call_poke_timer_now);
467 } else {
468 unsigned long nowj = jiffies, delayj, nextj;
469
470 delayj = max(nsecs_to_jiffies(delay), 1);
471 nextj = nowj + delayj;
472 if (time_before(nextj, call->timer.expires) ||
473 !timer_pending(&call->timer)) {
474 trace_rxrpc_timer_restart(call, delay, delayj);
475 timer_reduce(&call->timer, nextj);
476 }
477 }
478 }
479
480out:
481 if (__rxrpc_call_is_complete(call)) {
482 del_timer_sync(&call->timer);
483 if (!test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
484 rxrpc_disconnect_call(call);
485 if (call->security)
486 call->security->free_call_crypto(call);
487 }
488 if (call->acks_hard_ack != call->tx_bottom)
489 rxrpc_shrink_call_tx_buffer(call);
490 _leave("");
491 return true;
492
493expired:
494 if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) &&
495 (int)call->conn->hi_serial - (int)call->rx_serial > 0) {
496 trace_rxrpc_call_reset(call);
497 rxrpc_abort_call(call, 0, RX_CALL_DEAD, -ECONNRESET,
498 rxrpc_abort_call_reset);
499 } else {
500 rxrpc_abort_call(call, 0, RX_CALL_TIMEOUT, -ETIME,
501 rxrpc_abort_call_timeout);
502 }
503 goto out;
504}
1/* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <linux/module.h>
15#include <linux/circ_buf.h>
16#include <linux/net.h>
17#include <linux/skbuff.h>
18#include <linux/slab.h>
19#include <linux/udp.h>
20#include <net/sock.h>
21#include <net/af_rxrpc.h>
22#include "ar-internal.h"
23
24/*
25 * Set the timer
26 */
27void __rxrpc_set_timer(struct rxrpc_call *call, enum rxrpc_timer_trace why,
28 ktime_t now)
29{
30 unsigned long t_j, now_j = jiffies;
31 ktime_t t;
32 bool queue = false;
33
34 if (call->state < RXRPC_CALL_COMPLETE) {
35 t = call->expire_at;
36 if (!ktime_after(t, now)) {
37 trace_rxrpc_timer(call, why, now, now_j);
38 queue = true;
39 goto out;
40 }
41
42 if (!ktime_after(call->resend_at, now)) {
43 call->resend_at = call->expire_at;
44 if (!test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
45 queue = true;
46 } else if (ktime_before(call->resend_at, t)) {
47 t = call->resend_at;
48 }
49
50 if (!ktime_after(call->ack_at, now)) {
51 call->ack_at = call->expire_at;
52 if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events))
53 queue = true;
54 } else if (ktime_before(call->ack_at, t)) {
55 t = call->ack_at;
56 }
57
58 if (!ktime_after(call->ping_at, now)) {
59 call->ping_at = call->expire_at;
60 if (!test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
61 queue = true;
62 } else if (ktime_before(call->ping_at, t)) {
63 t = call->ping_at;
64 }
65
66 t_j = nsecs_to_jiffies(ktime_to_ns(ktime_sub(t, now)));
67 t_j += jiffies;
68
69 /* We have to make sure that the calculated jiffies value falls
70 * at or after the nsec value, or we may loop ceaselessly
71 * because the timer times out, but we haven't reached the nsec
72 * timeout yet.
73 */
74 t_j++;
75
76 if (call->timer.expires != t_j || !timer_pending(&call->timer)) {
77 mod_timer(&call->timer, t_j);
78 trace_rxrpc_timer(call, why, now, now_j);
79 }
80 }
81
82out:
83 if (queue)
84 rxrpc_queue_call(call);
85}
86
87/*
88 * Set the timer
89 */
90void rxrpc_set_timer(struct rxrpc_call *call, enum rxrpc_timer_trace why,
91 ktime_t now)
92{
93 read_lock_bh(&call->state_lock);
94 __rxrpc_set_timer(call, why, now);
95 read_unlock_bh(&call->state_lock);
96}
97
98/*
99 * Propose a PING ACK be sent.
100 */
101static void rxrpc_propose_ping(struct rxrpc_call *call,
102 bool immediate, bool background)
103{
104 if (immediate) {
105 if (background &&
106 !test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
107 rxrpc_queue_call(call);
108 } else {
109 ktime_t now = ktime_get_real();
110 ktime_t ping_at = ktime_add_ms(now, rxrpc_idle_ack_delay);
111
112 if (ktime_before(ping_at, call->ping_at)) {
113 call->ping_at = ping_at;
114 rxrpc_set_timer(call, rxrpc_timer_set_for_ping, now);
115 }
116 }
117}
118
119/*
120 * propose an ACK be sent
121 */
122static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
123 u16 skew, u32 serial, bool immediate,
124 bool background,
125 enum rxrpc_propose_ack_trace why)
126{
127 enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
128 unsigned int expiry = rxrpc_soft_ack_delay;
129 ktime_t now, ack_at;
130 s8 prior = rxrpc_ack_priority[ack_reason];
131
132 /* Pings are handled specially because we don't want to accidentally
133 * lose a ping response by subsuming it into a ping.
134 */
135 if (ack_reason == RXRPC_ACK_PING) {
136 rxrpc_propose_ping(call, immediate, background);
137 goto trace;
138 }
139
140 /* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
141 * numbers, but we don't alter the timeout.
142 */
143 _debug("prior %u %u vs %u %u",
144 ack_reason, prior,
145 call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]);
146 if (ack_reason == call->ackr_reason) {
147 if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) {
148 outcome = rxrpc_propose_ack_update;
149 call->ackr_serial = serial;
150 call->ackr_skew = skew;
151 }
152 if (!immediate)
153 goto trace;
154 } else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
155 call->ackr_reason = ack_reason;
156 call->ackr_serial = serial;
157 call->ackr_skew = skew;
158 } else {
159 outcome = rxrpc_propose_ack_subsume;
160 }
161
162 switch (ack_reason) {
163 case RXRPC_ACK_REQUESTED:
164 if (rxrpc_requested_ack_delay < expiry)
165 expiry = rxrpc_requested_ack_delay;
166 if (serial == 1)
167 immediate = false;
168 break;
169
170 case RXRPC_ACK_DELAY:
171 if (rxrpc_soft_ack_delay < expiry)
172 expiry = rxrpc_soft_ack_delay;
173 break;
174
175 case RXRPC_ACK_IDLE:
176 if (rxrpc_idle_ack_delay < expiry)
177 expiry = rxrpc_idle_ack_delay;
178 break;
179
180 default:
181 immediate = true;
182 break;
183 }
184
185 if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) {
186 _debug("already scheduled");
187 } else if (immediate || expiry == 0) {
188 _debug("immediate ACK %lx", call->events);
189 if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) &&
190 background)
191 rxrpc_queue_call(call);
192 } else {
193 now = ktime_get_real();
194 ack_at = ktime_add_ms(now, expiry);
195 if (ktime_before(ack_at, call->ack_at)) {
196 call->ack_at = ack_at;
197 rxrpc_set_timer(call, rxrpc_timer_set_for_ack, now);
198 }
199 }
200
201trace:
202 trace_rxrpc_propose_ack(call, why, ack_reason, serial, immediate,
203 background, outcome);
204}
205
206/*
207 * propose an ACK be sent, locking the call structure
208 */
209void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
210 u16 skew, u32 serial, bool immediate, bool background,
211 enum rxrpc_propose_ack_trace why)
212{
213 spin_lock_bh(&call->lock);
214 __rxrpc_propose_ACK(call, ack_reason, skew, serial,
215 immediate, background, why);
216 spin_unlock_bh(&call->lock);
217}
218
219/*
220 * Handle congestion being detected by the retransmit timeout.
221 */
222static void rxrpc_congestion_timeout(struct rxrpc_call *call)
223{
224 set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
225}
226
227/*
228 * Perform retransmission of NAK'd and unack'd packets.
229 */
230static void rxrpc_resend(struct rxrpc_call *call, ktime_t now)
231{
232 struct rxrpc_skb_priv *sp;
233 struct sk_buff *skb;
234 rxrpc_seq_t cursor, seq, top;
235 ktime_t max_age, oldest, ack_ts;
236 int ix;
237 u8 annotation, anno_type, retrans = 0, unacked = 0;
238
239 _enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
240
241 max_age = ktime_sub_ms(now, rxrpc_resend_timeout);
242
243 spin_lock_bh(&call->lock);
244
245 cursor = call->tx_hard_ack;
246 top = call->tx_top;
247 ASSERT(before_eq(cursor, top));
248 if (cursor == top)
249 goto out_unlock;
250
251 /* Scan the packet list without dropping the lock and decide which of
252 * the packets in the Tx buffer we're going to resend and what the new
253 * resend timeout will be.
254 */
255 oldest = now;
256 for (seq = cursor + 1; before_eq(seq, top); seq++) {
257 ix = seq & RXRPC_RXTX_BUFF_MASK;
258 annotation = call->rxtx_annotations[ix];
259 anno_type = annotation & RXRPC_TX_ANNO_MASK;
260 annotation &= ~RXRPC_TX_ANNO_MASK;
261 if (anno_type == RXRPC_TX_ANNO_ACK)
262 continue;
263
264 skb = call->rxtx_buffer[ix];
265 rxrpc_see_skb(skb, rxrpc_skb_tx_seen);
266 sp = rxrpc_skb(skb);
267
268 if (anno_type == RXRPC_TX_ANNO_UNACK) {
269 if (ktime_after(skb->tstamp, max_age)) {
270 if (ktime_before(skb->tstamp, oldest))
271 oldest = skb->tstamp;
272 continue;
273 }
274 if (!(annotation & RXRPC_TX_ANNO_RESENT))
275 unacked++;
276 }
277
278 /* Okay, we need to retransmit a packet. */
279 call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation;
280 retrans++;
281 trace_rxrpc_retransmit(call, seq, annotation | anno_type,
282 ktime_to_ns(ktime_sub(skb->tstamp, max_age)));
283 }
284
285 call->resend_at = ktime_add_ms(oldest, rxrpc_resend_timeout);
286
287 if (unacked)
288 rxrpc_congestion_timeout(call);
289
290 /* If there was nothing that needed retransmission then it's likely
291 * that an ACK got lost somewhere. Send a ping to find out instead of
292 * retransmitting data.
293 */
294 if (!retrans) {
295 rxrpc_set_timer(call, rxrpc_timer_set_for_resend, now);
296 spin_unlock_bh(&call->lock);
297 ack_ts = ktime_sub(now, call->acks_latest_ts);
298 if (ktime_to_ns(ack_ts) < call->peer->rtt)
299 goto out;
300 rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false,
301 rxrpc_propose_ack_ping_for_lost_ack);
302 rxrpc_send_ack_packet(call, true);
303 goto out;
304 }
305
306 /* Now go through the Tx window and perform the retransmissions. We
307 * have to drop the lock for each send. If an ACK comes in whilst the
308 * lock is dropped, it may clear some of the retransmission markers for
309 * packets that it soft-ACKs.
310 */
311 for (seq = cursor + 1; before_eq(seq, top); seq++) {
312 ix = seq & RXRPC_RXTX_BUFF_MASK;
313 annotation = call->rxtx_annotations[ix];
314 anno_type = annotation & RXRPC_TX_ANNO_MASK;
315 if (anno_type != RXRPC_TX_ANNO_RETRANS)
316 continue;
317
318 skb = call->rxtx_buffer[ix];
319 rxrpc_get_skb(skb, rxrpc_skb_tx_got);
320 spin_unlock_bh(&call->lock);
321
322 if (rxrpc_send_data_packet(call, skb, true) < 0) {
323 rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
324 return;
325 }
326
327 if (rxrpc_is_client_call(call))
328 rxrpc_expose_client_call(call);
329
330 rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
331 spin_lock_bh(&call->lock);
332
333 /* We need to clear the retransmit state, but there are two
334 * things we need to be aware of: A new ACK/NAK might have been
335 * received and the packet might have been hard-ACK'd (in which
336 * case it will no longer be in the buffer).
337 */
338 if (after(seq, call->tx_hard_ack)) {
339 annotation = call->rxtx_annotations[ix];
340 anno_type = annotation & RXRPC_TX_ANNO_MASK;
341 if (anno_type == RXRPC_TX_ANNO_RETRANS ||
342 anno_type == RXRPC_TX_ANNO_NAK) {
343 annotation &= ~RXRPC_TX_ANNO_MASK;
344 annotation |= RXRPC_TX_ANNO_UNACK;
345 }
346 annotation |= RXRPC_TX_ANNO_RESENT;
347 call->rxtx_annotations[ix] = annotation;
348 }
349
350 if (after(call->tx_hard_ack, seq))
351 seq = call->tx_hard_ack;
352 }
353
354out_unlock:
355 spin_unlock_bh(&call->lock);
356out:
357 _leave("");
358}
359
360/*
361 * Handle retransmission and deferred ACK/abort generation.
362 */
363void rxrpc_process_call(struct work_struct *work)
364{
365 struct rxrpc_call *call =
366 container_of(work, struct rxrpc_call, processor);
367 ktime_t now;
368
369 rxrpc_see_call(call);
370
371 //printk("\n--------------------\n");
372 _enter("{%d,%s,%lx}",
373 call->debug_id, rxrpc_call_states[call->state], call->events);
374
375recheck_state:
376 if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
377 rxrpc_send_abort_packet(call);
378 goto recheck_state;
379 }
380
381 if (call->state == RXRPC_CALL_COMPLETE) {
382 del_timer_sync(&call->timer);
383 rxrpc_notify_socket(call);
384 goto out_put;
385 }
386
387 now = ktime_get_real();
388 if (ktime_before(call->expire_at, now)) {
389 rxrpc_abort_call("EXP", call, 0, RX_CALL_TIMEOUT, ETIME);
390 set_bit(RXRPC_CALL_EV_ABORT, &call->events);
391 goto recheck_state;
392 }
393
394 if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events)) {
395 if (call->ackr_reason) {
396 rxrpc_send_ack_packet(call, false);
397 goto recheck_state;
398 }
399 }
400
401 if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {
402 rxrpc_send_ack_packet(call, true);
403 goto recheck_state;
404 }
405
406 if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) {
407 rxrpc_resend(call, now);
408 goto recheck_state;
409 }
410
411 rxrpc_set_timer(call, rxrpc_timer_set_for_resend, now);
412
413 /* other events may have been raised since we started checking */
414 if (call->events && call->state < RXRPC_CALL_COMPLETE) {
415 __rxrpc_queue_call(call);
416 goto out;
417 }
418
419out_put:
420 rxrpc_put_call(call, rxrpc_call_put);
421out:
422 _leave("");
423}