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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 unsigned long now = jiffies;
27 unsigned long ping_at = now + rxrpc_idle_ack_delay;
28
29 if (time_before(ping_at, call->ping_at)) {
30 WRITE_ONCE(call->ping_at, ping_at);
31 rxrpc_reduce_call_timer(call, ping_at, now,
32 rxrpc_timer_set_for_ping);
33 trace_rxrpc_propose_ack(call, why, RXRPC_ACK_PING, serial);
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 unsigned long expiry = rxrpc_soft_ack_delay;
44 unsigned long now = jiffies, ack_at;
45
46 call->ackr_serial = serial;
47
48 if (rxrpc_soft_ack_delay < expiry)
49 expiry = rxrpc_soft_ack_delay;
50 if (call->peer->srtt_us != 0)
51 ack_at = usecs_to_jiffies(call->peer->srtt_us >> 3);
52 else
53 ack_at = expiry;
54
55 ack_at += READ_ONCE(call->tx_backoff);
56 ack_at += now;
57 if (time_before(ack_at, call->delay_ack_at)) {
58 WRITE_ONCE(call->delay_ack_at, ack_at);
59 rxrpc_reduce_call_timer(call, ack_at, now,
60 rxrpc_timer_set_for_ack);
61 }
62
63 trace_rxrpc_propose_ack(call, why, RXRPC_ACK_DELAY, serial);
64}
65
66/*
67 * Queue an ACK for immediate transmission.
68 */
69void rxrpc_send_ACK(struct rxrpc_call *call, u8 ack_reason,
70 rxrpc_serial_t serial, enum rxrpc_propose_ack_trace why)
71{
72 struct rxrpc_txbuf *txb;
73
74 if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
75 return;
76
77 rxrpc_inc_stat(call->rxnet, stat_tx_acks[ack_reason]);
78
79 txb = rxrpc_alloc_txbuf(call, RXRPC_PACKET_TYPE_ACK,
80 rcu_read_lock_held() ? GFP_ATOMIC | __GFP_NOWARN : GFP_NOFS);
81 if (!txb) {
82 kleave(" = -ENOMEM");
83 return;
84 }
85
86 txb->ack_why = why;
87 txb->wire.seq = 0;
88 txb->wire.type = RXRPC_PACKET_TYPE_ACK;
89 txb->wire.flags |= RXRPC_SLOW_START_OK;
90 txb->ack.bufferSpace = 0;
91 txb->ack.maxSkew = 0;
92 txb->ack.firstPacket = 0;
93 txb->ack.previousPacket = 0;
94 txb->ack.serial = htonl(serial);
95 txb->ack.reason = ack_reason;
96 txb->ack.nAcks = 0;
97
98 trace_rxrpc_send_ack(call, why, ack_reason, serial);
99 rxrpc_send_ack_packet(call, txb);
100 rxrpc_put_txbuf(txb, rxrpc_txbuf_put_ack_tx);
101}
102
103/*
104 * Handle congestion being detected by the retransmit timeout.
105 */
106static void rxrpc_congestion_timeout(struct rxrpc_call *call)
107{
108 set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
109}
110
111/*
112 * Perform retransmission of NAK'd and unack'd packets.
113 */
114void rxrpc_resend(struct rxrpc_call *call, struct sk_buff *ack_skb)
115{
116 struct rxrpc_ackpacket *ack = NULL;
117 struct rxrpc_txbuf *txb;
118 unsigned long resend_at;
119 rxrpc_seq_t transmitted = READ_ONCE(call->tx_transmitted);
120 ktime_t now, max_age, oldest, ack_ts;
121 bool unacked = false;
122 unsigned int i;
123 LIST_HEAD(retrans_queue);
124
125 _enter("{%d,%d}", call->acks_hard_ack, call->tx_top);
126
127 now = ktime_get_real();
128 max_age = ktime_sub_us(now, jiffies_to_usecs(call->peer->rto_j));
129 oldest = now;
130
131 if (list_empty(&call->tx_buffer))
132 goto no_resend;
133
134 if (list_empty(&call->tx_buffer))
135 goto no_further_resend;
136
137 trace_rxrpc_resend(call, ack_skb);
138 txb = list_first_entry(&call->tx_buffer, struct rxrpc_txbuf, call_link);
139
140 /* Scan the soft ACK table without dropping the lock and resend any
141 * explicitly NAK'd packets.
142 */
143 if (ack_skb) {
144 ack = (void *)ack_skb->data + sizeof(struct rxrpc_wire_header);
145
146 for (i = 0; i < ack->nAcks; i++) {
147 rxrpc_seq_t seq;
148
149 if (ack->acks[i] & 1)
150 continue;
151 seq = ntohl(ack->firstPacket) + i;
152 if (after(txb->seq, transmitted))
153 break;
154 if (after(txb->seq, seq))
155 continue; /* A new hard ACK probably came in */
156 list_for_each_entry_from(txb, &call->tx_buffer, call_link) {
157 if (txb->seq == seq)
158 goto found_txb;
159 }
160 goto no_further_resend;
161
162 found_txb:
163 if (after(ntohl(txb->wire.serial), call->acks_highest_serial))
164 continue; /* Ack point not yet reached */
165
166 rxrpc_see_txbuf(txb, rxrpc_txbuf_see_unacked);
167
168 if (list_empty(&txb->tx_link)) {
169 list_add_tail(&txb->tx_link, &retrans_queue);
170 set_bit(RXRPC_TXBUF_RESENT, &txb->flags);
171 }
172
173 trace_rxrpc_retransmit(call, txb->seq,
174 ktime_to_ns(ktime_sub(txb->last_sent,
175 max_age)));
176
177 if (list_is_last(&txb->call_link, &call->tx_buffer))
178 goto no_further_resend;
179 txb = list_next_entry(txb, call_link);
180 }
181 }
182
183 /* Fast-forward through the Tx queue to the point the peer says it has
184 * seen. Anything between the soft-ACK table and that point will get
185 * ACK'd or NACK'd in due course, so don't worry about it here; here we
186 * need to consider retransmitting anything beyond that point.
187 *
188 * Note that ACK for a packet can beat the update of tx_transmitted.
189 */
190 if (after_eq(READ_ONCE(call->acks_prev_seq), READ_ONCE(call->tx_transmitted)))
191 goto no_further_resend;
192
193 list_for_each_entry_from(txb, &call->tx_buffer, call_link) {
194 if (before_eq(txb->seq, READ_ONCE(call->acks_prev_seq)))
195 continue;
196 if (after(txb->seq, READ_ONCE(call->tx_transmitted)))
197 break; /* Not transmitted yet */
198
199 if (ack && ack->reason == RXRPC_ACK_PING_RESPONSE &&
200 before(ntohl(txb->wire.serial), ntohl(ack->serial)))
201 goto do_resend; /* Wasn't accounted for by a more recent ping. */
202
203 if (ktime_after(txb->last_sent, max_age)) {
204 if (ktime_before(txb->last_sent, oldest))
205 oldest = txb->last_sent;
206 continue;
207 }
208
209 do_resend:
210 unacked = true;
211 if (list_empty(&txb->tx_link)) {
212 list_add_tail(&txb->tx_link, &retrans_queue);
213 set_bit(RXRPC_TXBUF_RESENT, &txb->flags);
214 rxrpc_inc_stat(call->rxnet, stat_tx_data_retrans);
215 }
216 }
217
218no_further_resend:
219no_resend:
220 resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
221 resend_at += jiffies + rxrpc_get_rto_backoff(call->peer,
222 !list_empty(&retrans_queue));
223 WRITE_ONCE(call->resend_at, resend_at);
224
225 if (unacked)
226 rxrpc_congestion_timeout(call);
227
228 /* If there was nothing that needed retransmission then it's likely
229 * that an ACK got lost somewhere. Send a ping to find out instead of
230 * retransmitting data.
231 */
232 if (list_empty(&retrans_queue)) {
233 rxrpc_reduce_call_timer(call, resend_at, jiffies,
234 rxrpc_timer_set_for_resend);
235 ack_ts = ktime_sub(now, call->acks_latest_ts);
236 if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3))
237 goto out;
238 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
239 rxrpc_propose_ack_ping_for_lost_ack);
240 goto out;
241 }
242
243 /* Retransmit the queue */
244 while ((txb = list_first_entry_or_null(&retrans_queue,
245 struct rxrpc_txbuf, tx_link))) {
246 list_del_init(&txb->tx_link);
247 rxrpc_transmit_one(call, txb);
248 }
249
250out:
251 _leave("");
252}
253
254/*
255 * Start transmitting the reply to a service. This cancels the need to ACK the
256 * request if we haven't yet done so.
257 */
258static void rxrpc_begin_service_reply(struct rxrpc_call *call)
259{
260 unsigned long now = jiffies;
261
262 rxrpc_set_call_state(call, RXRPC_CALL_SERVER_SEND_REPLY);
263 WRITE_ONCE(call->delay_ack_at, now + MAX_JIFFY_OFFSET);
264 if (call->ackr_reason == RXRPC_ACK_DELAY)
265 call->ackr_reason = 0;
266 trace_rxrpc_timer(call, rxrpc_timer_init_for_send_reply, now);
267}
268
269/*
270 * Close the transmission phase. After this point there is no more data to be
271 * transmitted in the call.
272 */
273static void rxrpc_close_tx_phase(struct rxrpc_call *call)
274{
275 _debug("________awaiting reply/ACK__________");
276
277 switch (__rxrpc_call_state(call)) {
278 case RXRPC_CALL_CLIENT_SEND_REQUEST:
279 rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_AWAIT_REPLY);
280 break;
281 case RXRPC_CALL_SERVER_SEND_REPLY:
282 rxrpc_set_call_state(call, RXRPC_CALL_SERVER_AWAIT_ACK);
283 break;
284 default:
285 break;
286 }
287}
288
289static bool rxrpc_tx_window_has_space(struct rxrpc_call *call)
290{
291 unsigned int winsize = min_t(unsigned int, call->tx_winsize,
292 call->cong_cwnd + call->cong_extra);
293 rxrpc_seq_t window = call->acks_hard_ack, wtop = window + winsize;
294 rxrpc_seq_t tx_top = call->tx_top;
295 int space;
296
297 space = wtop - tx_top;
298 return space > 0;
299}
300
301/*
302 * Decant some if the sendmsg prepared queue into the transmission buffer.
303 */
304static void rxrpc_decant_prepared_tx(struct rxrpc_call *call)
305{
306 struct rxrpc_txbuf *txb;
307
308 if (!test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
309 if (list_empty(&call->tx_sendmsg))
310 return;
311 rxrpc_expose_client_call(call);
312 }
313
314 while ((txb = list_first_entry_or_null(&call->tx_sendmsg,
315 struct rxrpc_txbuf, call_link))) {
316 spin_lock(&call->tx_lock);
317 list_del(&txb->call_link);
318 spin_unlock(&call->tx_lock);
319
320 call->tx_top = txb->seq;
321 list_add_tail(&txb->call_link, &call->tx_buffer);
322
323 if (txb->wire.flags & RXRPC_LAST_PACKET)
324 rxrpc_close_tx_phase(call);
325
326 rxrpc_transmit_one(call, txb);
327
328 if (!rxrpc_tx_window_has_space(call))
329 break;
330 }
331}
332
333static void rxrpc_transmit_some_data(struct rxrpc_call *call)
334{
335 switch (__rxrpc_call_state(call)) {
336 case RXRPC_CALL_SERVER_ACK_REQUEST:
337 if (list_empty(&call->tx_sendmsg))
338 return;
339 rxrpc_begin_service_reply(call);
340 fallthrough;
341
342 case RXRPC_CALL_SERVER_SEND_REPLY:
343 case RXRPC_CALL_CLIENT_SEND_REQUEST:
344 if (!rxrpc_tx_window_has_space(call))
345 return;
346 if (list_empty(&call->tx_sendmsg)) {
347 rxrpc_inc_stat(call->rxnet, stat_tx_data_underflow);
348 return;
349 }
350 rxrpc_decant_prepared_tx(call);
351 break;
352 default:
353 return;
354 }
355}
356
357/*
358 * Ping the other end to fill our RTT cache and to retrieve the rwind
359 * and MTU parameters.
360 */
361static void rxrpc_send_initial_ping(struct rxrpc_call *call)
362{
363 if (call->peer->rtt_count < 3 ||
364 ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000),
365 ktime_get_real()))
366 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
367 rxrpc_propose_ack_ping_for_params);
368}
369
370/*
371 * Handle retransmission and deferred ACK/abort generation.
372 */
373bool rxrpc_input_call_event(struct rxrpc_call *call, struct sk_buff *skb)
374{
375 unsigned long now, next, t;
376 rxrpc_serial_t ackr_serial;
377 bool resend = false, expired = false;
378 s32 abort_code;
379
380 rxrpc_see_call(call, rxrpc_call_see_input);
381
382 //printk("\n--------------------\n");
383 _enter("{%d,%s,%lx}",
384 call->debug_id, rxrpc_call_states[__rxrpc_call_state(call)],
385 call->events);
386
387 if (__rxrpc_call_is_complete(call))
388 goto out;
389
390 /* Handle abort request locklessly, vs rxrpc_propose_abort(). */
391 abort_code = smp_load_acquire(&call->send_abort);
392 if (abort_code) {
393 rxrpc_abort_call(call, 0, call->send_abort, call->send_abort_err,
394 call->send_abort_why);
395 goto out;
396 }
397
398 if (skb && skb->mark == RXRPC_SKB_MARK_ERROR)
399 goto out;
400
401 /* If we see our async-event poke, check for timeout trippage. */
402 now = jiffies;
403 t = READ_ONCE(call->expect_rx_by);
404 if (time_after_eq(now, t)) {
405 trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
406 expired = true;
407 }
408
409 t = READ_ONCE(call->expect_req_by);
410 if (__rxrpc_call_state(call) == RXRPC_CALL_SERVER_RECV_REQUEST &&
411 time_after_eq(now, t)) {
412 trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
413 expired = true;
414 }
415
416 t = READ_ONCE(call->expect_term_by);
417 if (time_after_eq(now, t)) {
418 trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
419 expired = true;
420 }
421
422 t = READ_ONCE(call->delay_ack_at);
423 if (time_after_eq(now, t)) {
424 trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
425 cmpxchg(&call->delay_ack_at, t, now + MAX_JIFFY_OFFSET);
426 ackr_serial = xchg(&call->ackr_serial, 0);
427 rxrpc_send_ACK(call, RXRPC_ACK_DELAY, ackr_serial,
428 rxrpc_propose_ack_ping_for_lost_ack);
429 }
430
431 t = READ_ONCE(call->ack_lost_at);
432 if (time_after_eq(now, t)) {
433 trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now);
434 cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET);
435 set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
436 }
437
438 t = READ_ONCE(call->keepalive_at);
439 if (time_after_eq(now, t)) {
440 trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now);
441 cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET);
442 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
443 rxrpc_propose_ack_ping_for_keepalive);
444 }
445
446 t = READ_ONCE(call->ping_at);
447 if (time_after_eq(now, t)) {
448 trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
449 cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
450 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
451 rxrpc_propose_ack_ping_for_keepalive);
452 }
453
454 t = READ_ONCE(call->resend_at);
455 if (time_after_eq(now, t)) {
456 trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
457 cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
458 resend = true;
459 }
460
461 if (skb)
462 rxrpc_input_call_packet(call, skb);
463
464 rxrpc_transmit_some_data(call);
465
466 if (skb) {
467 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
468
469 if (sp->hdr.type == RXRPC_PACKET_TYPE_ACK)
470 rxrpc_congestion_degrade(call);
471 }
472
473 if (test_and_clear_bit(RXRPC_CALL_EV_INITIAL_PING, &call->events))
474 rxrpc_send_initial_ping(call);
475
476 /* Process events */
477 if (expired) {
478 if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) &&
479 (int)call->conn->hi_serial - (int)call->rx_serial > 0) {
480 trace_rxrpc_call_reset(call);
481 rxrpc_abort_call(call, 0, RX_CALL_DEAD, -ECONNRESET,
482 rxrpc_abort_call_reset);
483 } else {
484 rxrpc_abort_call(call, 0, RX_CALL_TIMEOUT, -ETIME,
485 rxrpc_abort_call_timeout);
486 }
487 goto out;
488 }
489
490 if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events))
491 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
492 rxrpc_propose_ack_ping_for_lost_ack);
493
494 if (resend && __rxrpc_call_state(call) != RXRPC_CALL_CLIENT_RECV_REPLY)
495 rxrpc_resend(call, NULL);
496
497 if (test_and_clear_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags))
498 rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
499 rxrpc_propose_ack_rx_idle);
500
501 if (atomic_read(&call->ackr_nr_unacked) > 2)
502 rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
503 rxrpc_propose_ack_input_data);
504
505 /* Make sure the timer is restarted */
506 if (!__rxrpc_call_is_complete(call)) {
507 next = call->expect_rx_by;
508
509#define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }
510
511 set(call->expect_req_by);
512 set(call->expect_term_by);
513 set(call->delay_ack_at);
514 set(call->ack_lost_at);
515 set(call->resend_at);
516 set(call->keepalive_at);
517 set(call->ping_at);
518
519 now = jiffies;
520 if (time_after_eq(now, next))
521 rxrpc_poke_call(call, rxrpc_call_poke_timer_now);
522
523 rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
524 }
525
526out:
527 if (__rxrpc_call_is_complete(call)) {
528 del_timer_sync(&call->timer);
529 if (!test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
530 rxrpc_disconnect_call(call);
531 if (call->security)
532 call->security->free_call_crypto(call);
533 }
534 if (call->acks_hard_ack != call->tx_bottom)
535 rxrpc_shrink_call_tx_buffer(call);
536 _leave("");
537 return true;
538}
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 * Propose a PING ACK be sent.
26 */
27static void rxrpc_propose_ping(struct rxrpc_call *call,
28 bool immediate, bool background)
29{
30 if (immediate) {
31 if (background &&
32 !test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
33 rxrpc_queue_call(call);
34 } else {
35 unsigned long now = jiffies;
36 unsigned long ping_at = now + rxrpc_idle_ack_delay;
37
38 if (time_before(ping_at, call->ping_at)) {
39 WRITE_ONCE(call->ping_at, ping_at);
40 rxrpc_reduce_call_timer(call, ping_at, now,
41 rxrpc_timer_set_for_ping);
42 }
43 }
44}
45
46/*
47 * propose an ACK be sent
48 */
49static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
50 u16 skew, u32 serial, bool immediate,
51 bool background,
52 enum rxrpc_propose_ack_trace why)
53{
54 enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
55 unsigned long expiry = rxrpc_soft_ack_delay;
56 s8 prior = rxrpc_ack_priority[ack_reason];
57
58 /* Pings are handled specially because we don't want to accidentally
59 * lose a ping response by subsuming it into a ping.
60 */
61 if (ack_reason == RXRPC_ACK_PING) {
62 rxrpc_propose_ping(call, immediate, background);
63 goto trace;
64 }
65
66 /* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
67 * numbers, but we don't alter the timeout.
68 */
69 _debug("prior %u %u vs %u %u",
70 ack_reason, prior,
71 call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]);
72 if (ack_reason == call->ackr_reason) {
73 if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) {
74 outcome = rxrpc_propose_ack_update;
75 call->ackr_serial = serial;
76 call->ackr_skew = skew;
77 }
78 if (!immediate)
79 goto trace;
80 } else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
81 call->ackr_reason = ack_reason;
82 call->ackr_serial = serial;
83 call->ackr_skew = skew;
84 } else {
85 outcome = rxrpc_propose_ack_subsume;
86 }
87
88 switch (ack_reason) {
89 case RXRPC_ACK_REQUESTED:
90 if (rxrpc_requested_ack_delay < expiry)
91 expiry = rxrpc_requested_ack_delay;
92 if (serial == 1)
93 immediate = false;
94 break;
95
96 case RXRPC_ACK_DELAY:
97 if (rxrpc_soft_ack_delay < expiry)
98 expiry = rxrpc_soft_ack_delay;
99 break;
100
101 case RXRPC_ACK_IDLE:
102 if (rxrpc_idle_ack_delay < expiry)
103 expiry = rxrpc_idle_ack_delay;
104 break;
105
106 default:
107 immediate = true;
108 break;
109 }
110
111 if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) {
112 _debug("already scheduled");
113 } else if (immediate || expiry == 0) {
114 _debug("immediate ACK %lx", call->events);
115 if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) &&
116 background)
117 rxrpc_queue_call(call);
118 } else {
119 unsigned long now = jiffies, ack_at;
120
121 if (call->peer->rtt_usage > 0)
122 ack_at = nsecs_to_jiffies(call->peer->rtt);
123 else
124 ack_at = expiry;
125
126 ack_at += now;
127 if (time_before(ack_at, call->ack_at)) {
128 WRITE_ONCE(call->ack_at, ack_at);
129 rxrpc_reduce_call_timer(call, ack_at, now,
130 rxrpc_timer_set_for_ack);
131 }
132 }
133
134trace:
135 trace_rxrpc_propose_ack(call, why, ack_reason, serial, immediate,
136 background, outcome);
137}
138
139/*
140 * propose an ACK be sent, locking the call structure
141 */
142void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
143 u16 skew, u32 serial, bool immediate, bool background,
144 enum rxrpc_propose_ack_trace why)
145{
146 spin_lock_bh(&call->lock);
147 __rxrpc_propose_ACK(call, ack_reason, skew, serial,
148 immediate, background, why);
149 spin_unlock_bh(&call->lock);
150}
151
152/*
153 * Handle congestion being detected by the retransmit timeout.
154 */
155static void rxrpc_congestion_timeout(struct rxrpc_call *call)
156{
157 set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
158}
159
160/*
161 * Perform retransmission of NAK'd and unack'd packets.
162 */
163static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
164{
165 struct rxrpc_skb_priv *sp;
166 struct sk_buff *skb;
167 unsigned long resend_at;
168 rxrpc_seq_t cursor, seq, top;
169 ktime_t now, max_age, oldest, ack_ts, timeout, min_timeo;
170 int ix;
171 u8 annotation, anno_type, retrans = 0, unacked = 0;
172
173 _enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
174
175 if (call->peer->rtt_usage > 1)
176 timeout = ns_to_ktime(call->peer->rtt * 3 / 2);
177 else
178 timeout = ms_to_ktime(rxrpc_resend_timeout);
179 min_timeo = ns_to_ktime((1000000000 / HZ) * 4);
180 if (ktime_before(timeout, min_timeo))
181 timeout = min_timeo;
182
183 now = ktime_get_real();
184 max_age = ktime_sub(now, timeout);
185
186 spin_lock_bh(&call->lock);
187
188 cursor = call->tx_hard_ack;
189 top = call->tx_top;
190 ASSERT(before_eq(cursor, top));
191 if (cursor == top)
192 goto out_unlock;
193
194 /* Scan the packet list without dropping the lock and decide which of
195 * the packets in the Tx buffer we're going to resend and what the new
196 * resend timeout will be.
197 */
198 trace_rxrpc_resend(call, (cursor + 1) & RXRPC_RXTX_BUFF_MASK);
199 oldest = now;
200 for (seq = cursor + 1; before_eq(seq, top); seq++) {
201 ix = seq & RXRPC_RXTX_BUFF_MASK;
202 annotation = call->rxtx_annotations[ix];
203 anno_type = annotation & RXRPC_TX_ANNO_MASK;
204 annotation &= ~RXRPC_TX_ANNO_MASK;
205 if (anno_type == RXRPC_TX_ANNO_ACK)
206 continue;
207
208 skb = call->rxtx_buffer[ix];
209 rxrpc_see_skb(skb, rxrpc_skb_tx_seen);
210 sp = rxrpc_skb(skb);
211
212 if (anno_type == RXRPC_TX_ANNO_UNACK) {
213 if (ktime_after(skb->tstamp, max_age)) {
214 if (ktime_before(skb->tstamp, oldest))
215 oldest = skb->tstamp;
216 continue;
217 }
218 if (!(annotation & RXRPC_TX_ANNO_RESENT))
219 unacked++;
220 }
221
222 /* Okay, we need to retransmit a packet. */
223 call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation;
224 retrans++;
225 trace_rxrpc_retransmit(call, seq, annotation | anno_type,
226 ktime_to_ns(ktime_sub(skb->tstamp, max_age)));
227 }
228
229 resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
230 resend_at += jiffies + rxrpc_resend_timeout;
231 WRITE_ONCE(call->resend_at, resend_at);
232
233 if (unacked)
234 rxrpc_congestion_timeout(call);
235
236 /* If there was nothing that needed retransmission then it's likely
237 * that an ACK got lost somewhere. Send a ping to find out instead of
238 * retransmitting data.
239 */
240 if (!retrans) {
241 rxrpc_reduce_call_timer(call, resend_at, now_j,
242 rxrpc_timer_set_for_resend);
243 spin_unlock_bh(&call->lock);
244 ack_ts = ktime_sub(now, call->acks_latest_ts);
245 if (ktime_to_ns(ack_ts) < call->peer->rtt)
246 goto out;
247 rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false,
248 rxrpc_propose_ack_ping_for_lost_ack);
249 rxrpc_send_ack_packet(call, true, NULL);
250 goto out;
251 }
252
253 /* Now go through the Tx window and perform the retransmissions. We
254 * have to drop the lock for each send. If an ACK comes in whilst the
255 * lock is dropped, it may clear some of the retransmission markers for
256 * packets that it soft-ACKs.
257 */
258 for (seq = cursor + 1; before_eq(seq, top); seq++) {
259 ix = seq & RXRPC_RXTX_BUFF_MASK;
260 annotation = call->rxtx_annotations[ix];
261 anno_type = annotation & RXRPC_TX_ANNO_MASK;
262 if (anno_type != RXRPC_TX_ANNO_RETRANS)
263 continue;
264
265 skb = call->rxtx_buffer[ix];
266 rxrpc_get_skb(skb, rxrpc_skb_tx_got);
267 spin_unlock_bh(&call->lock);
268
269 if (rxrpc_send_data_packet(call, skb, true) < 0) {
270 rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
271 return;
272 }
273
274 if (rxrpc_is_client_call(call))
275 rxrpc_expose_client_call(call);
276
277 rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
278 spin_lock_bh(&call->lock);
279
280 /* We need to clear the retransmit state, but there are two
281 * things we need to be aware of: A new ACK/NAK might have been
282 * received and the packet might have been hard-ACK'd (in which
283 * case it will no longer be in the buffer).
284 */
285 if (after(seq, call->tx_hard_ack)) {
286 annotation = call->rxtx_annotations[ix];
287 anno_type = annotation & RXRPC_TX_ANNO_MASK;
288 if (anno_type == RXRPC_TX_ANNO_RETRANS ||
289 anno_type == RXRPC_TX_ANNO_NAK) {
290 annotation &= ~RXRPC_TX_ANNO_MASK;
291 annotation |= RXRPC_TX_ANNO_UNACK;
292 }
293 annotation |= RXRPC_TX_ANNO_RESENT;
294 call->rxtx_annotations[ix] = annotation;
295 }
296
297 if (after(call->tx_hard_ack, seq))
298 seq = call->tx_hard_ack;
299 }
300
301out_unlock:
302 spin_unlock_bh(&call->lock);
303out:
304 _leave("");
305}
306
307/*
308 * Handle retransmission and deferred ACK/abort generation.
309 */
310void rxrpc_process_call(struct work_struct *work)
311{
312 struct rxrpc_call *call =
313 container_of(work, struct rxrpc_call, processor);
314 rxrpc_serial_t *send_ack;
315 unsigned long now, next, t;
316
317 rxrpc_see_call(call);
318
319 //printk("\n--------------------\n");
320 _enter("{%d,%s,%lx}",
321 call->debug_id, rxrpc_call_states[call->state], call->events);
322
323recheck_state:
324 if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
325 rxrpc_send_abort_packet(call);
326 goto recheck_state;
327 }
328
329 if (call->state == RXRPC_CALL_COMPLETE) {
330 del_timer_sync(&call->timer);
331 rxrpc_notify_socket(call);
332 goto out_put;
333 }
334
335 /* Work out if any timeouts tripped */
336 now = jiffies;
337 t = READ_ONCE(call->expect_rx_by);
338 if (time_after_eq(now, t)) {
339 trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
340 set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
341 }
342
343 t = READ_ONCE(call->expect_req_by);
344 if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST &&
345 time_after_eq(now, t)) {
346 trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
347 set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
348 }
349
350 t = READ_ONCE(call->expect_term_by);
351 if (time_after_eq(now, t)) {
352 trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
353 set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
354 }
355
356 t = READ_ONCE(call->ack_at);
357 if (time_after_eq(now, t)) {
358 trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
359 cmpxchg(&call->ack_at, t, now + MAX_JIFFY_OFFSET);
360 set_bit(RXRPC_CALL_EV_ACK, &call->events);
361 }
362
363 t = READ_ONCE(call->ack_lost_at);
364 if (time_after_eq(now, t)) {
365 trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now);
366 cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET);
367 set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
368 }
369
370 t = READ_ONCE(call->keepalive_at);
371 if (time_after_eq(now, t)) {
372 trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now);
373 cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET);
374 rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, true,
375 rxrpc_propose_ack_ping_for_keepalive);
376 set_bit(RXRPC_CALL_EV_PING, &call->events);
377 }
378
379 t = READ_ONCE(call->ping_at);
380 if (time_after_eq(now, t)) {
381 trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
382 cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
383 set_bit(RXRPC_CALL_EV_PING, &call->events);
384 }
385
386 t = READ_ONCE(call->resend_at);
387 if (time_after_eq(now, t)) {
388 trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
389 cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
390 set_bit(RXRPC_CALL_EV_RESEND, &call->events);
391 }
392
393 /* Process events */
394 if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED, &call->events)) {
395 rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ETIME);
396 set_bit(RXRPC_CALL_EV_ABORT, &call->events);
397 goto recheck_state;
398 }
399
400 send_ack = NULL;
401 if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events)) {
402 call->acks_lost_top = call->tx_top;
403 rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false,
404 rxrpc_propose_ack_ping_for_lost_ack);
405 send_ack = &call->acks_lost_ping;
406 }
407
408 if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) ||
409 send_ack) {
410 if (call->ackr_reason) {
411 rxrpc_send_ack_packet(call, false, send_ack);
412 goto recheck_state;
413 }
414 }
415
416 if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {
417 rxrpc_send_ack_packet(call, true, NULL);
418 goto recheck_state;
419 }
420
421 if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) {
422 rxrpc_resend(call, now);
423 goto recheck_state;
424 }
425
426 /* Make sure the timer is restarted */
427 next = call->expect_rx_by;
428
429#define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }
430
431 set(call->expect_req_by);
432 set(call->expect_term_by);
433 set(call->ack_at);
434 set(call->ack_lost_at);
435 set(call->resend_at);
436 set(call->keepalive_at);
437 set(call->ping_at);
438
439 now = jiffies;
440 if (time_after_eq(now, next))
441 goto recheck_state;
442
443 rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
444
445 /* other events may have been raised since we started checking */
446 if (call->events && call->state < RXRPC_CALL_COMPLETE) {
447 __rxrpc_queue_call(call);
448 goto out;
449 }
450
451out_put:
452 rxrpc_put_call(call, rxrpc_call_put);
453out:
454 _leave("");
455}