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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 * 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}