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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// 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}