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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Processing of received RxRPC packets
3 *
4 * Copyright (C) 2020 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 "ar-internal.h"
11
12static void rxrpc_proto_abort(struct rxrpc_call *call, rxrpc_seq_t seq,
13 enum rxrpc_abort_reason why)
14{
15 rxrpc_abort_call(call, seq, RX_PROTOCOL_ERROR, -EBADMSG, why);
16}
17
18/*
19 * Do TCP-style congestion management [RFC 5681].
20 */
21static void rxrpc_congestion_management(struct rxrpc_call *call,
22 struct sk_buff *skb,
23 struct rxrpc_ack_summary *summary,
24 rxrpc_serial_t acked_serial)
25{
26 enum rxrpc_congest_change change = rxrpc_cong_no_change;
27 unsigned int cumulative_acks = call->cong_cumul_acks;
28 unsigned int cwnd = call->cong_cwnd;
29 bool resend = false;
30
31 summary->flight_size =
32 (call->tx_top - call->acks_hard_ack) - summary->nr_acks;
33
34 if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
35 summary->retrans_timeo = true;
36 call->cong_ssthresh = max_t(unsigned int,
37 summary->flight_size / 2, 2);
38 cwnd = 1;
39 if (cwnd >= call->cong_ssthresh &&
40 call->cong_mode == RXRPC_CALL_SLOW_START) {
41 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
42 call->cong_tstamp = skb->tstamp;
43 cumulative_acks = 0;
44 }
45 }
46
47 cumulative_acks += summary->nr_new_acks;
48 cumulative_acks += summary->nr_rot_new_acks;
49 if (cumulative_acks > 255)
50 cumulative_acks = 255;
51
52 summary->mode = call->cong_mode;
53 summary->cwnd = call->cong_cwnd;
54 summary->ssthresh = call->cong_ssthresh;
55 summary->cumulative_acks = cumulative_acks;
56 summary->dup_acks = call->cong_dup_acks;
57
58 switch (call->cong_mode) {
59 case RXRPC_CALL_SLOW_START:
60 if (summary->saw_nacks)
61 goto packet_loss_detected;
62 if (summary->cumulative_acks > 0)
63 cwnd += 1;
64 if (cwnd >= call->cong_ssthresh) {
65 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
66 call->cong_tstamp = skb->tstamp;
67 }
68 goto out;
69
70 case RXRPC_CALL_CONGEST_AVOIDANCE:
71 if (summary->saw_nacks)
72 goto packet_loss_detected;
73
74 /* We analyse the number of packets that get ACK'd per RTT
75 * period and increase the window if we managed to fill it.
76 */
77 if (call->peer->rtt_count == 0)
78 goto out;
79 if (ktime_before(skb->tstamp,
80 ktime_add_us(call->cong_tstamp,
81 call->peer->srtt_us >> 3)))
82 goto out_no_clear_ca;
83 change = rxrpc_cong_rtt_window_end;
84 call->cong_tstamp = skb->tstamp;
85 if (cumulative_acks >= cwnd)
86 cwnd++;
87 goto out;
88
89 case RXRPC_CALL_PACKET_LOSS:
90 if (!summary->saw_nacks)
91 goto resume_normality;
92
93 if (summary->new_low_nack) {
94 change = rxrpc_cong_new_low_nack;
95 call->cong_dup_acks = 1;
96 if (call->cong_extra > 1)
97 call->cong_extra = 1;
98 goto send_extra_data;
99 }
100
101 call->cong_dup_acks++;
102 if (call->cong_dup_acks < 3)
103 goto send_extra_data;
104
105 change = rxrpc_cong_begin_retransmission;
106 call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT;
107 call->cong_ssthresh = max_t(unsigned int,
108 summary->flight_size / 2, 2);
109 cwnd = call->cong_ssthresh + 3;
110 call->cong_extra = 0;
111 call->cong_dup_acks = 0;
112 resend = true;
113 goto out;
114
115 case RXRPC_CALL_FAST_RETRANSMIT:
116 if (!summary->new_low_nack) {
117 if (summary->nr_new_acks == 0)
118 cwnd += 1;
119 call->cong_dup_acks++;
120 if (call->cong_dup_acks == 2) {
121 change = rxrpc_cong_retransmit_again;
122 call->cong_dup_acks = 0;
123 resend = true;
124 }
125 } else {
126 change = rxrpc_cong_progress;
127 cwnd = call->cong_ssthresh;
128 if (!summary->saw_nacks)
129 goto resume_normality;
130 }
131 goto out;
132
133 default:
134 BUG();
135 goto out;
136 }
137
138resume_normality:
139 change = rxrpc_cong_cleared_nacks;
140 call->cong_dup_acks = 0;
141 call->cong_extra = 0;
142 call->cong_tstamp = skb->tstamp;
143 if (cwnd < call->cong_ssthresh)
144 call->cong_mode = RXRPC_CALL_SLOW_START;
145 else
146 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
147out:
148 cumulative_acks = 0;
149out_no_clear_ca:
150 if (cwnd >= RXRPC_TX_MAX_WINDOW)
151 cwnd = RXRPC_TX_MAX_WINDOW;
152 call->cong_cwnd = cwnd;
153 call->cong_cumul_acks = cumulative_acks;
154 trace_rxrpc_congest(call, summary, acked_serial, change);
155 if (resend)
156 rxrpc_resend(call, skb);
157 return;
158
159packet_loss_detected:
160 change = rxrpc_cong_saw_nack;
161 call->cong_mode = RXRPC_CALL_PACKET_LOSS;
162 call->cong_dup_acks = 0;
163 goto send_extra_data;
164
165send_extra_data:
166 /* Send some previously unsent DATA if we have some to advance the ACK
167 * state.
168 */
169 if (test_bit(RXRPC_CALL_TX_LAST, &call->flags) ||
170 summary->nr_acks != call->tx_top - call->acks_hard_ack) {
171 call->cong_extra++;
172 wake_up(&call->waitq);
173 }
174 goto out_no_clear_ca;
175}
176
177/*
178 * Degrade the congestion window if we haven't transmitted a packet for >1RTT.
179 */
180void rxrpc_congestion_degrade(struct rxrpc_call *call)
181{
182 ktime_t rtt, now;
183
184 if (call->cong_mode != RXRPC_CALL_SLOW_START &&
185 call->cong_mode != RXRPC_CALL_CONGEST_AVOIDANCE)
186 return;
187 if (__rxrpc_call_state(call) == RXRPC_CALL_CLIENT_AWAIT_REPLY)
188 return;
189
190 rtt = ns_to_ktime(call->peer->srtt_us * (1000 / 8));
191 now = ktime_get_real();
192 if (!ktime_before(ktime_add(call->tx_last_sent, rtt), now))
193 return;
194
195 trace_rxrpc_reset_cwnd(call, now);
196 rxrpc_inc_stat(call->rxnet, stat_tx_data_cwnd_reset);
197 call->tx_last_sent = now;
198 call->cong_mode = RXRPC_CALL_SLOW_START;
199 call->cong_ssthresh = max_t(unsigned int, call->cong_ssthresh,
200 call->cong_cwnd * 3 / 4);
201 call->cong_cwnd = max_t(unsigned int, call->cong_cwnd / 2, RXRPC_MIN_CWND);
202}
203
204/*
205 * Apply a hard ACK by advancing the Tx window.
206 */
207static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
208 struct rxrpc_ack_summary *summary)
209{
210 struct rxrpc_txbuf *txb;
211 bool rot_last = false;
212
213 list_for_each_entry_rcu(txb, &call->tx_buffer, call_link, false) {
214 if (before_eq(txb->seq, call->acks_hard_ack))
215 continue;
216 summary->nr_rot_new_acks++;
217 if (test_bit(RXRPC_TXBUF_LAST, &txb->flags)) {
218 set_bit(RXRPC_CALL_TX_LAST, &call->flags);
219 rot_last = true;
220 }
221 if (txb->seq == to)
222 break;
223 }
224
225 if (rot_last)
226 set_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags);
227
228 _enter("%x,%x,%x,%d", to, call->acks_hard_ack, call->tx_top, rot_last);
229
230 if (call->acks_lowest_nak == call->acks_hard_ack) {
231 call->acks_lowest_nak = to;
232 } else if (after(to, call->acks_lowest_nak)) {
233 summary->new_low_nack = true;
234 call->acks_lowest_nak = to;
235 }
236
237 smp_store_release(&call->acks_hard_ack, to);
238
239 trace_rxrpc_txqueue(call, (rot_last ?
240 rxrpc_txqueue_rotate_last :
241 rxrpc_txqueue_rotate));
242 wake_up(&call->waitq);
243 return rot_last;
244}
245
246/*
247 * End the transmission phase of a call.
248 *
249 * This occurs when we get an ACKALL packet, the first DATA packet of a reply,
250 * or a final ACK packet.
251 */
252static void rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
253 enum rxrpc_abort_reason abort_why)
254{
255 ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
256
257 switch (__rxrpc_call_state(call)) {
258 case RXRPC_CALL_CLIENT_SEND_REQUEST:
259 case RXRPC_CALL_CLIENT_AWAIT_REPLY:
260 if (reply_begun) {
261 rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_RECV_REPLY);
262 trace_rxrpc_txqueue(call, rxrpc_txqueue_end);
263 break;
264 }
265
266 rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_AWAIT_REPLY);
267 trace_rxrpc_txqueue(call, rxrpc_txqueue_await_reply);
268 break;
269
270 case RXRPC_CALL_SERVER_AWAIT_ACK:
271 rxrpc_call_completed(call);
272 trace_rxrpc_txqueue(call, rxrpc_txqueue_end);
273 break;
274
275 default:
276 kdebug("end_tx %s", rxrpc_call_states[__rxrpc_call_state(call)]);
277 rxrpc_proto_abort(call, call->tx_top, abort_why);
278 break;
279 }
280}
281
282/*
283 * Begin the reply reception phase of a call.
284 */
285static bool rxrpc_receiving_reply(struct rxrpc_call *call)
286{
287 struct rxrpc_ack_summary summary = { 0 };
288 unsigned long now, timo;
289 rxrpc_seq_t top = READ_ONCE(call->tx_top);
290
291 if (call->ackr_reason) {
292 now = jiffies;
293 timo = now + MAX_JIFFY_OFFSET;
294
295 WRITE_ONCE(call->delay_ack_at, timo);
296 trace_rxrpc_timer(call, rxrpc_timer_init_for_reply, now);
297 }
298
299 if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
300 if (!rxrpc_rotate_tx_window(call, top, &summary)) {
301 rxrpc_proto_abort(call, top, rxrpc_eproto_early_reply);
302 return false;
303 }
304 }
305
306 rxrpc_end_tx_phase(call, true, rxrpc_eproto_unexpected_reply);
307 return true;
308}
309
310/*
311 * End the packet reception phase.
312 */
313static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
314{
315 rxrpc_seq_t whigh = READ_ONCE(call->rx_highest_seq);
316
317 _enter("%d,%s", call->debug_id, rxrpc_call_states[__rxrpc_call_state(call)]);
318
319 trace_rxrpc_receive(call, rxrpc_receive_end, 0, whigh);
320
321 switch (__rxrpc_call_state(call)) {
322 case RXRPC_CALL_CLIENT_RECV_REPLY:
323 rxrpc_propose_delay_ACK(call, serial, rxrpc_propose_ack_terminal_ack);
324 rxrpc_call_completed(call);
325 break;
326
327 case RXRPC_CALL_SERVER_RECV_REQUEST:
328 rxrpc_set_call_state(call, RXRPC_CALL_SERVER_ACK_REQUEST);
329 call->expect_req_by = jiffies + MAX_JIFFY_OFFSET;
330 rxrpc_propose_delay_ACK(call, serial, rxrpc_propose_ack_processing_op);
331 break;
332
333 default:
334 break;
335 }
336}
337
338static void rxrpc_input_update_ack_window(struct rxrpc_call *call,
339 rxrpc_seq_t window, rxrpc_seq_t wtop)
340{
341 atomic64_set_release(&call->ackr_window, ((u64)wtop) << 32 | window);
342}
343
344/*
345 * Push a DATA packet onto the Rx queue.
346 */
347static void rxrpc_input_queue_data(struct rxrpc_call *call, struct sk_buff *skb,
348 rxrpc_seq_t window, rxrpc_seq_t wtop,
349 enum rxrpc_receive_trace why)
350{
351 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
352 bool last = sp->hdr.flags & RXRPC_LAST_PACKET;
353
354 __skb_queue_tail(&call->recvmsg_queue, skb);
355 rxrpc_input_update_ack_window(call, window, wtop);
356 trace_rxrpc_receive(call, last ? why + 1 : why, sp->hdr.serial, sp->hdr.seq);
357 if (last)
358 rxrpc_end_rx_phase(call, sp->hdr.serial);
359}
360
361/*
362 * Process a DATA packet.
363 */
364static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb,
365 bool *_notify)
366{
367 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
368 struct sk_buff *oos;
369 rxrpc_serial_t serial = sp->hdr.serial;
370 u64 win = atomic64_read(&call->ackr_window);
371 rxrpc_seq_t window = lower_32_bits(win);
372 rxrpc_seq_t wtop = upper_32_bits(win);
373 rxrpc_seq_t wlimit = window + call->rx_winsize - 1;
374 rxrpc_seq_t seq = sp->hdr.seq;
375 bool last = sp->hdr.flags & RXRPC_LAST_PACKET;
376 int ack_reason = -1;
377
378 rxrpc_inc_stat(call->rxnet, stat_rx_data);
379 if (sp->hdr.flags & RXRPC_REQUEST_ACK)
380 rxrpc_inc_stat(call->rxnet, stat_rx_data_reqack);
381 if (sp->hdr.flags & RXRPC_JUMBO_PACKET)
382 rxrpc_inc_stat(call->rxnet, stat_rx_data_jumbo);
383
384 if (last) {
385 if (test_and_set_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
386 seq + 1 != wtop)
387 return rxrpc_proto_abort(call, seq, rxrpc_eproto_different_last);
388 } else {
389 if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
390 after_eq(seq, wtop)) {
391 pr_warn("Packet beyond last: c=%x q=%x window=%x-%x wlimit=%x\n",
392 call->debug_id, seq, window, wtop, wlimit);
393 return rxrpc_proto_abort(call, seq, rxrpc_eproto_data_after_last);
394 }
395 }
396
397 if (after(seq, call->rx_highest_seq))
398 call->rx_highest_seq = seq;
399
400 trace_rxrpc_rx_data(call->debug_id, seq, serial, sp->hdr.flags);
401
402 if (before(seq, window)) {
403 ack_reason = RXRPC_ACK_DUPLICATE;
404 goto send_ack;
405 }
406 if (after(seq, wlimit)) {
407 ack_reason = RXRPC_ACK_EXCEEDS_WINDOW;
408 goto send_ack;
409 }
410
411 /* Queue the packet. */
412 if (seq == window) {
413 rxrpc_seq_t reset_from;
414 bool reset_sack = false;
415
416 if (sp->hdr.flags & RXRPC_REQUEST_ACK)
417 ack_reason = RXRPC_ACK_REQUESTED;
418 /* Send an immediate ACK if we fill in a hole */
419 else if (!skb_queue_empty(&call->rx_oos_queue))
420 ack_reason = RXRPC_ACK_DELAY;
421 else
422 atomic_inc_return(&call->ackr_nr_unacked);
423
424 window++;
425 if (after(window, wtop))
426 wtop = window;
427
428 rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg);
429
430 spin_lock(&call->recvmsg_queue.lock);
431 rxrpc_input_queue_data(call, skb, window, wtop, rxrpc_receive_queue);
432 *_notify = true;
433
434 while ((oos = skb_peek(&call->rx_oos_queue))) {
435 struct rxrpc_skb_priv *osp = rxrpc_skb(oos);
436
437 if (after(osp->hdr.seq, window))
438 break;
439
440 __skb_unlink(oos, &call->rx_oos_queue);
441 last = osp->hdr.flags & RXRPC_LAST_PACKET;
442 seq = osp->hdr.seq;
443 if (!reset_sack) {
444 reset_from = seq;
445 reset_sack = true;
446 }
447
448 window++;
449 rxrpc_input_queue_data(call, oos, window, wtop,
450 rxrpc_receive_queue_oos);
451 }
452
453 spin_unlock(&call->recvmsg_queue.lock);
454
455 if (reset_sack) {
456 do {
457 call->ackr_sack_table[reset_from % RXRPC_SACK_SIZE] = 0;
458 } while (reset_from++, before(reset_from, window));
459 }
460 } else {
461 bool keep = false;
462
463 ack_reason = RXRPC_ACK_OUT_OF_SEQUENCE;
464
465 if (!call->ackr_sack_table[seq % RXRPC_SACK_SIZE]) {
466 call->ackr_sack_table[seq % RXRPC_SACK_SIZE] = 1;
467 keep = 1;
468 }
469
470 if (after(seq + 1, wtop)) {
471 wtop = seq + 1;
472 rxrpc_input_update_ack_window(call, window, wtop);
473 }
474
475 if (!keep) {
476 ack_reason = RXRPC_ACK_DUPLICATE;
477 goto send_ack;
478 }
479
480 skb_queue_walk(&call->rx_oos_queue, oos) {
481 struct rxrpc_skb_priv *osp = rxrpc_skb(oos);
482
483 if (after(osp->hdr.seq, seq)) {
484 rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg_oos);
485 __skb_queue_before(&call->rx_oos_queue, oos, skb);
486 goto oos_queued;
487 }
488 }
489
490 rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg_oos);
491 __skb_queue_tail(&call->rx_oos_queue, skb);
492 oos_queued:
493 trace_rxrpc_receive(call, last ? rxrpc_receive_oos_last : rxrpc_receive_oos,
494 sp->hdr.serial, sp->hdr.seq);
495 }
496
497send_ack:
498 if (ack_reason >= 0)
499 rxrpc_send_ACK(call, ack_reason, serial,
500 rxrpc_propose_ack_input_data);
501 else
502 rxrpc_propose_delay_ACK(call, serial,
503 rxrpc_propose_ack_input_data);
504}
505
506/*
507 * Split a jumbo packet and file the bits separately.
508 */
509static bool rxrpc_input_split_jumbo(struct rxrpc_call *call, struct sk_buff *skb)
510{
511 struct rxrpc_jumbo_header jhdr;
512 struct rxrpc_skb_priv *sp = rxrpc_skb(skb), *jsp;
513 struct sk_buff *jskb;
514 unsigned int offset = sizeof(struct rxrpc_wire_header);
515 unsigned int len = skb->len - offset;
516 bool notify = false;
517
518 while (sp->hdr.flags & RXRPC_JUMBO_PACKET) {
519 if (len < RXRPC_JUMBO_SUBPKTLEN)
520 goto protocol_error;
521 if (sp->hdr.flags & RXRPC_LAST_PACKET)
522 goto protocol_error;
523 if (skb_copy_bits(skb, offset + RXRPC_JUMBO_DATALEN,
524 &jhdr, sizeof(jhdr)) < 0)
525 goto protocol_error;
526
527 jskb = skb_clone(skb, GFP_NOFS);
528 if (!jskb) {
529 kdebug("couldn't clone");
530 return false;
531 }
532 rxrpc_new_skb(jskb, rxrpc_skb_new_jumbo_subpacket);
533 jsp = rxrpc_skb(jskb);
534 jsp->offset = offset;
535 jsp->len = RXRPC_JUMBO_DATALEN;
536 rxrpc_input_data_one(call, jskb, ¬ify);
537 rxrpc_free_skb(jskb, rxrpc_skb_put_jumbo_subpacket);
538
539 sp->hdr.flags = jhdr.flags;
540 sp->hdr._rsvd = ntohs(jhdr._rsvd);
541 sp->hdr.seq++;
542 sp->hdr.serial++;
543 offset += RXRPC_JUMBO_SUBPKTLEN;
544 len -= RXRPC_JUMBO_SUBPKTLEN;
545 }
546
547 sp->offset = offset;
548 sp->len = len;
549 rxrpc_input_data_one(call, skb, ¬ify);
550 if (notify) {
551 trace_rxrpc_notify_socket(call->debug_id, sp->hdr.serial);
552 rxrpc_notify_socket(call);
553 }
554 return true;
555
556protocol_error:
557 return false;
558}
559
560/*
561 * Process a DATA packet, adding the packet to the Rx ring. The caller's
562 * packet ref must be passed on or discarded.
563 */
564static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
565{
566 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
567 rxrpc_serial_t serial = sp->hdr.serial;
568 rxrpc_seq_t seq0 = sp->hdr.seq;
569
570 _enter("{%llx,%x},{%u,%x}",
571 atomic64_read(&call->ackr_window), call->rx_highest_seq,
572 skb->len, seq0);
573
574 if (__rxrpc_call_is_complete(call))
575 return;
576
577 switch (__rxrpc_call_state(call)) {
578 case RXRPC_CALL_CLIENT_SEND_REQUEST:
579 case RXRPC_CALL_CLIENT_AWAIT_REPLY:
580 /* Received data implicitly ACKs all of the request
581 * packets we sent when we're acting as a client.
582 */
583 if (!rxrpc_receiving_reply(call))
584 goto out_notify;
585 break;
586
587 case RXRPC_CALL_SERVER_RECV_REQUEST: {
588 unsigned long timo = READ_ONCE(call->next_req_timo);
589 unsigned long now, expect_req_by;
590
591 if (timo) {
592 now = jiffies;
593 expect_req_by = now + timo;
594 WRITE_ONCE(call->expect_req_by, expect_req_by);
595 rxrpc_reduce_call_timer(call, expect_req_by, now,
596 rxrpc_timer_set_for_idle);
597 }
598 break;
599 }
600
601 default:
602 break;
603 }
604
605 if (!rxrpc_input_split_jumbo(call, skb)) {
606 rxrpc_proto_abort(call, sp->hdr.seq, rxrpc_badmsg_bad_jumbo);
607 goto out_notify;
608 }
609 skb = NULL;
610
611out_notify:
612 trace_rxrpc_notify_socket(call->debug_id, serial);
613 rxrpc_notify_socket(call);
614 _leave(" [queued]");
615}
616
617/*
618 * See if there's a cached RTT probe to complete.
619 */
620static void rxrpc_complete_rtt_probe(struct rxrpc_call *call,
621 ktime_t resp_time,
622 rxrpc_serial_t acked_serial,
623 rxrpc_serial_t ack_serial,
624 enum rxrpc_rtt_rx_trace type)
625{
626 rxrpc_serial_t orig_serial;
627 unsigned long avail;
628 ktime_t sent_at;
629 bool matched = false;
630 int i;
631
632 avail = READ_ONCE(call->rtt_avail);
633 smp_rmb(); /* Read avail bits before accessing data. */
634
635 for (i = 0; i < ARRAY_SIZE(call->rtt_serial); i++) {
636 if (!test_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &avail))
637 continue;
638
639 sent_at = call->rtt_sent_at[i];
640 orig_serial = call->rtt_serial[i];
641
642 if (orig_serial == acked_serial) {
643 clear_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
644 smp_mb(); /* Read data before setting avail bit */
645 set_bit(i, &call->rtt_avail);
646 if (type != rxrpc_rtt_rx_cancel)
647 rxrpc_peer_add_rtt(call, type, i, acked_serial, ack_serial,
648 sent_at, resp_time);
649 else
650 trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_cancel, i,
651 orig_serial, acked_serial, 0, 0);
652 matched = true;
653 }
654
655 /* If a later serial is being acked, then mark this slot as
656 * being available.
657 */
658 if (after(acked_serial, orig_serial)) {
659 trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_obsolete, i,
660 orig_serial, acked_serial, 0, 0);
661 clear_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
662 smp_wmb();
663 set_bit(i, &call->rtt_avail);
664 }
665 }
666
667 if (!matched)
668 trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_lost, 9, 0, acked_serial, 0, 0);
669}
670
671/*
672 * Process the extra information that may be appended to an ACK packet
673 */
674static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
675 struct rxrpc_ackinfo *ackinfo)
676{
677 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
678 struct rxrpc_peer *peer;
679 unsigned int mtu;
680 bool wake = false;
681 u32 rwind = ntohl(ackinfo->rwind);
682
683 if (rwind > RXRPC_TX_MAX_WINDOW)
684 rwind = RXRPC_TX_MAX_WINDOW;
685 if (call->tx_winsize != rwind) {
686 if (rwind > call->tx_winsize)
687 wake = true;
688 trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, rwind, wake);
689 call->tx_winsize = rwind;
690 }
691
692 if (call->cong_ssthresh > rwind)
693 call->cong_ssthresh = rwind;
694
695 mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
696
697 peer = call->peer;
698 if (mtu < peer->maxdata) {
699 spin_lock(&peer->lock);
700 peer->maxdata = mtu;
701 peer->mtu = mtu + peer->hdrsize;
702 spin_unlock(&peer->lock);
703 }
704
705 if (wake)
706 wake_up(&call->waitq);
707}
708
709/*
710 * Process individual soft ACKs.
711 *
712 * Each ACK in the array corresponds to one packet and can be either an ACK or
713 * a NAK. If we get find an explicitly NAK'd packet we resend immediately;
714 * packets that lie beyond the end of the ACK list are scheduled for resend by
715 * the timer on the basis that the peer might just not have processed them at
716 * the time the ACK was sent.
717 */
718static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
719 rxrpc_seq_t seq, int nr_acks,
720 struct rxrpc_ack_summary *summary)
721{
722 unsigned int i;
723
724 for (i = 0; i < nr_acks; i++) {
725 if (acks[i] == RXRPC_ACK_TYPE_ACK) {
726 summary->nr_acks++;
727 summary->nr_new_acks++;
728 } else {
729 if (!summary->saw_nacks &&
730 call->acks_lowest_nak != seq + i) {
731 call->acks_lowest_nak = seq + i;
732 summary->new_low_nack = true;
733 }
734 summary->saw_nacks = true;
735 }
736 }
737}
738
739/*
740 * Return true if the ACK is valid - ie. it doesn't appear to have regressed
741 * with respect to the ack state conveyed by preceding ACKs.
742 */
743static bool rxrpc_is_ack_valid(struct rxrpc_call *call,
744 rxrpc_seq_t first_pkt, rxrpc_seq_t prev_pkt)
745{
746 rxrpc_seq_t base = READ_ONCE(call->acks_first_seq);
747
748 if (after(first_pkt, base))
749 return true; /* The window advanced */
750
751 if (before(first_pkt, base))
752 return false; /* firstPacket regressed */
753
754 if (after_eq(prev_pkt, call->acks_prev_seq))
755 return true; /* previousPacket hasn't regressed. */
756
757 /* Some rx implementations put a serial number in previousPacket. */
758 if (after_eq(prev_pkt, base + call->tx_winsize))
759 return false;
760 return true;
761}
762
763/*
764 * Process an ACK packet.
765 *
766 * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
767 * in the ACK array. Anything before that is hard-ACK'd and may be discarded.
768 *
769 * A hard-ACK means that a packet has been processed and may be discarded; a
770 * soft-ACK means that the packet may be discarded and retransmission
771 * requested. A phase is complete when all packets are hard-ACK'd.
772 */
773static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
774{
775 struct rxrpc_ack_summary summary = { 0 };
776 struct rxrpc_ackpacket ack;
777 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
778 struct rxrpc_ackinfo info;
779 rxrpc_serial_t ack_serial, acked_serial;
780 rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
781 int nr_acks, offset, ioffset;
782
783 _enter("");
784
785 offset = sizeof(struct rxrpc_wire_header);
786 if (skb_copy_bits(skb, offset, &ack, sizeof(ack)) < 0)
787 return rxrpc_proto_abort(call, 0, rxrpc_badmsg_short_ack);
788 offset += sizeof(ack);
789
790 ack_serial = sp->hdr.serial;
791 acked_serial = ntohl(ack.serial);
792 first_soft_ack = ntohl(ack.firstPacket);
793 prev_pkt = ntohl(ack.previousPacket);
794 hard_ack = first_soft_ack - 1;
795 nr_acks = ack.nAcks;
796 summary.ack_reason = (ack.reason < RXRPC_ACK__INVALID ?
797 ack.reason : RXRPC_ACK__INVALID);
798
799 trace_rxrpc_rx_ack(call, ack_serial, acked_serial,
800 first_soft_ack, prev_pkt,
801 summary.ack_reason, nr_acks);
802 rxrpc_inc_stat(call->rxnet, stat_rx_acks[ack.reason]);
803
804 switch (ack.reason) {
805 case RXRPC_ACK_PING_RESPONSE:
806 rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
807 rxrpc_rtt_rx_ping_response);
808 break;
809 case RXRPC_ACK_REQUESTED:
810 rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
811 rxrpc_rtt_rx_requested_ack);
812 break;
813 default:
814 if (acked_serial != 0)
815 rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
816 rxrpc_rtt_rx_cancel);
817 break;
818 }
819
820 if (ack.reason == RXRPC_ACK_PING) {
821 rxrpc_send_ACK(call, RXRPC_ACK_PING_RESPONSE, ack_serial,
822 rxrpc_propose_ack_respond_to_ping);
823 } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
824 rxrpc_send_ACK(call, RXRPC_ACK_REQUESTED, ack_serial,
825 rxrpc_propose_ack_respond_to_ack);
826 }
827
828 /* If we get an EXCEEDS_WINDOW ACK from the server, it probably
829 * indicates that the client address changed due to NAT. The server
830 * lost the call because it switched to a different peer.
831 */
832 if (unlikely(ack.reason == RXRPC_ACK_EXCEEDS_WINDOW) &&
833 first_soft_ack == 1 &&
834 prev_pkt == 0 &&
835 rxrpc_is_client_call(call)) {
836 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
837 0, -ENETRESET);
838 return;
839 }
840
841 /* If we get an OUT_OF_SEQUENCE ACK from the server, that can also
842 * indicate a change of address. However, we can retransmit the call
843 * if we still have it buffered to the beginning.
844 */
845 if (unlikely(ack.reason == RXRPC_ACK_OUT_OF_SEQUENCE) &&
846 first_soft_ack == 1 &&
847 prev_pkt == 0 &&
848 call->acks_hard_ack == 0 &&
849 rxrpc_is_client_call(call)) {
850 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
851 0, -ENETRESET);
852 return;
853 }
854
855 /* Discard any out-of-order or duplicate ACKs (outside lock). */
856 if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
857 trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
858 first_soft_ack, call->acks_first_seq,
859 prev_pkt, call->acks_prev_seq);
860 return;
861 }
862
863 info.rxMTU = 0;
864 ioffset = offset + nr_acks + 3;
865 if (skb->len >= ioffset + sizeof(info) &&
866 skb_copy_bits(skb, ioffset, &info, sizeof(info)) < 0)
867 return rxrpc_proto_abort(call, 0, rxrpc_badmsg_short_ack_info);
868
869 if (nr_acks > 0)
870 skb_condense(skb);
871
872 call->acks_latest_ts = skb->tstamp;
873 call->acks_first_seq = first_soft_ack;
874 call->acks_prev_seq = prev_pkt;
875
876 switch (ack.reason) {
877 case RXRPC_ACK_PING:
878 break;
879 default:
880 if (after(acked_serial, call->acks_highest_serial))
881 call->acks_highest_serial = acked_serial;
882 break;
883 }
884
885 /* Parse rwind and mtu sizes if provided. */
886 if (info.rxMTU)
887 rxrpc_input_ackinfo(call, skb, &info);
888
889 if (first_soft_ack == 0)
890 return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_zero);
891
892 /* Ignore ACKs unless we are or have just been transmitting. */
893 switch (__rxrpc_call_state(call)) {
894 case RXRPC_CALL_CLIENT_SEND_REQUEST:
895 case RXRPC_CALL_CLIENT_AWAIT_REPLY:
896 case RXRPC_CALL_SERVER_SEND_REPLY:
897 case RXRPC_CALL_SERVER_AWAIT_ACK:
898 break;
899 default:
900 return;
901 }
902
903 if (before(hard_ack, call->acks_hard_ack) ||
904 after(hard_ack, call->tx_top))
905 return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_outside_window);
906 if (nr_acks > call->tx_top - hard_ack)
907 return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_sack_overflow);
908
909 if (after(hard_ack, call->acks_hard_ack)) {
910 if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
911 rxrpc_end_tx_phase(call, false, rxrpc_eproto_unexpected_ack);
912 return;
913 }
914 }
915
916 if (nr_acks > 0) {
917 if (offset > (int)skb->len - nr_acks)
918 return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_short_sack);
919 rxrpc_input_soft_acks(call, skb->data + offset, first_soft_ack,
920 nr_acks, &summary);
921 }
922
923 if (test_bit(RXRPC_CALL_TX_LAST, &call->flags) &&
924 summary.nr_acks == call->tx_top - hard_ack &&
925 rxrpc_is_client_call(call))
926 rxrpc_propose_ping(call, ack_serial,
927 rxrpc_propose_ack_ping_for_lost_reply);
928
929 rxrpc_congestion_management(call, skb, &summary, acked_serial);
930}
931
932/*
933 * Process an ACKALL packet.
934 */
935static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
936{
937 struct rxrpc_ack_summary summary = { 0 };
938
939 if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
940 rxrpc_end_tx_phase(call, false, rxrpc_eproto_unexpected_ackall);
941}
942
943/*
944 * Process an ABORT packet directed at a call.
945 */
946static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
947{
948 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
949
950 trace_rxrpc_rx_abort(call, sp->hdr.serial, skb->priority);
951
952 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
953 skb->priority, -ECONNABORTED);
954}
955
956/*
957 * Process an incoming call packet.
958 */
959void rxrpc_input_call_packet(struct rxrpc_call *call, struct sk_buff *skb)
960{
961 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
962 unsigned long timo;
963
964 _enter("%p,%p", call, skb);
965
966 if (sp->hdr.serviceId != call->dest_srx.srx_service)
967 call->dest_srx.srx_service = sp->hdr.serviceId;
968 if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
969 call->rx_serial = sp->hdr.serial;
970 if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
971 set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
972
973 timo = READ_ONCE(call->next_rx_timo);
974 if (timo) {
975 unsigned long now = jiffies, expect_rx_by;
976
977 expect_rx_by = now + timo;
978 WRITE_ONCE(call->expect_rx_by, expect_rx_by);
979 rxrpc_reduce_call_timer(call, expect_rx_by, now,
980 rxrpc_timer_set_for_normal);
981 }
982
983 switch (sp->hdr.type) {
984 case RXRPC_PACKET_TYPE_DATA:
985 return rxrpc_input_data(call, skb);
986
987 case RXRPC_PACKET_TYPE_ACK:
988 return rxrpc_input_ack(call, skb);
989
990 case RXRPC_PACKET_TYPE_BUSY:
991 /* Just ignore BUSY packets from the server; the retry and
992 * lifespan timers will take care of business. BUSY packets
993 * from the client don't make sense.
994 */
995 return;
996
997 case RXRPC_PACKET_TYPE_ABORT:
998 return rxrpc_input_abort(call, skb);
999
1000 case RXRPC_PACKET_TYPE_ACKALL:
1001 return rxrpc_input_ackall(call, skb);
1002
1003 default:
1004 break;
1005 }
1006}
1007
1008/*
1009 * Handle a new service call on a channel implicitly completing the preceding
1010 * call on that channel. This does not apply to client conns.
1011 *
1012 * TODO: If callNumber > call_id + 1, renegotiate security.
1013 */
1014void rxrpc_implicit_end_call(struct rxrpc_call *call, struct sk_buff *skb)
1015{
1016 switch (__rxrpc_call_state(call)) {
1017 case RXRPC_CALL_SERVER_AWAIT_ACK:
1018 rxrpc_call_completed(call);
1019 fallthrough;
1020 case RXRPC_CALL_COMPLETE:
1021 break;
1022 default:
1023 rxrpc_abort_call(call, 0, RX_CALL_DEAD, -ESHUTDOWN,
1024 rxrpc_eproto_improper_term);
1025 trace_rxrpc_improper_term(call);
1026 break;
1027 }
1028
1029 rxrpc_input_call_event(call, skb);
1030}