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 */
rxrpc_propose_ping(struct rxrpc_call * call,u32 serial,enum rxrpc_propose_ack_trace why)23 void 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 */
rxrpc_propose_delay_ACK(struct rxrpc_call * call,rxrpc_serial_t serial,enum rxrpc_propose_ack_trace why)40 void 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->srtt_us)
48 delay = (call->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 * Retransmit one or more packets.
59 */
rxrpc_retransmit_data(struct rxrpc_call * call,struct rxrpc_send_data_req * req)60 static bool rxrpc_retransmit_data(struct rxrpc_call *call,
61 struct rxrpc_send_data_req *req)
62 {
63 struct rxrpc_txqueue *tq = req->tq;
64 unsigned int ix = req->seq & RXRPC_TXQ_MASK;
65 struct rxrpc_txbuf *txb = tq->bufs[ix];
66
67 _enter("%x,%x,%x,%x", tq->qbase, req->seq, ix, txb->debug_id);
68
69 req->retrans = true;
70 trace_rxrpc_retransmit(call, req, txb);
71
72 txb->flags |= RXRPC_TXBUF_RESENT;
73 rxrpc_send_data_packet(call, req);
74 rxrpc_inc_stat(call->rxnet, stat_tx_data_retrans);
75
76 req->tq = NULL;
77 req->n = 0;
78 req->did_send = true;
79 req->now = ktime_get_real();
80 return true;
81 }
82
83 /*
84 * Perform retransmission of NAK'd and unack'd packets.
85 */
rxrpc_resend(struct rxrpc_call * call)86 static void rxrpc_resend(struct rxrpc_call *call)
87 {
88 struct rxrpc_send_data_req req = {
89 .now = ktime_get_real(),
90 .trace = rxrpc_txdata_retransmit,
91 };
92 struct rxrpc_txqueue *tq;
93
94 _enter("{%d,%d}", call->tx_bottom, call->tx_top);
95
96 trace_rxrpc_resend(call, call->acks_highest_serial);
97
98 /* Scan the transmission queue, looking for lost packets. */
99 for (tq = call->tx_queue; tq; tq = tq->next) {
100 unsigned long lost = tq->segment_lost;
101
102 if (after(tq->qbase, call->tx_transmitted))
103 break;
104
105 _debug("retr %16lx %u c=%08x [%x]",
106 tq->segment_acked, tq->nr_reported_acks, call->debug_id, tq->qbase);
107 _debug("lost %16lx", lost);
108
109 trace_rxrpc_resend_lost(call, tq, lost);
110 while (lost) {
111 unsigned int ix = __ffs(lost);
112 struct rxrpc_txbuf *txb = tq->bufs[ix];
113
114 __clear_bit(ix, &lost);
115 rxrpc_see_txbuf(txb, rxrpc_txbuf_see_lost);
116
117 req.tq = tq;
118 req.seq = tq->qbase + ix;
119 req.n = 1;
120 rxrpc_retransmit_data(call, &req);
121 }
122 }
123
124 rxrpc_get_rto_backoff(call, req.did_send);
125 _leave("");
126 }
127
128 /*
129 * Resend the highest-seq DATA packet so far transmitted for RACK-TLP [RFC8985 7.3].
130 */
rxrpc_resend_tlp(struct rxrpc_call * call)131 void rxrpc_resend_tlp(struct rxrpc_call *call)
132 {
133 struct rxrpc_send_data_req req = {
134 .now = ktime_get_real(),
135 .seq = call->tx_transmitted,
136 .n = 1,
137 .tlp_probe = true,
138 .trace = rxrpc_txdata_tlp_retransmit,
139 };
140
141 /* There's a chance it'll be on the tail segment of the queue. */
142 req.tq = READ_ONCE(call->tx_qtail);
143 if (req.tq &&
144 before(call->tx_transmitted, req.tq->qbase + RXRPC_NR_TXQUEUE)) {
145 rxrpc_retransmit_data(call, &req);
146 return;
147 }
148
149 for (req.tq = call->tx_queue; req.tq; req.tq = req.tq->next) {
150 if (after_eq(call->tx_transmitted, req.tq->qbase) &&
151 before(call->tx_transmitted, req.tq->qbase + RXRPC_NR_TXQUEUE)) {
152 rxrpc_retransmit_data(call, &req);
153 return;
154 }
155 }
156 }
157
158 /*
159 * Start transmitting the reply to a service. This cancels the need to ACK the
160 * request if we haven't yet done so.
161 */
rxrpc_begin_service_reply(struct rxrpc_call * call)162 static void rxrpc_begin_service_reply(struct rxrpc_call *call)
163 {
164 rxrpc_set_call_state(call, RXRPC_CALL_SERVER_SEND_REPLY);
165 if (call->ackr_reason == RXRPC_ACK_DELAY)
166 call->ackr_reason = 0;
167 call->delay_ack_at = KTIME_MAX;
168 trace_rxrpc_timer_can(call, rxrpc_timer_trace_delayed_ack);
169 }
170
171 /*
172 * Close the transmission phase. After this point there is no more data to be
173 * transmitted in the call.
174 */
rxrpc_close_tx_phase(struct rxrpc_call * call)175 static void rxrpc_close_tx_phase(struct rxrpc_call *call)
176 {
177 _debug("________awaiting reply/ACK__________");
178
179 switch (__rxrpc_call_state(call)) {
180 case RXRPC_CALL_CLIENT_SEND_REQUEST:
181 rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_AWAIT_ACK);
182 break;
183 case RXRPC_CALL_SERVER_SEND_REPLY:
184 rxrpc_set_call_state(call, RXRPC_CALL_SERVER_AWAIT_ACK);
185 break;
186 default:
187 break;
188 }
189 }
190
191 /*
192 * Transmit some as-yet untransmitted data, to a maximum of the supplied limit.
193 */
rxrpc_transmit_fresh_data(struct rxrpc_call * call,unsigned int limit,enum rxrpc_txdata_trace trace)194 static void rxrpc_transmit_fresh_data(struct rxrpc_call *call, unsigned int limit,
195 enum rxrpc_txdata_trace trace)
196 {
197 int space = rxrpc_tx_window_space(call);
198
199 if (!test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
200 if (call->send_top == call->tx_top)
201 return;
202 rxrpc_expose_client_call(call);
203 }
204
205 while (space > 0) {
206 struct rxrpc_send_data_req req = {
207 .now = ktime_get_real(),
208 .seq = call->tx_transmitted + 1,
209 .n = 0,
210 .trace = trace,
211 };
212 struct rxrpc_txqueue *tq;
213 struct rxrpc_txbuf *txb;
214 rxrpc_seq_t send_top, seq;
215 int limit = min(space, max(call->peer->pmtud_jumbo, 1));
216
217 /* Order send_top before the contents of the new txbufs and
218 * txqueue pointers
219 */
220 send_top = smp_load_acquire(&call->send_top);
221 if (call->tx_top == send_top)
222 break;
223
224 trace_rxrpc_transmit(call, send_top, space);
225
226 tq = call->tx_qtail;
227 seq = call->tx_top;
228 trace_rxrpc_tq(call, tq, seq, rxrpc_tq_decant);
229
230 do {
231 int ix;
232
233 seq++;
234 ix = seq & RXRPC_TXQ_MASK;
235 if (!ix) {
236 tq = tq->next;
237 trace_rxrpc_tq(call, tq, seq, rxrpc_tq_decant_advance);
238 }
239 if (!req.tq)
240 req.tq = tq;
241 txb = tq->bufs[ix];
242 req.n++;
243 if (!txb->jumboable)
244 break;
245 } while (req.n < limit && before(seq, send_top));
246
247 if (__rxrpc_call_state(call) == RXRPC_CALL_CLIENT_PRE_SEND)
248 rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_SEND_REQUEST);
249 if (txb->flags & RXRPC_LAST_PACKET) {
250 rxrpc_close_tx_phase(call);
251 tq = NULL;
252 }
253 call->tx_qtail = tq;
254 call->tx_top = seq;
255
256 space -= req.n;
257 rxrpc_send_data_packet(call, &req);
258 }
259 }
260
rxrpc_transmit_some_data(struct rxrpc_call * call,unsigned int limit,enum rxrpc_txdata_trace trace)261 void rxrpc_transmit_some_data(struct rxrpc_call *call, unsigned int limit,
262 enum rxrpc_txdata_trace trace)
263 {
264 switch (__rxrpc_call_state(call)) {
265 case RXRPC_CALL_SERVER_ACK_REQUEST:
266 if (call->tx_bottom == READ_ONCE(call->send_top))
267 return;
268 rxrpc_begin_service_reply(call);
269 fallthrough;
270
271 case RXRPC_CALL_SERVER_SEND_REPLY:
272 case RXRPC_CALL_CLIENT_PRE_SEND:
273 case RXRPC_CALL_CLIENT_SEND_REQUEST:
274 if (!rxrpc_tx_window_space(call))
275 return;
276 if (call->tx_bottom == READ_ONCE(call->send_top)) {
277 rxrpc_inc_stat(call->rxnet, stat_tx_data_underflow);
278 return;
279 }
280 rxrpc_transmit_fresh_data(call, limit, trace);
281 break;
282 default:
283 return;
284 }
285 }
286
287 /*
288 * Ping the other end to fill our RTT cache and to retrieve the rwind
289 * and MTU parameters.
290 */
rxrpc_send_initial_ping(struct rxrpc_call * call)291 static void rxrpc_send_initial_ping(struct rxrpc_call *call)
292 {
293 if (call->rtt_count < 3 ||
294 ktime_before(ktime_add_ms(call->rtt_last_req, 1000),
295 ktime_get_real()))
296 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
297 rxrpc_propose_ack_ping_for_params);
298 }
299
300 /*
301 * Handle retransmission and deferred ACK/abort generation.
302 */
rxrpc_input_call_event(struct rxrpc_call * call)303 bool rxrpc_input_call_event(struct rxrpc_call *call)
304 {
305 struct sk_buff *skb;
306 ktime_t now, t;
307 bool did_receive = false, saw_ack = false;
308 s32 abort_code;
309
310 rxrpc_see_call(call, rxrpc_call_see_input);
311
312 //printk("\n--------------------\n");
313 _enter("{%d,%s,%lx}",
314 call->debug_id, rxrpc_call_states[__rxrpc_call_state(call)],
315 call->events);
316
317 /* Handle abort request locklessly, vs rxrpc_propose_abort(). */
318 abort_code = smp_load_acquire(&call->send_abort);
319 if (abort_code) {
320 rxrpc_abort_call(call, 0, call->send_abort, call->send_abort_err,
321 call->send_abort_why);
322 goto out;
323 }
324
325 do {
326 skb = __skb_dequeue(&call->rx_queue);
327 if (skb) {
328 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
329
330 if (__rxrpc_call_is_complete(call) ||
331 skb->mark == RXRPC_SKB_MARK_ERROR) {
332 rxrpc_free_skb(skb, rxrpc_skb_put_call_rx);
333 goto out;
334 }
335
336 saw_ack |= sp->hdr.type == RXRPC_PACKET_TYPE_ACK;
337
338 rxrpc_input_call_packet(call, skb);
339 rxrpc_free_skb(skb, rxrpc_skb_put_call_rx);
340 did_receive = true;
341 }
342
343 t = ktime_sub(call->rack_timo_at, ktime_get_real());
344 if (t <= 0) {
345 trace_rxrpc_timer_exp(call, t,
346 rxrpc_timer_trace_rack_off + call->rack_timer_mode);
347 call->rack_timo_at = KTIME_MAX;
348 rxrpc_rack_timer_expired(call, t);
349 }
350
351 } while (!skb_queue_empty(&call->rx_queue));
352
353 /* If we see our async-event poke, check for timeout trippage. */
354 now = ktime_get_real();
355 t = ktime_sub(call->expect_rx_by, now);
356 if (t <= 0) {
357 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_expect_rx);
358 goto expired;
359 }
360
361 t = ktime_sub(call->expect_req_by, now);
362 if (t <= 0) {
363 call->expect_req_by = KTIME_MAX;
364 if (__rxrpc_call_state(call) == RXRPC_CALL_SERVER_RECV_REQUEST) {
365 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_idle);
366 goto expired;
367 }
368 }
369
370 t = ktime_sub(READ_ONCE(call->expect_term_by), now);
371 if (t <= 0) {
372 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_hard);
373 goto expired;
374 }
375
376 t = ktime_sub(call->delay_ack_at, now);
377 if (t <= 0) {
378 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_delayed_ack);
379 call->delay_ack_at = KTIME_MAX;
380 rxrpc_send_ACK(call, RXRPC_ACK_DELAY, 0,
381 rxrpc_propose_ack_delayed_ack);
382 }
383
384 t = ktime_sub(call->ping_at, now);
385 if (t <= 0) {
386 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_ping);
387 call->ping_at = KTIME_MAX;
388 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
389 rxrpc_propose_ack_ping_for_keepalive);
390 }
391
392 now = ktime_get_real();
393 t = ktime_sub(call->keepalive_at, now);
394 if (t <= 0) {
395 trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_keepalive);
396 call->keepalive_at = KTIME_MAX;
397 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
398 rxrpc_propose_ack_ping_for_keepalive);
399 }
400
401 if (test_and_clear_bit(RXRPC_CALL_EV_INITIAL_PING, &call->events))
402 rxrpc_send_initial_ping(call);
403
404 rxrpc_transmit_some_data(call, UINT_MAX, rxrpc_txdata_new_data);
405
406 if (saw_ack)
407 rxrpc_congestion_degrade(call);
408
409 if (did_receive &&
410 (__rxrpc_call_state(call) == RXRPC_CALL_CLIENT_SEND_REQUEST ||
411 __rxrpc_call_state(call) == RXRPC_CALL_SERVER_SEND_REPLY)) {
412 t = ktime_sub(call->rack_timo_at, ktime_get_real());
413 trace_rxrpc_rack(call, t);
414 }
415
416 /* Process events */
417 if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events))
418 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
419 rxrpc_propose_ack_ping_for_lost_ack);
420
421 if (call->tx_nr_lost > 0 &&
422 __rxrpc_call_state(call) != RXRPC_CALL_CLIENT_RECV_REPLY &&
423 !test_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags))
424 rxrpc_resend(call);
425
426 if (test_and_clear_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags))
427 rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
428 rxrpc_propose_ack_rx_idle);
429
430 if (call->ackr_nr_unacked > 2) {
431 if (call->rtt_count < 3)
432 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
433 rxrpc_propose_ack_ping_for_rtt);
434 else if (ktime_before(ktime_add_ms(call->rtt_last_req, 1000),
435 ktime_get_real()))
436 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
437 rxrpc_propose_ack_ping_for_old_rtt);
438 else
439 rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
440 rxrpc_propose_ack_input_data);
441 }
442
443 /* Make sure the timer is restarted */
444 if (!__rxrpc_call_is_complete(call)) {
445 ktime_t next = READ_ONCE(call->expect_term_by), delay;
446
447 #define set(T) { ktime_t _t = (T); if (ktime_before(_t, next)) next = _t; }
448
449 set(call->expect_req_by);
450 set(call->expect_rx_by);
451 set(call->delay_ack_at);
452 set(call->rack_timo_at);
453 set(call->keepalive_at);
454 set(call->ping_at);
455
456 now = ktime_get_real();
457 delay = ktime_sub(next, now);
458 if (delay <= 0) {
459 rxrpc_poke_call(call, rxrpc_call_poke_timer_now);
460 } else {
461 unsigned long nowj = jiffies, delayj, nextj;
462
463 delayj = umax(nsecs_to_jiffies(delay), 1);
464 nextj = nowj + delayj;
465 if (time_before(nextj, call->timer.expires) ||
466 !timer_pending(&call->timer)) {
467 trace_rxrpc_timer_restart(call, delay, delayj);
468 timer_reduce(&call->timer, nextj);
469 }
470 }
471 }
472
473 out:
474 if (__rxrpc_call_is_complete(call)) {
475 timer_delete_sync(&call->timer);
476 if (!test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
477 rxrpc_disconnect_call(call);
478 if (call->security)
479 call->security->free_call_crypto(call);
480 } else {
481 if (did_receive &&
482 call->peer->ackr_adv_pmtud &&
483 call->peer->pmtud_pending)
484 rxrpc_send_probe_for_pmtud(call);
485 }
486 _leave("");
487 return true;
488
489 expired:
490 if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) &&
491 (int)call->conn->hi_serial - (int)call->rx_serial > 0) {
492 trace_rxrpc_call_reset(call);
493 rxrpc_abort_call(call, 0, RX_CALL_DEAD, -ECONNRESET,
494 rxrpc_abort_call_reset);
495 } else {
496 rxrpc_abort_call(call, 0, RX_CALL_TIMEOUT, -ETIME,
497 rxrpc_abort_call_timeout);
498 }
499 goto out;
500 }
501