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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 */
23static void rxrpc_propose_ping(struct rxrpc_call *call,
24 bool immediate, bool background)
25{
26 if (immediate) {
27 if (background &&
28 !test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
29 rxrpc_queue_call(call);
30 } else {
31 unsigned long now = jiffies;
32 unsigned long ping_at = now + rxrpc_idle_ack_delay;
33
34 if (time_before(ping_at, call->ping_at)) {
35 WRITE_ONCE(call->ping_at, ping_at);
36 rxrpc_reduce_call_timer(call, ping_at, now,
37 rxrpc_timer_set_for_ping);
38 }
39 }
40}
41
42/*
43 * propose an ACK be sent
44 */
45static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
46 u32 serial, bool immediate, bool background,
47 enum rxrpc_propose_ack_trace why)
48{
49 enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
50 unsigned long expiry = rxrpc_soft_ack_delay;
51 s8 prior = rxrpc_ack_priority[ack_reason];
52
53 /* Pings are handled specially because we don't want to accidentally
54 * lose a ping response by subsuming it into a ping.
55 */
56 if (ack_reason == RXRPC_ACK_PING) {
57 rxrpc_propose_ping(call, immediate, background);
58 goto trace;
59 }
60
61 /* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
62 * numbers, but we don't alter the timeout.
63 */
64 _debug("prior %u %u vs %u %u",
65 ack_reason, prior,
66 call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]);
67 if (ack_reason == call->ackr_reason) {
68 if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) {
69 outcome = rxrpc_propose_ack_update;
70 call->ackr_serial = serial;
71 }
72 if (!immediate)
73 goto trace;
74 } else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
75 call->ackr_reason = ack_reason;
76 call->ackr_serial = serial;
77 } else {
78 outcome = rxrpc_propose_ack_subsume;
79 }
80
81 switch (ack_reason) {
82 case RXRPC_ACK_REQUESTED:
83 if (rxrpc_requested_ack_delay < expiry)
84 expiry = rxrpc_requested_ack_delay;
85 if (serial == 1)
86 immediate = false;
87 break;
88
89 case RXRPC_ACK_DELAY:
90 if (rxrpc_soft_ack_delay < expiry)
91 expiry = rxrpc_soft_ack_delay;
92 break;
93
94 case RXRPC_ACK_IDLE:
95 if (rxrpc_idle_ack_delay < expiry)
96 expiry = rxrpc_idle_ack_delay;
97 break;
98
99 default:
100 immediate = true;
101 break;
102 }
103
104 if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) {
105 _debug("already scheduled");
106 } else if (immediate || expiry == 0) {
107 _debug("immediate ACK %lx", call->events);
108 if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) &&
109 background)
110 rxrpc_queue_call(call);
111 } else {
112 unsigned long now = jiffies, ack_at;
113
114 if (call->peer->srtt_us != 0)
115 ack_at = usecs_to_jiffies(call->peer->srtt_us >> 3);
116 else
117 ack_at = expiry;
118
119 ack_at += READ_ONCE(call->tx_backoff);
120 ack_at += now;
121 if (time_before(ack_at, call->ack_at)) {
122 WRITE_ONCE(call->ack_at, ack_at);
123 rxrpc_reduce_call_timer(call, ack_at, now,
124 rxrpc_timer_set_for_ack);
125 }
126 }
127
128trace:
129 trace_rxrpc_propose_ack(call, why, ack_reason, serial, immediate,
130 background, outcome);
131}
132
133/*
134 * propose an ACK be sent, locking the call structure
135 */
136void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
137 u32 serial, bool immediate, bool background,
138 enum rxrpc_propose_ack_trace why)
139{
140 spin_lock_bh(&call->lock);
141 __rxrpc_propose_ACK(call, ack_reason, serial,
142 immediate, background, why);
143 spin_unlock_bh(&call->lock);
144}
145
146/*
147 * Handle congestion being detected by the retransmit timeout.
148 */
149static void rxrpc_congestion_timeout(struct rxrpc_call *call)
150{
151 set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
152}
153
154/*
155 * Perform retransmission of NAK'd and unack'd packets.
156 */
157static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
158{
159 struct sk_buff *skb;
160 unsigned long resend_at, rto_j;
161 rxrpc_seq_t cursor, seq, top;
162 ktime_t now, max_age, oldest, ack_ts;
163 int ix;
164 u8 annotation, anno_type, retrans = 0, unacked = 0;
165
166 _enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
167
168 rto_j = call->peer->rto_j;
169
170 now = ktime_get_real();
171 max_age = ktime_sub(now, jiffies_to_usecs(rto_j));
172
173 spin_lock_bh(&call->lock);
174
175 cursor = call->tx_hard_ack;
176 top = call->tx_top;
177 ASSERT(before_eq(cursor, top));
178 if (cursor == top)
179 goto out_unlock;
180
181 /* Scan the packet list without dropping the lock and decide which of
182 * the packets in the Tx buffer we're going to resend and what the new
183 * resend timeout will be.
184 */
185 trace_rxrpc_resend(call, (cursor + 1) & RXRPC_RXTX_BUFF_MASK);
186 oldest = now;
187 for (seq = cursor + 1; before_eq(seq, top); seq++) {
188 ix = seq & RXRPC_RXTX_BUFF_MASK;
189 annotation = call->rxtx_annotations[ix];
190 anno_type = annotation & RXRPC_TX_ANNO_MASK;
191 annotation &= ~RXRPC_TX_ANNO_MASK;
192 if (anno_type == RXRPC_TX_ANNO_ACK)
193 continue;
194
195 skb = call->rxtx_buffer[ix];
196 rxrpc_see_skb(skb, rxrpc_skb_seen);
197
198 if (anno_type == RXRPC_TX_ANNO_UNACK) {
199 if (ktime_after(skb->tstamp, max_age)) {
200 if (ktime_before(skb->tstamp, oldest))
201 oldest = skb->tstamp;
202 continue;
203 }
204 if (!(annotation & RXRPC_TX_ANNO_RESENT))
205 unacked++;
206 }
207
208 /* Okay, we need to retransmit a packet. */
209 call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation;
210 retrans++;
211 trace_rxrpc_retransmit(call, seq, annotation | anno_type,
212 ktime_to_ns(ktime_sub(skb->tstamp, max_age)));
213 }
214
215 resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
216 resend_at += jiffies + rto_j;
217 WRITE_ONCE(call->resend_at, resend_at);
218
219 if (unacked)
220 rxrpc_congestion_timeout(call);
221
222 /* If there was nothing that needed retransmission then it's likely
223 * that an ACK got lost somewhere. Send a ping to find out instead of
224 * retransmitting data.
225 */
226 if (!retrans) {
227 rxrpc_reduce_call_timer(call, resend_at, now_j,
228 rxrpc_timer_set_for_resend);
229 spin_unlock_bh(&call->lock);
230 ack_ts = ktime_sub(now, call->acks_latest_ts);
231 if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3))
232 goto out;
233 rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
234 rxrpc_propose_ack_ping_for_lost_ack);
235 rxrpc_send_ack_packet(call, true, NULL);
236 goto out;
237 }
238
239 /* Now go through the Tx window and perform the retransmissions. We
240 * have to drop the lock for each send. If an ACK comes in whilst the
241 * lock is dropped, it may clear some of the retransmission markers for
242 * packets that it soft-ACKs.
243 */
244 for (seq = cursor + 1; before_eq(seq, top); seq++) {
245 ix = seq & RXRPC_RXTX_BUFF_MASK;
246 annotation = call->rxtx_annotations[ix];
247 anno_type = annotation & RXRPC_TX_ANNO_MASK;
248 if (anno_type != RXRPC_TX_ANNO_RETRANS)
249 continue;
250
251 /* We need to reset the retransmission state, but we need to do
252 * so before we drop the lock as a new ACK/NAK may come in and
253 * confuse things
254 */
255 annotation &= ~RXRPC_TX_ANNO_MASK;
256 annotation |= RXRPC_TX_ANNO_UNACK | RXRPC_TX_ANNO_RESENT;
257 call->rxtx_annotations[ix] = annotation;
258
259 skb = call->rxtx_buffer[ix];
260 if (!skb)
261 continue;
262
263 rxrpc_get_skb(skb, rxrpc_skb_got);
264 spin_unlock_bh(&call->lock);
265
266 if (rxrpc_send_data_packet(call, skb, true) < 0) {
267 rxrpc_free_skb(skb, rxrpc_skb_freed);
268 return;
269 }
270
271 if (rxrpc_is_client_call(call))
272 rxrpc_expose_client_call(call);
273
274 rxrpc_free_skb(skb, rxrpc_skb_freed);
275 spin_lock_bh(&call->lock);
276 if (after(call->tx_hard_ack, seq))
277 seq = call->tx_hard_ack;
278 }
279
280out_unlock:
281 spin_unlock_bh(&call->lock);
282out:
283 _leave("");
284}
285
286/*
287 * Handle retransmission and deferred ACK/abort generation.
288 */
289void rxrpc_process_call(struct work_struct *work)
290{
291 struct rxrpc_call *call =
292 container_of(work, struct rxrpc_call, processor);
293 rxrpc_serial_t *send_ack;
294 unsigned long now, next, t;
295 unsigned int iterations = 0;
296
297 rxrpc_see_call(call);
298
299 //printk("\n--------------------\n");
300 _enter("{%d,%s,%lx}",
301 call->debug_id, rxrpc_call_states[call->state], call->events);
302
303recheck_state:
304 /* Limit the number of times we do this before returning to the manager */
305 iterations++;
306 if (iterations > 5)
307 goto requeue;
308
309 if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
310 rxrpc_send_abort_packet(call);
311 goto recheck_state;
312 }
313
314 if (call->state == RXRPC_CALL_COMPLETE) {
315 del_timer_sync(&call->timer);
316 goto out_put;
317 }
318
319 /* Work out if any timeouts tripped */
320 now = jiffies;
321 t = READ_ONCE(call->expect_rx_by);
322 if (time_after_eq(now, t)) {
323 trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
324 set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
325 }
326
327 t = READ_ONCE(call->expect_req_by);
328 if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST &&
329 time_after_eq(now, t)) {
330 trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
331 set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
332 }
333
334 t = READ_ONCE(call->expect_term_by);
335 if (time_after_eq(now, t)) {
336 trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
337 set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
338 }
339
340 t = READ_ONCE(call->ack_at);
341 if (time_after_eq(now, t)) {
342 trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
343 cmpxchg(&call->ack_at, t, now + MAX_JIFFY_OFFSET);
344 set_bit(RXRPC_CALL_EV_ACK, &call->events);
345 }
346
347 t = READ_ONCE(call->ack_lost_at);
348 if (time_after_eq(now, t)) {
349 trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now);
350 cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET);
351 set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
352 }
353
354 t = READ_ONCE(call->keepalive_at);
355 if (time_after_eq(now, t)) {
356 trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now);
357 cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET);
358 rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, true,
359 rxrpc_propose_ack_ping_for_keepalive);
360 set_bit(RXRPC_CALL_EV_PING, &call->events);
361 }
362
363 t = READ_ONCE(call->ping_at);
364 if (time_after_eq(now, t)) {
365 trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
366 cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
367 set_bit(RXRPC_CALL_EV_PING, &call->events);
368 }
369
370 t = READ_ONCE(call->resend_at);
371 if (time_after_eq(now, t)) {
372 trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
373 cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
374 set_bit(RXRPC_CALL_EV_RESEND, &call->events);
375 }
376
377 /* Process events */
378 if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED, &call->events)) {
379 if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) &&
380 (int)call->conn->hi_serial - (int)call->rx_serial > 0) {
381 trace_rxrpc_call_reset(call);
382 rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ECONNRESET);
383 } else {
384 rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ETIME);
385 }
386 set_bit(RXRPC_CALL_EV_ABORT, &call->events);
387 goto recheck_state;
388 }
389
390 send_ack = NULL;
391 if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events)) {
392 call->acks_lost_top = call->tx_top;
393 rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
394 rxrpc_propose_ack_ping_for_lost_ack);
395 send_ack = &call->acks_lost_ping;
396 }
397
398 if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) ||
399 send_ack) {
400 if (call->ackr_reason) {
401 rxrpc_send_ack_packet(call, false, send_ack);
402 goto recheck_state;
403 }
404 }
405
406 if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {
407 rxrpc_send_ack_packet(call, true, NULL);
408 goto recheck_state;
409 }
410
411 if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) {
412 rxrpc_resend(call, now);
413 goto recheck_state;
414 }
415
416 /* Make sure the timer is restarted */
417 next = call->expect_rx_by;
418
419#define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }
420
421 set(call->expect_req_by);
422 set(call->expect_term_by);
423 set(call->ack_at);
424 set(call->ack_lost_at);
425 set(call->resend_at);
426 set(call->keepalive_at);
427 set(call->ping_at);
428
429 now = jiffies;
430 if (time_after_eq(now, next))
431 goto recheck_state;
432
433 rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
434
435 /* other events may have been raised since we started checking */
436 if (call->events && call->state < RXRPC_CALL_COMPLETE)
437 goto requeue;
438
439out_put:
440 rxrpc_put_call(call, rxrpc_call_put);
441out:
442 _leave("");
443 return;
444
445requeue:
446 __rxrpc_queue_call(call);
447 goto out;
448}
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 if (rxrpc_soft_ack_delay < expiry)
47 expiry = rxrpc_soft_ack_delay;
48 if (call->peer->srtt_us != 0)
49 ack_at = usecs_to_jiffies(call->peer->srtt_us >> 3);
50 else
51 ack_at = expiry;
52
53 ack_at += READ_ONCE(call->tx_backoff);
54 ack_at += now;
55 if (time_before(ack_at, call->delay_ack_at)) {
56 WRITE_ONCE(call->delay_ack_at, ack_at);
57 rxrpc_reduce_call_timer(call, ack_at, now,
58 rxrpc_timer_set_for_ack);
59 }
60
61 trace_rxrpc_propose_ack(call, why, RXRPC_ACK_DELAY, serial);
62}
63
64/*
65 * Queue an ACK for immediate transmission.
66 */
67void rxrpc_send_ACK(struct rxrpc_call *call, u8 ack_reason,
68 rxrpc_serial_t serial, enum rxrpc_propose_ack_trace why)
69{
70 struct rxrpc_txbuf *txb;
71
72 if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
73 return;
74
75 rxrpc_inc_stat(call->rxnet, stat_tx_acks[ack_reason]);
76
77 txb = rxrpc_alloc_txbuf(call, RXRPC_PACKET_TYPE_ACK,
78 rcu_read_lock_held() ? GFP_ATOMIC | __GFP_NOWARN : GFP_NOFS);
79 if (!txb) {
80 kleave(" = -ENOMEM");
81 return;
82 }
83
84 txb->ack_why = why;
85 txb->wire.seq = 0;
86 txb->wire.type = RXRPC_PACKET_TYPE_ACK;
87 txb->wire.flags |= RXRPC_SLOW_START_OK;
88 txb->ack.bufferSpace = 0;
89 txb->ack.maxSkew = 0;
90 txb->ack.firstPacket = 0;
91 txb->ack.previousPacket = 0;
92 txb->ack.serial = htonl(serial);
93 txb->ack.reason = ack_reason;
94 txb->ack.nAcks = 0;
95
96 trace_rxrpc_send_ack(call, why, ack_reason, serial);
97 rxrpc_send_ack_packet(call, txb);
98 rxrpc_put_txbuf(txb, rxrpc_txbuf_put_ack_tx);
99}
100
101/*
102 * Handle congestion being detected by the retransmit timeout.
103 */
104static void rxrpc_congestion_timeout(struct rxrpc_call *call)
105{
106 set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
107}
108
109/*
110 * Perform retransmission of NAK'd and unack'd packets.
111 */
112void rxrpc_resend(struct rxrpc_call *call, struct sk_buff *ack_skb)
113{
114 struct rxrpc_ackpacket *ack = NULL;
115 struct rxrpc_skb_priv *sp;
116 struct rxrpc_txbuf *txb;
117 unsigned long resend_at;
118 rxrpc_seq_t transmitted = READ_ONCE(call->tx_transmitted);
119 ktime_t now, max_age, oldest, ack_ts;
120 bool unacked = false;
121 unsigned int i;
122 LIST_HEAD(retrans_queue);
123
124 _enter("{%d,%d}", call->acks_hard_ack, call->tx_top);
125
126 now = ktime_get_real();
127 max_age = ktime_sub_us(now, jiffies_to_usecs(call->peer->rto_j));
128 oldest = now;
129
130 if (list_empty(&call->tx_buffer))
131 goto no_resend;
132
133 if (list_empty(&call->tx_buffer))
134 goto no_further_resend;
135
136 trace_rxrpc_resend(call, ack_skb);
137 txb = list_first_entry(&call->tx_buffer, struct rxrpc_txbuf, call_link);
138
139 /* Scan the soft ACK table without dropping the lock and resend any
140 * explicitly NAK'd packets.
141 */
142 if (ack_skb) {
143 sp = rxrpc_skb(ack_skb);
144 ack = (void *)ack_skb->data + sizeof(struct rxrpc_wire_header);
145
146 for (i = 0; i < sp->nr_acks; i++) {
147 rxrpc_seq_t seq;
148
149 if (ack->acks[i] & 1)
150 continue;
151 seq = sp->first_ack + 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 bool resend = false, expired = false;
377 s32 abort_code;
378
379 rxrpc_see_call(call, rxrpc_call_see_input);
380
381 //printk("\n--------------------\n");
382 _enter("{%d,%s,%lx}",
383 call->debug_id, rxrpc_call_states[__rxrpc_call_state(call)],
384 call->events);
385
386 if (__rxrpc_call_is_complete(call))
387 goto out;
388
389 /* Handle abort request locklessly, vs rxrpc_propose_abort(). */
390 abort_code = smp_load_acquire(&call->send_abort);
391 if (abort_code) {
392 rxrpc_abort_call(call, 0, call->send_abort, call->send_abort_err,
393 call->send_abort_why);
394 goto out;
395 }
396
397 if (skb && skb->mark == RXRPC_SKB_MARK_ERROR)
398 goto out;
399
400 /* If we see our async-event poke, check for timeout trippage. */
401 now = jiffies;
402 t = READ_ONCE(call->expect_rx_by);
403 if (time_after_eq(now, t)) {
404 trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
405 expired = true;
406 }
407
408 t = READ_ONCE(call->expect_req_by);
409 if (__rxrpc_call_state(call) == RXRPC_CALL_SERVER_RECV_REQUEST &&
410 time_after_eq(now, t)) {
411 trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
412 expired = true;
413 }
414
415 t = READ_ONCE(call->expect_term_by);
416 if (time_after_eq(now, t)) {
417 trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
418 expired = true;
419 }
420
421 t = READ_ONCE(call->delay_ack_at);
422 if (time_after_eq(now, t)) {
423 trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
424 cmpxchg(&call->delay_ack_at, t, now + MAX_JIFFY_OFFSET);
425 rxrpc_send_ACK(call, RXRPC_ACK_DELAY, 0,
426 rxrpc_propose_ack_ping_for_lost_ack);
427 }
428
429 t = READ_ONCE(call->ack_lost_at);
430 if (time_after_eq(now, t)) {
431 trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now);
432 cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET);
433 set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
434 }
435
436 t = READ_ONCE(call->keepalive_at);
437 if (time_after_eq(now, t)) {
438 trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now);
439 cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET);
440 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
441 rxrpc_propose_ack_ping_for_keepalive);
442 }
443
444 t = READ_ONCE(call->ping_at);
445 if (time_after_eq(now, t)) {
446 trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
447 cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
448 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
449 rxrpc_propose_ack_ping_for_keepalive);
450 }
451
452 t = READ_ONCE(call->resend_at);
453 if (time_after_eq(now, t)) {
454 trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
455 cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
456 resend = true;
457 }
458
459 if (skb)
460 rxrpc_input_call_packet(call, skb);
461
462 rxrpc_transmit_some_data(call);
463
464 if (skb) {
465 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
466
467 if (sp->hdr.type == RXRPC_PACKET_TYPE_ACK)
468 rxrpc_congestion_degrade(call);
469 }
470
471 if (test_and_clear_bit(RXRPC_CALL_EV_INITIAL_PING, &call->events))
472 rxrpc_send_initial_ping(call);
473
474 /* Process events */
475 if (expired) {
476 if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) &&
477 (int)call->conn->hi_serial - (int)call->rx_serial > 0) {
478 trace_rxrpc_call_reset(call);
479 rxrpc_abort_call(call, 0, RX_CALL_DEAD, -ECONNRESET,
480 rxrpc_abort_call_reset);
481 } else {
482 rxrpc_abort_call(call, 0, RX_CALL_TIMEOUT, -ETIME,
483 rxrpc_abort_call_timeout);
484 }
485 goto out;
486 }
487
488 if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events))
489 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
490 rxrpc_propose_ack_ping_for_lost_ack);
491
492 if (resend && __rxrpc_call_state(call) != RXRPC_CALL_CLIENT_RECV_REPLY)
493 rxrpc_resend(call, NULL);
494
495 if (test_and_clear_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags))
496 rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
497 rxrpc_propose_ack_rx_idle);
498
499 if (call->ackr_nr_unacked > 2) {
500 if (call->peer->rtt_count < 3)
501 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
502 rxrpc_propose_ack_ping_for_rtt);
503 else if (ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000),
504 ktime_get_real()))
505 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
506 rxrpc_propose_ack_ping_for_old_rtt);
507 else
508 rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
509 rxrpc_propose_ack_input_data);
510 }
511
512 /* Make sure the timer is restarted */
513 if (!__rxrpc_call_is_complete(call)) {
514 next = call->expect_rx_by;
515
516#define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }
517
518 set(call->expect_req_by);
519 set(call->expect_term_by);
520 set(call->delay_ack_at);
521 set(call->ack_lost_at);
522 set(call->resend_at);
523 set(call->keepalive_at);
524 set(call->ping_at);
525
526 now = jiffies;
527 if (time_after_eq(now, next))
528 rxrpc_poke_call(call, rxrpc_call_poke_timer_now);
529
530 rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
531 }
532
533out:
534 if (__rxrpc_call_is_complete(call)) {
535 del_timer_sync(&call->timer);
536 if (!test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
537 rxrpc_disconnect_call(call);
538 if (call->security)
539 call->security->free_call_crypto(call);
540 }
541 if (call->acks_hard_ack != call->tx_bottom)
542 rxrpc_shrink_call_tx_buffer(call);
543 _leave("");
544 return true;
545}