xref: /linux/net/rxrpc/input.c (revision 1e15510b71c99c6e49134d756df91069f7d18141)
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 
12 /* Override priority when generating ACKs for received DATA */
13 static const u8 rxrpc_ack_priority[RXRPC_ACK__INVALID] = {
14 	[RXRPC_ACK_IDLE]		= 1,
15 	[RXRPC_ACK_DELAY]		= 2,
16 	[RXRPC_ACK_REQUESTED]		= 3,
17 	[RXRPC_ACK_DUPLICATE]		= 4,
18 	[RXRPC_ACK_EXCEEDS_WINDOW]	= 5,
19 	[RXRPC_ACK_NOSPACE]		= 6,
20 	[RXRPC_ACK_OUT_OF_SEQUENCE]	= 7,
21 };
22 
rxrpc_proto_abort(struct rxrpc_call * call,rxrpc_seq_t seq,enum rxrpc_abort_reason why)23 static void rxrpc_proto_abort(struct rxrpc_call *call, rxrpc_seq_t seq,
24 			      enum rxrpc_abort_reason why)
25 {
26 	rxrpc_abort_call(call, seq, RX_PROTOCOL_ERROR, -EBADMSG, why);
27 }
28 
29 /*
30  * Do TCP-style congestion management [RFC5681].
31  */
rxrpc_congestion_management(struct rxrpc_call * call,struct rxrpc_ack_summary * summary)32 static void rxrpc_congestion_management(struct rxrpc_call *call,
33 					struct rxrpc_ack_summary *summary)
34 {
35 	summary->change = rxrpc_cong_no_change;
36 	summary->in_flight = rxrpc_tx_in_flight(call);
37 
38 	if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
39 		summary->retrans_timeo = true;
40 		call->cong_ssthresh = umax(summary->in_flight / 2, 2);
41 		call->cong_cwnd = 1;
42 		if (call->cong_cwnd >= call->cong_ssthresh &&
43 		    call->cong_ca_state == RXRPC_CA_SLOW_START) {
44 			call->cong_ca_state = RXRPC_CA_CONGEST_AVOIDANCE;
45 			call->cong_tstamp = call->acks_latest_ts;
46 			call->cong_cumul_acks = 0;
47 		}
48 	}
49 
50 	call->cong_cumul_acks += summary->nr_new_sacks;
51 	call->cong_cumul_acks += summary->nr_new_hacks;
52 	if (call->cong_cumul_acks > 255)
53 		call->cong_cumul_acks = 255;
54 
55 	switch (call->cong_ca_state) {
56 	case RXRPC_CA_SLOW_START:
57 		if (call->acks_nr_snacks > 0)
58 			goto packet_loss_detected;
59 		if (call->cong_cumul_acks > 0)
60 			call->cong_cwnd += 1;
61 		if (call->cong_cwnd >= call->cong_ssthresh) {
62 			call->cong_ca_state = RXRPC_CA_CONGEST_AVOIDANCE;
63 			call->cong_tstamp = call->acks_latest_ts;
64 		}
65 		goto out;
66 
67 	case RXRPC_CA_CONGEST_AVOIDANCE:
68 		if (call->acks_nr_snacks > 0)
69 			goto packet_loss_detected;
70 
71 		/* We analyse the number of packets that get ACK'd per RTT
72 		 * period and increase the window if we managed to fill it.
73 		 */
74 		if (call->rtt_count == 0)
75 			goto out;
76 		if (ktime_before(call->acks_latest_ts,
77 				 ktime_add_us(call->cong_tstamp,
78 					      call->srtt_us >> 3)))
79 			goto out_no_clear_ca;
80 		summary->change = rxrpc_cong_rtt_window_end;
81 		call->cong_tstamp = call->acks_latest_ts;
82 		if (call->cong_cumul_acks >= call->cong_cwnd)
83 			call->cong_cwnd++;
84 		goto out;
85 
86 	case RXRPC_CA_PACKET_LOSS:
87 		if (call->acks_nr_snacks == 0)
88 			goto resume_normality;
89 
90 		if (summary->new_low_snack) {
91 			summary->change = rxrpc_cong_new_low_nack;
92 			call->cong_dup_acks = 1;
93 			if (call->cong_extra > 1)
94 				call->cong_extra = 1;
95 			goto send_extra_data;
96 		}
97 
98 		call->cong_dup_acks++;
99 		if (call->cong_dup_acks < 3)
100 			goto send_extra_data;
101 
102 		summary->change = rxrpc_cong_begin_retransmission;
103 		call->cong_ca_state = RXRPC_CA_FAST_RETRANSMIT;
104 		call->cong_ssthresh = umax(summary->in_flight / 2, 2);
105 		call->cong_cwnd = call->cong_ssthresh + 3;
106 		call->cong_extra = 0;
107 		call->cong_dup_acks = 0;
108 		summary->need_retransmit = true;
109 		summary->in_fast_or_rto_recovery = true;
110 		goto out;
111 
112 	case RXRPC_CA_FAST_RETRANSMIT:
113 		rxrpc_tlp_init(call);
114 		summary->in_fast_or_rto_recovery = true;
115 		if (!summary->new_low_snack) {
116 			if (summary->nr_new_sacks == 0)
117 				call->cong_cwnd += 1;
118 			call->cong_dup_acks++;
119 			if (call->cong_dup_acks == 2) {
120 				summary->change = rxrpc_cong_retransmit_again;
121 				call->cong_dup_acks = 0;
122 				summary->need_retransmit = true;
123 			}
124 		} else {
125 			summary->change = rxrpc_cong_progress;
126 			call->cong_cwnd = call->cong_ssthresh;
127 			if (call->acks_nr_snacks == 0) {
128 				summary->exiting_fast_or_rto_recovery = true;
129 				goto resume_normality;
130 			}
131 		}
132 		goto out;
133 
134 	default:
135 		BUG();
136 		goto out;
137 	}
138 
139 resume_normality:
140 	summary->change = rxrpc_cong_cleared_nacks;
141 	call->cong_dup_acks = 0;
142 	call->cong_extra = 0;
143 	call->cong_tstamp = call->acks_latest_ts;
144 	if (call->cong_cwnd < call->cong_ssthresh)
145 		call->cong_ca_state = RXRPC_CA_SLOW_START;
146 	else
147 		call->cong_ca_state = RXRPC_CA_CONGEST_AVOIDANCE;
148 out:
149 	call->cong_cumul_acks = 0;
150 out_no_clear_ca:
151 	if (call->cong_cwnd >= RXRPC_TX_MAX_WINDOW)
152 		call->cong_cwnd = RXRPC_TX_MAX_WINDOW;
153 	trace_rxrpc_congest(call, summary);
154 	return;
155 
156 packet_loss_detected:
157 	summary->change = rxrpc_cong_saw_nack;
158 	call->cong_ca_state = RXRPC_CA_PACKET_LOSS;
159 	call->cong_dup_acks = 0;
160 	goto send_extra_data;
161 
162 send_extra_data:
163 	/* Send some previously unsent DATA if we have some to advance the ACK
164 	 * state.
165 	 */
166 	if (test_bit(RXRPC_CALL_TX_LAST, &call->flags) ||
167 	    call->acks_nr_sacks != call->tx_top - call->tx_bottom) {
168 		call->cong_extra++;
169 		wake_up(&call->waitq);
170 	}
171 	goto out_no_clear_ca;
172 }
173 
174 /*
175  * Degrade the congestion window if we haven't transmitted a packet for >1RTT.
176  */
rxrpc_congestion_degrade(struct rxrpc_call * call)177 void rxrpc_congestion_degrade(struct rxrpc_call *call)
178 {
179 	ktime_t rtt, now, time_since;
180 
181 	if (call->cong_ca_state != RXRPC_CA_SLOW_START &&
182 	    call->cong_ca_state != RXRPC_CA_CONGEST_AVOIDANCE)
183 		return;
184 	if (__rxrpc_call_state(call) == RXRPC_CALL_CLIENT_AWAIT_REPLY)
185 		return;
186 
187 	rtt = ns_to_ktime(call->srtt_us * (NSEC_PER_USEC / 8));
188 	now = ktime_get_real();
189 	time_since = ktime_sub(now, call->tx_last_sent);
190 	if (ktime_before(time_since, rtt))
191 		return;
192 
193 	trace_rxrpc_reset_cwnd(call, time_since, rtt);
194 	rxrpc_inc_stat(call->rxnet, stat_tx_data_cwnd_reset);
195 	call->tx_last_sent = now;
196 	call->cong_ca_state = RXRPC_CA_SLOW_START;
197 	call->cong_ssthresh = umax(call->cong_ssthresh, call->cong_cwnd * 3 / 4);
198 	call->cong_cwnd = umax(call->cong_cwnd / 2, RXRPC_MIN_CWND);
199 }
200 
201 /*
202  * Add an RTT sample derived from an ACK'd DATA packet.
203  */
rxrpc_add_data_rtt_sample(struct rxrpc_call * call,struct rxrpc_ack_summary * summary,struct rxrpc_txqueue * tq,int ix)204 static void rxrpc_add_data_rtt_sample(struct rxrpc_call *call,
205 				      struct rxrpc_ack_summary *summary,
206 				      struct rxrpc_txqueue *tq,
207 				      int ix)
208 {
209 	ktime_t xmit_ts = ktime_add_us(tq->xmit_ts_base, tq->segment_xmit_ts[ix]);
210 
211 	rxrpc_call_add_rtt(call, rxrpc_rtt_rx_data_ack, -1,
212 			   summary->acked_serial, summary->ack_serial,
213 			   xmit_ts, call->acks_latest_ts);
214 	__clear_bit(ix, &tq->rtt_samples); /* Prevent repeat RTT sample */
215 }
216 
217 /*
218  * Apply a hard ACK by advancing the Tx window.
219  */
rxrpc_rotate_tx_window(struct rxrpc_call * call,rxrpc_seq_t to,struct rxrpc_ack_summary * summary)220 static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
221 				   struct rxrpc_ack_summary *summary)
222 {
223 	struct rxrpc_txqueue *tq = call->tx_queue;
224 	rxrpc_seq_t seq = call->tx_bottom + 1;
225 	bool rot_last = false, trace = false;
226 
227 	_enter("%x,%x", call->tx_bottom, to);
228 
229 	trace_rxrpc_tx_rotate(call, seq, to);
230 	trace_rxrpc_tq(call, tq, seq, rxrpc_tq_rotate);
231 
232 	if (call->acks_lowest_nak == call->tx_bottom) {
233 		call->acks_lowest_nak = to;
234 	} else if (after(to, call->acks_lowest_nak)) {
235 		summary->new_low_snack = true;
236 		call->acks_lowest_nak = to;
237 	}
238 
239 	/* We may have a left over fully-consumed buffer at the front that we
240 	 * couldn't drop before (rotate_and_keep below).
241 	 */
242 	if (seq == call->tx_qbase + RXRPC_NR_TXQUEUE) {
243 		call->tx_qbase += RXRPC_NR_TXQUEUE;
244 		call->tx_queue = tq->next;
245 		trace_rxrpc_tq(call, tq, seq, rxrpc_tq_rotate_and_free);
246 		kfree(tq);
247 		tq = call->tx_queue;
248 	}
249 
250 	do {
251 		unsigned int ix = seq - call->tx_qbase;
252 
253 		_debug("tq=%x seq=%x i=%d f=%x", tq->qbase, seq, ix, tq->bufs[ix]->flags);
254 		if (tq->bufs[ix]->flags & RXRPC_LAST_PACKET) {
255 			set_bit(RXRPC_CALL_TX_LAST, &call->flags);
256 			rot_last = true;
257 		}
258 
259 		if (summary->acked_serial == tq->segment_serial[ix] &&
260 		    test_bit(ix, &tq->rtt_samples))
261 			rxrpc_add_data_rtt_sample(call, summary, tq, ix);
262 
263 		if (ix == tq->nr_reported_acks) {
264 			/* Packet directly hard ACK'd. */
265 			tq->nr_reported_acks++;
266 			rxrpc_input_rack_one(call, summary, tq, ix);
267 			if (seq == call->tlp_seq)
268 				summary->tlp_probe_acked = true;
269 			summary->nr_new_hacks++;
270 			__set_bit(ix, &tq->segment_acked);
271 			trace_rxrpc_rotate(call, tq, summary, seq, rxrpc_rotate_trace_hack);
272 		} else if (test_bit(ix, &tq->segment_acked)) {
273 			/* Soft ACK -> hard ACK. */
274 			call->acks_nr_sacks--;
275 			trace_rxrpc_rotate(call, tq, summary, seq, rxrpc_rotate_trace_sack);
276 		} else {
277 			/* Soft NAK -> hard ACK. */
278 			call->acks_nr_snacks--;
279 			rxrpc_input_rack_one(call, summary, tq, ix);
280 			if (seq == call->tlp_seq)
281 				summary->tlp_probe_acked = true;
282 			summary->nr_new_hacks++;
283 			__set_bit(ix, &tq->segment_acked);
284 			trace_rxrpc_rotate(call, tq, summary, seq, rxrpc_rotate_trace_snak);
285 		}
286 
287 		call->tx_nr_sent--;
288 		if (__test_and_clear_bit(ix, &tq->segment_lost))
289 			call->tx_nr_lost--;
290 		if (__test_and_clear_bit(ix, &tq->segment_retransmitted))
291 			call->tx_nr_resent--;
292 		__clear_bit(ix, &tq->ever_retransmitted);
293 
294 		rxrpc_put_txbuf(tq->bufs[ix], rxrpc_txbuf_put_rotated);
295 		tq->bufs[ix] = NULL;
296 
297 		WRITE_ONCE(call->tx_bottom, seq);
298 		trace_rxrpc_txqueue(call, (rot_last ?
299 					   rxrpc_txqueue_rotate_last :
300 					   rxrpc_txqueue_rotate));
301 
302 		seq++;
303 		trace = true;
304 		if (!(seq & RXRPC_TXQ_MASK)) {
305 			trace_rxrpc_rack_update(call, summary);
306 			trace = false;
307 			prefetch(tq->next);
308 			if (tq != call->tx_qtail) {
309 				call->tx_qbase += RXRPC_NR_TXQUEUE;
310 				call->tx_queue = tq->next;
311 				trace_rxrpc_tq(call, tq, seq, rxrpc_tq_rotate_and_free);
312 				kfree(tq);
313 				tq = call->tx_queue;
314 			} else {
315 				trace_rxrpc_tq(call, tq, seq, rxrpc_tq_rotate_and_keep);
316 				tq = NULL;
317 				break;
318 			}
319 		}
320 
321 	} while (before_eq(seq, to));
322 
323 	if (trace)
324 		trace_rxrpc_rack_update(call, summary);
325 
326 	if (rot_last) {
327 		set_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags);
328 		if (tq) {
329 			trace_rxrpc_tq(call, tq, seq, rxrpc_tq_rotate_and_free);
330 			kfree(tq);
331 			call->tx_queue = NULL;
332 		}
333 	}
334 
335 	_debug("%x,%x,%x,%d", to, call->tx_bottom, call->tx_top, rot_last);
336 
337 	wake_up(&call->waitq);
338 	return rot_last;
339 }
340 
341 /*
342  * End the transmission phase of a call.
343  *
344  * This occurs when we get an ACKALL packet, the first DATA packet of a reply,
345  * or a final ACK packet.
346  */
rxrpc_end_tx_phase(struct rxrpc_call * call,bool reply_begun,enum rxrpc_abort_reason abort_why)347 static void rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
348 			       enum rxrpc_abort_reason abort_why)
349 {
350 	ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
351 
352 	call->rack_timer_mode = RXRPC_CALL_RACKTIMER_OFF;
353 	call->rack_timo_at = KTIME_MAX;
354 	trace_rxrpc_rack_timer(call, 0, false);
355 	trace_rxrpc_timer_can(call, rxrpc_timer_trace_rack_off + call->rack_timer_mode);
356 
357 	switch (__rxrpc_call_state(call)) {
358 	case RXRPC_CALL_CLIENT_SEND_REQUEST:
359 	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
360 		if (reply_begun) {
361 			rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_RECV_REPLY);
362 			trace_rxrpc_txqueue(call, rxrpc_txqueue_end);
363 			break;
364 		}
365 
366 		rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_AWAIT_REPLY);
367 		trace_rxrpc_txqueue(call, rxrpc_txqueue_await_reply);
368 		break;
369 
370 	case RXRPC_CALL_SERVER_AWAIT_ACK:
371 		rxrpc_call_completed(call);
372 		trace_rxrpc_txqueue(call, rxrpc_txqueue_end);
373 		break;
374 
375 	default:
376 		kdebug("end_tx %s", rxrpc_call_states[__rxrpc_call_state(call)]);
377 		rxrpc_proto_abort(call, call->tx_top, abort_why);
378 		break;
379 	}
380 }
381 
382 /*
383  * Begin the reply reception phase of a call.
384  */
rxrpc_receiving_reply(struct rxrpc_call * call)385 static bool rxrpc_receiving_reply(struct rxrpc_call *call)
386 {
387 	struct rxrpc_ack_summary summary = { 0 };
388 	rxrpc_seq_t top = READ_ONCE(call->tx_top);
389 
390 	if (call->ackr_reason) {
391 		call->delay_ack_at = KTIME_MAX;
392 		trace_rxrpc_timer_can(call, rxrpc_timer_trace_delayed_ack);
393 	}
394 
395 	if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
396 		if (!rxrpc_rotate_tx_window(call, top, &summary)) {
397 			rxrpc_proto_abort(call, top, rxrpc_eproto_early_reply);
398 			return false;
399 		}
400 	}
401 
402 	rxrpc_end_tx_phase(call, true, rxrpc_eproto_unexpected_reply);
403 	return true;
404 }
405 
406 /*
407  * End the packet reception phase.
408  */
rxrpc_end_rx_phase(struct rxrpc_call * call,rxrpc_serial_t serial)409 static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
410 {
411 	rxrpc_seq_t whigh = READ_ONCE(call->rx_highest_seq);
412 
413 	_enter("%d,%s", call->debug_id, rxrpc_call_states[__rxrpc_call_state(call)]);
414 
415 	trace_rxrpc_receive(call, rxrpc_receive_end, 0, whigh);
416 
417 	switch (__rxrpc_call_state(call)) {
418 	case RXRPC_CALL_CLIENT_RECV_REPLY:
419 		rxrpc_propose_delay_ACK(call, serial, rxrpc_propose_ack_terminal_ack);
420 		rxrpc_call_completed(call);
421 		break;
422 
423 	case RXRPC_CALL_SERVER_RECV_REQUEST:
424 		rxrpc_set_call_state(call, RXRPC_CALL_SERVER_ACK_REQUEST);
425 		call->expect_req_by = KTIME_MAX;
426 		rxrpc_propose_delay_ACK(call, serial, rxrpc_propose_ack_processing_op);
427 		break;
428 
429 	default:
430 		break;
431 	}
432 }
433 
rxrpc_input_update_ack_window(struct rxrpc_call * call,rxrpc_seq_t window,rxrpc_seq_t wtop)434 static void rxrpc_input_update_ack_window(struct rxrpc_call *call,
435 					  rxrpc_seq_t window, rxrpc_seq_t wtop)
436 {
437 	call->ackr_window = window;
438 	call->ackr_wtop = wtop;
439 }
440 
441 /*
442  * Push a DATA packet onto the Rx queue.
443  */
rxrpc_input_queue_data(struct rxrpc_call * call,struct sk_buff * skb,rxrpc_seq_t window,rxrpc_seq_t wtop,enum rxrpc_receive_trace why)444 static void rxrpc_input_queue_data(struct rxrpc_call *call, struct sk_buff *skb,
445 				   rxrpc_seq_t window, rxrpc_seq_t wtop,
446 				   enum rxrpc_receive_trace why)
447 {
448 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
449 	bool last = sp->hdr.flags & RXRPC_LAST_PACKET;
450 
451 	spin_lock_irq(&call->recvmsg_queue.lock);
452 
453 	__skb_queue_tail(&call->recvmsg_queue, skb);
454 	rxrpc_input_update_ack_window(call, window, wtop);
455 	trace_rxrpc_receive(call, last ? why + 1 : why, sp->hdr.serial, sp->hdr.seq);
456 	if (last)
457 		/* Change the state inside the lock so that recvmsg syncs
458 		 * correctly with it and using sendmsg() to send a reply
459 		 * doesn't race.
460 		 */
461 		rxrpc_end_rx_phase(call, sp->hdr.serial);
462 
463 	spin_unlock_irq(&call->recvmsg_queue.lock);
464 }
465 
466 /*
467  * Process a DATA packet.
468  */
rxrpc_input_data_one(struct rxrpc_call * call,struct sk_buff * skb,bool * _notify,rxrpc_serial_t * _ack_serial,int * _ack_reason)469 static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb,
470 				 bool *_notify, rxrpc_serial_t *_ack_serial, int *_ack_reason)
471 {
472 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
473 	struct sk_buff *oos;
474 	rxrpc_serial_t serial = sp->hdr.serial;
475 	unsigned int sack = call->ackr_sack_base;
476 	rxrpc_seq_t window = call->ackr_window;
477 	rxrpc_seq_t wtop = call->ackr_wtop;
478 	rxrpc_seq_t wlimit = window + call->rx_winsize - 1;
479 	rxrpc_seq_t seq = sp->hdr.seq;
480 	bool last = sp->hdr.flags & RXRPC_LAST_PACKET;
481 	int ack_reason = -1;
482 
483 	rxrpc_inc_stat(call->rxnet, stat_rx_data);
484 	if (sp->hdr.flags & RXRPC_REQUEST_ACK)
485 		rxrpc_inc_stat(call->rxnet, stat_rx_data_reqack);
486 	if (sp->hdr.flags & RXRPC_JUMBO_PACKET)
487 		rxrpc_inc_stat(call->rxnet, stat_rx_data_jumbo);
488 
489 	if (last) {
490 		if (test_and_set_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
491 		    seq + 1 != wtop)
492 			return rxrpc_proto_abort(call, seq, rxrpc_eproto_different_last);
493 	} else {
494 		if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
495 		    after_eq(seq, wtop)) {
496 			pr_warn("Packet beyond last: c=%x q=%x window=%x-%x wlimit=%x\n",
497 				call->debug_id, seq, window, wtop, wlimit);
498 			return rxrpc_proto_abort(call, seq, rxrpc_eproto_data_after_last);
499 		}
500 	}
501 
502 	if (after(seq, call->rx_highest_seq))
503 		call->rx_highest_seq = seq;
504 
505 	trace_rxrpc_rx_data(call->debug_id, seq, serial, sp->hdr.flags);
506 
507 	if (before(seq, window)) {
508 		ack_reason = RXRPC_ACK_DUPLICATE;
509 		goto send_ack;
510 	}
511 	if (after(seq, wlimit)) {
512 		ack_reason = RXRPC_ACK_EXCEEDS_WINDOW;
513 		goto send_ack;
514 	}
515 
516 	/* Queue the packet. */
517 	if (seq == window) {
518 		if (sp->hdr.flags & RXRPC_REQUEST_ACK)
519 			ack_reason = RXRPC_ACK_REQUESTED;
520 		/* Send an immediate ACK if we fill in a hole */
521 		else if (!skb_queue_empty(&call->rx_oos_queue))
522 			ack_reason = RXRPC_ACK_DELAY;
523 
524 		window++;
525 		if (after(window, wtop)) {
526 			trace_rxrpc_sack(call, seq, sack, rxrpc_sack_none);
527 			wtop = window;
528 		} else {
529 			trace_rxrpc_sack(call, seq, sack, rxrpc_sack_advance);
530 			sack = (sack + 1) % RXRPC_SACK_SIZE;
531 		}
532 
533 
534 		rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg);
535 
536 		rxrpc_input_queue_data(call, skb, window, wtop, rxrpc_receive_queue);
537 		*_notify = true;
538 
539 		while ((oos = skb_peek(&call->rx_oos_queue))) {
540 			struct rxrpc_skb_priv *osp = rxrpc_skb(oos);
541 
542 			if (after(osp->hdr.seq, window))
543 				break;
544 
545 			__skb_unlink(oos, &call->rx_oos_queue);
546 			last = osp->hdr.flags & RXRPC_LAST_PACKET;
547 			seq = osp->hdr.seq;
548 			call->ackr_sack_table[sack] = 0;
549 			trace_rxrpc_sack(call, seq, sack, rxrpc_sack_fill);
550 			sack = (sack + 1) % RXRPC_SACK_SIZE;
551 
552 			window++;
553 			rxrpc_input_queue_data(call, oos, window, wtop,
554 					       rxrpc_receive_queue_oos);
555 		}
556 
557 		call->ackr_sack_base = sack;
558 	} else {
559 		unsigned int slot;
560 
561 		ack_reason = RXRPC_ACK_OUT_OF_SEQUENCE;
562 
563 		slot = seq - window;
564 		sack = (sack + slot) % RXRPC_SACK_SIZE;
565 
566 		if (call->ackr_sack_table[sack % RXRPC_SACK_SIZE]) {
567 			ack_reason = RXRPC_ACK_DUPLICATE;
568 			goto send_ack;
569 		}
570 
571 		call->ackr_sack_table[sack % RXRPC_SACK_SIZE] |= 1;
572 		trace_rxrpc_sack(call, seq, sack, rxrpc_sack_oos);
573 
574 		if (after(seq + 1, wtop)) {
575 			wtop = seq + 1;
576 			rxrpc_input_update_ack_window(call, window, wtop);
577 		}
578 
579 		skb_queue_walk(&call->rx_oos_queue, oos) {
580 			struct rxrpc_skb_priv *osp = rxrpc_skb(oos);
581 
582 			if (after(osp->hdr.seq, seq)) {
583 				rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg_oos);
584 				__skb_queue_before(&call->rx_oos_queue, oos, skb);
585 				goto oos_queued;
586 			}
587 		}
588 
589 		rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg_oos);
590 		__skb_queue_tail(&call->rx_oos_queue, skb);
591 	oos_queued:
592 		trace_rxrpc_receive(call, last ? rxrpc_receive_oos_last : rxrpc_receive_oos,
593 				    sp->hdr.serial, sp->hdr.seq);
594 	}
595 
596 send_ack:
597 	if (ack_reason >= 0) {
598 		if (rxrpc_ack_priority[ack_reason] > rxrpc_ack_priority[*_ack_reason]) {
599 			*_ack_serial = serial;
600 			*_ack_reason = ack_reason;
601 		} else if (rxrpc_ack_priority[ack_reason] == rxrpc_ack_priority[*_ack_reason] &&
602 			   ack_reason == RXRPC_ACK_REQUESTED) {
603 			*_ack_serial = serial;
604 			*_ack_reason = ack_reason;
605 		}
606 	}
607 }
608 
609 /*
610  * Split a jumbo packet and file the bits separately.
611  */
rxrpc_input_split_jumbo(struct rxrpc_call * call,struct sk_buff * skb)612 static bool rxrpc_input_split_jumbo(struct rxrpc_call *call, struct sk_buff *skb)
613 {
614 	struct rxrpc_jumbo_header jhdr;
615 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb), *jsp;
616 	struct sk_buff *jskb;
617 	rxrpc_serial_t ack_serial = 0;
618 	unsigned int offset = sizeof(struct rxrpc_wire_header);
619 	unsigned int len = skb->len - offset;
620 	bool notify = false;
621 	int ack_reason = 0, count = 1, stat_ix;
622 
623 	while (sp->hdr.flags & RXRPC_JUMBO_PACKET) {
624 		if (len < RXRPC_JUMBO_SUBPKTLEN)
625 			goto protocol_error;
626 		if (sp->hdr.flags & RXRPC_LAST_PACKET)
627 			goto protocol_error;
628 		if (skb_copy_bits(skb, offset + RXRPC_JUMBO_DATALEN,
629 				  &jhdr, sizeof(jhdr)) < 0)
630 			goto protocol_error;
631 
632 		jskb = skb_clone(skb, GFP_NOFS);
633 		if (!jskb) {
634 			kdebug("couldn't clone");
635 			return false;
636 		}
637 		rxrpc_new_skb(jskb, rxrpc_skb_new_jumbo_subpacket);
638 		jsp = rxrpc_skb(jskb);
639 		jsp->offset = offset;
640 		jsp->len = RXRPC_JUMBO_DATALEN;
641 		rxrpc_input_data_one(call, jskb, &notify, &ack_serial, &ack_reason);
642 		rxrpc_free_skb(jskb, rxrpc_skb_put_jumbo_subpacket);
643 
644 		sp->hdr.flags = jhdr.flags;
645 		sp->hdr._rsvd = ntohs(jhdr._rsvd);
646 		sp->hdr.seq++;
647 		sp->hdr.serial++;
648 		offset += RXRPC_JUMBO_SUBPKTLEN;
649 		len -= RXRPC_JUMBO_SUBPKTLEN;
650 		count++;
651 	}
652 
653 	sp->offset = offset;
654 	sp->len    = len;
655 	rxrpc_input_data_one(call, skb, &notify, &ack_serial, &ack_reason);
656 
657 	stat_ix = umin(count, ARRAY_SIZE(call->rxnet->stat_rx_jumbo)) - 1;
658 	atomic_inc(&call->rxnet->stat_rx_jumbo[stat_ix]);
659 
660 	if (ack_reason > 0) {
661 		rxrpc_send_ACK(call, ack_reason, ack_serial,
662 			       rxrpc_propose_ack_input_data);
663 	} else {
664 		call->ackr_nr_unacked++;
665 		rxrpc_propose_delay_ACK(call, sp->hdr.serial,
666 					rxrpc_propose_ack_input_data);
667 	}
668 	if (notify && !test_bit(RXRPC_CALL_CONN_CHALLENGING, &call->flags)) {
669 		trace_rxrpc_notify_socket(call->debug_id, sp->hdr.serial);
670 		rxrpc_notify_socket(call);
671 	}
672 	return true;
673 
674 protocol_error:
675 	return false;
676 }
677 
678 /*
679  * Process a DATA packet, adding the packet to the Rx ring.  The caller's
680  * packet ref must be passed on or discarded.
681  */
rxrpc_input_data(struct rxrpc_call * call,struct sk_buff * skb)682 static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
683 {
684 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
685 	rxrpc_serial_t serial = sp->hdr.serial;
686 	rxrpc_seq_t seq0 = sp->hdr.seq;
687 
688 	_enter("{%x,%x,%x},{%u,%x}",
689 	       call->ackr_window, call->ackr_wtop, call->rx_highest_seq,
690 	       skb->len, seq0);
691 
692 	if (__rxrpc_call_is_complete(call))
693 		return;
694 
695 	switch (__rxrpc_call_state(call)) {
696 	case RXRPC_CALL_CLIENT_SEND_REQUEST:
697 	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
698 		/* Received data implicitly ACKs all of the request
699 		 * packets we sent when we're acting as a client.
700 		 */
701 		if (!rxrpc_receiving_reply(call))
702 			goto out_notify;
703 		break;
704 
705 	case RXRPC_CALL_SERVER_RECV_REQUEST: {
706 		unsigned long timo = READ_ONCE(call->next_req_timo);
707 
708 		if (timo) {
709 			ktime_t delay = ms_to_ktime(timo);
710 
711 			call->expect_req_by = ktime_add(ktime_get_real(), delay);
712 			trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_idle);
713 		}
714 		break;
715 	}
716 
717 	default:
718 		break;
719 	}
720 
721 	if (!rxrpc_input_split_jumbo(call, skb)) {
722 		rxrpc_proto_abort(call, sp->hdr.seq, rxrpc_badmsg_bad_jumbo);
723 		goto out_notify;
724 	}
725 	return;
726 
727 out_notify:
728 	trace_rxrpc_notify_socket(call->debug_id, serial);
729 	rxrpc_notify_socket(call);
730 	_leave(" [queued]");
731 }
732 
733 /*
734  * See if there's a cached RTT probe to complete.
735  */
rxrpc_complete_rtt_probe(struct rxrpc_call * call,ktime_t resp_time,rxrpc_serial_t acked_serial,rxrpc_serial_t ack_serial,enum rxrpc_rtt_rx_trace type)736 static void rxrpc_complete_rtt_probe(struct rxrpc_call *call,
737 				     ktime_t resp_time,
738 				     rxrpc_serial_t acked_serial,
739 				     rxrpc_serial_t ack_serial,
740 				     enum rxrpc_rtt_rx_trace type)
741 {
742 	rxrpc_serial_t orig_serial;
743 	unsigned long avail;
744 	ktime_t sent_at;
745 	bool matched = false;
746 	int i;
747 
748 	avail = READ_ONCE(call->rtt_avail);
749 	smp_rmb(); /* Read avail bits before accessing data. */
750 
751 	for (i = 0; i < ARRAY_SIZE(call->rtt_serial); i++) {
752 		if (!test_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &avail))
753 			continue;
754 
755 		sent_at = call->rtt_sent_at[i];
756 		orig_serial = call->rtt_serial[i];
757 
758 		if (orig_serial == acked_serial) {
759 			clear_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
760 			smp_mb(); /* Read data before setting avail bit */
761 			set_bit(i, &call->rtt_avail);
762 			rxrpc_call_add_rtt(call, type, i, acked_serial, ack_serial,
763 					   sent_at, resp_time);
764 			matched = true;
765 		}
766 
767 		/* If a later serial is being acked, then mark this slot as
768 		 * being available.
769 		 */
770 		if (after(acked_serial, orig_serial)) {
771 			trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_obsolete, i,
772 					   orig_serial, acked_serial, 0, 0, 0);
773 			clear_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
774 			smp_wmb();
775 			set_bit(i, &call->rtt_avail);
776 		}
777 	}
778 
779 	if (!matched)
780 		trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_lost, 9, 0, acked_serial, 0, 0, 0);
781 }
782 
783 /*
784  * Process the extra information that may be appended to an ACK packet
785  */
rxrpc_input_ack_trailer(struct rxrpc_call * call,struct sk_buff * skb,struct rxrpc_acktrailer * trailer)786 static void rxrpc_input_ack_trailer(struct rxrpc_call *call, struct sk_buff *skb,
787 				    struct rxrpc_acktrailer *trailer)
788 {
789 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
790 	struct rxrpc_peer *peer = call->peer;
791 	unsigned int max_data, capacity;
792 	bool wake = false;
793 	u32 max_mtu	= ntohl(trailer->maxMTU);
794 	//u32 if_mtu	= ntohl(trailer->ifMTU);
795 	u32 rwind	= ntohl(trailer->rwind);
796 	u32 jumbo_max	= ntohl(trailer->jumbo_max);
797 
798 	if (rwind > RXRPC_TX_MAX_WINDOW)
799 		rwind = RXRPC_TX_MAX_WINDOW;
800 	if (call->tx_winsize != rwind) {
801 		if (rwind > call->tx_winsize)
802 			wake = true;
803 		trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, rwind, wake);
804 		call->tx_winsize = rwind;
805 	}
806 
807 	max_mtu = clamp(max_mtu, 500, 65535);
808 	peer->ackr_max_data = max_mtu;
809 
810 	if (max_mtu < peer->max_data) {
811 		trace_rxrpc_pmtud_reduce(peer, sp->hdr.serial, max_mtu,
812 					 rxrpc_pmtud_reduce_ack);
813 		peer->max_data = max_mtu;
814 	}
815 
816 	max_data = umin(max_mtu, peer->max_data);
817 	capacity = max_data;
818 	capacity += sizeof(struct rxrpc_jumbo_header); /* First subpacket has main hdr, not jumbo */
819 	capacity /= sizeof(struct rxrpc_jumbo_header) + RXRPC_JUMBO_DATALEN;
820 
821 	if (jumbo_max == 0) {
822 		/* The peer says it supports pmtu discovery */
823 		peer->ackr_adv_pmtud = true;
824 	} else {
825 		peer->ackr_adv_pmtud = false;
826 		capacity = clamp(capacity, 1, jumbo_max);
827 	}
828 
829 	call->tx_jumbo_max = capacity;
830 
831 	if (wake)
832 		wake_up(&call->waitq);
833 }
834 
835 #if defined(CONFIG_X86) && __GNUC__ && !defined(__clang__)
836 /* Clang doesn't support the %z constraint modifier */
837 #define shiftr_adv_rotr(shift_from, rotate_into) ({			\
838 			asm(" shr%z1 %1\n"				\
839 			    " inc %0\n"					\
840 			    " rcr%z2 %2\n"				\
841 			    : "+d"(shift_from), "+m"(*(shift_from)), "+rm"(rotate_into) \
842 			    );						\
843 		})
844 #else
845 #define shiftr_adv_rotr(shift_from, rotate_into) ({	\
846 			typeof(rotate_into) __bit0 = *(shift_from) & 1;	\
847 			*(shift_from) >>= 1;				\
848 			shift_from++;					\
849 			rotate_into >>= 1;				\
850 			rotate_into |= __bit0 << (sizeof(rotate_into) * 8 - 1); \
851 		})
852 #endif
853 
854 /*
855  * Deal with RTT samples from soft ACKs.
856  */
rxrpc_input_soft_rtt(struct rxrpc_call * call,struct rxrpc_ack_summary * summary,struct rxrpc_txqueue * tq)857 static void rxrpc_input_soft_rtt(struct rxrpc_call *call,
858 				 struct rxrpc_ack_summary *summary,
859 				 struct rxrpc_txqueue *tq)
860 {
861 	for (int ix = 0; ix < RXRPC_NR_TXQUEUE; ix++)
862 		if (summary->acked_serial == tq->segment_serial[ix])
863 			return rxrpc_add_data_rtt_sample(call, summary, tq, ix);
864 }
865 
866 /*
867  * Process a batch of soft ACKs specific to a transmission queue segment.
868  */
rxrpc_input_soft_ack_tq(struct rxrpc_call * call,struct rxrpc_ack_summary * summary,struct rxrpc_txqueue * tq,unsigned long extracted_acks,int nr_reported,rxrpc_seq_t seq,rxrpc_seq_t * lowest_nak)869 static void rxrpc_input_soft_ack_tq(struct rxrpc_call *call,
870 				    struct rxrpc_ack_summary *summary,
871 				    struct rxrpc_txqueue *tq,
872 				    unsigned long extracted_acks,
873 				    int nr_reported,
874 				    rxrpc_seq_t seq,
875 				    rxrpc_seq_t *lowest_nak)
876 {
877 	unsigned long old_reported = 0, flipped, new_acks = 0;
878 	unsigned long a_to_n, n_to_a = 0;
879 	int new, a, n;
880 
881 	if (tq->nr_reported_acks > 0)
882 		old_reported = ~0UL >> (RXRPC_NR_TXQUEUE - tq->nr_reported_acks);
883 
884 	_enter("{%x,%lx,%d},%lx,%d,%x",
885 	       tq->qbase, tq->segment_acked, tq->nr_reported_acks,
886 	       extracted_acks, nr_reported, seq);
887 
888 	_debug("[%x]", tq->qbase);
889 	_debug("tq    %16lx %u", tq->segment_acked, tq->nr_reported_acks);
890 	_debug("sack  %16lx %u", extracted_acks, nr_reported);
891 
892 	/* See how many previously logged ACKs/NAKs have flipped. */
893 	flipped = (tq->segment_acked ^ extracted_acks) & old_reported;
894 	if (flipped) {
895 		n_to_a = ~tq->segment_acked & flipped; /* Old NAK -> ACK */
896 		a_to_n =  tq->segment_acked & flipped; /* Old ACK -> NAK */
897 		a = hweight_long(n_to_a);
898 		n = hweight_long(a_to_n);
899 		_debug("flip  %16lx", flipped);
900 		_debug("ntoa  %16lx %d", n_to_a, a);
901 		_debug("aton  %16lx %d", a_to_n, n);
902 		call->acks_nr_sacks	+= a - n;
903 		call->acks_nr_snacks	+= n - a;
904 		summary->nr_new_sacks	+= a;
905 		summary->nr_new_snacks	+= n;
906 	}
907 
908 	/* See how many new ACKs/NAKs have been acquired. */
909 	new = nr_reported - tq->nr_reported_acks;
910 	if (new > 0) {
911 		new_acks = extracted_acks & ~old_reported;
912 		if (new_acks) {
913 			a = hweight_long(new_acks);
914 			n = new - a;
915 			_debug("new_a %16lx new=%d a=%d n=%d", new_acks, new, a, n);
916 			call->acks_nr_sacks	+= a;
917 			call->acks_nr_snacks	+= n;
918 			summary->nr_new_sacks	+= a;
919 			summary->nr_new_snacks	+= n;
920 		} else {
921 			call->acks_nr_snacks	+= new;
922 			summary->nr_new_snacks	+= new;
923 		}
924 	}
925 
926 	tq->nr_reported_acks = nr_reported;
927 	tq->segment_acked = extracted_acks;
928 	trace_rxrpc_apply_acks(call, tq);
929 
930 	if (extracted_acks != ~0UL) {
931 		rxrpc_seq_t lowest = seq + ffz(extracted_acks);
932 
933 		if (before(lowest, *lowest_nak))
934 			*lowest_nak = lowest;
935 	}
936 
937 	if (summary->acked_serial)
938 		rxrpc_input_soft_rtt(call, summary, tq);
939 
940 	new_acks |= n_to_a;
941 	if (new_acks)
942 		rxrpc_input_rack(call, summary, tq, new_acks);
943 
944 	if (call->tlp_serial &&
945 	    rxrpc_seq_in_txq(tq, call->tlp_seq) &&
946 	    test_bit(call->tlp_seq - tq->qbase, &new_acks))
947 		summary->tlp_probe_acked = true;
948 }
949 
950 /*
951  * Process individual soft ACKs.
952  *
953  * Each ACK in the array corresponds to one packet and can be either an ACK or
954  * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
955  * packets that lie beyond the end of the ACK list are scheduled for resend by
956  * the timer on the basis that the peer might just not have processed them at
957  * the time the ACK was sent.
958  */
rxrpc_input_soft_acks(struct rxrpc_call * call,struct rxrpc_ack_summary * summary,struct sk_buff * skb)959 static void rxrpc_input_soft_acks(struct rxrpc_call *call,
960 				  struct rxrpc_ack_summary *summary,
961 				  struct sk_buff *skb)
962 {
963 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
964 	struct rxrpc_txqueue *tq = call->tx_queue;
965 	unsigned long extracted = ~0UL;
966 	unsigned int nr = 0;
967 	rxrpc_seq_t seq = call->acks_hard_ack + 1;
968 	rxrpc_seq_t lowest_nak = seq + sp->ack.nr_acks;
969 	u8 *acks = skb->data + sizeof(struct rxrpc_wire_header) + sizeof(struct rxrpc_ackpacket);
970 
971 	_enter("%x,%x,%u", tq->qbase, seq, sp->ack.nr_acks);
972 
973 	while (after(seq, tq->qbase + RXRPC_NR_TXQUEUE - 1))
974 		tq = tq->next;
975 
976 	for (unsigned int i = 0; i < sp->ack.nr_acks; i++) {
977 		/* Decant ACKs until we hit a txqueue boundary. */
978 		shiftr_adv_rotr(acks, extracted);
979 		if (i == 256) {
980 			acks -= i;
981 			i = 0;
982 		}
983 		seq++;
984 		nr++;
985 		if ((seq & RXRPC_TXQ_MASK) != 0)
986 			continue;
987 
988 		_debug("bound %16lx %u", extracted, nr);
989 
990 		rxrpc_input_soft_ack_tq(call, summary, tq, extracted, RXRPC_NR_TXQUEUE,
991 					seq - RXRPC_NR_TXQUEUE, &lowest_nak);
992 		extracted = ~0UL;
993 		nr = 0;
994 		tq = tq->next;
995 		prefetch(tq);
996 	}
997 
998 	if (nr) {
999 		unsigned int nr_reported = seq & RXRPC_TXQ_MASK;
1000 
1001 		extracted >>= RXRPC_NR_TXQUEUE - nr_reported;
1002 		_debug("tail  %16lx %u", extracted, nr_reported);
1003 		rxrpc_input_soft_ack_tq(call, summary, tq, extracted, nr_reported,
1004 					seq & ~RXRPC_TXQ_MASK, &lowest_nak);
1005 	}
1006 
1007 	/* We *can* have more nacks than we did - the peer is permitted to drop
1008 	 * packets it has soft-acked and re-request them.  Further, it is
1009 	 * possible for the nack distribution to change whilst the number of
1010 	 * nacks stays the same or goes down.
1011 	 */
1012 	if (lowest_nak != call->acks_lowest_nak) {
1013 		call->acks_lowest_nak = lowest_nak;
1014 		summary->new_low_snack = true;
1015 	}
1016 
1017 	_debug("summary A=%d+%d N=%d+%d",
1018 	       call->acks_nr_sacks,  summary->nr_new_sacks,
1019 	       call->acks_nr_snacks, summary->nr_new_snacks);
1020 }
1021 
1022 /*
1023  * Return true if the ACK is valid - ie. it doesn't appear to have regressed
1024  * with respect to the ack state conveyed by preceding ACKs.
1025  */
rxrpc_is_ack_valid(struct rxrpc_call * call,rxrpc_seq_t hard_ack,rxrpc_seq_t prev_pkt)1026 static bool rxrpc_is_ack_valid(struct rxrpc_call *call,
1027 			       rxrpc_seq_t hard_ack, rxrpc_seq_t prev_pkt)
1028 {
1029 	rxrpc_seq_t base = READ_ONCE(call->acks_hard_ack);
1030 
1031 	if (after(hard_ack, base))
1032 		return true; /* The window advanced */
1033 
1034 	if (before(hard_ack, base))
1035 		return false; /* firstPacket regressed */
1036 
1037 	if (after_eq(prev_pkt, call->acks_prev_seq))
1038 		return true; /* previousPacket hasn't regressed. */
1039 
1040 	/* Some rx implementations put a serial number in previousPacket. */
1041 	if (after(prev_pkt, base + call->tx_winsize))
1042 		return false;
1043 	return true;
1044 }
1045 
1046 /*
1047  * Process an ACK packet.
1048  *
1049  * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
1050  * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
1051  *
1052  * A hard-ACK means that a packet has been processed and may be discarded; a
1053  * soft-ACK means that the packet may be discarded and retransmission
1054  * requested.  A phase is complete when all packets are hard-ACK'd.
1055  */
rxrpc_input_ack(struct rxrpc_call * call,struct sk_buff * skb)1056 static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
1057 {
1058 	struct rxrpc_ack_summary summary = { 0 };
1059 	struct rxrpc_acktrailer trailer;
1060 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1061 	rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
1062 	int nr_acks, offset, ioffset;
1063 
1064 	_enter("");
1065 
1066 	offset = sizeof(struct rxrpc_wire_header) + sizeof(struct rxrpc_ackpacket);
1067 
1068 	summary.ack_serial	= sp->hdr.serial;
1069 	first_soft_ack		= sp->ack.first_ack;
1070 	prev_pkt		= sp->ack.prev_ack;
1071 	nr_acks			= sp->ack.nr_acks;
1072 	hard_ack		= first_soft_ack - 1;
1073 	summary.acked_serial	= sp->ack.acked_serial;
1074 	summary.ack_reason	= (sp->ack.reason < RXRPC_ACK__INVALID ?
1075 				   sp->ack.reason : RXRPC_ACK__INVALID);
1076 
1077 	trace_rxrpc_rx_ack(call, sp);
1078 	rxrpc_inc_stat(call->rxnet, stat_rx_acks[summary.ack_reason]);
1079 	prefetch(call->tx_queue);
1080 
1081 	/* If we get an EXCEEDS_WINDOW ACK from the server, it probably
1082 	 * indicates that the client address changed due to NAT.  The server
1083 	 * lost the call because it switched to a different peer.
1084 	 */
1085 	if (unlikely(summary.ack_reason == RXRPC_ACK_EXCEEDS_WINDOW) &&
1086 	    hard_ack == 0 &&
1087 	    prev_pkt == 0 &&
1088 	    rxrpc_is_client_call(call)) {
1089 		rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
1090 					  0, -ENETRESET);
1091 		goto send_response;
1092 	}
1093 
1094 	/* If we get an OUT_OF_SEQUENCE ACK from the server, that can also
1095 	 * indicate a change of address.  However, we can retransmit the call
1096 	 * if we still have it buffered to the beginning.
1097 	 */
1098 	if (unlikely(summary.ack_reason == RXRPC_ACK_OUT_OF_SEQUENCE) &&
1099 	    hard_ack == 0 &&
1100 	    prev_pkt == 0 &&
1101 	    call->tx_bottom == 0 &&
1102 	    rxrpc_is_client_call(call)) {
1103 		rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
1104 					  0, -ENETRESET);
1105 		goto send_response;
1106 	}
1107 
1108 	/* Discard any out-of-order or duplicate ACKs (outside lock). */
1109 	if (!rxrpc_is_ack_valid(call, hard_ack, prev_pkt)) {
1110 		trace_rxrpc_rx_discard_ack(call, summary.ack_serial, hard_ack, prev_pkt);
1111 		goto send_response; /* Still respond if requested. */
1112 	}
1113 
1114 	trailer.maxMTU = 0;
1115 	ioffset = offset + nr_acks + 3;
1116 	if (skb->len >= ioffset + sizeof(trailer) &&
1117 	    skb_copy_bits(skb, ioffset, &trailer, sizeof(trailer)) < 0)
1118 		return rxrpc_proto_abort(call, 0, rxrpc_badmsg_short_ack_trailer);
1119 
1120 	if (nr_acks > 0)
1121 		skb_condense(skb);
1122 
1123 	call->acks_latest_ts = ktime_get_real();
1124 	call->acks_hard_ack = hard_ack;
1125 	call->acks_prev_seq = prev_pkt;
1126 
1127 	if (summary.acked_serial) {
1128 		switch (summary.ack_reason) {
1129 		case RXRPC_ACK_PING_RESPONSE:
1130 			rxrpc_complete_rtt_probe(call, call->acks_latest_ts,
1131 						 summary.acked_serial, summary.ack_serial,
1132 						 rxrpc_rtt_rx_ping_response);
1133 			break;
1134 		default:
1135 			if (after(summary.acked_serial, call->acks_highest_serial))
1136 				call->acks_highest_serial = summary.acked_serial;
1137 			summary.rtt_sample_avail = true;
1138 			break;
1139 		}
1140 	}
1141 
1142 	/* Parse rwind and mtu sizes if provided. */
1143 	if (trailer.maxMTU)
1144 		rxrpc_input_ack_trailer(call, skb, &trailer);
1145 
1146 	if (hard_ack + 1 == 0)
1147 		return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_zero);
1148 
1149 	/* Ignore ACKs unless we are or have just been transmitting. */
1150 	switch (__rxrpc_call_state(call)) {
1151 	case RXRPC_CALL_CLIENT_SEND_REQUEST:
1152 	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
1153 	case RXRPC_CALL_SERVER_SEND_REPLY:
1154 	case RXRPC_CALL_SERVER_AWAIT_ACK:
1155 		break;
1156 	default:
1157 		goto send_response;
1158 	}
1159 
1160 	if (before(hard_ack, call->tx_bottom) ||
1161 	    after(hard_ack, call->tx_top))
1162 		return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_outside_window);
1163 	if (nr_acks > call->tx_top - hard_ack)
1164 		return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_sack_overflow);
1165 
1166 	if (after(hard_ack, call->tx_bottom)) {
1167 		if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
1168 			rxrpc_end_tx_phase(call, false, rxrpc_eproto_unexpected_ack);
1169 			goto send_response;
1170 		}
1171 	}
1172 
1173 	if (nr_acks > 0) {
1174 		if (offset > (int)skb->len - nr_acks)
1175 			return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_short_sack);
1176 		rxrpc_input_soft_acks(call, &summary, skb);
1177 	}
1178 
1179 	if (test_bit(RXRPC_CALL_TX_LAST, &call->flags) &&
1180 	    call->acks_nr_sacks == call->tx_top - hard_ack &&
1181 	    rxrpc_is_client_call(call))
1182 		rxrpc_propose_ping(call, summary.ack_serial,
1183 				   rxrpc_propose_ack_ping_for_lost_reply);
1184 
1185 	/* Drive the congestion management algorithm first and then RACK-TLP as
1186 	 * the latter depends on the state/change in state in the former.
1187 	 */
1188 	rxrpc_congestion_management(call, &summary);
1189 	rxrpc_rack_detect_loss_and_arm_timer(call, &summary);
1190 	rxrpc_tlp_process_ack(call, &summary);
1191 	if (call->tlp_serial && after_eq(summary.acked_serial, call->tlp_serial))
1192 		call->tlp_serial = 0;
1193 
1194 send_response:
1195 	if (summary.ack_reason == RXRPC_ACK_PING)
1196 		rxrpc_send_ACK(call, RXRPC_ACK_PING_RESPONSE, summary.ack_serial,
1197 			       rxrpc_propose_ack_respond_to_ping);
1198 	else if (sp->hdr.flags & RXRPC_REQUEST_ACK)
1199 		rxrpc_send_ACK(call, RXRPC_ACK_REQUESTED, summary.ack_serial,
1200 			       rxrpc_propose_ack_respond_to_ack);
1201 }
1202 
1203 /*
1204  * Process an ACKALL packet.
1205  */
rxrpc_input_ackall(struct rxrpc_call * call,struct sk_buff * skb)1206 static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
1207 {
1208 	struct rxrpc_ack_summary summary = { 0 };
1209 
1210 	if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
1211 		rxrpc_end_tx_phase(call, false, rxrpc_eproto_unexpected_ackall);
1212 }
1213 
1214 /*
1215  * Process an ABORT packet directed at a call.
1216  */
rxrpc_input_abort(struct rxrpc_call * call,struct sk_buff * skb)1217 static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
1218 {
1219 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1220 
1221 	trace_rxrpc_rx_abort(call, sp->hdr.serial, skb->priority);
1222 
1223 	rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
1224 				  skb->priority, -ECONNABORTED);
1225 }
1226 
1227 /*
1228  * Process an incoming call packet.
1229  */
rxrpc_input_call_packet(struct rxrpc_call * call,struct sk_buff * skb)1230 void rxrpc_input_call_packet(struct rxrpc_call *call, struct sk_buff *skb)
1231 {
1232 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1233 	unsigned long timo;
1234 
1235 	_enter("%p,%p", call, skb);
1236 
1237 	if (sp->hdr.serviceId != call->dest_srx.srx_service)
1238 		call->dest_srx.srx_service = sp->hdr.serviceId;
1239 	if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
1240 		call->rx_serial = sp->hdr.serial;
1241 	if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
1242 		set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
1243 
1244 	timo = READ_ONCE(call->next_rx_timo);
1245 	if (timo) {
1246 		ktime_t delay = ms_to_ktime(timo);
1247 
1248 		call->expect_rx_by = ktime_add(ktime_get_real(), delay);
1249 		trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_expect_rx);
1250 	}
1251 
1252 	switch (sp->hdr.type) {
1253 	case RXRPC_PACKET_TYPE_DATA:
1254 		return rxrpc_input_data(call, skb);
1255 
1256 	case RXRPC_PACKET_TYPE_ACK:
1257 		return rxrpc_input_ack(call, skb);
1258 
1259 	case RXRPC_PACKET_TYPE_BUSY:
1260 		/* Just ignore BUSY packets from the server; the retry and
1261 		 * lifespan timers will take care of business.  BUSY packets
1262 		 * from the client don't make sense.
1263 		 */
1264 		return;
1265 
1266 	case RXRPC_PACKET_TYPE_ABORT:
1267 		return rxrpc_input_abort(call, skb);
1268 
1269 	case RXRPC_PACKET_TYPE_ACKALL:
1270 		return rxrpc_input_ackall(call, skb);
1271 
1272 	default:
1273 		break;
1274 	}
1275 }
1276 
1277 /*
1278  * Handle a new service call on a channel implicitly completing the preceding
1279  * call on that channel.  This does not apply to client conns.
1280  *
1281  * TODO: If callNumber > call_id + 1, renegotiate security.
1282  */
rxrpc_implicit_end_call(struct rxrpc_call * call,struct sk_buff * skb)1283 void rxrpc_implicit_end_call(struct rxrpc_call *call, struct sk_buff *skb)
1284 {
1285 	switch (__rxrpc_call_state(call)) {
1286 	case RXRPC_CALL_SERVER_AWAIT_ACK:
1287 		rxrpc_call_completed(call);
1288 		fallthrough;
1289 	case RXRPC_CALL_COMPLETE:
1290 		break;
1291 	default:
1292 		rxrpc_abort_call(call, 0, RX_CALL_DEAD, -ESHUTDOWN,
1293 				 rxrpc_eproto_improper_term);
1294 		trace_rxrpc_improper_term(call);
1295 		break;
1296 	}
1297 
1298 	rxrpc_input_call_event(call);
1299 }
1300