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 */ 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 */ 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 */ 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 */ 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 */ 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 */ 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 */ 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 */ 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 } 260 261 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 */ 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 */ 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