xref: /openbmc/linux/net/rxrpc/output.c (revision 966a9b49033b472dcfb453abdc34bca7df17adce)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* RxRPC packet transmission
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/net.h>
11 #include <linux/gfp.h>
12 #include <linux/skbuff.h>
13 #include <linux/export.h>
14 #include <net/sock.h>
15 #include <net/af_rxrpc.h>
16 #include <net/udp.h>
17 #include "ar-internal.h"
18 
19 extern int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len);
20 
21 static ssize_t do_udp_sendmsg(struct socket *sk, struct msghdr *msg, size_t len)
22 {
23 #if IS_ENABLED(CONFIG_AF_RXRPC_IPV6)
24 	struct sockaddr *sa = msg->msg_name;
25 
26 	if (sa->sa_family == AF_INET6)
27 		return udpv6_sendmsg(sk->sk, msg, len);
28 #endif
29 	return udp_sendmsg(sk->sk, msg, len);
30 }
31 
32 struct rxrpc_abort_buffer {
33 	struct rxrpc_wire_header whdr;
34 	__be32 abort_code;
35 };
36 
37 static const char rxrpc_keepalive_string[] = "";
38 
39 /*
40  * Increase Tx backoff on transmission failure and clear it on success.
41  */
42 static void rxrpc_tx_backoff(struct rxrpc_call *call, int ret)
43 {
44 	if (ret < 0) {
45 		u16 tx_backoff = READ_ONCE(call->tx_backoff);
46 
47 		if (tx_backoff < HZ)
48 			WRITE_ONCE(call->tx_backoff, tx_backoff + 1);
49 	} else {
50 		WRITE_ONCE(call->tx_backoff, 0);
51 	}
52 }
53 
54 /*
55  * Arrange for a keepalive ping a certain time after we last transmitted.  This
56  * lets the far side know we're still interested in this call and helps keep
57  * the route through any intervening firewall open.
58  *
59  * Receiving a response to the ping will prevent the ->expect_rx_by timer from
60  * expiring.
61  */
62 static void rxrpc_set_keepalive(struct rxrpc_call *call)
63 {
64 	unsigned long now = jiffies, keepalive_at = call->next_rx_timo / 6;
65 
66 	keepalive_at += now;
67 	WRITE_ONCE(call->keepalive_at, keepalive_at);
68 	rxrpc_reduce_call_timer(call, keepalive_at, now,
69 				rxrpc_timer_set_for_keepalive);
70 }
71 
72 /*
73  * Fill out an ACK packet.
74  */
75 static size_t rxrpc_fill_out_ack(struct rxrpc_connection *conn,
76 				 struct rxrpc_call *call,
77 				 struct rxrpc_txbuf *txb)
78 {
79 	struct rxrpc_ackinfo ackinfo;
80 	unsigned int qsize;
81 	rxrpc_seq_t window, wtop, wrap_point, ix, first;
82 	int rsize;
83 	u64 wtmp;
84 	u32 mtu, jmax;
85 	u8 *ackp = txb->acks;
86 	u8 sack_buffer[sizeof(call->ackr_sack_table)] __aligned(8);
87 
88 	atomic_set(&call->ackr_nr_unacked, 0);
89 	atomic_set(&call->ackr_nr_consumed, 0);
90 	rxrpc_inc_stat(call->rxnet, stat_tx_ack_fill);
91 
92 	/* Barrier against rxrpc_input_data(). */
93 retry:
94 	wtmp   = atomic64_read_acquire(&call->ackr_window);
95 	window = lower_32_bits(wtmp);
96 	wtop   = upper_32_bits(wtmp);
97 	txb->ack.firstPacket = htonl(window);
98 	txb->ack.nAcks = 0;
99 
100 	if (after(wtop, window)) {
101 		/* Try to copy the SACK ring locklessly.  We can use the copy,
102 		 * only if the now-current top of the window didn't go past the
103 		 * previously read base - otherwise we can't know whether we
104 		 * have old data or new data.
105 		 */
106 		memcpy(sack_buffer, call->ackr_sack_table, sizeof(sack_buffer));
107 		wrap_point = window + RXRPC_SACK_SIZE - 1;
108 		wtmp   = atomic64_read_acquire(&call->ackr_window);
109 		window = lower_32_bits(wtmp);
110 		wtop   = upper_32_bits(wtmp);
111 		if (after(wtop, wrap_point)) {
112 			cond_resched();
113 			goto retry;
114 		}
115 
116 		/* The buffer is maintained as a ring with an invariant mapping
117 		 * between bit position and sequence number, so we'll probably
118 		 * need to rotate it.
119 		 */
120 		txb->ack.nAcks = wtop - window;
121 		ix = window % RXRPC_SACK_SIZE;
122 		first = sizeof(sack_buffer) - ix;
123 
124 		if (ix + txb->ack.nAcks <= RXRPC_SACK_SIZE) {
125 			memcpy(txb->acks, sack_buffer + ix, txb->ack.nAcks);
126 		} else {
127 			memcpy(txb->acks, sack_buffer + ix, first);
128 			memcpy(txb->acks + first, sack_buffer,
129 			       txb->ack.nAcks - first);
130 		}
131 
132 		ackp += txb->ack.nAcks;
133 	} else if (before(wtop, window)) {
134 		pr_warn("ack window backward %x %x", window, wtop);
135 	} else if (txb->ack.reason == RXRPC_ACK_DELAY) {
136 		txb->ack.reason = RXRPC_ACK_IDLE;
137 	}
138 
139 	mtu = conn->params.peer->if_mtu;
140 	mtu -= conn->params.peer->hdrsize;
141 	jmax = rxrpc_rx_jumbo_max;
142 	qsize = (window - 1) - call->rx_consumed;
143 	rsize = max_t(int, call->rx_winsize - qsize, 0);
144 	ackinfo.rxMTU		= htonl(rxrpc_rx_mtu);
145 	ackinfo.maxMTU		= htonl(mtu);
146 	ackinfo.rwind		= htonl(rsize);
147 	ackinfo.jumbo_max	= htonl(jmax);
148 
149 	*ackp++ = 0;
150 	*ackp++ = 0;
151 	*ackp++ = 0;
152 	memcpy(ackp, &ackinfo, sizeof(ackinfo));
153 	return txb->ack.nAcks + 3 + sizeof(ackinfo);
154 }
155 
156 /*
157  * Record the beginning of an RTT probe.
158  */
159 static int rxrpc_begin_rtt_probe(struct rxrpc_call *call, rxrpc_serial_t serial,
160 				 enum rxrpc_rtt_tx_trace why)
161 {
162 	unsigned long avail = call->rtt_avail;
163 	int rtt_slot = 9;
164 
165 	if (!(avail & RXRPC_CALL_RTT_AVAIL_MASK))
166 		goto no_slot;
167 
168 	rtt_slot = __ffs(avail & RXRPC_CALL_RTT_AVAIL_MASK);
169 	if (!test_and_clear_bit(rtt_slot, &call->rtt_avail))
170 		goto no_slot;
171 
172 	call->rtt_serial[rtt_slot] = serial;
173 	call->rtt_sent_at[rtt_slot] = ktime_get_real();
174 	smp_wmb(); /* Write data before avail bit */
175 	set_bit(rtt_slot + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
176 
177 	trace_rxrpc_rtt_tx(call, why, rtt_slot, serial);
178 	return rtt_slot;
179 
180 no_slot:
181 	trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_no_slot, rtt_slot, serial);
182 	return -1;
183 }
184 
185 /*
186  * Cancel an RTT probe.
187  */
188 static void rxrpc_cancel_rtt_probe(struct rxrpc_call *call,
189 				   rxrpc_serial_t serial, int rtt_slot)
190 {
191 	if (rtt_slot != -1) {
192 		clear_bit(rtt_slot + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
193 		smp_wmb(); /* Clear pending bit before setting slot */
194 		set_bit(rtt_slot, &call->rtt_avail);
195 		trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_cancel, rtt_slot, serial);
196 	}
197 }
198 
199 /*
200  * Send an ACK call packet.
201  */
202 static int rxrpc_send_ack_packet(struct rxrpc_local *local, struct rxrpc_txbuf *txb)
203 {
204 	struct rxrpc_connection *conn;
205 	struct rxrpc_ack_buffer *pkt;
206 	struct rxrpc_call *call = txb->call;
207 	struct msghdr msg;
208 	struct kvec iov[1];
209 	rxrpc_serial_t serial;
210 	size_t len, n;
211 	int ret, rtt_slot = -1;
212 
213 	if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
214 		return -ECONNRESET;
215 
216 	conn = call->conn;
217 
218 	msg.msg_name	= &call->peer->srx.transport;
219 	msg.msg_namelen	= call->peer->srx.transport_len;
220 	msg.msg_control	= NULL;
221 	msg.msg_controllen = 0;
222 	msg.msg_flags	= 0;
223 
224 	if (txb->ack.reason == RXRPC_ACK_PING)
225 		txb->wire.flags |= RXRPC_REQUEST_ACK;
226 
227 	if (txb->ack.reason == RXRPC_ACK_DELAY)
228 		clear_bit(RXRPC_CALL_DELAY_ACK_PENDING, &call->flags);
229 	if (txb->ack.reason == RXRPC_ACK_IDLE)
230 		clear_bit(RXRPC_CALL_IDLE_ACK_PENDING, &call->flags);
231 
232 	n = rxrpc_fill_out_ack(conn, call, txb);
233 	if (n == 0)
234 		return 0;
235 
236 	iov[0].iov_base	= &txb->wire;
237 	iov[0].iov_len	= sizeof(txb->wire) + sizeof(txb->ack) + n;
238 	len = iov[0].iov_len;
239 
240 	serial = atomic_inc_return(&conn->serial);
241 	txb->wire.serial = htonl(serial);
242 	trace_rxrpc_tx_ack(call->debug_id, serial,
243 			   ntohl(txb->ack.firstPacket),
244 			   ntohl(txb->ack.serial), txb->ack.reason, txb->ack.nAcks);
245 	if (txb->ack_why == rxrpc_propose_ack_ping_for_lost_ack)
246 		call->acks_lost_ping = serial;
247 
248 	if (txb->ack.reason == RXRPC_ACK_PING)
249 		rtt_slot = rxrpc_begin_rtt_probe(call, serial, rxrpc_rtt_tx_ping);
250 
251 	rxrpc_inc_stat(call->rxnet, stat_tx_ack_send);
252 
253 	/* Grab the highest received seq as late as possible */
254 	txb->ack.previousPacket	= htonl(call->rx_highest_seq);
255 
256 	iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, len);
257 	ret = do_udp_sendmsg(conn->params.local->socket, &msg, len);
258 	call->peer->last_tx_at = ktime_get_seconds();
259 	if (ret < 0)
260 		trace_rxrpc_tx_fail(call->debug_id, serial, ret,
261 				    rxrpc_tx_point_call_ack);
262 	else
263 		trace_rxrpc_tx_packet(call->debug_id, &txb->wire,
264 				      rxrpc_tx_point_call_ack);
265 	rxrpc_tx_backoff(call, ret);
266 
267 	if (call->state < RXRPC_CALL_COMPLETE) {
268 		if (ret < 0)
269 			rxrpc_cancel_rtt_probe(call, serial, rtt_slot);
270 		rxrpc_set_keepalive(call);
271 	}
272 
273 	kfree(pkt);
274 	return ret;
275 }
276 
277 /*
278  * ACK transmitter for a local endpoint.  The UDP socket locks around each
279  * transmission, so we can only transmit one packet at a time, ACK, DATA or
280  * otherwise.
281  */
282 void rxrpc_transmit_ack_packets(struct rxrpc_local *local)
283 {
284 	LIST_HEAD(queue);
285 	int ret;
286 
287 	trace_rxrpc_local(local->debug_id, rxrpc_local_tx_ack,
288 			  refcount_read(&local->ref), NULL);
289 
290 	if (list_empty(&local->ack_tx_queue))
291 		return;
292 
293 	spin_lock_bh(&local->ack_tx_lock);
294 	list_splice_tail_init(&local->ack_tx_queue, &queue);
295 	spin_unlock_bh(&local->ack_tx_lock);
296 
297 	while (!list_empty(&queue)) {
298 		struct rxrpc_txbuf *txb =
299 			list_entry(queue.next, struct rxrpc_txbuf, tx_link);
300 
301 		ret = rxrpc_send_ack_packet(local, txb);
302 		if (ret < 0 && ret != -ECONNRESET) {
303 			spin_lock_bh(&local->ack_tx_lock);
304 			list_splice_init(&queue, &local->ack_tx_queue);
305 			spin_unlock_bh(&local->ack_tx_lock);
306 			break;
307 		}
308 
309 		list_del_init(&txb->tx_link);
310 		rxrpc_put_call(txb->call, rxrpc_call_put);
311 		rxrpc_put_txbuf(txb, rxrpc_txbuf_put_ack_tx);
312 	}
313 }
314 
315 /*
316  * Send an ABORT call packet.
317  */
318 int rxrpc_send_abort_packet(struct rxrpc_call *call)
319 {
320 	struct rxrpc_connection *conn;
321 	struct rxrpc_abort_buffer pkt;
322 	struct msghdr msg;
323 	struct kvec iov[1];
324 	rxrpc_serial_t serial;
325 	int ret;
326 
327 	/* Don't bother sending aborts for a client call once the server has
328 	 * hard-ACK'd all of its request data.  After that point, we're not
329 	 * going to stop the operation proceeding, and whilst we might limit
330 	 * the reply, it's not worth it if we can send a new call on the same
331 	 * channel instead, thereby closing off this call.
332 	 */
333 	if (rxrpc_is_client_call(call) &&
334 	    test_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags))
335 		return 0;
336 
337 	if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
338 		return -ECONNRESET;
339 
340 	conn = call->conn;
341 
342 	msg.msg_name	= &call->peer->srx.transport;
343 	msg.msg_namelen	= call->peer->srx.transport_len;
344 	msg.msg_control	= NULL;
345 	msg.msg_controllen = 0;
346 	msg.msg_flags	= 0;
347 
348 	pkt.whdr.epoch		= htonl(conn->proto.epoch);
349 	pkt.whdr.cid		= htonl(call->cid);
350 	pkt.whdr.callNumber	= htonl(call->call_id);
351 	pkt.whdr.seq		= 0;
352 	pkt.whdr.type		= RXRPC_PACKET_TYPE_ABORT;
353 	pkt.whdr.flags		= conn->out_clientflag;
354 	pkt.whdr.userStatus	= 0;
355 	pkt.whdr.securityIndex	= call->security_ix;
356 	pkt.whdr._rsvd		= 0;
357 	pkt.whdr.serviceId	= htons(call->service_id);
358 	pkt.abort_code		= htonl(call->abort_code);
359 
360 	iov[0].iov_base	= &pkt;
361 	iov[0].iov_len	= sizeof(pkt);
362 
363 	serial = atomic_inc_return(&conn->serial);
364 	pkt.whdr.serial = htonl(serial);
365 
366 	iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, sizeof(pkt));
367 	ret = do_udp_sendmsg(conn->params.local->socket, &msg, sizeof(pkt));
368 	conn->params.peer->last_tx_at = ktime_get_seconds();
369 	if (ret < 0)
370 		trace_rxrpc_tx_fail(call->debug_id, serial, ret,
371 				    rxrpc_tx_point_call_abort);
372 	else
373 		trace_rxrpc_tx_packet(call->debug_id, &pkt.whdr,
374 				      rxrpc_tx_point_call_abort);
375 	rxrpc_tx_backoff(call, ret);
376 	return ret;
377 }
378 
379 /*
380  * send a packet through the transport endpoint
381  */
382 int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
383 {
384 	enum rxrpc_req_ack_trace why;
385 	struct rxrpc_connection *conn = call->conn;
386 	struct msghdr msg;
387 	struct kvec iov[1];
388 	rxrpc_serial_t serial;
389 	size_t len;
390 	int ret, rtt_slot = -1;
391 
392 	_enter("%x,{%d}", txb->seq, txb->len);
393 
394 	if (hlist_unhashed(&call->error_link)) {
395 		spin_lock_bh(&call->peer->lock);
396 		hlist_add_head_rcu(&call->error_link, &call->peer->error_targets);
397 		spin_unlock_bh(&call->peer->lock);
398 	}
399 
400 	/* Each transmission of a Tx packet needs a new serial number */
401 	serial = atomic_inc_return(&conn->serial);
402 	txb->wire.serial = htonl(serial);
403 
404 	if (test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags) &&
405 	    txb->seq == 1)
406 		txb->wire.userStatus = RXRPC_USERSTATUS_SERVICE_UPGRADE;
407 
408 	iov[0].iov_base = &txb->wire;
409 	iov[0].iov_len = sizeof(txb->wire) + txb->len;
410 	len = iov[0].iov_len;
411 	iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, len);
412 
413 	msg.msg_name = &call->peer->srx.transport;
414 	msg.msg_namelen = call->peer->srx.transport_len;
415 	msg.msg_control = NULL;
416 	msg.msg_controllen = 0;
417 	msg.msg_flags = 0;
418 
419 	/* If our RTT cache needs working on, request an ACK.  Also request
420 	 * ACKs if a DATA packet appears to have been lost.
421 	 *
422 	 * However, we mustn't request an ACK on the last reply packet of a
423 	 * service call, lest OpenAFS incorrectly send us an ACK with some
424 	 * soft-ACKs in it and then never follow up with a proper hard ACK.
425 	 */
426 	if (txb->wire.flags & RXRPC_REQUEST_ACK)
427 		why = rxrpc_reqack_already_on;
428 	else if (test_bit(RXRPC_TXBUF_LAST, &txb->flags) && rxrpc_sending_to_client(txb))
429 		why = rxrpc_reqack_no_srv_last;
430 	else if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events))
431 		why = rxrpc_reqack_ack_lost;
432 	else if (test_bit(RXRPC_TXBUF_RESENT, &txb->flags))
433 		why = rxrpc_reqack_retrans;
434 	else if (call->cong_mode == RXRPC_CALL_SLOW_START && call->cong_cwnd <= 2)
435 		why = rxrpc_reqack_slow_start;
436 	else if (call->tx_winsize <= 2)
437 		why = rxrpc_reqack_small_txwin;
438 	else if (call->peer->rtt_count < 3 && txb->seq & 1)
439 		why = rxrpc_reqack_more_rtt;
440 	else if (ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), ktime_get_real()))
441 		why = rxrpc_reqack_old_rtt;
442 	else
443 		goto dont_set_request_ack;
444 
445 	rxrpc_inc_stat(call->rxnet, stat_why_req_ack[why]);
446 	trace_rxrpc_req_ack(call->debug_id, txb->seq, why);
447 	if (why != rxrpc_reqack_no_srv_last)
448 		txb->wire.flags |= RXRPC_REQUEST_ACK;
449 dont_set_request_ack:
450 
451 	if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
452 		static int lose;
453 		if ((lose++ & 7) == 7) {
454 			ret = 0;
455 			trace_rxrpc_tx_data(call, txb->seq, serial,
456 					    txb->wire.flags,
457 					    test_bit(RXRPC_TXBUF_RESENT, &txb->flags),
458 					    true);
459 			goto done;
460 		}
461 	}
462 
463 	trace_rxrpc_tx_data(call, txb->seq, serial, txb->wire.flags,
464 			    test_bit(RXRPC_TXBUF_RESENT, &txb->flags), false);
465 	cmpxchg(&call->tx_transmitted, txb->seq - 1, txb->seq);
466 
467 	/* send the packet with the don't fragment bit set if we currently
468 	 * think it's small enough */
469 	if (txb->len >= call->peer->maxdata)
470 		goto send_fragmentable;
471 
472 	down_read(&conn->params.local->defrag_sem);
473 
474 	txb->last_sent = ktime_get_real();
475 	if (txb->wire.flags & RXRPC_REQUEST_ACK)
476 		rtt_slot = rxrpc_begin_rtt_probe(call, serial, rxrpc_rtt_tx_data);
477 
478 	/* send the packet by UDP
479 	 * - returns -EMSGSIZE if UDP would have to fragment the packet
480 	 *   to go out of the interface
481 	 *   - in which case, we'll have processed the ICMP error
482 	 *     message and update the peer record
483 	 */
484 	rxrpc_inc_stat(call->rxnet, stat_tx_data_send);
485 	ret = do_udp_sendmsg(conn->params.local->socket, &msg, len);
486 	conn->params.peer->last_tx_at = ktime_get_seconds();
487 
488 	up_read(&conn->params.local->defrag_sem);
489 	if (ret < 0) {
490 		rxrpc_cancel_rtt_probe(call, serial, rtt_slot);
491 		trace_rxrpc_tx_fail(call->debug_id, serial, ret,
492 				    rxrpc_tx_point_call_data_nofrag);
493 	} else {
494 		trace_rxrpc_tx_packet(call->debug_id, &txb->wire,
495 				      rxrpc_tx_point_call_data_nofrag);
496 	}
497 
498 	rxrpc_tx_backoff(call, ret);
499 	if (ret == -EMSGSIZE)
500 		goto send_fragmentable;
501 
502 done:
503 	if (ret >= 0) {
504 		call->tx_last_sent = txb->last_sent;
505 		if (txb->wire.flags & RXRPC_REQUEST_ACK) {
506 			call->peer->rtt_last_req = txb->last_sent;
507 			if (call->peer->rtt_count > 1) {
508 				unsigned long nowj = jiffies, ack_lost_at;
509 
510 				ack_lost_at = rxrpc_get_rto_backoff(call->peer, false);
511 				ack_lost_at += nowj;
512 				WRITE_ONCE(call->ack_lost_at, ack_lost_at);
513 				rxrpc_reduce_call_timer(call, ack_lost_at, nowj,
514 							rxrpc_timer_set_for_lost_ack);
515 			}
516 		}
517 
518 		if (txb->seq == 1 &&
519 		    !test_and_set_bit(RXRPC_CALL_BEGAN_RX_TIMER,
520 				      &call->flags)) {
521 			unsigned long nowj = jiffies, expect_rx_by;
522 
523 			expect_rx_by = nowj + call->next_rx_timo;
524 			WRITE_ONCE(call->expect_rx_by, expect_rx_by);
525 			rxrpc_reduce_call_timer(call, expect_rx_by, nowj,
526 						rxrpc_timer_set_for_normal);
527 		}
528 
529 		rxrpc_set_keepalive(call);
530 	} else {
531 		/* Cancel the call if the initial transmission fails,
532 		 * particularly if that's due to network routing issues that
533 		 * aren't going away anytime soon.  The layer above can arrange
534 		 * the retransmission.
535 		 */
536 		if (!test_and_set_bit(RXRPC_CALL_BEGAN_RX_TIMER, &call->flags))
537 			rxrpc_set_call_completion(call, RXRPC_CALL_LOCAL_ERROR,
538 						  RX_USER_ABORT, ret);
539 	}
540 
541 	_leave(" = %d [%u]", ret, call->peer->maxdata);
542 	return ret;
543 
544 send_fragmentable:
545 	/* attempt to send this message with fragmentation enabled */
546 	_debug("send fragment");
547 
548 	down_write(&conn->params.local->defrag_sem);
549 
550 	txb->last_sent = ktime_get_real();
551 	if (txb->wire.flags & RXRPC_REQUEST_ACK)
552 		rtt_slot = rxrpc_begin_rtt_probe(call, serial, rxrpc_rtt_tx_data);
553 
554 	switch (conn->params.local->srx.transport.family) {
555 	case AF_INET6:
556 	case AF_INET:
557 		ip_sock_set_mtu_discover(conn->params.local->socket->sk,
558 					 IP_PMTUDISC_DONT);
559 		rxrpc_inc_stat(call->rxnet, stat_tx_data_send_frag);
560 		ret = do_udp_sendmsg(conn->params.local->socket, &msg, len);
561 		conn->params.peer->last_tx_at = ktime_get_seconds();
562 
563 		ip_sock_set_mtu_discover(conn->params.local->socket->sk,
564 					 IP_PMTUDISC_DO);
565 		break;
566 
567 	default:
568 		BUG();
569 	}
570 
571 	if (ret < 0) {
572 		rxrpc_cancel_rtt_probe(call, serial, rtt_slot);
573 		trace_rxrpc_tx_fail(call->debug_id, serial, ret,
574 				    rxrpc_tx_point_call_data_frag);
575 	} else {
576 		trace_rxrpc_tx_packet(call->debug_id, &txb->wire,
577 				      rxrpc_tx_point_call_data_frag);
578 	}
579 	rxrpc_tx_backoff(call, ret);
580 
581 	up_write(&conn->params.local->defrag_sem);
582 	goto done;
583 }
584 
585 /*
586  * reject packets through the local endpoint
587  */
588 void rxrpc_reject_packets(struct rxrpc_local *local)
589 {
590 	struct sockaddr_rxrpc srx;
591 	struct rxrpc_skb_priv *sp;
592 	struct rxrpc_wire_header whdr;
593 	struct sk_buff *skb;
594 	struct msghdr msg;
595 	struct kvec iov[2];
596 	size_t size;
597 	__be32 code;
598 	int ret, ioc;
599 
600 	_enter("%d", local->debug_id);
601 
602 	iov[0].iov_base = &whdr;
603 	iov[0].iov_len = sizeof(whdr);
604 	iov[1].iov_base = &code;
605 	iov[1].iov_len = sizeof(code);
606 
607 	msg.msg_name = &srx.transport;
608 	msg.msg_control = NULL;
609 	msg.msg_controllen = 0;
610 	msg.msg_flags = 0;
611 
612 	memset(&whdr, 0, sizeof(whdr));
613 
614 	while ((skb = skb_dequeue(&local->reject_queue))) {
615 		rxrpc_see_skb(skb, rxrpc_skb_seen);
616 		sp = rxrpc_skb(skb);
617 
618 		switch (skb->mark) {
619 		case RXRPC_SKB_MARK_REJECT_BUSY:
620 			whdr.type = RXRPC_PACKET_TYPE_BUSY;
621 			size = sizeof(whdr);
622 			ioc = 1;
623 			break;
624 		case RXRPC_SKB_MARK_REJECT_ABORT:
625 			whdr.type = RXRPC_PACKET_TYPE_ABORT;
626 			code = htonl(skb->priority);
627 			size = sizeof(whdr) + sizeof(code);
628 			ioc = 2;
629 			break;
630 		default:
631 			rxrpc_free_skb(skb, rxrpc_skb_freed);
632 			continue;
633 		}
634 
635 		if (rxrpc_extract_addr_from_skb(&srx, skb) == 0) {
636 			msg.msg_namelen = srx.transport_len;
637 
638 			whdr.epoch	= htonl(sp->hdr.epoch);
639 			whdr.cid	= htonl(sp->hdr.cid);
640 			whdr.callNumber	= htonl(sp->hdr.callNumber);
641 			whdr.serviceId	= htons(sp->hdr.serviceId);
642 			whdr.flags	= sp->hdr.flags;
643 			whdr.flags	^= RXRPC_CLIENT_INITIATED;
644 			whdr.flags	&= RXRPC_CLIENT_INITIATED;
645 
646 			iov_iter_kvec(&msg.msg_iter, WRITE, iov, ioc, size);
647 			ret = do_udp_sendmsg(local->socket, &msg, size);
648 			if (ret < 0)
649 				trace_rxrpc_tx_fail(local->debug_id, 0, ret,
650 						    rxrpc_tx_point_reject);
651 			else
652 				trace_rxrpc_tx_packet(local->debug_id, &whdr,
653 						      rxrpc_tx_point_reject);
654 		}
655 
656 		rxrpc_free_skb(skb, rxrpc_skb_freed);
657 	}
658 
659 	_leave("");
660 }
661 
662 /*
663  * Send a VERSION reply to a peer as a keepalive.
664  */
665 void rxrpc_send_keepalive(struct rxrpc_peer *peer)
666 {
667 	struct rxrpc_wire_header whdr;
668 	struct msghdr msg;
669 	struct kvec iov[2];
670 	size_t len;
671 	int ret;
672 
673 	_enter("");
674 
675 	msg.msg_name	= &peer->srx.transport;
676 	msg.msg_namelen	= peer->srx.transport_len;
677 	msg.msg_control	= NULL;
678 	msg.msg_controllen = 0;
679 	msg.msg_flags	= 0;
680 
681 	whdr.epoch	= htonl(peer->local->rxnet->epoch);
682 	whdr.cid	= 0;
683 	whdr.callNumber	= 0;
684 	whdr.seq	= 0;
685 	whdr.serial	= 0;
686 	whdr.type	= RXRPC_PACKET_TYPE_VERSION; /* Not client-initiated */
687 	whdr.flags	= RXRPC_LAST_PACKET;
688 	whdr.userStatus	= 0;
689 	whdr.securityIndex = 0;
690 	whdr._rsvd	= 0;
691 	whdr.serviceId	= 0;
692 
693 	iov[0].iov_base	= &whdr;
694 	iov[0].iov_len	= sizeof(whdr);
695 	iov[1].iov_base	= (char *)rxrpc_keepalive_string;
696 	iov[1].iov_len	= sizeof(rxrpc_keepalive_string);
697 
698 	len = iov[0].iov_len + iov[1].iov_len;
699 
700 	_proto("Tx VERSION (keepalive)");
701 
702 	iov_iter_kvec(&msg.msg_iter, WRITE, iov, 2, len);
703 	ret = do_udp_sendmsg(peer->local->socket, &msg, len);
704 	if (ret < 0)
705 		trace_rxrpc_tx_fail(peer->debug_id, 0, ret,
706 				    rxrpc_tx_point_version_keepalive);
707 	else
708 		trace_rxrpc_tx_packet(peer->debug_id, &whdr,
709 				      rxrpc_tx_point_version_keepalive);
710 
711 	peer->last_tx_at = ktime_get_seconds();
712 	_leave("");
713 }
714