xref: /openbmc/linux/net/rxrpc/output.c (revision 32ced09d)
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 "ar-internal.h"
17 
18 struct rxrpc_ack_buffer {
19 	struct rxrpc_wire_header whdr;
20 	struct rxrpc_ackpacket ack;
21 	u8 acks[255];
22 	u8 pad[3];
23 	struct rxrpc_ackinfo ackinfo;
24 };
25 
26 struct rxrpc_abort_buffer {
27 	struct rxrpc_wire_header whdr;
28 	__be32 abort_code;
29 };
30 
31 static const char rxrpc_keepalive_string[] = "";
32 
33 /*
34  * Increase Tx backoff on transmission failure and clear it on success.
35  */
36 static void rxrpc_tx_backoff(struct rxrpc_call *call, int ret)
37 {
38 	if (ret < 0) {
39 		u16 tx_backoff = READ_ONCE(call->tx_backoff);
40 
41 		if (tx_backoff < HZ)
42 			WRITE_ONCE(call->tx_backoff, tx_backoff + 1);
43 	} else {
44 		WRITE_ONCE(call->tx_backoff, 0);
45 	}
46 }
47 
48 /*
49  * Arrange for a keepalive ping a certain time after we last transmitted.  This
50  * lets the far side know we're still interested in this call and helps keep
51  * the route through any intervening firewall open.
52  *
53  * Receiving a response to the ping will prevent the ->expect_rx_by timer from
54  * expiring.
55  */
56 static void rxrpc_set_keepalive(struct rxrpc_call *call)
57 {
58 	unsigned long now = jiffies, keepalive_at = call->next_rx_timo / 6;
59 
60 	keepalive_at += now;
61 	WRITE_ONCE(call->keepalive_at, keepalive_at);
62 	rxrpc_reduce_call_timer(call, keepalive_at, now,
63 				rxrpc_timer_set_for_keepalive);
64 }
65 
66 /*
67  * Fill out an ACK packet.
68  */
69 static size_t rxrpc_fill_out_ack(struct rxrpc_connection *conn,
70 				 struct rxrpc_call *call,
71 				 struct rxrpc_ack_buffer *pkt,
72 				 rxrpc_seq_t *_hard_ack,
73 				 rxrpc_seq_t *_top,
74 				 u8 reason)
75 {
76 	rxrpc_serial_t serial;
77 	rxrpc_seq_t hard_ack, top, seq;
78 	int ix;
79 	u32 mtu, jmax;
80 	u8 *ackp = pkt->acks;
81 
82 	/* Barrier against rxrpc_input_data(). */
83 	serial = call->ackr_serial;
84 	hard_ack = READ_ONCE(call->rx_hard_ack);
85 	top = smp_load_acquire(&call->rx_top);
86 	*_hard_ack = hard_ack;
87 	*_top = top;
88 
89 	pkt->ack.bufferSpace	= htons(8);
90 	pkt->ack.maxSkew	= htons(0);
91 	pkt->ack.firstPacket	= htonl(hard_ack + 1);
92 	pkt->ack.previousPacket	= htonl(call->ackr_prev_seq);
93 	pkt->ack.serial		= htonl(serial);
94 	pkt->ack.reason		= reason;
95 	pkt->ack.nAcks		= top - hard_ack;
96 
97 	if (reason == RXRPC_ACK_PING)
98 		pkt->whdr.flags |= RXRPC_REQUEST_ACK;
99 
100 	if (after(top, hard_ack)) {
101 		seq = hard_ack + 1;
102 		do {
103 			ix = seq & RXRPC_RXTX_BUFF_MASK;
104 			if (call->rxtx_buffer[ix])
105 				*ackp++ = RXRPC_ACK_TYPE_ACK;
106 			else
107 				*ackp++ = RXRPC_ACK_TYPE_NACK;
108 			seq++;
109 		} while (before_eq(seq, top));
110 	}
111 
112 	mtu = conn->params.peer->if_mtu;
113 	mtu -= conn->params.peer->hdrsize;
114 	jmax = (call->nr_jumbo_bad > 3) ? 1 : rxrpc_rx_jumbo_max;
115 	pkt->ackinfo.rxMTU	= htonl(rxrpc_rx_mtu);
116 	pkt->ackinfo.maxMTU	= htonl(mtu);
117 	pkt->ackinfo.rwind	= htonl(call->rx_winsize);
118 	pkt->ackinfo.jumbo_max	= htonl(jmax);
119 
120 	*ackp++ = 0;
121 	*ackp++ = 0;
122 	*ackp++ = 0;
123 	return top - hard_ack + 3;
124 }
125 
126 /*
127  * Send an ACK call packet.
128  */
129 int rxrpc_send_ack_packet(struct rxrpc_call *call, bool ping,
130 			  rxrpc_serial_t *_serial)
131 {
132 	struct rxrpc_connection *conn;
133 	struct rxrpc_ack_buffer *pkt;
134 	struct msghdr msg;
135 	struct kvec iov[2];
136 	rxrpc_serial_t serial;
137 	rxrpc_seq_t hard_ack, top;
138 	size_t len, n;
139 	int ret;
140 	u8 reason;
141 
142 	if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
143 		return -ECONNRESET;
144 
145 	pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
146 	if (!pkt)
147 		return -ENOMEM;
148 
149 	conn = call->conn;
150 
151 	msg.msg_name	= &call->peer->srx.transport;
152 	msg.msg_namelen	= call->peer->srx.transport_len;
153 	msg.msg_control	= NULL;
154 	msg.msg_controllen = 0;
155 	msg.msg_flags	= 0;
156 
157 	pkt->whdr.epoch		= htonl(conn->proto.epoch);
158 	pkt->whdr.cid		= htonl(call->cid);
159 	pkt->whdr.callNumber	= htonl(call->call_id);
160 	pkt->whdr.seq		= 0;
161 	pkt->whdr.type		= RXRPC_PACKET_TYPE_ACK;
162 	pkt->whdr.flags		= RXRPC_SLOW_START_OK | conn->out_clientflag;
163 	pkt->whdr.userStatus	= 0;
164 	pkt->whdr.securityIndex	= call->security_ix;
165 	pkt->whdr._rsvd		= 0;
166 	pkt->whdr.serviceId	= htons(call->service_id);
167 
168 	spin_lock_bh(&call->lock);
169 	if (ping) {
170 		reason = RXRPC_ACK_PING;
171 	} else {
172 		reason = call->ackr_reason;
173 		if (!call->ackr_reason) {
174 			spin_unlock_bh(&call->lock);
175 			ret = 0;
176 			goto out;
177 		}
178 		call->ackr_reason = 0;
179 	}
180 	n = rxrpc_fill_out_ack(conn, call, pkt, &hard_ack, &top, reason);
181 
182 	spin_unlock_bh(&call->lock);
183 
184 	iov[0].iov_base	= pkt;
185 	iov[0].iov_len	= sizeof(pkt->whdr) + sizeof(pkt->ack) + n;
186 	iov[1].iov_base = &pkt->ackinfo;
187 	iov[1].iov_len	= sizeof(pkt->ackinfo);
188 	len = iov[0].iov_len + iov[1].iov_len;
189 
190 	serial = atomic_inc_return(&conn->serial);
191 	pkt->whdr.serial = htonl(serial);
192 	trace_rxrpc_tx_ack(call->debug_id, serial,
193 			   ntohl(pkt->ack.firstPacket),
194 			   ntohl(pkt->ack.serial),
195 			   pkt->ack.reason, pkt->ack.nAcks);
196 	if (_serial)
197 		*_serial = serial;
198 
199 	if (ping) {
200 		call->ping_serial = serial;
201 		smp_wmb();
202 		/* We need to stick a time in before we send the packet in case
203 		 * the reply gets back before kernel_sendmsg() completes - but
204 		 * asking UDP to send the packet can take a relatively long
205 		 * time.
206 		 */
207 		call->ping_time = ktime_get_real();
208 		set_bit(RXRPC_CALL_PINGING, &call->flags);
209 		trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_ping, serial);
210 	}
211 
212 	ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len);
213 	conn->params.peer->last_tx_at = ktime_get_seconds();
214 	if (ret < 0)
215 		trace_rxrpc_tx_fail(call->debug_id, serial, ret,
216 				    rxrpc_tx_point_call_ack);
217 	else
218 		trace_rxrpc_tx_packet(call->debug_id, &pkt->whdr,
219 				      rxrpc_tx_point_call_ack);
220 	rxrpc_tx_backoff(call, ret);
221 
222 	if (call->state < RXRPC_CALL_COMPLETE) {
223 		if (ret < 0) {
224 			if (ping)
225 				clear_bit(RXRPC_CALL_PINGING, &call->flags);
226 			rxrpc_propose_ACK(call, pkt->ack.reason,
227 					  ntohl(pkt->ack.serial),
228 					  false, true,
229 					  rxrpc_propose_ack_retry_tx);
230 		} else {
231 			spin_lock_bh(&call->lock);
232 			if (after(hard_ack, call->ackr_consumed))
233 				call->ackr_consumed = hard_ack;
234 			if (after(top, call->ackr_seen))
235 				call->ackr_seen = top;
236 			spin_unlock_bh(&call->lock);
237 		}
238 
239 		rxrpc_set_keepalive(call);
240 	}
241 
242 out:
243 	kfree(pkt);
244 	return ret;
245 }
246 
247 /*
248  * Send an ABORT call packet.
249  */
250 int rxrpc_send_abort_packet(struct rxrpc_call *call)
251 {
252 	struct rxrpc_connection *conn;
253 	struct rxrpc_abort_buffer pkt;
254 	struct msghdr msg;
255 	struct kvec iov[1];
256 	rxrpc_serial_t serial;
257 	int ret;
258 
259 	/* Don't bother sending aborts for a client call once the server has
260 	 * hard-ACK'd all of its request data.  After that point, we're not
261 	 * going to stop the operation proceeding, and whilst we might limit
262 	 * the reply, it's not worth it if we can send a new call on the same
263 	 * channel instead, thereby closing off this call.
264 	 */
265 	if (rxrpc_is_client_call(call) &&
266 	    test_bit(RXRPC_CALL_TX_LAST, &call->flags))
267 		return 0;
268 
269 	if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
270 		return -ECONNRESET;
271 
272 	conn = call->conn;
273 
274 	msg.msg_name	= &call->peer->srx.transport;
275 	msg.msg_namelen	= call->peer->srx.transport_len;
276 	msg.msg_control	= NULL;
277 	msg.msg_controllen = 0;
278 	msg.msg_flags	= 0;
279 
280 	pkt.whdr.epoch		= htonl(conn->proto.epoch);
281 	pkt.whdr.cid		= htonl(call->cid);
282 	pkt.whdr.callNumber	= htonl(call->call_id);
283 	pkt.whdr.seq		= 0;
284 	pkt.whdr.type		= RXRPC_PACKET_TYPE_ABORT;
285 	pkt.whdr.flags		= conn->out_clientflag;
286 	pkt.whdr.userStatus	= 0;
287 	pkt.whdr.securityIndex	= call->security_ix;
288 	pkt.whdr._rsvd		= 0;
289 	pkt.whdr.serviceId	= htons(call->service_id);
290 	pkt.abort_code		= htonl(call->abort_code);
291 
292 	iov[0].iov_base	= &pkt;
293 	iov[0].iov_len	= sizeof(pkt);
294 
295 	serial = atomic_inc_return(&conn->serial);
296 	pkt.whdr.serial = htonl(serial);
297 
298 	ret = kernel_sendmsg(conn->params.local->socket,
299 			     &msg, iov, 1, sizeof(pkt));
300 	conn->params.peer->last_tx_at = ktime_get_seconds();
301 	if (ret < 0)
302 		trace_rxrpc_tx_fail(call->debug_id, serial, ret,
303 				    rxrpc_tx_point_call_abort);
304 	else
305 		trace_rxrpc_tx_packet(call->debug_id, &pkt.whdr,
306 				      rxrpc_tx_point_call_abort);
307 	rxrpc_tx_backoff(call, ret);
308 	return ret;
309 }
310 
311 /*
312  * send a packet through the transport endpoint
313  */
314 int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb,
315 			   bool retrans)
316 {
317 	struct rxrpc_connection *conn = call->conn;
318 	struct rxrpc_wire_header whdr;
319 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
320 	struct msghdr msg;
321 	struct kvec iov[2];
322 	rxrpc_serial_t serial;
323 	size_t len;
324 	int ret, opt;
325 
326 	_enter(",{%d}", skb->len);
327 
328 	/* Each transmission of a Tx packet needs a new serial number */
329 	serial = atomic_inc_return(&conn->serial);
330 
331 	whdr.epoch	= htonl(conn->proto.epoch);
332 	whdr.cid	= htonl(call->cid);
333 	whdr.callNumber	= htonl(call->call_id);
334 	whdr.seq	= htonl(sp->hdr.seq);
335 	whdr.serial	= htonl(serial);
336 	whdr.type	= RXRPC_PACKET_TYPE_DATA;
337 	whdr.flags	= sp->hdr.flags;
338 	whdr.userStatus	= 0;
339 	whdr.securityIndex = call->security_ix;
340 	whdr._rsvd	= htons(sp->hdr._rsvd);
341 	whdr.serviceId	= htons(call->service_id);
342 
343 	if (test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags) &&
344 	    sp->hdr.seq == 1)
345 		whdr.userStatus	= RXRPC_USERSTATUS_SERVICE_UPGRADE;
346 
347 	iov[0].iov_base = &whdr;
348 	iov[0].iov_len = sizeof(whdr);
349 	iov[1].iov_base = skb->head;
350 	iov[1].iov_len = skb->len;
351 	len = iov[0].iov_len + iov[1].iov_len;
352 
353 	msg.msg_name = &call->peer->srx.transport;
354 	msg.msg_namelen = call->peer->srx.transport_len;
355 	msg.msg_control = NULL;
356 	msg.msg_controllen = 0;
357 	msg.msg_flags = 0;
358 
359 	/* If our RTT cache needs working on, request an ACK.  Also request
360 	 * ACKs if a DATA packet appears to have been lost.
361 	 *
362 	 * However, we mustn't request an ACK on the last reply packet of a
363 	 * service call, lest OpenAFS incorrectly send us an ACK with some
364 	 * soft-ACKs in it and then never follow up with a proper hard ACK.
365 	 */
366 	if ((!(sp->hdr.flags & RXRPC_LAST_PACKET) ||
367 	     rxrpc_to_server(sp)
368 	     ) &&
369 	    (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events) ||
370 	     retrans ||
371 	     call->cong_mode == RXRPC_CALL_SLOW_START ||
372 	     (call->peer->rtt_usage < 3 && sp->hdr.seq & 1) ||
373 	     ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000),
374 			  ktime_get_real())))
375 		whdr.flags |= RXRPC_REQUEST_ACK;
376 
377 	if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
378 		static int lose;
379 		if ((lose++ & 7) == 7) {
380 			ret = 0;
381 			trace_rxrpc_tx_data(call, sp->hdr.seq, serial,
382 					    whdr.flags, retrans, true);
383 			goto done;
384 		}
385 	}
386 
387 	trace_rxrpc_tx_data(call, sp->hdr.seq, serial, whdr.flags, retrans,
388 			    false);
389 
390 	/* send the packet with the don't fragment bit set if we currently
391 	 * think it's small enough */
392 	if (iov[1].iov_len >= call->peer->maxdata)
393 		goto send_fragmentable;
394 
395 	down_read(&conn->params.local->defrag_sem);
396 
397 	sp->hdr.serial = serial;
398 	smp_wmb(); /* Set serial before timestamp */
399 	skb->tstamp = ktime_get_real();
400 
401 	/* send the packet by UDP
402 	 * - returns -EMSGSIZE if UDP would have to fragment the packet
403 	 *   to go out of the interface
404 	 *   - in which case, we'll have processed the ICMP error
405 	 *     message and update the peer record
406 	 */
407 	ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len);
408 	conn->params.peer->last_tx_at = ktime_get_seconds();
409 
410 	up_read(&conn->params.local->defrag_sem);
411 	if (ret < 0)
412 		trace_rxrpc_tx_fail(call->debug_id, serial, ret,
413 				    rxrpc_tx_point_call_data_nofrag);
414 	else
415 		trace_rxrpc_tx_packet(call->debug_id, &whdr,
416 				      rxrpc_tx_point_call_data_nofrag);
417 	rxrpc_tx_backoff(call, ret);
418 	if (ret == -EMSGSIZE)
419 		goto send_fragmentable;
420 
421 done:
422 	if (ret >= 0) {
423 		if (whdr.flags & RXRPC_REQUEST_ACK) {
424 			call->peer->rtt_last_req = skb->tstamp;
425 			trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_data, serial);
426 			if (call->peer->rtt_usage > 1) {
427 				unsigned long nowj = jiffies, ack_lost_at;
428 
429 				ack_lost_at = nsecs_to_jiffies(2 * call->peer->rtt);
430 				if (ack_lost_at < 1)
431 					ack_lost_at = 1;
432 
433 				ack_lost_at += nowj;
434 				WRITE_ONCE(call->ack_lost_at, ack_lost_at);
435 				rxrpc_reduce_call_timer(call, ack_lost_at, nowj,
436 							rxrpc_timer_set_for_lost_ack);
437 			}
438 		}
439 
440 		if (sp->hdr.seq == 1 &&
441 		    !test_and_set_bit(RXRPC_CALL_BEGAN_RX_TIMER,
442 				      &call->flags)) {
443 			unsigned long nowj = jiffies, expect_rx_by;
444 
445 			expect_rx_by = nowj + call->next_rx_timo;
446 			WRITE_ONCE(call->expect_rx_by, expect_rx_by);
447 			rxrpc_reduce_call_timer(call, expect_rx_by, nowj,
448 						rxrpc_timer_set_for_normal);
449 		}
450 
451 		rxrpc_set_keepalive(call);
452 	} else {
453 		/* Cancel the call if the initial transmission fails,
454 		 * particularly if that's due to network routing issues that
455 		 * aren't going away anytime soon.  The layer above can arrange
456 		 * the retransmission.
457 		 */
458 		if (!test_and_set_bit(RXRPC_CALL_BEGAN_RX_TIMER, &call->flags))
459 			rxrpc_set_call_completion(call, RXRPC_CALL_LOCAL_ERROR,
460 						  RX_USER_ABORT, ret);
461 	}
462 
463 	_leave(" = %d [%u]", ret, call->peer->maxdata);
464 	return ret;
465 
466 send_fragmentable:
467 	/* attempt to send this message with fragmentation enabled */
468 	_debug("send fragment");
469 
470 	down_write(&conn->params.local->defrag_sem);
471 
472 	sp->hdr.serial = serial;
473 	smp_wmb(); /* Set serial before timestamp */
474 	skb->tstamp = ktime_get_real();
475 
476 	switch (conn->params.local->srx.transport.family) {
477 	case AF_INET:
478 		opt = IP_PMTUDISC_DONT;
479 		ret = kernel_setsockopt(conn->params.local->socket,
480 					SOL_IP, IP_MTU_DISCOVER,
481 					(char *)&opt, sizeof(opt));
482 		if (ret == 0) {
483 			ret = kernel_sendmsg(conn->params.local->socket, &msg,
484 					     iov, 2, len);
485 			conn->params.peer->last_tx_at = ktime_get_seconds();
486 
487 			opt = IP_PMTUDISC_DO;
488 			kernel_setsockopt(conn->params.local->socket, SOL_IP,
489 					  IP_MTU_DISCOVER,
490 					  (char *)&opt, sizeof(opt));
491 		}
492 		break;
493 
494 #ifdef CONFIG_AF_RXRPC_IPV6
495 	case AF_INET6:
496 		opt = IPV6_PMTUDISC_DONT;
497 		ret = kernel_setsockopt(conn->params.local->socket,
498 					SOL_IPV6, IPV6_MTU_DISCOVER,
499 					(char *)&opt, sizeof(opt));
500 		if (ret == 0) {
501 			ret = kernel_sendmsg(conn->params.local->socket, &msg,
502 					     iov, 2, len);
503 			conn->params.peer->last_tx_at = ktime_get_seconds();
504 
505 			opt = IPV6_PMTUDISC_DO;
506 			kernel_setsockopt(conn->params.local->socket,
507 					  SOL_IPV6, IPV6_MTU_DISCOVER,
508 					  (char *)&opt, sizeof(opt));
509 		}
510 		break;
511 #endif
512 
513 	default:
514 		BUG();
515 	}
516 
517 	if (ret < 0)
518 		trace_rxrpc_tx_fail(call->debug_id, serial, ret,
519 				    rxrpc_tx_point_call_data_frag);
520 	else
521 		trace_rxrpc_tx_packet(call->debug_id, &whdr,
522 				      rxrpc_tx_point_call_data_frag);
523 	rxrpc_tx_backoff(call, ret);
524 
525 	up_write(&conn->params.local->defrag_sem);
526 	goto done;
527 }
528 
529 /*
530  * reject packets through the local endpoint
531  */
532 void rxrpc_reject_packets(struct rxrpc_local *local)
533 {
534 	struct sockaddr_rxrpc srx;
535 	struct rxrpc_skb_priv *sp;
536 	struct rxrpc_wire_header whdr;
537 	struct sk_buff *skb;
538 	struct msghdr msg;
539 	struct kvec iov[2];
540 	size_t size;
541 	__be32 code;
542 	int ret, ioc;
543 
544 	_enter("%d", local->debug_id);
545 
546 	iov[0].iov_base = &whdr;
547 	iov[0].iov_len = sizeof(whdr);
548 	iov[1].iov_base = &code;
549 	iov[1].iov_len = sizeof(code);
550 
551 	msg.msg_name = &srx.transport;
552 	msg.msg_control = NULL;
553 	msg.msg_controllen = 0;
554 	msg.msg_flags = 0;
555 
556 	memset(&whdr, 0, sizeof(whdr));
557 
558 	while ((skb = skb_dequeue(&local->reject_queue))) {
559 		rxrpc_see_skb(skb, rxrpc_skb_seen);
560 		sp = rxrpc_skb(skb);
561 
562 		switch (skb->mark) {
563 		case RXRPC_SKB_MARK_REJECT_BUSY:
564 			whdr.type = RXRPC_PACKET_TYPE_BUSY;
565 			size = sizeof(whdr);
566 			ioc = 1;
567 			break;
568 		case RXRPC_SKB_MARK_REJECT_ABORT:
569 			whdr.type = RXRPC_PACKET_TYPE_ABORT;
570 			code = htonl(skb->priority);
571 			size = sizeof(whdr) + sizeof(code);
572 			ioc = 2;
573 			break;
574 		default:
575 			rxrpc_free_skb(skb, rxrpc_skb_freed);
576 			continue;
577 		}
578 
579 		if (rxrpc_extract_addr_from_skb(&srx, skb) == 0) {
580 			msg.msg_namelen = srx.transport_len;
581 
582 			whdr.epoch	= htonl(sp->hdr.epoch);
583 			whdr.cid	= htonl(sp->hdr.cid);
584 			whdr.callNumber	= htonl(sp->hdr.callNumber);
585 			whdr.serviceId	= htons(sp->hdr.serviceId);
586 			whdr.flags	= sp->hdr.flags;
587 			whdr.flags	^= RXRPC_CLIENT_INITIATED;
588 			whdr.flags	&= RXRPC_CLIENT_INITIATED;
589 
590 			ret = kernel_sendmsg(local->socket, &msg,
591 					     iov, ioc, size);
592 			if (ret < 0)
593 				trace_rxrpc_tx_fail(local->debug_id, 0, ret,
594 						    rxrpc_tx_point_reject);
595 			else
596 				trace_rxrpc_tx_packet(local->debug_id, &whdr,
597 						      rxrpc_tx_point_reject);
598 		}
599 
600 		rxrpc_free_skb(skb, rxrpc_skb_freed);
601 	}
602 
603 	_leave("");
604 }
605 
606 /*
607  * Send a VERSION reply to a peer as a keepalive.
608  */
609 void rxrpc_send_keepalive(struct rxrpc_peer *peer)
610 {
611 	struct rxrpc_wire_header whdr;
612 	struct msghdr msg;
613 	struct kvec iov[2];
614 	size_t len;
615 	int ret;
616 
617 	_enter("");
618 
619 	msg.msg_name	= &peer->srx.transport;
620 	msg.msg_namelen	= peer->srx.transport_len;
621 	msg.msg_control	= NULL;
622 	msg.msg_controllen = 0;
623 	msg.msg_flags	= 0;
624 
625 	whdr.epoch	= htonl(peer->local->rxnet->epoch);
626 	whdr.cid	= 0;
627 	whdr.callNumber	= 0;
628 	whdr.seq	= 0;
629 	whdr.serial	= 0;
630 	whdr.type	= RXRPC_PACKET_TYPE_VERSION; /* Not client-initiated */
631 	whdr.flags	= RXRPC_LAST_PACKET;
632 	whdr.userStatus	= 0;
633 	whdr.securityIndex = 0;
634 	whdr._rsvd	= 0;
635 	whdr.serviceId	= 0;
636 
637 	iov[0].iov_base	= &whdr;
638 	iov[0].iov_len	= sizeof(whdr);
639 	iov[1].iov_base	= (char *)rxrpc_keepalive_string;
640 	iov[1].iov_len	= sizeof(rxrpc_keepalive_string);
641 
642 	len = iov[0].iov_len + iov[1].iov_len;
643 
644 	_proto("Tx VERSION (keepalive)");
645 
646 	ret = kernel_sendmsg(peer->local->socket, &msg, iov, 2, len);
647 	if (ret < 0)
648 		trace_rxrpc_tx_fail(peer->debug_id, 0, ret,
649 				    rxrpc_tx_point_version_keepalive);
650 	else
651 		trace_rxrpc_tx_packet(peer->debug_id, &whdr,
652 				      rxrpc_tx_point_version_keepalive);
653 
654 	peer->last_tx_at = ktime_get_seconds();
655 	_leave("");
656 }
657