xref: /freebsd/sys/netinet/tcp_lro.c (revision 1f4bcc459a76b7aa664f3fd557684cd0ba6da352)
1 /*-
2  * Copyright (c) 2007, Myricom Inc.
3  * Copyright (c) 2008, Intel Corporation.
4  * Copyright (c) 2012 The FreeBSD Foundation
5  * Copyright (c) 2016 Mellanox Technologies.
6  * All rights reserved.
7  *
8  * Portions of this software were developed by Bjoern Zeeb
9  * under sponsorship from the FreeBSD Foundation.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35 
36 #include "opt_inet.h"
37 #include "opt_inet6.h"
38 
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/kernel.h>
42 #include <sys/malloc.h>
43 #include <sys/mbuf.h>
44 #include <sys/socket.h>
45 
46 #include <net/if.h>
47 #include <net/if_var.h>
48 #include <net/ethernet.h>
49 #include <net/vnet.h>
50 
51 #include <netinet/in_systm.h>
52 #include <netinet/in.h>
53 #include <netinet/ip6.h>
54 #include <netinet/ip.h>
55 #include <netinet/ip_var.h>
56 #include <netinet/tcp.h>
57 #include <netinet/tcp_lro.h>
58 
59 #include <netinet6/ip6_var.h>
60 
61 #include <machine/in_cksum.h>
62 
63 static MALLOC_DEFINE(M_LRO, "LRO", "LRO control structures");
64 
65 #define	TCP_LRO_UPDATE_CSUM	1
66 #ifndef	TCP_LRO_UPDATE_CSUM
67 #define	TCP_LRO_INVALID_CSUM	0x0000
68 #endif
69 
70 int
71 tcp_lro_init(struct lro_ctrl *lc)
72 {
73 	return (tcp_lro_init_args(lc, NULL, TCP_LRO_ENTRIES, 0));
74 }
75 
76 int
77 tcp_lro_init_args(struct lro_ctrl *lc, struct ifnet *ifp,
78     unsigned lro_entries, unsigned lro_mbufs)
79 {
80 	struct lro_entry *le;
81 	size_t size;
82 	unsigned i;
83 
84 	lc->lro_bad_csum = 0;
85 	lc->lro_queued = 0;
86 	lc->lro_flushed = 0;
87 	lc->lro_cnt = 0;
88 	lc->lro_mbuf_count = 0;
89 	lc->lro_mbuf_max = lro_mbufs;
90 	lc->lro_cnt = lro_entries;
91 	lc->ifp = ifp;
92 	SLIST_INIT(&lc->lro_free);
93 	SLIST_INIT(&lc->lro_active);
94 
95 	/* compute size to allocate */
96 	size = (lro_mbufs * sizeof(struct mbuf *)) +
97 	    (lro_entries * sizeof(*le));
98 	lc->lro_mbuf_data = (struct mbuf **)
99 	    malloc(size, M_LRO, M_NOWAIT | M_ZERO);
100 
101 	/* check for out of memory */
102 	if (lc->lro_mbuf_data == NULL) {
103 		memset(lc, 0, sizeof(*lc));
104 		return (ENOMEM);
105 	}
106 	/* compute offset for LRO entries */
107 	le = (struct lro_entry *)
108 	    (lc->lro_mbuf_data + lro_mbufs);
109 
110 	/* setup linked list */
111 	for (i = 0; i != lro_entries; i++)
112 		SLIST_INSERT_HEAD(&lc->lro_free, le + i, next);
113 
114 	return (0);
115 }
116 
117 void
118 tcp_lro_free(struct lro_ctrl *lc)
119 {
120 	struct lro_entry *le;
121 	unsigned x;
122 
123 	/* reset LRO free list */
124 	SLIST_INIT(&lc->lro_free);
125 
126 	/* free active mbufs, if any */
127 	while ((le = SLIST_FIRST(&lc->lro_active)) != NULL) {
128 		SLIST_REMOVE_HEAD(&lc->lro_active, next);
129 		m_freem(le->m_head);
130 	}
131 
132 	/* free mbuf array, if any */
133 	for (x = 0; x != lc->lro_mbuf_count; x++)
134 		m_freem(lc->lro_mbuf_data[x]);
135 	lc->lro_mbuf_count = 0;
136 
137 	/* free allocated memory, if any */
138 	free(lc->lro_mbuf_data, M_LRO);
139 	lc->lro_mbuf_data = NULL;
140 }
141 
142 #ifdef TCP_LRO_UPDATE_CSUM
143 static uint16_t
144 tcp_lro_csum_th(struct tcphdr *th)
145 {
146 	uint32_t ch;
147 	uint16_t *p, l;
148 
149 	ch = th->th_sum = 0x0000;
150 	l = th->th_off;
151 	p = (uint16_t *)th;
152 	while (l > 0) {
153 		ch += *p;
154 		p++;
155 		ch += *p;
156 		p++;
157 		l--;
158 	}
159 	while (ch > 0xffff)
160 		ch = (ch >> 16) + (ch & 0xffff);
161 
162 	return (ch & 0xffff);
163 }
164 
165 static uint16_t
166 tcp_lro_rx_csum_fixup(struct lro_entry *le, void *l3hdr, struct tcphdr *th,
167     uint16_t tcp_data_len, uint16_t csum)
168 {
169 	uint32_t c;
170 	uint16_t cs;
171 
172 	c = csum;
173 
174 	/* Remove length from checksum. */
175 	switch (le->eh_type) {
176 #ifdef INET6
177 	case ETHERTYPE_IPV6:
178 	{
179 		struct ip6_hdr *ip6;
180 
181 		ip6 = (struct ip6_hdr *)l3hdr;
182 		if (le->append_cnt == 0)
183 			cs = ip6->ip6_plen;
184 		else {
185 			uint32_t cx;
186 
187 			cx = ntohs(ip6->ip6_plen);
188 			cs = in6_cksum_pseudo(ip6, cx, ip6->ip6_nxt, 0);
189 		}
190 		break;
191 	}
192 #endif
193 #ifdef INET
194 	case ETHERTYPE_IP:
195 	{
196 		struct ip *ip4;
197 
198 		ip4 = (struct ip *)l3hdr;
199 		if (le->append_cnt == 0)
200 			cs = ip4->ip_len;
201 		else {
202 			cs = in_addword(ntohs(ip4->ip_len) - sizeof(*ip4),
203 			    IPPROTO_TCP);
204 			cs = in_pseudo(ip4->ip_src.s_addr, ip4->ip_dst.s_addr,
205 			    htons(cs));
206 		}
207 		break;
208 	}
209 #endif
210 	default:
211 		cs = 0;		/* Keep compiler happy. */
212 	}
213 
214 	cs = ~cs;
215 	c += cs;
216 
217 	/* Remove TCP header csum. */
218 	cs = ~tcp_lro_csum_th(th);
219 	c += cs;
220 	while (c > 0xffff)
221 		c = (c >> 16) + (c & 0xffff);
222 
223 	return (c & 0xffff);
224 }
225 #endif
226 
227 void
228 tcp_lro_flush_inactive(struct lro_ctrl *lc, const struct timeval *timeout)
229 {
230 	struct lro_entry *le, *le_tmp;
231 	struct timeval tv;
232 
233 	if (SLIST_EMPTY(&lc->lro_active))
234 		return;
235 
236 	getmicrotime(&tv);
237 	timevalsub(&tv, timeout);
238 	SLIST_FOREACH_SAFE(le, &lc->lro_active, next, le_tmp) {
239 		if (timevalcmp(&tv, &le->mtime, >=)) {
240 			SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
241 			tcp_lro_flush(lc, le);
242 		}
243 	}
244 }
245 
246 void
247 tcp_lro_flush(struct lro_ctrl *lc, struct lro_entry *le)
248 {
249 
250 	if (le->append_cnt > 0) {
251 		struct tcphdr *th;
252 		uint16_t p_len;
253 
254 		p_len = htons(le->p_len);
255 		switch (le->eh_type) {
256 #ifdef INET6
257 		case ETHERTYPE_IPV6:
258 		{
259 			struct ip6_hdr *ip6;
260 
261 			ip6 = le->le_ip6;
262 			ip6->ip6_plen = p_len;
263 			th = (struct tcphdr *)(ip6 + 1);
264 			le->m_head->m_pkthdr.csum_flags = CSUM_DATA_VALID |
265 			    CSUM_PSEUDO_HDR;
266 			le->p_len += ETHER_HDR_LEN + sizeof(*ip6);
267 			break;
268 		}
269 #endif
270 #ifdef INET
271 		case ETHERTYPE_IP:
272 		{
273 			struct ip *ip4;
274 #ifdef TCP_LRO_UPDATE_CSUM
275 			uint32_t cl;
276 			uint16_t c;
277 #endif
278 
279 			ip4 = le->le_ip4;
280 #ifdef TCP_LRO_UPDATE_CSUM
281 			/* Fix IP header checksum for new length. */
282 			c = ~ip4->ip_sum;
283 			cl = c;
284 			c = ~ip4->ip_len;
285 			cl += c + p_len;
286 			while (cl > 0xffff)
287 				cl = (cl >> 16) + (cl & 0xffff);
288 			c = cl;
289 			ip4->ip_sum = ~c;
290 #else
291 			ip4->ip_sum = TCP_LRO_INVALID_CSUM;
292 #endif
293 			ip4->ip_len = p_len;
294 			th = (struct tcphdr *)(ip4 + 1);
295 			le->m_head->m_pkthdr.csum_flags = CSUM_DATA_VALID |
296 			    CSUM_PSEUDO_HDR | CSUM_IP_CHECKED | CSUM_IP_VALID;
297 			le->p_len += ETHER_HDR_LEN;
298 			break;
299 		}
300 #endif
301 		default:
302 			th = NULL;	/* Keep compiler happy. */
303 		}
304 		le->m_head->m_pkthdr.csum_data = 0xffff;
305 		le->m_head->m_pkthdr.len = le->p_len;
306 
307 		/* Incorporate the latest ACK into the TCP header. */
308 		th->th_ack = le->ack_seq;
309 		th->th_win = le->window;
310 		/* Incorporate latest timestamp into the TCP header. */
311 		if (le->timestamp != 0) {
312 			uint32_t *ts_ptr;
313 
314 			ts_ptr = (uint32_t *)(th + 1);
315 			ts_ptr[1] = htonl(le->tsval);
316 			ts_ptr[2] = le->tsecr;
317 		}
318 #ifdef TCP_LRO_UPDATE_CSUM
319 		/* Update the TCP header checksum. */
320 		le->ulp_csum += p_len;
321 		le->ulp_csum += tcp_lro_csum_th(th);
322 		while (le->ulp_csum > 0xffff)
323 			le->ulp_csum = (le->ulp_csum >> 16) +
324 			    (le->ulp_csum & 0xffff);
325 		th->th_sum = (le->ulp_csum & 0xffff);
326 		th->th_sum = ~th->th_sum;
327 #else
328 		th->th_sum = TCP_LRO_INVALID_CSUM;
329 #endif
330 	}
331 
332 	(*lc->ifp->if_input)(lc->ifp, le->m_head);
333 	lc->lro_queued += le->append_cnt + 1;
334 	lc->lro_flushed++;
335 	bzero(le, sizeof(*le));
336 	SLIST_INSERT_HEAD(&lc->lro_free, le, next);
337 }
338 
339 static int
340 tcp_lro_mbuf_compare_header(const void *ppa, const void *ppb)
341 {
342 	const struct mbuf *ma = *((const struct mbuf * const *)ppa);
343 	const struct mbuf *mb = *((const struct mbuf * const *)ppb);
344 	int ret;
345 
346 	ret = M_HASHTYPE_GET(ma) - M_HASHTYPE_GET(mb);
347 	if (ret != 0)
348 		goto done;
349 
350 	ret = ma->m_pkthdr.flowid - mb->m_pkthdr.flowid;
351 	if (ret != 0)
352 		goto done;
353 
354 	ret = TCP_LRO_SEQUENCE(ma) - TCP_LRO_SEQUENCE(mb);
355 done:
356 	return (ret);
357 }
358 
359 void
360 tcp_lro_flush_all(struct lro_ctrl *lc)
361 {
362 	struct lro_entry *le;
363 	uint32_t hashtype;
364 	uint32_t flowid;
365 	unsigned x;
366 
367 	/* check if no mbufs to flush */
368 	if (__predict_false(lc->lro_mbuf_count == 0))
369 		goto done;
370 
371 	/* sort all mbufs according to stream */
372 	qsort(lc->lro_mbuf_data, lc->lro_mbuf_count, sizeof(struct mbuf *),
373 	    &tcp_lro_mbuf_compare_header);
374 
375 	/* input data into LRO engine, stream by stream */
376 	flowid = 0;
377 	hashtype = M_HASHTYPE_NONE;
378 	for (x = 0; x != lc->lro_mbuf_count; x++) {
379 		struct mbuf *mb;
380 
381 		mb = lc->lro_mbuf_data[x];
382 
383 		/* check for new stream */
384 		if (mb->m_pkthdr.flowid != flowid ||
385 		    M_HASHTYPE_GET(mb) != hashtype) {
386 			flowid = mb->m_pkthdr.flowid;
387 			hashtype = M_HASHTYPE_GET(mb);
388 
389 			/* flush active streams */
390 			while ((le = SLIST_FIRST(&lc->lro_active)) != NULL) {
391 				SLIST_REMOVE_HEAD(&lc->lro_active, next);
392 				tcp_lro_flush(lc, le);
393 			}
394 		}
395 #ifdef TCP_LRO_RESET_SEQUENCE
396 		/* reset sequence number */
397 		TCP_LRO_SEQUENCE(mb) = 0;
398 #endif
399 		/* add packet to LRO engine */
400 		if (tcp_lro_rx(lc, mb, 0) != 0) {
401 			/* input packet to network layer */
402 			(*lc->ifp->if_input)(lc->ifp, mb);
403 			lc->lro_queued++;
404 			lc->lro_flushed++;
405 		}
406 	}
407 done:
408 	/* flush active streams */
409 	while ((le = SLIST_FIRST(&lc->lro_active)) != NULL) {
410 		SLIST_REMOVE_HEAD(&lc->lro_active, next);
411 		tcp_lro_flush(lc, le);
412 	}
413 	lc->lro_mbuf_count = 0;
414 }
415 
416 #ifdef INET6
417 static int
418 tcp_lro_rx_ipv6(struct lro_ctrl *lc, struct mbuf *m, struct ip6_hdr *ip6,
419     struct tcphdr **th)
420 {
421 
422 	/* XXX-BZ we should check the flow-label. */
423 
424 	/* XXX-BZ We do not yet support ext. hdrs. */
425 	if (ip6->ip6_nxt != IPPROTO_TCP)
426 		return (TCP_LRO_NOT_SUPPORTED);
427 
428 	/* Find the TCP header. */
429 	*th = (struct tcphdr *)(ip6 + 1);
430 
431 	return (0);
432 }
433 #endif
434 
435 #ifdef INET
436 static int
437 tcp_lro_rx_ipv4(struct lro_ctrl *lc, struct mbuf *m, struct ip *ip4,
438     struct tcphdr **th)
439 {
440 	int csum_flags;
441 	uint16_t csum;
442 
443 	if (ip4->ip_p != IPPROTO_TCP)
444 		return (TCP_LRO_NOT_SUPPORTED);
445 
446 	/* Ensure there are no options. */
447 	if ((ip4->ip_hl << 2) != sizeof (*ip4))
448 		return (TCP_LRO_CANNOT);
449 
450 	/* .. and the packet is not fragmented. */
451 	if (ip4->ip_off & htons(IP_MF|IP_OFFMASK))
452 		return (TCP_LRO_CANNOT);
453 
454 	/* Legacy IP has a header checksum that needs to be correct. */
455 	csum_flags = m->m_pkthdr.csum_flags;
456 	if (csum_flags & CSUM_IP_CHECKED) {
457 		if (__predict_false((csum_flags & CSUM_IP_VALID) == 0)) {
458 			lc->lro_bad_csum++;
459 			return (TCP_LRO_CANNOT);
460 		}
461 	} else {
462 		csum = in_cksum_hdr(ip4);
463 		if (__predict_false((csum) != 0)) {
464 			lc->lro_bad_csum++;
465 			return (TCP_LRO_CANNOT);
466 		}
467 	}
468 
469 	/* Find the TCP header (we assured there are no IP options). */
470 	*th = (struct tcphdr *)(ip4 + 1);
471 
472 	return (0);
473 }
474 #endif
475 
476 int
477 tcp_lro_rx(struct lro_ctrl *lc, struct mbuf *m, uint32_t csum)
478 {
479 	struct lro_entry *le;
480 	struct ether_header *eh;
481 #ifdef INET6
482 	struct ip6_hdr *ip6 = NULL;	/* Keep compiler happy. */
483 #endif
484 #ifdef INET
485 	struct ip *ip4 = NULL;		/* Keep compiler happy. */
486 #endif
487 	struct tcphdr *th;
488 	void *l3hdr = NULL;		/* Keep compiler happy. */
489 	uint32_t *ts_ptr;
490 	tcp_seq seq;
491 	int error, ip_len, l;
492 	uint16_t eh_type, tcp_data_len;
493 
494 	/* We expect a contiguous header [eh, ip, tcp]. */
495 
496 	eh = mtod(m, struct ether_header *);
497 	eh_type = ntohs(eh->ether_type);
498 	switch (eh_type) {
499 #ifdef INET6
500 	case ETHERTYPE_IPV6:
501 	{
502 		CURVNET_SET(lc->ifp->if_vnet);
503 		if (V_ip6_forwarding != 0) {
504 			/* XXX-BZ stats but changing lro_ctrl is a problem. */
505 			CURVNET_RESTORE();
506 			return (TCP_LRO_CANNOT);
507 		}
508 		CURVNET_RESTORE();
509 		l3hdr = ip6 = (struct ip6_hdr *)(eh + 1);
510 		error = tcp_lro_rx_ipv6(lc, m, ip6, &th);
511 		if (error != 0)
512 			return (error);
513 		tcp_data_len = ntohs(ip6->ip6_plen);
514 		ip_len = sizeof(*ip6) + tcp_data_len;
515 		break;
516 	}
517 #endif
518 #ifdef INET
519 	case ETHERTYPE_IP:
520 	{
521 		CURVNET_SET(lc->ifp->if_vnet);
522 		if (V_ipforwarding != 0) {
523 			/* XXX-BZ stats but changing lro_ctrl is a problem. */
524 			CURVNET_RESTORE();
525 			return (TCP_LRO_CANNOT);
526 		}
527 		CURVNET_RESTORE();
528 		l3hdr = ip4 = (struct ip *)(eh + 1);
529 		error = tcp_lro_rx_ipv4(lc, m, ip4, &th);
530 		if (error != 0)
531 			return (error);
532 		ip_len = ntohs(ip4->ip_len);
533 		tcp_data_len = ip_len - sizeof(*ip4);
534 		break;
535 	}
536 #endif
537 	/* XXX-BZ what happens in case of VLAN(s)? */
538 	default:
539 		return (TCP_LRO_NOT_SUPPORTED);
540 	}
541 
542 	/*
543 	 * If the frame is padded beyond the end of the IP packet, then we must
544 	 * trim the extra bytes off.
545 	 */
546 	l = m->m_pkthdr.len - (ETHER_HDR_LEN + ip_len);
547 	if (l != 0) {
548 		if (l < 0)
549 			/* Truncated packet. */
550 			return (TCP_LRO_CANNOT);
551 
552 		m_adj(m, -l);
553 	}
554 
555 	/*
556 	 * Check TCP header constraints.
557 	 */
558 	/* Ensure no bits set besides ACK or PSH. */
559 	if ((th->th_flags & ~(TH_ACK | TH_PUSH)) != 0)
560 		return (TCP_LRO_CANNOT);
561 
562 	/* XXX-BZ We lose a AKC|PUSH flag concatinating multiple segments. */
563 	/* XXX-BZ Ideally we'd flush on PUSH? */
564 
565 	/*
566 	 * Check for timestamps.
567 	 * Since the only option we handle are timestamps, we only have to
568 	 * handle the simple case of aligned timestamps.
569 	 */
570 	l = (th->th_off << 2);
571 	tcp_data_len -= l;
572 	l -= sizeof(*th);
573 	ts_ptr = (uint32_t *)(th + 1);
574 	if (l != 0 && (__predict_false(l != TCPOLEN_TSTAMP_APPA) ||
575 	    (*ts_ptr != ntohl(TCPOPT_NOP<<24|TCPOPT_NOP<<16|
576 	    TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP))))
577 		return (TCP_LRO_CANNOT);
578 
579 	/* If the driver did not pass in the checksum, set it now. */
580 	if (csum == 0x0000)
581 		csum = th->th_sum;
582 
583 	seq = ntohl(th->th_seq);
584 
585 	/* Try to find a matching previous segment. */
586 	SLIST_FOREACH(le, &lc->lro_active, next) {
587 		if (le->eh_type != eh_type)
588 			continue;
589 		if (le->source_port != th->th_sport ||
590 		    le->dest_port != th->th_dport)
591 			continue;
592 		switch (eh_type) {
593 #ifdef INET6
594 		case ETHERTYPE_IPV6:
595 			if (bcmp(&le->source_ip6, &ip6->ip6_src,
596 			    sizeof(struct in6_addr)) != 0 ||
597 			    bcmp(&le->dest_ip6, &ip6->ip6_dst,
598 			    sizeof(struct in6_addr)) != 0)
599 				continue;
600 			break;
601 #endif
602 #ifdef INET
603 		case ETHERTYPE_IP:
604 			if (le->source_ip4 != ip4->ip_src.s_addr ||
605 			    le->dest_ip4 != ip4->ip_dst.s_addr)
606 				continue;
607 			break;
608 #endif
609 		}
610 
611 		/* Flush now if appending will result in overflow. */
612 		if (le->p_len > (65535 - tcp_data_len)) {
613 			SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
614 			tcp_lro_flush(lc, le);
615 			break;
616 		}
617 
618 		/* Try to append the new segment. */
619 		if (__predict_false(seq != le->next_seq ||
620 		    (tcp_data_len == 0 && le->ack_seq == th->th_ack))) {
621 			/* Out of order packet or duplicate ACK. */
622 			SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
623 			tcp_lro_flush(lc, le);
624 			return (TCP_LRO_CANNOT);
625 		}
626 
627 		if (l != 0) {
628 			uint32_t tsval = ntohl(*(ts_ptr + 1));
629 			/* Make sure timestamp values are increasing. */
630 			/* XXX-BZ flip and use TSTMP_GEQ macro for this? */
631 			if (__predict_false(le->tsval > tsval ||
632 			    *(ts_ptr + 2) == 0))
633 				return (TCP_LRO_CANNOT);
634 			le->tsval = tsval;
635 			le->tsecr = *(ts_ptr + 2);
636 		}
637 
638 		le->next_seq += tcp_data_len;
639 		le->ack_seq = th->th_ack;
640 		le->window = th->th_win;
641 		le->append_cnt++;
642 
643 #ifdef TCP_LRO_UPDATE_CSUM
644 		le->ulp_csum += tcp_lro_rx_csum_fixup(le, l3hdr, th,
645 		    tcp_data_len, ~csum);
646 #endif
647 
648 		if (tcp_data_len == 0) {
649 			m_freem(m);
650 			return (0);
651 		}
652 
653 		le->p_len += tcp_data_len;
654 
655 		/*
656 		 * Adjust the mbuf so that m_data points to the first byte of
657 		 * the ULP payload.  Adjust the mbuf to avoid complications and
658 		 * append new segment to existing mbuf chain.
659 		 */
660 		m_adj(m, m->m_pkthdr.len - tcp_data_len);
661 		m_demote_pkthdr(m);
662 
663 		le->m_tail->m_next = m;
664 		le->m_tail = m_last(m);
665 
666 		/*
667 		 * If a possible next full length packet would cause an
668 		 * overflow, pro-actively flush now.
669 		 */
670 		if (le->p_len > (65535 - lc->ifp->if_mtu)) {
671 			SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
672 			tcp_lro_flush(lc, le);
673 		} else
674 			getmicrotime(&le->mtime);
675 
676 		return (0);
677 	}
678 
679 	/* Try to find an empty slot. */
680 	if (SLIST_EMPTY(&lc->lro_free))
681 		return (TCP_LRO_CANNOT);
682 
683 	/* Start a new segment chain. */
684 	le = SLIST_FIRST(&lc->lro_free);
685 	SLIST_REMOVE_HEAD(&lc->lro_free, next);
686 	SLIST_INSERT_HEAD(&lc->lro_active, le, next);
687 	getmicrotime(&le->mtime);
688 
689 	/* Start filling in details. */
690 	switch (eh_type) {
691 #ifdef INET6
692 	case ETHERTYPE_IPV6:
693 		le->le_ip6 = ip6;
694 		le->source_ip6 = ip6->ip6_src;
695 		le->dest_ip6 = ip6->ip6_dst;
696 		le->eh_type = eh_type;
697 		le->p_len = m->m_pkthdr.len - ETHER_HDR_LEN - sizeof(*ip6);
698 		break;
699 #endif
700 #ifdef INET
701 	case ETHERTYPE_IP:
702 		le->le_ip4 = ip4;
703 		le->source_ip4 = ip4->ip_src.s_addr;
704 		le->dest_ip4 = ip4->ip_dst.s_addr;
705 		le->eh_type = eh_type;
706 		le->p_len = m->m_pkthdr.len - ETHER_HDR_LEN;
707 		break;
708 #endif
709 	}
710 	le->source_port = th->th_sport;
711 	le->dest_port = th->th_dport;
712 
713 	le->next_seq = seq + tcp_data_len;
714 	le->ack_seq = th->th_ack;
715 	le->window = th->th_win;
716 	if (l != 0) {
717 		le->timestamp = 1;
718 		le->tsval = ntohl(*(ts_ptr + 1));
719 		le->tsecr = *(ts_ptr + 2);
720 	}
721 
722 #ifdef TCP_LRO_UPDATE_CSUM
723 	/*
724 	 * Do not touch the csum of the first packet.  However save the
725 	 * "adjusted" checksum of just the source and destination addresses,
726 	 * the next header and the TCP payload.  The length and TCP header
727 	 * parts may change, so we remove those from the saved checksum and
728 	 * re-add with final values on tcp_lro_flush() if needed.
729 	 */
730 	KASSERT(le->ulp_csum == 0, ("%s: le=%p le->ulp_csum=0x%04x\n",
731 	    __func__, le, le->ulp_csum));
732 
733 	le->ulp_csum = tcp_lro_rx_csum_fixup(le, l3hdr, th, tcp_data_len,
734 	    ~csum);
735 	th->th_sum = csum;	/* Restore checksum on first packet. */
736 #endif
737 
738 	le->m_head = m;
739 	le->m_tail = m_last(m);
740 
741 	return (0);
742 }
743 
744 void
745 tcp_lro_queue_mbuf(struct lro_ctrl *lc, struct mbuf *mb)
746 {
747 	/* sanity checks */
748 	if (__predict_false(lc->ifp == NULL || lc->lro_mbuf_data == NULL ||
749 	    lc->lro_mbuf_max == 0)) {
750 		/* packet drop */
751 		m_freem(mb);
752 		return;
753 	}
754 
755 	/* check if packet is not LRO capable */
756 	if (__predict_false(mb->m_pkthdr.csum_flags == 0 ||
757 	    (lc->ifp->if_capenable & IFCAP_LRO) == 0)) {
758 		lc->lro_flushed++;
759 		lc->lro_queued++;
760 
761 		/* input packet to network layer */
762 		(*lc->ifp->if_input) (lc->ifp, mb);
763 		return;
764 	}
765 
766 	/* check if array is full */
767 	if (__predict_false(lc->lro_mbuf_count == lc->lro_mbuf_max))
768 		tcp_lro_flush_all(lc);
769 
770 	/* store sequence number */
771 	TCP_LRO_SEQUENCE(mb) = lc->lro_mbuf_count;
772 
773 	/* enter mbuf */
774 	lc->lro_mbuf_data[lc->lro_mbuf_count++] = mb;
775 }
776 
777 /* end */
778