freebsd-dev/sys/netinet/tcp_lro.c
Navdeep Parhar 7127e6acf0 Merge r254336 from user/np/cxl_tuning.
Add a last-modified timestamp to each LRO entry and provide an interface
to flush all inactive entries.  Drivers decide when to flush and what
the inactivity threshold should be.

Network drivers that process an rx queue to completion can enter a
livelock type situation when the rate at which packets are received
reaches equilibrium with the rate at which the rx thread is processing
them.  When this happens the final LRO flush (normally when the rx
routine is done) does not occur.  Pure ACKs and segments with total
payload < 64K can get stuck in an LRO entry.  Symptoms are that TCP
tx-mostly connections' performance falls off a cliff during heavy,
unrelated rx on the interface.

Flushing only inactive LRO entries works better than any of these
alternates that I tried:
- don't LRO pure ACKs
- flush _all_ LRO entries periodically (every 'x' microseconds or every
  'y' descriptors)
- stop rx processing in the driver periodically and schedule remaining
  work for later.

Reviewed by:	andre
2013-08-28 23:00:34 +00:00

637 lines
15 KiB
C

/*-
* Copyright (c) 2007, Myricom Inc.
* Copyright (c) 2008, Intel Corporation.
* Copyright (c) 2012 The FreeBSD Foundation
* All rights reserved.
*
* Portions of this software were developed by Bjoern Zeeb
* under sponsorship from the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet.h"
#include "opt_inet6.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/ethernet.h>
#include <net/vnet.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <netinet/tcp_lro.h>
#include <netinet6/ip6_var.h>
#include <machine/in_cksum.h>
#ifndef LRO_ENTRIES
#define LRO_ENTRIES 8 /* # of LRO entries per RX queue. */
#endif
#define TCP_LRO_UPDATE_CSUM 1
#ifndef TCP_LRO_UPDATE_CSUM
#define TCP_LRO_INVALID_CSUM 0x0000
#endif
int
tcp_lro_init(struct lro_ctrl *lc)
{
struct lro_entry *le;
int error, i;
lc->lro_bad_csum = 0;
lc->lro_queued = 0;
lc->lro_flushed = 0;
lc->lro_cnt = 0;
SLIST_INIT(&lc->lro_free);
SLIST_INIT(&lc->lro_active);
error = 0;
for (i = 0; i < LRO_ENTRIES; i++) {
le = (struct lro_entry *)malloc(sizeof(*le), M_DEVBUF,
M_NOWAIT | M_ZERO);
if (le == NULL) {
if (i == 0)
error = ENOMEM;
break;
}
lc->lro_cnt = i + 1;
SLIST_INSERT_HEAD(&lc->lro_free, le, next);
}
return (error);
}
void
tcp_lro_free(struct lro_ctrl *lc)
{
struct lro_entry *le;
while (!SLIST_EMPTY(&lc->lro_free)) {
le = SLIST_FIRST(&lc->lro_free);
SLIST_REMOVE_HEAD(&lc->lro_free, next);
free(le, M_DEVBUF);
}
}
#ifdef TCP_LRO_UPDATE_CSUM
static uint16_t
tcp_lro_csum_th(struct tcphdr *th)
{
uint32_t ch;
uint16_t *p, l;
ch = th->th_sum = 0x0000;
l = th->th_off;
p = (uint16_t *)th;
while (l > 0) {
ch += *p;
p++;
ch += *p;
p++;
l--;
}
while (ch > 0xffff)
ch = (ch >> 16) + (ch & 0xffff);
return (ch & 0xffff);
}
static uint16_t
tcp_lro_rx_csum_fixup(struct lro_entry *le, void *l3hdr, struct tcphdr *th,
uint16_t tcp_data_len, uint16_t csum)
{
uint32_t c;
uint16_t cs;
c = csum;
/* Remove length from checksum. */
switch (le->eh_type) {
#ifdef INET6
case ETHERTYPE_IPV6:
{
struct ip6_hdr *ip6;
ip6 = (struct ip6_hdr *)l3hdr;
if (le->append_cnt == 0)
cs = ip6->ip6_plen;
else {
uint32_t cx;
cx = ntohs(ip6->ip6_plen);
cs = in6_cksum_pseudo(ip6, cx, ip6->ip6_nxt, 0);
}
break;
}
#endif
#ifdef INET
case ETHERTYPE_IP:
{
struct ip *ip4;
ip4 = (struct ip *)l3hdr;
if (le->append_cnt == 0)
cs = ip4->ip_len;
else {
cs = in_addword(ntohs(ip4->ip_len) - sizeof(*ip4),
IPPROTO_TCP);
cs = in_pseudo(ip4->ip_src.s_addr, ip4->ip_dst.s_addr,
htons(cs));
}
break;
}
#endif
default:
cs = 0; /* Keep compiler happy. */
}
cs = ~cs;
c += cs;
/* Remove TCP header csum. */
cs = ~tcp_lro_csum_th(th);
c += cs;
while (c > 0xffff)
c = (c >> 16) + (c & 0xffff);
return (c & 0xffff);
}
#endif
void
tcp_lro_flush_inactive(struct lro_ctrl *lc, const struct timeval *timeout)
{
struct lro_entry *le, *le_tmp;
struct timeval tv;
if (SLIST_EMPTY(&lc->lro_active))
return;
getmicrotime(&tv);
timevalsub(&tv, timeout);
SLIST_FOREACH_SAFE(le, &lc->lro_active, next, le_tmp) {
if (timevalcmp(&tv, &le->mtime, >=)) {
SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
tcp_lro_flush(lc, le);
}
}
}
void
tcp_lro_flush(struct lro_ctrl *lc, struct lro_entry *le)
{
if (le->append_cnt > 0) {
struct tcphdr *th;
uint16_t p_len;
p_len = htons(le->p_len);
switch (le->eh_type) {
#ifdef INET6
case ETHERTYPE_IPV6:
{
struct ip6_hdr *ip6;
ip6 = le->le_ip6;
ip6->ip6_plen = p_len;
th = (struct tcphdr *)(ip6 + 1);
le->m_head->m_pkthdr.csum_flags = CSUM_DATA_VALID |
CSUM_PSEUDO_HDR;
le->p_len += ETHER_HDR_LEN + sizeof(*ip6);
break;
}
#endif
#ifdef INET
case ETHERTYPE_IP:
{
struct ip *ip4;
#ifdef TCP_LRO_UPDATE_CSUM
uint32_t cl;
uint16_t c;
#endif
ip4 = le->le_ip4;
#ifdef TCP_LRO_UPDATE_CSUM
/* Fix IP header checksum for new length. */
c = ~ip4->ip_sum;
cl = c;
c = ~ip4->ip_len;
cl += c + p_len;
while (cl > 0xffff)
cl = (cl >> 16) + (cl & 0xffff);
c = cl;
ip4->ip_sum = ~c;
#else
ip4->ip_sum = TCP_LRO_INVALID_CSUM;
#endif
ip4->ip_len = p_len;
th = (struct tcphdr *)(ip4 + 1);
le->m_head->m_pkthdr.csum_flags = CSUM_DATA_VALID |
CSUM_PSEUDO_HDR | CSUM_IP_CHECKED | CSUM_IP_VALID;
le->p_len += ETHER_HDR_LEN;
break;
}
#endif
default:
th = NULL; /* Keep compiler happy. */
}
le->m_head->m_pkthdr.csum_data = 0xffff;
le->m_head->m_pkthdr.len = le->p_len;
/* Incorporate the latest ACK into the TCP header. */
th->th_ack = le->ack_seq;
th->th_win = le->window;
/* Incorporate latest timestamp into the TCP header. */
if (le->timestamp != 0) {
uint32_t *ts_ptr;
ts_ptr = (uint32_t *)(th + 1);
ts_ptr[1] = htonl(le->tsval);
ts_ptr[2] = le->tsecr;
}
#ifdef TCP_LRO_UPDATE_CSUM
/* Update the TCP header checksum. */
le->ulp_csum += p_len;
le->ulp_csum += tcp_lro_csum_th(th);
while (le->ulp_csum > 0xffff)
le->ulp_csum = (le->ulp_csum >> 16) +
(le->ulp_csum & 0xffff);
th->th_sum = (le->ulp_csum & 0xffff);
th->th_sum = ~th->th_sum;
#else
th->th_sum = TCP_LRO_INVALID_CSUM;
#endif
}
(*lc->ifp->if_input)(lc->ifp, le->m_head);
lc->lro_queued += le->append_cnt + 1;
lc->lro_flushed++;
bzero(le, sizeof(*le));
SLIST_INSERT_HEAD(&lc->lro_free, le, next);
}
#ifdef INET6
static int
tcp_lro_rx_ipv6(struct lro_ctrl *lc, struct mbuf *m, struct ip6_hdr *ip6,
struct tcphdr **th)
{
/* XXX-BZ we should check the flow-label. */
/* XXX-BZ We do not yet support ext. hdrs. */
if (ip6->ip6_nxt != IPPROTO_TCP)
return (TCP_LRO_NOT_SUPPORTED);
/* Find the TCP header. */
*th = (struct tcphdr *)(ip6 + 1);
return (0);
}
#endif
#ifdef INET
static int
tcp_lro_rx_ipv4(struct lro_ctrl *lc, struct mbuf *m, struct ip *ip4,
struct tcphdr **th)
{
int csum_flags;
uint16_t csum;
if (ip4->ip_p != IPPROTO_TCP)
return (TCP_LRO_NOT_SUPPORTED);
/* Ensure there are no options. */
if ((ip4->ip_hl << 2) != sizeof (*ip4))
return (TCP_LRO_CANNOT);
/* .. and the packet is not fragmented. */
if (ip4->ip_off & htons(IP_MF|IP_OFFMASK))
return (TCP_LRO_CANNOT);
/* Legacy IP has a header checksum that needs to be correct. */
csum_flags = m->m_pkthdr.csum_flags;
if (csum_flags & CSUM_IP_CHECKED) {
if (__predict_false((csum_flags & CSUM_IP_VALID) == 0)) {
lc->lro_bad_csum++;
return (TCP_LRO_CANNOT);
}
} else {
csum = in_cksum_hdr(ip4);
if (__predict_false((csum) != 0)) {
lc->lro_bad_csum++;
return (TCP_LRO_CANNOT);
}
}
/* Find the TCP header (we assured there are no IP options). */
*th = (struct tcphdr *)(ip4 + 1);
return (0);
}
#endif
int
tcp_lro_rx(struct lro_ctrl *lc, struct mbuf *m, uint32_t csum)
{
struct lro_entry *le;
struct ether_header *eh;
#ifdef INET6
struct ip6_hdr *ip6 = NULL; /* Keep compiler happy. */
#endif
#ifdef INET
struct ip *ip4 = NULL; /* Keep compiler happy. */
#endif
struct tcphdr *th;
void *l3hdr = NULL; /* Keep compiler happy. */
uint32_t *ts_ptr;
tcp_seq seq;
int error, ip_len, l;
uint16_t eh_type, tcp_data_len;
/* We expect a contiguous header [eh, ip, tcp]. */
eh = mtod(m, struct ether_header *);
eh_type = ntohs(eh->ether_type);
switch (eh_type) {
#ifdef INET6
case ETHERTYPE_IPV6:
{
CURVNET_SET(lc->ifp->if_vnet);
if (V_ip6_forwarding != 0) {
/* XXX-BZ stats but changing lro_ctrl is a problem. */
CURVNET_RESTORE();
return (TCP_LRO_CANNOT);
}
CURVNET_RESTORE();
l3hdr = ip6 = (struct ip6_hdr *)(eh + 1);
error = tcp_lro_rx_ipv6(lc, m, ip6, &th);
if (error != 0)
return (error);
tcp_data_len = ntohs(ip6->ip6_plen);
ip_len = sizeof(*ip6) + tcp_data_len;
break;
}
#endif
#ifdef INET
case ETHERTYPE_IP:
{
CURVNET_SET(lc->ifp->if_vnet);
if (V_ipforwarding != 0) {
/* XXX-BZ stats but changing lro_ctrl is a problem. */
CURVNET_RESTORE();
return (TCP_LRO_CANNOT);
}
CURVNET_RESTORE();
l3hdr = ip4 = (struct ip *)(eh + 1);
error = tcp_lro_rx_ipv4(lc, m, ip4, &th);
if (error != 0)
return (error);
ip_len = ntohs(ip4->ip_len);
tcp_data_len = ip_len - sizeof(*ip4);
break;
}
#endif
/* XXX-BZ what happens in case of VLAN(s)? */
default:
return (TCP_LRO_NOT_SUPPORTED);
}
/*
* If the frame is padded beyond the end of the IP packet, then we must
* trim the extra bytes off.
*/
l = m->m_pkthdr.len - (ETHER_HDR_LEN + ip_len);
if (l != 0) {
if (l < 0)
/* Truncated packet. */
return (TCP_LRO_CANNOT);
m_adj(m, -l);
}
/*
* Check TCP header constraints.
*/
/* Ensure no bits set besides ACK or PSH. */
if ((th->th_flags & ~(TH_ACK | TH_PUSH)) != 0)
return (TCP_LRO_CANNOT);
/* XXX-BZ We lose a AKC|PUSH flag concatinating multiple segments. */
/* XXX-BZ Ideally we'd flush on PUSH? */
/*
* Check for timestamps.
* Since the only option we handle are timestamps, we only have to
* handle the simple case of aligned timestamps.
*/
l = (th->th_off << 2);
tcp_data_len -= l;
l -= sizeof(*th);
ts_ptr = (uint32_t *)(th + 1);
if (l != 0 && (__predict_false(l != TCPOLEN_TSTAMP_APPA) ||
(*ts_ptr != ntohl(TCPOPT_NOP<<24|TCPOPT_NOP<<16|
TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP))))
return (TCP_LRO_CANNOT);
/* If the driver did not pass in the checksum, set it now. */
if (csum == 0x0000)
csum = th->th_sum;
seq = ntohl(th->th_seq);
/* Try to find a matching previous segment. */
SLIST_FOREACH(le, &lc->lro_active, next) {
if (le->eh_type != eh_type)
continue;
if (le->source_port != th->th_sport ||
le->dest_port != th->th_dport)
continue;
switch (eh_type) {
#ifdef INET6
case ETHERTYPE_IPV6:
if (bcmp(&le->source_ip6, &ip6->ip6_src,
sizeof(struct in6_addr)) != 0 ||
bcmp(&le->dest_ip6, &ip6->ip6_dst,
sizeof(struct in6_addr)) != 0)
continue;
break;
#endif
#ifdef INET
case ETHERTYPE_IP:
if (le->source_ip4 != ip4->ip_src.s_addr ||
le->dest_ip4 != ip4->ip_dst.s_addr)
continue;
break;
#endif
}
/* Flush now if appending will result in overflow. */
if (le->p_len > (65535 - tcp_data_len)) {
SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
tcp_lro_flush(lc, le);
break;
}
/* Try to append the new segment. */
if (__predict_false(seq != le->next_seq ||
(tcp_data_len == 0 && le->ack_seq == th->th_ack))) {
/* Out of order packet or duplicate ACK. */
SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
tcp_lro_flush(lc, le);
return (TCP_LRO_CANNOT);
}
if (l != 0) {
uint32_t tsval = ntohl(*(ts_ptr + 1));
/* Make sure timestamp values are increasing. */
/* XXX-BZ flip and use TSTMP_GEQ macro for this? */
if (__predict_false(le->tsval > tsval ||
*(ts_ptr + 2) == 0))
return (TCP_LRO_CANNOT);
le->tsval = tsval;
le->tsecr = *(ts_ptr + 2);
}
le->next_seq += tcp_data_len;
le->ack_seq = th->th_ack;
le->window = th->th_win;
le->append_cnt++;
#ifdef TCP_LRO_UPDATE_CSUM
le->ulp_csum += tcp_lro_rx_csum_fixup(le, l3hdr, th,
tcp_data_len, ~csum);
#endif
if (tcp_data_len == 0) {
m_freem(m);
return (0);
}
le->p_len += tcp_data_len;
/*
* Adjust the mbuf so that m_data points to the first byte of
* the ULP payload. Adjust the mbuf to avoid complications and
* append new segment to existing mbuf chain.
*/
m_adj(m, m->m_pkthdr.len - tcp_data_len);
m->m_flags &= ~M_PKTHDR;
le->m_tail->m_next = m;
le->m_tail = m_last(m);
/*
* If a possible next full length packet would cause an
* overflow, pro-actively flush now.
*/
if (le->p_len > (65535 - lc->ifp->if_mtu)) {
SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
tcp_lro_flush(lc, le);
} else
getmicrotime(&le->mtime);
return (0);
}
/* Try to find an empty slot. */
if (SLIST_EMPTY(&lc->lro_free))
return (TCP_LRO_CANNOT);
/* Start a new segment chain. */
le = SLIST_FIRST(&lc->lro_free);
SLIST_REMOVE_HEAD(&lc->lro_free, next);
SLIST_INSERT_HEAD(&lc->lro_active, le, next);
getmicrotime(&le->mtime);
/* Start filling in details. */
switch (eh_type) {
#ifdef INET6
case ETHERTYPE_IPV6:
le->le_ip6 = ip6;
le->source_ip6 = ip6->ip6_src;
le->dest_ip6 = ip6->ip6_dst;
le->eh_type = eh_type;
le->p_len = m->m_pkthdr.len - ETHER_HDR_LEN - sizeof(*ip6);
break;
#endif
#ifdef INET
case ETHERTYPE_IP:
le->le_ip4 = ip4;
le->source_ip4 = ip4->ip_src.s_addr;
le->dest_ip4 = ip4->ip_dst.s_addr;
le->eh_type = eh_type;
le->p_len = m->m_pkthdr.len - ETHER_HDR_LEN;
break;
#endif
}
le->source_port = th->th_sport;
le->dest_port = th->th_dport;
le->next_seq = seq + tcp_data_len;
le->ack_seq = th->th_ack;
le->window = th->th_win;
if (l != 0) {
le->timestamp = 1;
le->tsval = ntohl(*(ts_ptr + 1));
le->tsecr = *(ts_ptr + 2);
}
#ifdef TCP_LRO_UPDATE_CSUM
/*
* Do not touch the csum of the first packet. However save the
* "adjusted" checksum of just the source and destination addresses,
* the next header and the TCP payload. The length and TCP header
* parts may change, so we remove those from the saved checksum and
* re-add with final values on tcp_lro_flush() if needed.
*/
KASSERT(le->ulp_csum == 0, ("%s: le=%p le->ulp_csum=0x%04x\n",
__func__, le, le->ulp_csum));
le->ulp_csum = tcp_lro_rx_csum_fixup(le, l3hdr, th, tcp_data_len,
~csum);
th->th_sum = csum; /* Restore checksum on first packet. */
#endif
le->m_head = m;
le->m_tail = m_last(m);
return (0);
}
/* end */