svn commit: r235053 - stable/8/sys/netinet
Gleb Smirnoff
glebius at FreeBSD.org
Sat May 5 10:05:14 UTC 2012
Author: glebius
Date: Sat May 5 10:05:13 2012
New Revision: 235053
URL: http://svn.freebsd.org/changeset/base/235053
Log:
Merge 234342 from head:
When we receive an ICMP unreach need fragmentation datagram, we take
proposed MTU value from it and update the TCP host cache. Then
tcp_mss_update() is called on the corresponding tcpcb. It finds the
just allocated entry in the TCP host cache and updates MSS on the
tcpcb. And then we do a fast retransmit of what we have in the tcp
send buffer.
This sequence gets broken if the TCP host cache is exausted. In this
case allocation fails, and later called tcp_mss_update() finds nothing
in cache. The fast retransmit is done with not reduced MSS and is
immidiately replied by remote host with new ICMP datagrams and the
cycle repeats. This ping-pong can go up to wirespeed.
To fix this:
- tcp_mss_update() gets new parameter - mtuoffer, that is like
offer, but needs to have min_protoh subtracted.
- tcp_mtudisc() as notification method renamed to tcp_mtudisc_notify().
- tcp_mtudisc() now accepts not a useless error argument, but proposed
MTU value, that is passed to tcp_mss_update() as mtuoffer.
Reported by: az
Reported by: Andrey Zonov <andrey zonov.org>
Reviewed by: andre (previous version of patch)
Tested by: Andrey Zonov <andrey zonov.org>
Modified:
stable/8/sys/netinet/tcp_input.c
stable/8/sys/netinet/tcp_output.c
stable/8/sys/netinet/tcp_subr.c
stable/8/sys/netinet/tcp_var.h
Directory Properties:
stable/8/sys/ (props changed)
Modified: stable/8/sys/netinet/tcp_input.c
==============================================================================
--- stable/8/sys/netinet/tcp_input.c Sat May 5 09:34:35 2012 (r235052)
+++ stable/8/sys/netinet/tcp_input.c Sat May 5 10:05:13 2012 (r235053)
@@ -3286,22 +3286,19 @@ tcp_xmit_timer(struct tcpcb *tp, int rtt
* are present. Store the upper limit of the length of options plus
* data in maxopd.
*
- * In case of T/TCP, we call this routine during implicit connection
- * setup as well (offer = -1), to initialize maxseg from the cached
- * MSS of our peer.
- *
* NOTE that this routine is only called when we process an incoming
- * segment. Outgoing SYN/ACK MSS settings are handled in tcp_mssopt().
+ * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS
+ * settings are handled in tcp_mssopt().
*/
void
-tcp_mss_update(struct tcpcb *tp, int offer,
+tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer,
struct hc_metrics_lite *metricptr, int *mtuflags)
{
int mss;
u_long maxmtu;
struct inpcb *inp = tp->t_inpcb;
struct hc_metrics_lite metrics;
- int origoffer = offer;
+ int origoffer;
#ifdef INET6
int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0;
size_t min_protoh = isipv6 ?
@@ -3313,6 +3310,12 @@ tcp_mss_update(struct tcpcb *tp, int off
INP_WLOCK_ASSERT(tp->t_inpcb);
+ if (mtuoffer != -1) {
+ KASSERT(offer == -1, ("%s: conflict", __func__));
+ offer = mtuoffer - min_protoh;
+ }
+ origoffer = offer;
+
/* Initialize. */
#ifdef INET6
if (isipv6) {
@@ -3461,7 +3464,7 @@ tcp_mss(struct tcpcb *tp, int offer)
KASSERT(tp != NULL, ("%s: tp == NULL", __func__));
- tcp_mss_update(tp, offer, &metrics, &mtuflags);
+ tcp_mss_update(tp, offer, -1, &metrics, &mtuflags);
mss = tp->t_maxseg;
inp = tp->t_inpcb;
Modified: stable/8/sys/netinet/tcp_output.c
==============================================================================
--- stable/8/sys/netinet/tcp_output.c Sat May 5 09:34:35 2012 (r235052)
+++ stable/8/sys/netinet/tcp_output.c Sat May 5 10:05:13 2012 (r235053)
@@ -1288,7 +1288,7 @@ out:
*/
if (tso)
tp->t_flags &= ~TF_TSO;
- tcp_mtudisc(tp->t_inpcb, 0);
+ tcp_mtudisc(tp->t_inpcb, -1);
return (0);
case EHOSTDOWN:
case EHOSTUNREACH:
Modified: stable/8/sys/netinet/tcp_subr.c
==============================================================================
--- stable/8/sys/netinet/tcp_subr.c Sat May 5 09:34:35 2012 (r235052)
+++ stable/8/sys/netinet/tcp_subr.c Sat May 5 10:05:13 2012 (r235053)
@@ -271,6 +271,7 @@ VNET_DEFINE(uma_zone_t, sack_hole_zone);
VNET_DEFINE(struct hhook_head *, tcp_hhh[HHOOK_TCP_LAST+1]);
static struct inpcb *tcp_notify(struct inpcb *, int);
+static struct inpcb *tcp_mtudisc_notify(struct inpcb *, int);
static void tcp_isn_tick(void *);
static char * tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th,
void *ip4hdr, const void *ip6hdr);
@@ -1372,7 +1373,7 @@ tcp_ctlinput(int cmd, struct sockaddr *s
return;
if (cmd == PRC_MSGSIZE)
- notify = tcp_mtudisc;
+ notify = tcp_mtudisc_notify;
else if (V_icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB ||
cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip)
notify = tcp_drop_syn_sent;
@@ -1446,9 +1447,10 @@ tcp_ctlinput(int cmd, struct sockaddr *s
*/
if (mtu <= tcp_maxmtu(&inc, NULL))
tcp_hc_updatemtu(&inc, mtu);
- }
-
- inp = (*notify)(inp, inetctlerrmap[cmd]);
+ tcp_mtudisc(inp, mtu);
+ } else
+ inp = (*notify)(inp,
+ inetctlerrmap[cmd]);
}
}
if (inp != NULL)
@@ -1487,7 +1489,7 @@ tcp6_ctlinput(int cmd, struct sockaddr *
return;
if (cmd == PRC_MSGSIZE)
- notify = tcp_mtudisc;
+ notify = tcp_mtudisc_notify;
else if (!PRC_IS_REDIRECT(cmd) &&
((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0))
return;
@@ -1706,12 +1708,19 @@ tcp_drop_syn_sent(struct inpcb *inp, int
/*
* When `need fragmentation' ICMP is received, update our idea of the MSS
- * based on the new value in the route. Also nudge TCP to send something,
- * since we know the packet we just sent was dropped.
+ * based on the new value. Also nudge TCP to send something, since we
+ * know the packet we just sent was dropped.
* This duplicates some code in the tcp_mss() function in tcp_input.c.
*/
+static struct inpcb *
+tcp_mtudisc_notify(struct inpcb *inp, int error)
+{
+
+ return (tcp_mtudisc(inp, -1));
+}
+
struct inpcb *
-tcp_mtudisc(struct inpcb *inp, int errno)
+tcp_mtudisc(struct inpcb *inp, int mtuoffer)
{
struct tcpcb *tp;
struct socket *so;
@@ -1724,7 +1733,7 @@ tcp_mtudisc(struct inpcb *inp, int errno
tp = intotcpcb(inp);
KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL"));
- tcp_mss_update(tp, -1, NULL, NULL);
+ tcp_mss_update(tp, -1, mtuoffer, NULL, NULL);
so = inp->inp_socket;
SOCKBUF_LOCK(&so->so_snd);
Modified: stable/8/sys/netinet/tcp_var.h
==============================================================================
--- stable/8/sys/netinet/tcp_var.h Sat May 5 09:34:35 2012 (r235052)
+++ stable/8/sys/netinet/tcp_var.h Sat May 5 10:05:13 2012 (r235053)
@@ -661,7 +661,8 @@ void tcp_reass_destroy(void);
void tcp_input(struct mbuf *, int);
u_long tcp_maxmtu(struct in_conninfo *, int *);
u_long tcp_maxmtu6(struct in_conninfo *, int *);
-void tcp_mss_update(struct tcpcb *, int, struct hc_metrics_lite *, int *);
+void tcp_mss_update(struct tcpcb *, int, int, struct hc_metrics_lite *,
+ int *);
void tcp_mss(struct tcpcb *, int);
int tcp_mssopt(struct in_conninfo *);
struct inpcb *
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