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Fix a bug introduced with r182851 splitting tcp_mss() into

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tcp_mss() and tcp_mss_update() so that tcp_mtudisc() could
re-use the same code.

Move the TSO logic back to tcp_mss() and out of tcp_mss_update().
We tried to avoid that initially but if were are called from
tcp_output() with EMSGSIZE, we cleared the TSO flag on the tcpcb
there, called into tcp_mtudisc() and tcp_mss_update() which
then would reenable TSO on the tcpcb based on TSO capabilities
of the interface as learnt in tcp_maxmtu/6().
So if TSO was enabled on the (possibly new) outgoing interface
it was turned back on, which lead to an endless loop between
tcp_output() and tcp_mtudisc() until we overflew the stack.

Reported by:	kmacy
MFC after:	2 months (along with r182851)
This commit is contained in:
Bjoern A. Zeeb 2008-11-06 13:25:59 +00:00
parent 4b3f4d3818
commit 91d6cfa6b1
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=184722
3 changed files with 12 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
sys/netinet/tcp_input.c
View File

@ -2812,7 +2812,8 @@ tcp_xmit_timer(struct tcpcb *tp, int rtt)
* segment. Outgoing SYN/ACK MSS settings are handled in tcp_mssopt().
*/
void
tcp_mss_update(struct tcpcb *tp, int offer, struct hc_metrics_lite *metricptr)
tcp_mss_update(struct tcpcb *tp, int offer,
struct hc_metrics_lite *metricptr, int *mtuflags)
{
INIT_VNET_INET(tp->t_inpcb->inp_vnet);
int mss;
@ -2820,7 +2821,6 @@ tcp_mss_update(struct tcpcb *tp, int offer, struct hc_metrics_lite *metricptr)
struct inpcb *inp = tp->t_inpcb;
struct hc_metrics_lite metrics;
int origoffer = offer;
int mtuflags = 0;
#ifdef INET6
int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0;
size_t min_protoh = isipv6 ?
@ -2835,12 +2835,12 @@ tcp_mss_update(struct tcpcb *tp, int offer, struct hc_metrics_lite *metricptr)
/* Initialize. */
#ifdef INET6
if (isipv6) {
maxmtu = tcp_maxmtu6(&inp->inp_inc, &mtuflags);
maxmtu = tcp_maxmtu6(&inp->inp_inc, mtuflags);
tp->t_maxopd = tp->t_maxseg = V_tcp_v6mssdflt;
} else
#endif
{
maxmtu = tcp_maxmtu(&inp->inp_inc, &mtuflags);
maxmtu = tcp_maxmtu(&inp->inp_inc, mtuflags);
tp->t_maxopd = tp->t_maxseg = V_tcp_mssdflt;
}
@ -2858,10 +2858,6 @@ tcp_mss_update(struct tcpcb *tp, int offer, struct hc_metrics_lite *metricptr)
return;
}
/* Check the interface for TSO capabilities. */
if (mtuflags & CSUM_TSO)
tp->t_flags |= TF_TSO;
/* What have we got? */
switch (offer) {
case 0:
@ -2980,12 +2976,13 @@ tcp_mss(struct tcpcb *tp, int offer)
struct inpcb *inp;
struct socket *so;
struct hc_metrics_lite metrics;
int mtuflags = 0;
#ifdef INET6
int isipv6;
#endif
KASSERT(tp != NULL, ("%s: tp == NULL", __func__));
tcp_mss_update(tp, offer, &metrics);
tcp_mss_update(tp, offer, &metrics, &mtuflags);
mss = tp->t_maxseg;
inp = tp->t_inpcb;
@ -3098,6 +3095,10 @@ tcp_mss(struct tcpcb *tp, int offer)
tp->snd_cwnd = mss * V_ss_fltsz_local;
else
tp->snd_cwnd = mss * V_ss_fltsz;
/* Check the interface for TSO capabilities. */
if (mtuflags & CSUM_TSO)
tp->t_flags |= TF_TSO;
}
/*

2
sys/netinet/tcp_subr.c
View File

@ -1562,7 +1562,7 @@ tcp_mtudisc(struct inpcb *inp, int errno)
tp = intotcpcb(inp);
KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL"));
tcp_mss_update(tp, -1, NULL);
tcp_mss_update(tp, -1, NULL, NULL);
so = inp->inp_socket;
SOCKBUF_LOCK(&so->so_snd);

2
sys/netinet/tcp_var.h
View File

@ -546,7 +546,7 @@ void tcp_reass_init(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 *);
void tcp_mss_update(struct tcpcb *, int, struct hc_metrics_lite *, int *);
void tcp_mss(struct tcpcb *, int);
int tcp_mssopt(struct in_conninfo *);
struct inpcb *