Page MenuHomeFreeBSD
Files F131782047

D24308.diff
No OneTemporary
Actions

D24308.diff
View Options

Index: head/sys/netinet/tcp_timer.c
===================================================================
--- head/sys/netinet/tcp_timer.c
+++ head/sys/netinet/tcp_timer.c
@@ -723,16 +723,40 @@
(V_tcp_pmtud_blackhole_detect == 3 && isipv6)) &&
((tp->t_state == TCPS_ESTABLISHED) ||
(tp->t_state == TCPS_FIN_WAIT_1))) {
- /*
- * Idea here is that at each stage of mtu probe (usually, 1448
- * -> 1188 -> 524) should be given 2 chances to recover before
- * further clamping down. 'tp->t_rxtshift % 2 == 0' should
- * take care of that.
- */
+ if (tp->t_rxtshift == 1) {
+ /*
+ * We enter blackhole detection after the first
+ * unsuccessful timer based retransmission.
+ * Then we reduce up to two times the MSS, each
+ * candidate giving two tries of retransmissions.
+ * But we give a candidate only two tries, if it
+ * actually reduces the MSS.
+ */
+ tp->t_blackhole_enter = 2;
+ tp->t_blackhole_exit = tp->t_blackhole_enter;
+ if (isipv6) {
+#ifdef INET6
+ if (tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss)
+ tp->t_blackhole_exit += 2;
+ if (tp->t_maxseg > V_tcp_v6mssdflt &&
+ V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt)
+ tp->t_blackhole_exit += 2;
+#endif
+ } else {
+#ifdef INET
+ if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss)
+ tp->t_blackhole_exit += 2;
+ if (tp->t_maxseg > V_tcp_mssdflt &&
+ V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt)
+ tp->t_blackhole_exit += 2;
+#endif
+ }
+ }
if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
(TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
- (tp->t_rxtshift >= 2 && tp->t_rxtshift < 6 &&
- tp->t_rxtshift % 2 == 0)) {
+ (tp->t_rxtshift >= tp->t_blackhole_enter &&
+ tp->t_rxtshift < tp->t_blackhole_exit &&
+ (tp->t_rxtshift - tp->t_blackhole_enter) % 2 == 0)) {
/*
* Enter Path MTU Black-hole Detection mechanism:
* - Disable Path MTU Discovery (IP "DF" bit).
@@ -752,7 +776,8 @@
*/
#ifdef INET6
if (isipv6 &&
- tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss) {
+ tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss &&
+ V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt) {
/* Use the sysctl tuneable blackhole MSS. */
tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
TCPSTAT_INC(tcps_pmtud_blackhole_activated);
@@ -771,7 +796,8 @@
else
#endif
#ifdef INET
- if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss) {
+ if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss &&
+ V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt) {
/* Use the sysctl tuneable blackhole MSS. */
tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
TCPSTAT_INC(tcps_pmtud_blackhole_activated);
@@ -798,11 +824,9 @@
* with a lowered MTU, maybe this isn't a blackhole and
* we restore the previous MSS and blackhole detection
* flags.
- * The limit '6' is determined by giving each probe
- * stage (1448, 1188, 524) 2 chances to recover.
*/
if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
- (tp->t_rxtshift >= 6)) {
+ (tp->t_rxtshift >= tp->t_blackhole_exit)) {
tp->t_flags2 |= TF2_PLPMTU_PMTUD;
tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
tp->t_maxseg = tp->t_pmtud_saved_maxseg;
Index: head/sys/netinet/tcp_var.h
===================================================================
--- head/sys/netinet/tcp_var.h
+++ head/sys/netinet/tcp_var.h
@@ -169,6 +169,8 @@
u_int t_starttime; /* time connection was established */
u_int t_pmtud_saved_maxseg; /* pre-blackhole MSS */
+ int t_blackhole_enter; /* when to enter blackhole detection */
+ int t_blackhole_exit; /* when to exit blackhole detection */
u_int t_rttmin; /* minimum rtt allowed */
u_int t_rttbest; /* best rtt we've seen */

File Metadata

Mime Type
text/plain
Expires
Sun, Oct 12, 3:07 AM (7 h, 1 m)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
23605454
Default Alt Text
D24308.diff (3 KB)

Event Timeline