The most possible way to trigger TWKilled is using tcp_tw_recycle, but
tcp_tw_recycle was removed. The TWKilled could still be triggered if
below conditions are satisfied:
1 the tw_timer expires in fin_wait_2 status
2 the timeout value of tw_timer is changed to less than 4 seconds
(via net.ipv4.tcp_fin_timeout or TCP_LINGER2 option)
But the 4 seconds threshold makes no sense in this scenario. So remove
this counter.
Signed-off-by: yupeng <yupeng0...@gmail.com>
---
include/net/inet_timewait_sock.h | 3 +--
include/uapi/linux/snmp.h | 1 -
net/ipv4/inet_timewait_sock.c | 31 +------------------------------
net/ipv4/proc.c | 1 -
4 files changed, 2 insertions(+), 34 deletions(-)
diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h
index 78775038f011..b042c0baa2ca 100644
--- a/include/net/inet_timewait_sock.h
+++ b/include/net/inet_timewait_sock.h
@@ -69,8 +69,7 @@ struct inet_timewait_sock {
/* these three are in inet_sock */
__be16 tw_sport;
/* And these are ours. */
- unsigned int tw_kill : 1,
- tw_transparent : 1,
+ unsigned int tw_transparent : 1,
tw_flowlabel : 20,
tw_pad : 2, /* 2 bits hole */
tw_tos : 8;
diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index 86dc24a96c90..fb0a17337bf2 100644
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -178,7 +178,6 @@ enum
LINUX_MIB_ARPFILTER, /* ArpFilter */
LINUX_MIB_TIMEWAITED, /* TimeWaited */
LINUX_MIB_TIMEWAITRECYCLED, /* TimeWaitRecycled */
- LINUX_MIB_TIMEWAITKILLED, /* TimeWaitKilled */
LINUX_MIB_PAWSACTIVEREJECTED, /* PAWSActiveRejected */
LINUX_MIB_PAWSESTABREJECTED, /* PAWSEstabRejected */
LINUX_MIB_DELAYEDACKS, /* DelayedACKs */
diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 88c5069b5d20..f0c4fe21909d 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -144,10 +144,7 @@ static void tw_timer_handler(struct timer_list *t)
{
struct inet_timewait_sock *tw = from_timer(tw, t, tw_timer);
- if (tw->tw_kill)
- __NET_INC_STATS(twsk_net(tw), LINUX_MIB_TIMEWAITKILLED);
- else
- __NET_INC_STATS(twsk_net(tw), LINUX_MIB_TIMEWAITED);
+ __NET_INC_STATS(twsk_net(tw), LINUX_MIB_TIMEWAITED);
inet_twsk_kill(tw);
}
@@ -218,32 +215,6 @@ EXPORT_SYMBOL(inet_twsk_deschedule_put);
void __inet_twsk_schedule(struct inet_timewait_sock *tw, int timeo, bool rearm)
{
- /* timeout := RTO * 3.5
- *
- * 3.5 = 1+2+0.5 to wait for two retransmits.
- *
- * RATIONALE: if FIN arrived and we entered TIME-WAIT state,
- * our ACK acking that FIN can be lost. If N subsequent retransmitted
- * FINs (or previous seqments) are lost (probability of such event
- * is p^(N+1), where p is probability to lose single packet and
- * time to detect the loss is about RTO*(2^N - 1) with exponential
- * backoff). Normal timewait length is calculated so, that we
- * waited at least for one retransmitted FIN (maximal RTO is 120sec).
- * [ BTW Linux. following BSD, violates this requirement waiting
- * only for 60sec, we should wait at least for 240 secs.
- * Well, 240 consumes too much of resources 8)
- * ]
- * This interval is not reduced to catch old duplicate and
- * responces to our wandering segments living for two MSLs.
- * However, if we use PAWS to detect
- * old duplicates, we can reduce the interval to bounds required
- * by RTO, rather than MSL. So, if peer understands PAWS, we
- * kill tw bucket after 3.5*RTO (it is important that this number
- * is greater than TS tick!) and detect old duplicates with help
- * of PAWS.
- */
-
- tw->tw_kill = timeo <= 4*HZ;
if (!rearm) {
BUG_ON(mod_timer(&tw->tw_timer, jiffies + timeo));
atomic_inc(&tw->tw_dr->tw_count);
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index c3610b37bb4c..20a29736d07e 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -186,7 +186,6 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("ArpFilter", LINUX_MIB_ARPFILTER),
SNMP_MIB_ITEM("TW", LINUX_MIB_TIMEWAITED),
SNMP_MIB_ITEM("TWRecycled", LINUX_MIB_TIMEWAITRECYCLED),
- SNMP_MIB_ITEM("TWKilled", LINUX_MIB_TIMEWAITKILLED),
SNMP_MIB_ITEM("PAWSActive", LINUX_MIB_PAWSACTIVEREJECTED),
SNMP_MIB_ITEM("PAWSEstab", LINUX_MIB_PAWSESTABREJECTED),
SNMP_MIB_ITEM("DelayedACKs", LINUX_MIB_DELAYEDACKS),
--
2.17.1
