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Date: Tue, 28 Sep 2010 21:44:54 +0200
From: Damian Lukowski <damian@....rwth-aachen.de>
To: netdev@...r.kernel.org
Subject: [PATCH] net-2.6: SYN retransmits: Add new parameter to
retransmits_timed_out()
This patch adds a syn_set parameter to the retransmits_timed_out()
routine and updates its callers. If not set, TCP_RTO_MIN is taken
as the calculation basis as before. If set, TCP_TIMEOUT_INIT is
used instead, so that sysctl_syn_retries represents the actual
amount of SYN retransmissions in case no SYNACKs are received when
establishing a new connection.
Signed-off-by: Damian Lukowski <damian@....rwth-aachen.de>
---
net/ipv4/tcp_timer.c | 24 ++++++++++++++----------
1 files changed, 14 insertions(+), 10 deletions(-)
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index c35b469..74c54b3 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -135,13 +135,16 @@ static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
/* This function calculates a "timeout" which is equivalent to the timeout of a
* TCP connection after "boundary" unsuccessful, exponentially backed-off
- * retransmissions with an initial RTO of TCP_RTO_MIN.
+ * retransmissions with an initial RTO of TCP_RTO_MIN or TCP_TIMEOUT_INIT if
+ * syn_set flag is set.
*/
static bool retransmits_timed_out(struct sock *sk,
- unsigned int boundary)
+ unsigned int boundary,
+ bool syn_set)
{
unsigned int timeout, linear_backoff_thresh;
unsigned int start_ts;
+ unsigned int rto_base = syn_set ? TCP_TIMEOUT_INIT : TCP_RTO_MIN;
if (!inet_csk(sk)->icsk_retransmits)
return false;
@@ -151,12 +154,12 @@ static bool retransmits_timed_out(struct sock *sk,
else
start_ts = tcp_sk(sk)->retrans_stamp;
- linear_backoff_thresh = ilog2(TCP_RTO_MAX/TCP_RTO_MIN);
+ linear_backoff_thresh = ilog2(TCP_RTO_MAX/rto_base);
if (boundary <= linear_backoff_thresh)
- timeout = ((2 << boundary) - 1) * TCP_RTO_MIN;
+ timeout = ((2 << boundary) - 1) * rto_base;
else
- timeout = ((2 << linear_backoff_thresh) - 1) * TCP_RTO_MIN +
+ timeout = ((2 << linear_backoff_thresh) - 1) * rto_base +
(boundary - linear_backoff_thresh) * TCP_RTO_MAX;
return (tcp_time_stamp - start_ts) >= timeout;
@@ -167,14 +170,15 @@ static int tcp_write_timeout(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
int retry_until;
- bool do_reset;
+ bool do_reset, syn_set = 0;
if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
if (icsk->icsk_retransmits)
dst_negative_advice(sk);
retry_until = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
+ syn_set = 1;
} else {
- if (retransmits_timed_out(sk, sysctl_tcp_retries1)) {
+ if (retransmits_timed_out(sk, sysctl_tcp_retries1, 0)) {
/* Black hole detection */
tcp_mtu_probing(icsk, sk);
@@ -187,14 +191,14 @@ static int tcp_write_timeout(struct sock *sk)
retry_until = tcp_orphan_retries(sk, alive);
do_reset = alive ||
- !retransmits_timed_out(sk, retry_until);
+ !retransmits_timed_out(sk, retry_until, 0);
if (tcp_out_of_resources(sk, do_reset))
return 1;
}
}
- if (retransmits_timed_out(sk, retry_until)) {
+ if (retransmits_timed_out(sk, retry_until, syn_set)) {
/* Has it gone just too far? */
tcp_write_err(sk);
return 1;
@@ -436,7 +440,7 @@ out_reset_timer:
icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
}
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX);
- if (retransmits_timed_out(sk, sysctl_tcp_retries1 + 1))
+ if (retransmits_timed_out(sk, sysctl_tcp_retries1 + 1, 0))
__sk_dst_reset(sk);
out:;
--
1.7.2.2
--
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