From db0fd9c9a6eb1173ec453f8cbffd20a464a47a61 Mon Sep 17 00:00:00 2001
From: Yuchung Cheng <ycheng@google.com>
Date: Wed, 16 Jan 2019 15:05:32 -0800
Subject: [PATCH] tcp: create a helper to model exponential backoff
commit 01a523b071618abbc634d1958229fe3bd2dfa5fa upstream.
Create a helper to model TCP exponential backoff for the next patch.
This is pure refactor w no behavior change.
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Qiumiao Zhang <zhangqiumiao1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/tcp_timer.c | 31 ++++++++++++++++++-------------
1 file changed, 18 insertions(+), 13 deletions(-)
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 9a904bf8deccba..9e9507f125a2a9 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -160,7 +160,20 @@ static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
}
-
+static unsigned int tcp_model_timeout(struct sock *sk,
+ unsigned int boundary,
+ unsigned int rto_base)
+{
+ unsigned int linear_backoff_thresh, timeout;
+
+ linear_backoff_thresh = ilog2(TCP_RTO_MAX / rto_base);
+ if (boundary <= linear_backoff_thresh)
+ timeout = ((2 << boundary) - 1) * rto_base;
+ else
+ timeout = ((2 << linear_backoff_thresh) - 1) * rto_base +
+ (boundary - linear_backoff_thresh) * TCP_RTO_MAX;
+ return jiffies_to_msecs(timeout);
+}
/**
* retransmits_timed_out() - returns true if this connection has timed out
* @sk: The current socket
@@ -178,23 +191,15 @@ static bool retransmits_timed_out(struct sock *sk,
unsigned int boundary,
unsigned int timeout)
{
- const unsigned int rto_base = TCP_RTO_MIN;
- unsigned int linear_backoff_thresh, start_ts;
+ unsigned int start_ts;
if (!inet_csk(sk)->icsk_retransmits)
return false;
start_ts = tcp_sk(sk)->retrans_stamp;
- if (likely(timeout == 0)) {
- linear_backoff_thresh = ilog2(TCP_RTO_MAX/rto_base);
-
- if (boundary <= linear_backoff_thresh)
- timeout = ((2 << boundary) - 1) * rto_base;
- else
- timeout = ((2 << linear_backoff_thresh) - 1) * rto_base +
- (boundary - linear_backoff_thresh) * TCP_RTO_MAX;
- timeout = jiffies_to_msecs(timeout);
- }
+ if (likely(timeout == 0))
+ timeout = tcp_model_timeout(sk, boundary, TCP_RTO_MIN);
+
return (s32)(tcp_time_stamp(tcp_sk(sk)) - start_ts - timeout) >= 0;
}
--
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