tcp: Stalling connections: Move timeout calculation routine
This patch moves retransmits_timed_out() from include/net/tcp.h
to tcp_timer.c, where it is used.
Reported-by: Frederic Leroy <fredo@starox.org>
Signed-off-by: Damian Lukowski <damian@tvk.rwth-aachen.de>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 8353a53..8816a20 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -132,6 +132,35 @@
}
}
+/* This function calculates a "timeout" which is equivalent to the timeout of a
+ * TCP connection after "boundary" unsucessful, exponentially backed-off
+ * retransmissions with an initial RTO of TCP_RTO_MIN.
+ */
+static bool retransmits_timed_out(struct sock *sk,
+ unsigned int boundary)
+{
+ unsigned int timeout, linear_backoff_thresh;
+ unsigned int start_ts;
+
+ if (!inet_csk(sk)->icsk_retransmits)
+ return false;
+
+ if (unlikely(!tcp_sk(sk)->retrans_stamp))
+ start_ts = TCP_SKB_CB(tcp_write_queue_head(sk))->when;
+ else
+ start_ts = tcp_sk(sk)->retrans_stamp;
+
+ linear_backoff_thresh = ilog2(TCP_RTO_MAX/TCP_RTO_MIN);
+
+ if (boundary <= linear_backoff_thresh)
+ timeout = ((2 << boundary) - 1) * TCP_RTO_MIN;
+ else
+ timeout = ((2 << linear_backoff_thresh) - 1) * TCP_RTO_MIN +
+ (boundary - linear_backoff_thresh) * TCP_RTO_MAX;
+
+ return (tcp_time_stamp - start_ts) >= timeout;
+}
+
/* A write timeout has occurred. Process the after effects. */
static int tcp_write_timeout(struct sock *sk)
{