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Commit 4d22f7d3 authored by Damian Lukowski's avatar Damian Lukowski Committed by David S. Miller
Browse files

net-2.6: SYN retransmits: Add new parameter to retransmits_timed_out() 



Fixes kernel Bugzilla Bug 18952

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: default avatarDamian Lukowski <damian@tvk.rwth-aachen.de>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 01db403c

net/ipv4/tcp_timer.c

+14 −10
Original line number Diff line number Diff line
@@ -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 @@ void tcp_retransmit_timer(struct sock *sk) 
		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:;