[PATCH] tcp: fix ssthresh u16 leftover

[PATCH] tcp: fix ssthresh u16 leftover

[Ilpo Järvinen]

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It was once upon time so that snd_sthresh was a 16-bit quantity.
...That has not been true for long period of time. I run across
some ancient compares which still seem to trust such legacy.
Put all that magic into a single place, I hopefully found all
of them.

Compile tested, though linking of allyesconfig is ridiculous
nowadays it seems.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>

---
  include/net/tcp.h        |    7 +++++++
  net/ipv4/tcp.c           |    2 +-
  net/ipv4/tcp_input.c     |    2 +-
  net/ipv4/tcp_ipv4.c      |    4 ++--
  net/ipv4/tcp_minisocks.c |    2 +-
  net/ipv6/tcp_ipv6.c      |    5 +++--
  6 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index b71a446..56b7602 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -793,6 +793,13 @@ static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
  	return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
  }

+#define TCP_INFINITE_SSTHRESH	0x7fffffff
+
+static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
+{
+	return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
+}
+
  /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
   * The exception is rate halving phase, when cwnd is decreasing towards
   * ssthresh.
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index edeea06..19a0612 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2012,7 +2012,7 @@ int tcp_disconnect(struct sock *sk, int flags)
  	tp->snd_cwnd = 2;
  	icsk->icsk_probes_out = 0;
  	tp->packets_out = 0;
-	tp->snd_ssthresh = 0x7fffffff;
+	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
  	tp->snd_cwnd_cnt = 0;
  	tp->bytes_acked = 0;
  	tcp_set_ca_state(sk, TCP_CA_Open);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index af6d6fa..d86784b 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -761,7 +761,7 @@ void tcp_update_metrics(struct sock *sk)
  			set_dst_metric_rtt(dst, RTAX_RTTVAR, var);
  		}

-		if (tp->snd_ssthresh >= 0xFFFF) {
+		if (tcp_in_initial_slowstart(tp)) {
  			/* Slow start still did not finish. */
  			if (dst_metric(dst, RTAX_SSTHRESH) &&
  			    !dst_metric_locked(dst, RTAX_SSTHRESH) &&
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 0543561..7cda24b 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1808,7 +1808,7 @@ static int tcp_v4_init_sock(struct sock *sk)
  	/* See draft-stevens-tcpca-spec-01 for discussion of the
  	 * initialization of these values.
  	 */
-	tp->snd_ssthresh = 0x7fffffff;	/* Infinity */
+	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
  	tp->snd_cwnd_clamp = ~0;
  	tp->mss_cache = 536;

@@ -2284,7 +2284,7 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
  		jiffies_to_clock_t(icsk->icsk_ack.ato),
  		(icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
  		tp->snd_cwnd,
-		tp->snd_ssthresh >= 0xFFFF ? -1 : tp->snd_ssthresh,
+		tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh,
  		len);
  }

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index e48c37d..045bcfd 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -410,7 +410,7 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
  		newtp->retrans_out = 0;
  		newtp->sacked_out = 0;
  		newtp->fackets_out = 0;
-		newtp->snd_ssthresh = 0x7fffffff;
+		newtp->snd_ssthresh = TCP_INFINITE_SSTHRESH;

  		/* So many TCP implementations out there (incorrectly) count the
  		 * initial SYN frame in their delayed-ACK and congestion control
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 3aae0f2..6e3f0dc 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1846,7 +1846,7 @@ static int tcp_v6_init_sock(struct sock *sk)
  	/* See draft-stevens-tcpca-spec-01 for discussion of the
  	 * initialization of these values.
  	 */
-	tp->snd_ssthresh = 0x7fffffff;
+	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
  	tp->snd_cwnd_clamp = ~0;
  	tp->mss_cache = 536;

@@ -1969,7 +1969,8 @@ static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i)
  		   jiffies_to_clock_t(icsk->icsk_rto),
  		   jiffies_to_clock_t(icsk->icsk_ack.ato),
  		   (icsk->icsk_ack.quick << 1 ) | icsk->icsk_ack.pingpong,
-		   tp->snd_cwnd, tp->snd_ssthresh>=0xFFFF?-1:tp->snd_ssthresh
+		   tp->snd_cwnd,
+		   tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh
  		   );
  }

-- 
tg: (13af7a6..) fix/ssthresh (depends on: origin/master)

Re: [PATCH] tcp: fix ssthresh u16 leftover

[David Miller]

From: "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi>
Date: Mon, 14 Sep 2009 17:09:08 +0300 (EEST)

> It was once upon time so that snd_sthresh was a 16-bit quantity.
> ...That has not been true for long period of time. I run across
> some ancient compares which still seem to trust such legacy.
> Put all that magic into a single place, I hopefully found all
> of them.
> 
> Compile tested, though linking of allyesconfig is ridiculous
> nowadays it seems.
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>

This patch doesn't apply.

All of the context lines of the diff have been corrupted to have two
leading spaces instead of just one.  Likely this was done by your
email client.

Please fix this up and resubmit, thanks.

Re: [PATCH 2nd try] tcp: fix ssthresh u16 leftover

[David Miller]

From: "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi>
Date: Tue, 15 Sep 2009 11:19:11 +0300 (EEST)

> [PATCH 2nd try] tcp: fix ssthresh u16 leftover
> 
> It was once upon time so that snd_sthresh was a 16-bit quantity.
> ...That has not been true for long period of time. I run across
> some ancient compares which still seem to trust such legacy.
> Put all that magic into a single place, I hopefully found all
> of them.
> 
> Compile tested, though linking of allyesconfig is ridiculous
> nowadays it seems.
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>

Much better, applied, thanks!