Patch "tcp_bbr: introduce bbr_bw_to_pacing_rate() helper" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    tcp_bbr: introduce bbr_bw_to_pacing_rate() helper

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tcp_bbr-introduce-bbr_bw_to_pacing_rate-helper.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Tue Aug  8 16:27:53 PDT 2017
From: Neal Cardwell <ncardwell@google.com>
Date: Fri, 14 Jul 2017 17:49:22 -0400
Subject: tcp_bbr: introduce bbr_bw_to_pacing_rate() helper

From: Neal Cardwell <ncardwell@google.com>


[ Upstream commit f19fd62dafaf1ed6cf615dba655b82fa9df59074 ]

Introduce a helper to convert a BBR bandwidth and gain factor to a
pacing rate in bytes per second. This is a pure refactor, but is
needed for two following fixes.

Fixes: 0f8782ea1497 ("tcp_bbr: add BBR congestion control")
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv4/tcp_bbr.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c
@@ -182,6 +182,16 @@ static u64 bbr_rate_bytes_per_sec(struct
 	return rate >> BW_SCALE;
 }
 
+/* Convert a BBR bw and gain factor to a pacing rate in bytes per second. */
+static u32 bbr_bw_to_pacing_rate(struct sock *sk, u32 bw, int gain)
+{
+	u64 rate = bw;
+
+	rate = bbr_rate_bytes_per_sec(sk, rate, gain);
+	rate = min_t(u64, rate, sk->sk_max_pacing_rate);
+	return rate;
+}
+
 /* Pace using current bw estimate and a gain factor. In order to help drive the
  * network toward lower queues while maintaining high utilization and low
  * latency, the average pacing rate aims to be slightly (~1%) lower than the
@@ -191,10 +201,8 @@ static u64 bbr_rate_bytes_per_sec(struct
  */
 static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain)
 {
-	u64 rate = bw;
+	u32 rate = bbr_bw_to_pacing_rate(sk, bw, gain);
 
-	rate = bbr_rate_bytes_per_sec(sk, rate, gain);
-	rate = min_t(u64, rate, sk->sk_max_pacing_rate);
 	if (bbr_full_bw_reached(sk) || rate > sk->sk_pacing_rate)
 		sk->sk_pacing_rate = rate;
 }


Patches currently in stable-queue which might be from ncardwell@google.com are

queue-4.9/tcp_bbr-remove-sk_pacing_rate-0-transient-during-init.patch
queue-4.9/tcp_bbr-introduce-bbr_bw_to_pacing_rate-helper.patch
queue-4.9/tcp_bbr-introduce-bbr_init_pacing_rate_from_rtt-helper.patch
queue-4.9/tcp_bbr-init-pacing-rate-on-first-rtt-sample.patch
queue-4.9/tcp_bbr-cut-pacing-rate-only-if-filled-pipe.patch