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From: Stephen Hemminger <shemminger@vyatta•com>
To: davem@davemloft•net, sangtae.ha@gmail•com, rhee@ncsu•edu
Cc: netdev@vger•kernel.org
Subject: [PATCH 3/6] tcp_cubic: fix comparison of jiffies
Date: Thu, 10 Mar 2011 08:51:25 -0800	[thread overview]
Message-ID: <20110310165328.999266946@vyatta.com> (raw)
In-Reply-To: 20110310165119.224046957@vyatta.com

[-- Attachment #1: tcp-cubic-jiffies-wrap.patch --]
[-- Type: text/plain, Size: 952 bytes --]

Jiffies wraps around therefore the correct way to compare is
to use cast to signed value.

Note: cubic is not using full jiffies value on 64 bit arch
because using full unsigned long makes struct bictcp grow too
large for the available ca_priv area.

Signed-off-by: Stephen Hemminger <shemminger@vyatta•com>

--- a/net/ipv4/tcp_cubic.c	2011-03-10 08:08:32.867492953 -0800
+++ b/net/ipv4/tcp_cubic.c	2011-03-10 08:24:39.658201745 -0800
@@ -342,9 +342,11 @@ static void hystart_update(struct sock *
 		u32 curr_jiffies = jiffies;
 
 		/* first detection parameter - ack-train detection */
-		if (curr_jiffies - ca->last_jiffies <= msecs_to_jiffies(2)) {
+		if ((s32)(curr_jiffies - ca->last_jiffies) <=
+		    msecs_to_jiffies(2)) {
 			ca->last_jiffies = curr_jiffies;
-			if (curr_jiffies - ca->round_start >= ca->delay_min>>4)
+			if ((s32) (curr_jiffies - ca->round_start) <=
+			    ca->delay_min >> 4)
 				ca->found |= HYSTART_ACK_TRAIN;
 		}
 



  parent reply	other threads:[~2011-03-10 16:56 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-10 16:51 [PATCH 0/6] TCP CUBIC and Hystart Stephen Hemminger
2011-03-10 16:51 ` [PATCH 1/6] tcp: fix RTT for quick packets in congestion control Stephen Hemminger
2011-03-10 16:51 ` [PATCH 2/6] tcp: timestamp code clarification Stephen Hemminger
2011-03-10 16:51 ` Stephen Hemminger [this message]
2011-03-11  9:40   ` [PATCH 3/6] tcp_cubic: fix comparison of jiffies Lucas Nussbaum
2011-03-10 16:51 ` [PATCH 4/6] tcp_cubic: make ack train delta value a parameter Stephen Hemminger
2011-03-10 16:51 ` [PATCH 5/6] tcp_cubic: fix clock dependency Stephen Hemminger
2011-03-11 16:26   ` Sangtae Ha
2011-03-10 16:51 ` [PATCH 6/6] tcp_cubic: enable high resolution ack time if needed Stephen Hemminger
2011-03-11 10:28 ` [PATCH 0/6] TCP CUBIC and Hystart Lucas Nussbaum
2011-03-11 10:49   ` Injong Rhee
2011-03-11 15:58   ` Sangtae Ha
2011-03-11 16:08     ` Lucas Nussbaum

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