netdev - [PATCH net-next 1/5] dp83640: Include hash in timestamp/packet matching

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Date:	Fri, 30 Oct 2015 13:14:00 +0100
From:	Stefan Sørensen 
	<stefan.sorensen@...ctralink.com>
To:	<davem@...emloft.net>
CC:	<netdev@...r.kernel.org>, <richardcochran@...il.com>,
	Stefan Sørensen 
	<stefan.sorensen@...ctralink.com>
Subject: [PATCH net-next 1/5] dp83640: Include hash in timestamp/packet matching

Only using the message type and sequence id for matching timestamps with
packets is error prone, particularly if packets can be reordered. Fix by
extending the check to include the hash of bytes 20-29 (source id in PTPv2)
that is provided with the timestamps.

Signed-off-by: Stefan Sørensen <stefan.sorensen@...ctralink.com>
---
 drivers/net/phy/dp83640.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/net/phy/dp83640.c b/drivers/net/phy/dp83640.c
index 185b03c..9534478 100644
--- a/drivers/net/phy/dp83640.c
+++ b/drivers/net/phy/dp83640.c
@@ -20,6 +20,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/crc32.h>
 #include <linux/ethtool.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
@@ -789,7 +790,7 @@ static int decode_evnt(struct dp83640_private *dp83640,
 
 static int match(struct sk_buff *skb, unsigned int type, struct rxts *rxts)
 {
-	u16 *seqid;
+	u16 *seqid, hash;
 	unsigned int offset = 0;
 	u8 *msgtype, *data = skb_mac_header(skb);
 
@@ -819,11 +820,18 @@ static int match(struct sk_buff *skb, unsigned int type, struct rxts *rxts)
 		msgtype = data + offset + OFF_PTP_CONTROL;
 	else
 		msgtype = data + offset;
+	if (rxts->msgtype != (*msgtype & 0xf))
+		return 0;
 
 	seqid = (u16 *)(data + offset + OFF_PTP_SEQUENCE_ID);
+	if (rxts->seqid != ntohs(*seqid))
+		return 0;
+
+	hash = ether_crc(10, data + offset + 20) >> 20;
+	if (rxts->hash != hash)
+		return 0;
 
-	return rxts->msgtype == (*msgtype & 0xf) &&
-		rxts->seqid   == ntohs(*seqid);
+	return 1;
 }
 
 static void decode_rxts(struct dp83640_private *dp83640,
-- 
2.5.0

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