[PATCH] bridge: Have tx_bytes count headers like rx_bytes.

[PATCH] bridge: Have tx_bytes count headers like rx_bytes.

[Ashish Sharma]

Since rx_bytes accounting does not include Ethernet Headers in
br_input.c, excluding ETH_HLEN on the transmit path for consistent
measurement of packet length on both the Tx and Rx chains.

Signed-off-by: Ashish Sharma <ashishsharma@google.com>
Signed-off-by: JP Abgrall <jpa@google.com>
---
:100644 100644 32b8f9f... a9dd166... M	net/bridge/br_device.c
 net/bridge/br_device.c |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 32b8f9f..a9dd166 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -38,16 +38,17 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 	}
 #endif
 
-	u64_stats_update_begin(&brstats->syncp);
-	brstats->tx_packets++;
-	brstats->tx_bytes += skb->len;
-	u64_stats_update_end(&brstats->syncp);
-
 	BR_INPUT_SKB_CB(skb)->brdev = dev;
 
 	skb_reset_mac_header(skb);
 	skb_pull(skb, ETH_HLEN);
 
+	u64_stats_update_begin(&brstats->syncp);
+	brstats->tx_packets++;
+	/* Exclude ETH_HLEN from byte stats for consistency with Rx chain */
+	brstats->tx_bytes += skb->len;
+	u64_stats_update_end(&brstats->syncp);
+
 	rcu_read_lock();
 	if (is_broadcast_ether_addr(dest))
 		br_flood_deliver(br, skb);
-- 
1.7.3.1

Re: [PATCH] bridge: Have tx_bytes count headers like rx_bytes.

[Ben Hutchings]

On Fri, 2011-10-07 at 13:47 -0700, Ashish Sharma wrote:
> Since rx_bytes accounting does not include Ethernet Headers in
> br_input.c, excluding ETH_HLEN on the transmit path for consistent
> measurement of packet length on both the Tx and Rx chains.
[...]

I think the TX path is correct in this regard, and the RX path should be
changed to include header length.

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.