linux-kernel - [34-longterm 187/196] vmxnet3: Fix inconsistent LRO state after initialization

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Date:	Mon, 12 Mar 2012 20:21:40 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org,
	Thomas Jarosch <thomas.jarosch@...ra2net.com>,
	"David S. Miller" <davem@...emloft.net>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 187/196] vmxnet3: Fix inconsistent LRO state after initialization

From: Thomas Jarosch <thomas.jarosch@...ra2net.com>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit ebde6f8acba92abfc203585198a54f47e83e2cd0 upstream.

During initialization of vmxnet3, the state of LRO
gets out of sync with netdev->features.

This leads to very poor TCP performance in a IP forwarding
setup and is hitting many VMware users.

Simplified call sequence:
1. vmxnet3_declare_features() initializes "adapter->lro" to true.

2. The kernel automatically disables LRO if IP forwarding is enabled,
so vmxnet3_set_flags() gets called. This also updates netdev->features.

3. Now vmxnet3_setup_driver_shared() is called. "adapter->lro" is still
set to true and LRO gets enabled again, even though
netdev->features shows it's disabled.

Fix it by updating "adapter->lro", too.

The private vmxnet3 adapter flags are scheduled for removal
in net-next, see commit a0d2730c9571aeba793cb5d3009094ee1d8fda35
"net: vmxnet3: convert to hw_features".

Patch applies to 2.6.37 / 2.6.38 and 2.6.39-rc6.

Please CC: comments.

Signed-off-by: Thomas Jarosch <thomas.jarosch@...ra2net.com>
Acked-by: Stephen Hemminger <shemminger@...tta.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 drivers/net/vmxnet3/vmxnet3_ethtool.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/vmxnet3/vmxnet3_ethtool.c b/drivers/net/vmxnet3/vmxnet3_ethtool.c
index 3935c44..df7cddd 100644
--- a/drivers/net/vmxnet3/vmxnet3_ethtool.c
+++ b/drivers/net/vmxnet3/vmxnet3_ethtool.c
@@ -290,6 +290,9 @@ vmxnet3_set_flags(struct net_device *netdev, u32 data) {
 		/* toggle the LRO feature*/
 		netdev->features ^= NETIF_F_LRO;
 
+		/* Update private LRO flag */
+		adapter->lro = lro_requested;
+
 		/* update harware LRO capability accordingly */
 		if (lro_requested)
 			adapter->shared->devRead.misc.uptFeatures &= UPT1_F_LRO;
-- 
1.7.9.3

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