linux-kernel - [20/21] vmxnet3: Fix inconsistent LRO state after initialization

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Message-Id: <20110519182438.279400058@clark.kroah.org>
Date:	Thu, 19 May 2011 11:23:50 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Thomas Jarosch <thomas.jarosch@...ra2net.com>,
	Stephen Hemminger <shemminger@...tta.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [20/21] vmxnet3: Fix inconsistent LRO state after initialization

2.6.32-longterm review patch.  If anyone has any objections, please let us know.

------------------

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

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: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/net/vmxnet3/vmxnet3_ethtool.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/net/vmxnet3/vmxnet3_ethtool.c
+++ b/drivers/net/vmxnet3/vmxnet3_ethtool.c
@@ -288,6 +288,9 @@ vmxnet3_set_flags(struct net_device *net
 		/* 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;

--
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