From: AMEET M. PARANJAPE <aparanja@redhat.com>
Date: Thu, 23 Oct 2008 17:01:13 -0400
Subject: [net] ixgbe: bring up device without crashing fix
Message-id: 20081023210055.12753.69072.sendpatchset@squad5-lp1.lab.bos.redhat.com
O-Subject: [PATCH RHEL5.3 BZ467777] Fix devices using ixgbe module crashing on bring-up
Bugzilla: 467777
RH-Acked-by: Neil Horman <nhorman@redhat.com>
RH-Acked-by: Andy Gospodarek <gospo@redhat.com>
RH-Acked-by: David Howells <dhowells@redhat.com>

RHBZ#:
======
https://bugzilla.redhat.com/show_bug.cgi?id=467777

Description:
===========
The problem is a structure mismatch, that the root cause is in the following
block of code:

               struct ixgbe_q_vector *q_vector = &adapter->q_vector[i];

                q_vector->dummy_netdev = alloc_netdev(0, "", ether_setup);
                if (!q_vector->dummy_netdev)
                        return -ENOMEM;
                q_vector->dummy_netdev->priv = q_vector;

So, it assigns a ixgbe_q_vector to the priv field in a NAPI structure. So, when
the code gets into ixgbe_poll(), it calls netdev_priv() which will return a
ixgbe_q_vector in this case, but it's expecting a ixgbe_adpter, instead of a
ixgbe_q_vector. Here is this line:

        struct ixgbe_adapter *adapter = netdev_priv(netdev);

So, here after, adapter points to an structure different from what is expected.
And, every filed it points is mismached (points to somewhere else). For
example:

	netif_carrier_ok(adapter->netdev)

Points to a place that doesn't has anything there, because of the structure are
different.

RHEL Version Found:
================
RHEL 5.3 alpha

kABI Status:
============
No symbols were harmed.

Brew:
=====
Built on all platforms.
http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1537870

Upstream Status:
================
This problem is not see upstream.  There may have been a mistake during the
1.3.18-k4 backport.

Test Status:
============
The steps to recreate:
	-load ixgbe module
	- ifup the ixgbe adapater

Without the patch the steps above crash the system and with the patch the
system and device are up for I/O.

===============================================================
Ameet Paranjape 978-392-3903 ext 23903
IBM on-site partner

Proposed Patch:
===============

diff --git a/drivers/net/ixgbe/ixgbe_main.c b/drivers/net/ixgbe/ixgbe_main.c
index c61d4c3..02762fd 100644
--- a/drivers/net/ixgbe/ixgbe_main.c
+++ b/drivers/net/ixgbe/ixgbe_main.c
@@ -1924,7 +1924,8 @@ static void ixgbe_shutdown(struct pci_dev *pdev)
  **/
 static int ixgbe_poll(struct net_device *netdev, int *budget)
 {
-	struct ixgbe_adapter *adapter = netdev_priv(netdev);
+	struct ixgbe_q_vector *q_vector = netdev->priv;
+	struct ixgbe_adapter *adapter = q_vector->adapter;
 	int work_to_do = min(*budget, netdev->quota);
 	int tx_cleaned = 0, work_done = 0;