xen/pciback: Fix proper FLR steps.

When we do FLR and save PCI config we did it in the wrong order.
The end result was that if a PCI device was unbind from
its driver, then binded to xen-pciback, and then back to its
driver we would get:

> lspci -s 04:00.0
04:00.0 Ethernet controller: Intel Corporation 82574L Gigabit Network Connection
13:42:12 # 4 :~/
> echo "0000:04:00.0" > /sys/bus/pci/drivers/pciback/unbind
> modprobe e1000e
e1000e: Intel(R) PRO/1000 Network Driver - 2.0.0-k
e1000e: Copyright(c) 1999 - 2012 Intel Corporation.
e1000e 0000:04:00.0: Disabling ASPM L0s L1
e1000e 0000:04:00.0: enabling device (0000 -> 0002)
xen: registering gsi 48 triggering 0 polarity 1
Already setup the GSI :48
e1000e 0000:04:00.0: Interrupt Throttling Rate (ints/sec) set to dynamic conservative mode
e1000e: probe of 0000:04:00.0 failed with error -2

This fixes it by first saving the PCI configuration space, then
doing the FLR.

Reported-by: Ren, Yongjie <yongjie.ren@intel.com>
Reported-and-Tested-by: Tobias Geiger <tobias.geiger@vido.info>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: stable@vger.kernel.org

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 097e536e8672..03342728bf23 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -353,16 +353,16 @@ static int __devinit pcistub_init_device(struct pci_dev *dev)
         if (err)
                 goto config_release;
 
-        dev_dbg(&dev->dev, "reseting (FLR, D3, etc) the device\n");
-        __pci_reset_function_locked(dev);
-
         /* We need the device active to save the state. */
         dev_dbg(&dev->dev, "save state of device\n");
         pci_save_state(dev);
         dev_data->pci_saved_state = pci_store_saved_state(dev);
         if (!dev_data->pci_saved_state)
                 dev_err(&dev->dev, "Could not store PCI conf saved state!\n");
-
+        else {
+                dev_dbg(&dev->dev, "reseting (FLR, D3, etc) the device\n");
+                __pci_reset_function_locked(dev);
+        }
         /* Now disable the device (this also ensures some private device
          * data is setup before we export)
          */