[PATCH 78/88] xen/pciback: Don't disable a PCI device that is already disabled.

[Luis Henriques]

3.5.7.8 -stable review patch.  If anyone has any objections, please let me know.

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

From: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>

commit bdc5c1812cea6efe1aaefb3131fcba28cd0b2b68 upstream.

While shuting down a HVM guest with pci devices passed through we
get this:

pciback 0000:04:00.0: restoring config space at offset 0x4 (was 0x100000, writing 0x100002)
------------[ cut here ]------------
WARNING: at drivers/pci/pci.c:1397 pci_disable_device+0x88/0xa0()
Hardware name: MS-7640
Device pciback
disabling already-disabled device
Modules linked in:
Pid: 53, comm: xenwatch Not tainted 3.9.0-rc1-20130304a+ #1
Call Trace:
 [<ffffffff8106994a>] warn_slowpath_common+0x7a/0xc0
 [<ffffffff81069a31>] warn_slowpath_fmt+0x41/0x50
 [<ffffffff813cf288>] pci_disable_device+0x88/0xa0
 [<ffffffff814554a7>] xen_pcibk_reset_device+0x37/0xd0
 [<ffffffff81454b6f>] ? pcistub_put_pci_dev+0x6f/0x120
 [<ffffffff81454b8d>] pcistub_put_pci_dev+0x8d/0x120
 [<ffffffff814582a9>] __xen_pcibk_release_devices+0x59/0xa0

This fixes the bug.

Reported-and-Tested-by: Sander Eikelenboom <linux at eikelenboom.it>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/xen/xen-pciback/pciback_ops.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
index 37c1f82..b98cf0c 100644
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -113,7 +113,8 @@ void xen_pcibk_reset_device(struct pci_dev *dev)
 		if (dev->msi_enabled)
 			pci_disable_msi(dev);
 #endif
-		pci_disable_device(dev);
+		if (pci_is_enabled(dev))
+			pci_disable_device(dev);
 
 		pci_write_config_word(dev, PCI_COMMAND, 0);
 
-- 
1.8.1.2