[ 46/82] xen/pciback: Dont disable a PCI device that is already disabled.

[Ben Hutchings]

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

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

From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

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@xxxxxxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/xen/xen-pciback/pciback_ops.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -114,7 +114,8 @@ void xen_pcibk_reset_device(struct pci_d
 		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);
 


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