From 0c4b9e27b09eeb4da84451c038a587b92ce93ff5 Mon Sep 17 00:00:00 2001
From: Gavin Shan <shangw@linux.vnet.ibm.com>
Date: Mon, 13 Jan 2014 11:36:22 +0800
Subject: [PATCH] powerpc/iommu: Don't detach device without IOMMU group

Some devices, for example PCI root port, don't have IOMMU table and
group. We needn't detach them from their IOMMU group. Otherwise, it
potentially incurs kernel crash because of referring NULL IOMMU group
as following backtrace indicates:

  .iommu_group_remove_device+0x74/0x1b0
  .iommu_bus_notifier+0x94/0xb4
  .notifier_call_chain+0x78/0xe8
  .__blocking_notifier_call_chain+0x7c/0xbc
  .blocking_notifier_call_chain+0x38/0x48
  .device_del+0x50/0x234
  .pci_remove_bus_device+0x88/0x138
  .pci_stop_and_remove_bus_device+0x2c/0x40
  .pcibios_remove_pci_devices+0xcc/0xfc
  .pcibios_remove_pci_devices+0x3c/0xfc

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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