UBUNTU: SAUCE: PCI: vmd: guard device addition and removal

BugLink: https://bugs.launchpad.net/bugs/2011389

vmd may fail to create sysfs entry while `pci_rescan_bus()` called in
some other drivers like wwan.

  sysfs: cannot create duplicate filename '/devices/.../resource0'
  Call Trace:
   <TASK>
   sysfs_warn_dup.cold+0x17/0x34
   sysfs_add_bin_file_mode_ns+0xc0/0xf0
   sysfs_create_bin_file+0x6d/0xb0
   pci_create_attr+0x117/0x260
   pci_create_resource_files+0x6b/0x150
   pci_create_sysfs_dev_files+0x18/0x30
   pci_bus_add_device+0x30/0x80
   pci_bus_add_devices+0x31/0x80
   pci_bus_add_devices+0x5b/0x80
   vmd_enable_domain.constprop.0+0x6b7/0x880 [vmd]
   vmd_probe+0x16d/0x193 [vmd]

Fixes: 185a383ada ("x86/PCI: Add driver for Intel Volume Management Device (VMD)")
Suggested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: You-Sheng Yang (vicamo) <vicamo.yang@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

drivers/pci/controller/vmd.c

@@ -907,9 +907,13 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	pci_add_resource_offset(&resources, &vmd->resources[1], offset[0]);
 	pci_add_resource_offset(&resources, &vmd->resources[2], offset[1]);
 
+	pci_lock_rescan_remove();
+
 	vmd->bus = pci_create_root_bus(&vmd->dev->dev, vmd->busn_start,
 				       &vmd_ops, sd, &resources);
 	if (!vmd->bus) {
+		pci_unlock_rescan_remove();
+
 		pci_free_resource_list(&resources);
 		vmd_remove_irq_domain(vmd);
 		return -ENODEV;
@@ -965,6 +969,8 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 
 	vmd_acpi_end();
 
+	pci_unlock_rescan_remove();
+
 	WARN(sysfs_create_link(&vmd->dev->dev.kobj, &vmd->bus->dev.kobj,
 			       "domain"), "Can't create symlink to domain\n");
 	return 0;