PCI: hv: Add hv_pci_remove_slots() when we unload the driver

When we unload the pci-hyperv host controller driver, the host does not
send us a PCI_EJECT message.

In this case we also need to make sure the sysfs PCI slot directory is
removed, otherwise a command on a slot file eg:

"cat /sys/bus/pci/slots/2/address"

will trigger a

"BUG: unable to handle kernel paging request"

and, if we unload/reload the driver several times we would end up with
stale slot entries in PCI slot directories in /sys/bus/pci/slots/

root@localhost:~# ls -rtl  /sys/bus/pci/slots/
total 0
drwxr-xr-x 2 root root 0 Feb  7 10:49 2
drwxr-xr-x 2 root root 0 Feb  7 10:49 2-1
drwxr-xr-x 2 root root 0 Feb  7 10:51 2-2

Add the missing code to remove the PCI slot and fix the current
behaviour.

Fixes: a15f2c08 ("PCI: hv: support reporting serial number as slot information")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
[lorenzo.pieralisi@arm.com: reformatted the log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Stephen Hemminger <sthemmin@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Cc: stable@vger.kernel.org

drivers/pci/controller/pci-hyperv.c

@@ -1486,6 +1486,21 @@ static void hv_pci_assign_slots(struct hv_pcibus_device *hbus)
 	}
 }
 
+/*
+ * Remove entries in sysfs pci slot directory.
+ */
+static void hv_pci_remove_slots(struct hv_pcibus_device *hbus)
+{
+	struct hv_pci_dev *hpdev;
+
+	list_for_each_entry(hpdev, &hbus->children, list_entry) {
+		if (!hpdev->pci_slot)
+			continue;
+		pci_destroy_slot(hpdev->pci_slot);
+		hpdev->pci_slot = NULL;
+	}
+}
+
 /**
  * create_root_hv_pci_bus() - Expose a new root PCI bus
  * @hbus:	Root PCI bus, as understood by this driver
@@ -2680,6 +2695,7 @@ static int hv_pci_remove(struct hv_device *hdev)
 		pci_lock_rescan_remove();
 		pci_stop_root_bus(hbus->pci_bus);
 		pci_remove_root_bus(hbus->pci_bus);
+		hv_pci_remove_slots(hbus);
 		pci_unlock_rescan_remove();
 		hbus->state = hv_pcibus_removed;
 	}