PCI: hv: Properly handle PCI bus remove

hv_pci_devices_present() is called in hv_pci_remove() when we remove a PCI
device from the host, e.g., by disabling SR-IOV on a device.  In
hv_pci_remove(), the bus is already removed before the call, so we don't
need to rescan the bus in the workqueue scheduled from
hv_pci_devices_present().

By introducing bus state hv_pcibus_removed, we can avoid this situation.

Reported-by: Xiaofeng Wang <xiaofwan@redhat.com>
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index ada9856..39fafda 100644 (file)
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -350,6 +350,7 @@ enum hv_pcibus_state {
        hv_pcibus_init = 0,
        hv_pcibus_probed,
        hv_pcibus_installed,
+       hv_pcibus_removed,
        hv_pcibus_maximum
 };
 
@@ -1504,13 +1505,24 @@ static void pci_devices_present_work(struct work_struct *work)
                put_pcichild(hpdev, hv_pcidev_ref_initial);
        }
 
-       /* Tell the core to rescan bus because there may have been changes. */
-       if (hbus->state == hv_pcibus_installed) {
+       switch(hbus->state) {
+       case hv_pcibus_installed:
+               /*
+               * Tell the core to rescan bus
+               * because there may have been changes.
+               */
                pci_lock_rescan_remove();
                pci_scan_child_bus(hbus->pci_bus);
                pci_unlock_rescan_remove();
-       } else {
+               break;
+
+       case hv_pcibus_init:
+       case hv_pcibus_probed:
                survey_child_resources(hbus);
+               break;
+
+       default:
+               break;
        }
 
        up(&hbus->enum_sem);
@@ -2185,6 +2197,7 @@ static int hv_pci_probe(struct hv_device *hdev,
        hbus = kzalloc(sizeof(*hbus), GFP_KERNEL);
        if (!hbus)
                return -ENOMEM;
+       hbus->state = hv_pcibus_init;
 
        /*
         * The PCI bus "domain" is what is called "segment" in ACPI and
@@ -2348,6 +2361,7 @@ static int hv_pci_remove(struct hv_device *hdev)
                pci_stop_root_bus(hbus->pci_bus);
                pci_remove_root_bus(hbus->pci_bus);
                pci_unlock_rescan_remove();
+               hbus->state = hv_pcibus_removed;
        }
 
        hv_pci_bus_exit(hdev);