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>

1 files changed, 17 insertions, 3 deletions

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index ada98569b78e..39fafda4deff 100644
--- 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);