[Please ignore this is a test] pci-hyperv: properly handle pci bus remove

[Long Li <longli@exchange.microsoft.com>]

From: Long Li <longli@microsoft.com>

hv_pci_devices_present is called in hv_pci_remove when we remove a PCI 
device from host (e.g. by disabling SRIOV 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 status hv_pcibus_removed, we can avoid this situation.

Signed-off-by: Long Li <longli@microsoft.com>
---
 drivers/pci/host/pci-hyperv.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index ada9856..8a92244 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
 };
 
@@ -1504,12 +1505,19 @@ 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);
 	}
 
@@ -2185,6 +2193,7 @@ 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 +2357,7 @@ 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);
-- 
2.7.4