Staging: hv: Properly handle errors in hv_pci_probe()

Much of the vmbus driver initialization is done within the hv_pci_probe()
function. Properly handle errors in hv_pci_probe so that we can
appropriately deal with loading of the vmbus driver.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Abhishek Kane <v-abkane@microsoft.com>
Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/hv/vmbus_drv.c

@@ -54,6 +54,8 @@ EXPORT_SYMBOL(vmbus_loglevel);
 	/* (ALL_MODULES << 16 | DEBUG_LVL_ENTEREXIT); */
 	/* (((VMBUS | VMBUS_DRV)<<16) | DEBUG_LVL_ENTEREXIT); */
 
+static int pci_probe_error;
+static struct completion probe_event;
 
 static void get_channel_info(struct hv_device *device,
 			     struct hv_device_info *info)
@@ -722,19 +724,19 @@ void vmbus_child_device_unregister(struct hv_device *device_obj)
 static int __devinit hv_pci_probe(struct pci_dev *pdev,
 				const struct pci_device_id *ent)
 {
-	int err;
-
 	hv_pci_dev = pdev;
 
-	err = pci_enable_device(pdev);
-	if (err)
-		return err;
+	pci_probe_error = pci_enable_device(pdev);
+	if (pci_probe_error)
+		goto probe_cleanup;
 
-	err = vmbus_bus_init(pdev);
-	if (err)
+	pci_probe_error = vmbus_bus_init(pdev);
+	if (pci_probe_error)
 		pci_disable_device(pdev);
 
-	return err;
+probe_cleanup:
+	complete(&probe_event);
+	return pci_probe_error;
 }
 
 /*
@@ -757,7 +759,21 @@ static struct pci_driver hv_bus_driver = {
 
 static int __init hv_pci_init(void)
 {
-	return pci_register_driver(&hv_bus_driver);
+	int ret;
+	init_completion(&probe_event);
+	ret = pci_register_driver(&hv_bus_driver);
+	if (ret)
+		return ret;
+	/*
+	 * All the vmbus initialization occurs within the
+	 * hv_pci_probe() function. Wait for hv_pci_probe()
+	 * to complete.
+	 */
+	wait_for_completion(&probe_event);
+
+	if (pci_probe_error)
+		pci_unregister_driver(&hv_bus_driver);
+	return pci_probe_error;
 }