datapath-windows: Solved BSOD when loading an activated extension

If the OVS extension was previously enabled and the driver unloaded,
when the driver is loaded again a BSOD is triggered.

This happens because the OVS extension registers its FilterXxx routines
to NDIS, by calling NdisFRegisterFilterDriver, before performing all
the necessary initialization. Because drivers that call
NdisFRegisterFilterDriver must be prepared for an immediate call to any
of their FilterXxx functions.

The BSOD is triggered because the FilterAttach routine, OvsExtAttach,
tries to acquire the control lock, when the lock is not yet initialized.
This happens because the FilterAttach is called before the driver
finishes initialization, in OvsInit().

The solution is to perform all necessary initialization before
registering OVS FilterXxx routines.

If device object creation fails, all allocated resources during init
phase are released by calling OvsCleanup and NdisFDeregisterFilterDriver
functions.

Signed-off-by: Sorin Vinturis <svinturis@cloudbasesolutions.com>
Reported-by: Sorin Vinturis <svinturis@cloudbasesolutions.com>
Reported-at: openvswitch/ovs-issues#67
Acked-by: Nithin Raju <nithin@vmware.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>

datapath-windows/ovsext/Datapath.c

@@ -448,10 +448,8 @@ OvsCreateDeviceObject(NDIS_HANDLE ovsExtDriverHandle)
         if (ovsExt) {
             ovsExt->numberOpenInstance = 0;
         }
-    } else {
-        /* Initialize the associated data structures. */
-        OvsInit();
     }
+
     OVS_LOG_TRACE("DeviceObject: %p", gOvsDeviceObject);
     return status;
 }
@@ -474,7 +472,6 @@ OvsDeleteDeviceObject()
         gOvsDeviceHandle = NULL;
         gOvsDeviceObject = NULL;
     }
-    OvsCleanup();
 }
 
 POVS_OPEN_INSTANCE

datapath-windows/ovsext/Datapath.h

@@ -81,6 +81,8 @@ typedef struct _OVS_OPEN_INSTANCE {
 
 NDIS_STATUS OvsCreateDeviceObject(NDIS_HANDLE ovsExtDriverHandle);
 VOID OvsDeleteDeviceObject();
+VOID OvsInit();
+VOID OvsCleanup();
 
 POVS_OPEN_INSTANCE OvsGetOpenInstance(PFILE_OBJECT fileObject,
                                       UINT32 dpNo);

datapath-windows/ovsext/Driver.c

@@ -95,6 +95,9 @@ DriverEntry(PDRIVER_OBJECT driverObject,
 
     UNREFERENCED_PARAMETER(registryPath);
 
+    /* Initialize driver associated data structures. */
+    OvsInit();
+
     gOvsExtDriverObject = driverObject;
 
     RtlZeroMemory(&driverChars, sizeof driverChars);
@@ -145,6 +148,7 @@ DriverEntry(PDRIVER_OBJECT driverObject,
     /* Create the communication channel for usersapce. */
     status = OvsCreateDeviceObject(gOvsExtDriverHandle);
     if (status != NDIS_STATUS_SUCCESS) {
+        OvsCleanup();
         NdisFDeregisterFilterDriver(gOvsExtDriverHandle);
         gOvsExtDriverHandle = NULL;
     }
@@ -163,7 +167,11 @@ OvsExtUnload(struct _DRIVER_OBJECT *driverObject)
 {
     UNREFERENCED_PARAMETER(driverObject);
 
+    /* Release driver associated data structures. */
+    OvsCleanup();
+
     OvsDeleteDeviceObject();
+
     NdisFDeregisterFilterDriver(gOvsExtDriverHandle);
 }