CM_Query_And_Remove_SubTreeW function (cfgmgr32.h)

The CM_Query_And_Remove_SubTree function checks whether a device instance and its children can be removed and, if so, it removes them.


CMAPI CONFIGRET CM_Query_And_Remove_SubTreeW(
  [in]            DEVINST        dnAncestor,
  [out, optional] PPNP_VETO_TYPE pVetoType,
  [out, optional] LPWSTR         pszVetoName,
  [in]            ULONG          ulNameLength,
  [in]            ULONG          ulFlags


[in] dnAncestor

Caller-supplied device instance handle to the device at the root of the subtree to be removed. This device instance handle is bound to the local machine.

[out, optional] pVetoType

(Optional) If the caller does not pass NULL and the removal request is vetoed (that is, the function returns CR_REMOVE_VETOED), on return this points to a PNP_VETO_TYPE-typed value that indicates the reason for the veto.

[out, optional] pszVetoName

(Optional) If the caller does not pass NULL and the removal request is vetoed (that is, the function returns CR_REMOVE_VETOED), on return this points to a text string that is associated with the veto type. The type of information this string provides is dependent on the value received by pVetoType. For information about these strings, see PNP_VETO_TYPE.

[in] ulNameLength

Caller-supplied value representing the length (number of characters) of the string buffer supplied by pszVetoName. This should be set to MAX_PATH.

[in] ulFlags

A bitwise OR of the caller-supplied flag constants that are described in the Remarks section.

Return value

If the operation succeeds, the function returns CR_SUCCESS. Otherwise, it returns one of the other CR_-prefixed error codes defined in Cfgmgr32.h.


The purpose of the CM_Query_And_Remove_SubTree function is to allow an application to prepare a device for safe removal from the local machine. Use this function to remove devices only if a driver has not set the SurpriseRemovalOK member of DEVICE_CAPABILITIES. If a driver has set SurpriseRemovalOK, the application should call CM_Request_Device_Eject instead of CM_Query_And_Remove_SubTree.

CM_Query_And_Remove_SubTree supports setting the flags parameter ulFlags with one of the following two flags; these flags apply only if Windows or an installer vetoes the removal of a device:

Flag Description
CM_REMOVE_UI_OK The function allows a user dialog box to be displayed to indicate the reason for the veto. This is the default flag setting.
CM_REMOVE_UI_NOT_OK The function suppresses the display of a user dialog box that indicates the reason for the veto.

Beginning with Windows XP, CM_Query_And_Remove_SubTree also supports setting the following additional flag; this flag applies only if the function successfully removes the device instance:

Flag Description
CM_REMOVE_NO_RESTART If this flag is set, the function configures the device status such that the device cannot be restarted until after the device status is reset.

The device status is reset by the one of the following:

  • Calling CM_Setup_DevNode for the device and specifying CM_SETUP_DEVNODE_RESET. After the device status is reset in this manner, the device can be restarted by calling CM_Reenumerate_DevNode for the device instance. After resetting the device status, any other operation that enumerates the device will also restart the device, for example, if the Device Manager is used to reenumerate devices.
  • The device is detached and reattached, or the computer is restarted. In this case, the device status will be reset and the device will be restarted.
  • If this flag is not set, the device status does not have to be reset. You can restart the removed device by a calling CM_Setup_DevNode for the device and by specifying CM_SETUP_DEVNODE_READY. Any other operation that reenumerates the device will also restart the device. An example of an operation that reenumerates a device is calling CM_Reenumerate_DevNode for the device, detaching and reattaching the device, or restarting the computer. |

Windows applications that do not require the low-level operation CM_Query_And_Remove_SubTree should use the DIF_PROPERTYCHANGE request to disable a device instead of using CM_Query_And_Remove_SubTree to remove a device. The DIF_PROPERTYCHANGE request can be used to enable, disable, restart, stop, or change the properties of a device.

Callers of this function must have SeLoadDriverPrivilege. (Privileges are described in the Microsoft Windows SDK documentation.)

For information about using device instance handles that are bound to the local machine, see CM_Get_Child.


Requirement Value
Minimum supported client Available in Microsoft Windows 2000 and later versions of Windows.
Target Platform Universal
Header cfgmgr32.h (include Cfgmgr32.h)
Library Cfgmgr32.lib

See also