NdisCoSendNetBufferLists function (ndis.h)

Article
04/18/2022

The NdisCoSendNetBufferLists function sends network data that is contained in a specified list of NET_BUFFER_LIST structures.

Syntax

void NdisCoSendNetBufferLists(
  [in] NDIS_HANDLE      NdisVcHandle,
  [in] PNET_BUFFER_LIST NetBufferLists,
  [in] ULONG            SendFlags
);

Parameters

[in] NdisVcHandle

A handle to a virtual connection (VC) that identifies the target of the send request.

[in] NetBufferLists

A pointer to a linked list of NET_BUFFER_LIST structures. Each NET_BUFFER_LIST structure describes a list of NET_BUFFER structures.

[in] SendFlags

Flags that define attributes for the send operation. The flags can be combined with a bitwise OR operation. To clear all of the flags, set this parameter to zero. NdisCoSendNetBufferLists supports the following flags:

NDIS_SEND_FLAGS_DISPATCH_LEVEL

The current IRQL is DISPATCH_LEVEL. For more information about this flag, see Dispatch IRQL Tracking.

NDIS_SEND_FLAGS_CHECK_FOR_LOOPBACK

NDIS should check for loopback. By default, NDIS does not loop back data to the driver that submitted the send request. An overlying driver can override this behavior by setting NDIS_SEND_FLAGS_CHECK_FOR_LOOPBACK. When this flag is set, NDIS identifies all of the NET_BUFFER structures that contain data that matches the receive criteria for the binding. NDIS indicates NET_BUFFER structures that match the criteria to the overlying driver. This flag does not affect checking for loopback, or looping back, on other bindings.

Return value

None

Remarks

After a CoNDIS protocol driver calls NdisCoSendNetBufferLists, NDIS submits the NET_BUFFER_LIST structures that the NetBufferLists parameter specifies to an underlying driver's MiniportCoSendNetBufferLists function.

The protocol driver must allocate each NET_BUFFER_LIST structure from a pool by calling one of the following functions:

The protocol driver can preallocate NET_BUFFER_LIST structures--for example, in its DriverEntry routine. Alternatively, the protocol driver can allocate the structures immediately prior to calling NdisCoSendNetBufferLists and then can free them when the send operation is complete. When NDIS returns a NET_BUFFER_LIST structure to the ProtocolCoSendNetBufferListsComplete function, the protocol driver can prepare the NET_BUFFER_LIST structure and any associated resources for reuse. If you reuse the NET_BUFFER_LIST structures, you can get better performance than returning the structures to a pool and then reallocating them for another send operation.

A protocol driver must set the SourceHandle member of each NET_BUFFER_LIST structure to the same value that it passes at the NdisVcHandle parameter. The source handle provides the information that NDIS requires to return the NET_BUFFER_LIST structure to the protocol driver after the underlying miniport driver calls the NdisMCoSendNetBufferListsComplete function.

Before a protocol driver calls NdisCoSendNetBufferLists, the driver can set information that accompanies the send request with the NET_BUFFER_LIST_INFO macro. The underlying driver can retrieve this information with the NET_BUFFER_LIST_INFO macro.

Before a protocol driver calls NdisCoSendNetBufferLists with a list of NET_BUFFER_LIST structures, the protocol driver must ensure that the NET_BUFFER_LIST structures are set up in the order that the network data should be sent.

As soon as a protocol driver calls NdisCoSendNetBufferLists, it no longer owns the NET_BUFFER_LIST structures and all of the associated resources. NDIS calls the ProtocolCoSendNetBufferListsComplete function to return the structures and data to the protocol driver. NDIS can collect the structures and data from multiple send requests into a single linked list of NET_BUFFER_LIST structures before it passes the list to ProtocolCoSendNetBufferListsComplete.

Until NDIS calls ProtocolCoSendNetBufferListsComplete, the current status of a protocol driver-initiated send is not available to the protocol driver. A protocol driver temporarily releases ownership of all of the resources that it allocated for a send request when it calls NdisCoSendNetBufferLists. A protocol driver should never attempt to examine the NET_BUFFER_LIST structures or any associated data after the driver calls NdisCoSendNetBufferLists.

Requirements

Requirement	Value
Minimum supported client	Supported for NDIS 6.0 drivers in Windows Vista.
Target Platform	Desktop
Header	ndis.h (include Ndis.h)
Library	Ndis.lib
IRQL	<=DISPATCH_LEVEL
DDI compliance rules	Irql_Connection_Function(ndis)