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NdisAllocateNetBufferListContext function

Call the NdisAllocateNetBufferListContext function to allocate more context space in the NET_BUFFER_LIST_CONTEXT structure of a NET_BUFFER_LIST structure.

Syntax

C++


NDIS_STATUS NdisAllocateNetBufferListContext(
  _In_  PNET_BUFFER_LIST NetBufferList,
  _In_  USHORT ContextSize,
  _In_  USHORT ContextBackFill,
  _In_  ULONG PoolTag
);

Parameters

NetBufferList [in]: A pointer to a previously allocated NET_BUFFER_LIST structure.
ContextSize [in]: The amount of context space to allocate in the NET_BUFFER_LIST_CONTEXT structure. This amount must be a multiple of the value defined by MEMORY_ALLOCATION_ALIGNMENT.
ContextBackFill [in]: The amount of memory, in addition to the value of ContextSize, to allocate if NDIS must allocate memory to satisfy the request. This amount must be a multiple of the value defined by MEMORY_ALLOCATION_ALIGNMENT.
PoolTag [in]: A kernel pool tag that NDIS uses to allocate the memory for the NET_BUFFER_LIST_CONTEXT structure, if allocation is required. The tag is a string, delimited by single quotation marks, with up to four characters, usually specified in reversed order. The kernel pool tag helps NDIS to identify the owner of the memory.

Return value

NdisAllocateNetBufferListContext returns one of the following:

Return code	Description
NDIS_STATUS_SUCCESS	NdisAllocateNetBufferListContext successfully allocated context space either by reducing the value of the Offset member of the NET_BUFFER_LIST_CONTEXT structure or by allocating new memory.
NDIS_STATUS_RESOURCES	NdisAllocateNetBufferListContext failed due to insufficient resources.
NDIS_STATUS_FAILURE	NdisAllocateNetBufferListContext failed for reasons other than insufficient resources.

Remarks

If there is enough unused context space available in the NET_BUFFER_LIST_CONTEXT structure to satisfy the request, NdisAllocateNetBufferListContext simply reduces the value of the Offset member in the NET_BUFFER_LIST_CONTEXT structure. Otherwise, NDIS allocates new memory for context space. You can specify ContextBackFill to allocate extra memory so that the next call to NdisAllocateNetBufferListContext does not have to allocate memory.

Call the NdisFreeNetBufferListContext function to release the context space in the NET_BUFFER_LIST_CONTEXT structure that was allocated with NdisAllocateNetBufferListContext.

Requirements