RxCeAllocateIrpWithMDL function (rxce.h)

Article
03/15/2022

RxCeAllocateIrpWithMDL allocates an IRP and associates it with an existing memory descriptor list.

Syntax

PIRP RxCeAllocateIrpWithMDL(
  [in] IN CCHAR   StackSize,
  [in] IN BOOLEAN ChargeQuota,
  [in] IN PMDL    Buffer
);

Parameters

[in] StackSize

The stack size to allocate for the IRP.

[in] ChargeQuota

This parameter should be set to FALSE by intermediate drivers. This can be set to TRUE only by highest-level drivers that are called in the context of the thread that originates the I/O request for which the driver is allocating another IRP.

[in] Buffer

A pointer to the buffer that contains the memory descriptor list to be associated with this IRP.

Return value

RxCeAllocateIrpWithMDL returns a pointer to the IRP on success or a NULL pointer on error.

Remarks

The goal of RxCeAllocateIrpWithMDL is to allow easier debugging of IRPs that are issued to other components and then stall. IRPs issued using RxCeAllocateIrpWithMDL are queued to a global list of IRPs maintained by RDBSS. Thus, when an RX_CONTEXT is waiting for a send completion, it is possible to walk the global list to find the IRP that is waiting in the transport.

An IRP allocated with an associated memory descriptor list allocated with RxCeAllocateIrpWithMDL should be freed when the IRP is completed using RxCeFreeIrp.

IoAllocateIrp automatically initializes the IRP's members and inserts the IRP into a global list of IRPs maintained by RDBSS. If memory for the MDL to be associated with the IRP cannot be allocated, then the IRP that was created is freed and RxCeAllocateIrpWithMDL returns a NULL pointer indicating failure.

Requirements

Requirement	Value
Minimum supported client	The RxCeAllocateIrpWithMDL routine is only available on Windows XP.
Target Platform	Desktop
Header	rxce.h (include Rxce.h)
IRQL	<= APC_LEVEL