IoSetNextIrpStackLocation

IoSetNextIrpStackLocation

VOID
IoSetNextIrpStackLocation(
IN OUT PIRP Irp
);

IoSetNextIrpStackLocation sets the IRP stack location in a driver-allocated IRP to that of the caller.

Parameters

Irp

Points to the IRP whose stack location is to be set.

Comments

In general, this routine is seldom used by drivers. It is primarily used by drivers that require their own stack location in an IRP that they have allocated, on their own, to send to another driver.

IoSetNextIrpStackLocation is generally not needed because either:

·The driver received the IRP it is passing from another, higher-level driver, and so it already owns a stack location,

·Or, the driver allocated the IRP but does not need its own stack location because it can keep everything that it needs in a context block whose address can be passed to its IoCompletion routine.

Care should be taken if this routine is called, especially when allocating the IRP with IoAllocateIrp or IoMakeAssociatedIrp. The writer of the allocating driver must remember that a caller-specific stack location is not included in the number of stack locations required by the lower-level drivers to which it sends IRPs with IoCallDriver. A driver must explicitly specify a stack location for itself in its call to IoAllocateIrp or IoMakeAssociatedIrp if it calls IoSetNextIrpStackLocation with the IRP returned by either routine.

A driver cannot call IoSetNextIrpStackLocation with any IRP it allocates by calling IoBuildAsynchronousFsdRequest, IoBuildDeviceIoControlRequest, or IoBuildSynchronousFsdRequest.

Callers of IoSetNextIrpStackLocation must be running at IRQL <= DISPATCH_LEVEL.