IoStartNextPacketByKey function (wdm.h)

Article
02/22/2024

The IoStartNextPacketByKey routine dequeues the next I/O request packet from the specified device object's associated device queue according to a specified sort-key value and calls the driver's StartIo routine with that IRP.

Syntax

void IoStartNextPacketByKey(
  [in] PDEVICE_OBJECT DeviceObject,
  [in] BOOLEAN        Cancelable,
  [in] ULONG          Key
);

Parameters

[in] DeviceObject

Pointer to the device object for which the IRP is to be dequeued.

[in] Cancelable

Specifies whether IRPs in the device queue can be canceled.

[in] Key

Specifies the sort key that determines which entry to remove from the queue.

Return value

None

Remarks

If there are no IRPs currently in the device queue for the target device object, this routine simply returns control to the caller.

If the driver passed a pointer to a cancel routine when it called IoStartPacket, it should pass TRUE in the Cancelable parameter. If Cancelable is TRUE, the I/O manager will use the cancel spin lock to protect the device queue and the current IRP.

Drivers that do not have a StartIo routine cannot call IoStartNextPacketByKey.

Callers of IoStartNextPacketByKey must be running at IRQL <= DISPATCH_LEVEL. Usually, this routine is called from a device driver's DpcForIsr or CustomDpc routine, both of which are run at IRQL = DISPATCH_LEVEL.

Requirements

Requirement	Value
Minimum supported client	Available starting with Windows 2000.
Target Platform	Universal
Header	wdm.h (include Wdm.h, Ntddk.h, Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	<= DISPATCH_LEVEL