Windows Driver Model >> C/C++

Deferred Procedure Call(DPC)

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參考資訊：
1. Source Code

一般在處理中斷副程式(ISR)，由於中斷是一個相當高優先級別的事件，因此，不能停留太久(不能處理太久)，否則將拖垮系統，針對中斷事件，如果需要比較長的處理時間，取而代之，會安排一個Deferred Procedure Call(DPC)處理，DPC是一個高優先級別的排程，但比中斷更低的優先級別。

main.c

#include <wdm.h>

#define DEV_NAME L"\\Device\\MyDriver"
#define SYM_NAME L"\\DosDevices\\MyDriver"

KDPC stDPC={0};
PDEVICE_OBJECT pNextDevice=NULL;

void DPC_Handler(struct _KDPC *Dpc, PVOID DeferredContext, PVOID SystemArgument1, PVOID SystemArgument2)
{
  DbgPrint("DPC_Handler\n");
}

NTSTATUS AddDevice(PDRIVER_OBJECT pOurDriver, PDEVICE_OBJECT pPhyDevice)
{
  PDEVICE_OBJECT pOurDevice=NULL;
  UNICODE_STRING usDeviceName;
  UNICODE_STRING usSymboName;

  RtlInitUnicodeString(&usDeviceName, DEV_NAME);
  IoCreateDevice(pOurDriver, 0, &usDeviceName, FILE_DEVICE_UNKNOWN, 0, FALSE, &pOurDevice);
  RtlInitUnicodeString(&usSymboName, SYM_NAME);
  IoCreateSymbolicLink(&usSymboName, &usDeviceName);
  pNextDevice = IoAttachDeviceToDeviceStack(pOurDevice, pPhyDevice);
  pOurDevice->Flags&= ~DO_DEVICE_INITIALIZING;
  pOurDevice->Flags|= DO_BUFFERED_IO;
  
  KeInitializeDpc(&stDPC, DPC_Handler, pOurDevice);
  return STATUS_SUCCESS;
}

void Unload(PDRIVER_OBJECT pOurDriver)
{
  pOurDriver = pOurDriver;
}

NTSTATUS IrpPnp(PDEVICE_OBJECT pOurDevice, PIRP pIrp)
{
  PIO_STACK_LOCATION psk = IoGetCurrentIrpStackLocation(pIrp);
  UNICODE_STRING usSymboName;

  if(psk->MinorFunction == IRP_MN_START_DEVICE){
    KeInsertQueueDpc(&stDPC, 0, 0);
  }
  else if(psk->MinorFunction == IRP_MN_REMOVE_DEVICE){
    RtlInitUnicodeString(&usSymboName, SYM_NAME);
    IoDeleteSymbolicLink(&usSymboName);
    IoDetachDevice(pNextDevice);
    IoDeleteDevice(pOurDevice);
  }
  IoSkipCurrentIrpStackLocation(pIrp);
  return IoCallDriver(pNextDevice, pIrp);
}

NTSTATUS DriverEntry(PDRIVER_OBJECT pOurDriver, PUNICODE_STRING pOurRegistry)
{
  pOurDriver->MajorFunction[IRP_MJ_PNP] = IrpPnp;
  pOurDriver->DriverExtension->AddDevice = AddDevice;
  pOurDriver->DriverUnload = Unload;
  return STATUS_SUCCESS;
}

IRP_MN_START_DEVICE插入一個新的DPC Task

結果

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