Windows NT Driver >> C/C++
Queue IRP
參考資訊:
1. Source Code
驅動程式作為User Application跟硬體的溝通橋樑,最常遇到的問題就是硬體處理速度不夠快,導致驅動程式需要等待硬體完成後,再繼續處理下一筆資料,但是驅動程式如果要跟User Application溝通這些同步事情,會產生額外的等待時間,因此,為了達到比較好的處理效能,一般驅動程式做會Queue Irp的動作,讓處理的間隔可以縮到最小,這也是這篇教學要說明的東西,教導使用者一些Queue Irp的基本觀念和作法。
首先要知道的就是,儲存Irp的地方在哪?在Windows驅動程式裡,可以使用List作為儲存媒介(使用者也可以使用其它方式儲存),使用步驟相當簡單,如下所示:
1. InitializeListHead()
2. InsertHeadList()
3. IsListEmpty()
4. RemoveHeadList()
首先初始化List(InitializeListHead()),接著插入(InsertHeadList())需要儲存的資料,接著判斷List是否還有資料(IsListEmpty()),假如還有資料,則取出(RemoveHeadList())處裡
Irp是處裡資料的最小單位,一個Irp通常代表處理一筆資料的訊息,因此,當硬體來不及處理資料時,驅動程式需要做Pending Irp的動作,讓User Application知道這筆資料稍後處理,Pending Irp的步驟如下:
1. IoMarkIrpPending()
2. IoCompleteRequest(STATUS_PENDING)
回傳Pending,告知I/O Manager,這筆Irp資料先Pending一下,稍後處理
接著就是User Application如何知道資料是否處理完畢或者被Pending了呢?在CreateFile()時,如果沒有用FILE_FLAG_OVERLAPPED,則代表每一筆資料都是必須完成才會回傳,此種寫法也稱為Blocking方式,如:呼叫WriteFile()後,必須等待驅動程式完成該Irp才會繼續往下,否則呼叫WriteFile()後,會卡在這個Win32 API,相反地,如果CreateFile()使用FILE_FLAG_OVERLAPPED,而呼叫WriteFile()時,驅動程式回傳Pending,則WriteFile()會馬上回傳ERROR_IO_PENDING,告知User Application,該筆資料驅動程式會稍後處裡,此種寫法也稱為Non-Blocking方式,那如何得知該筆資料處理完畢了呢?當使用Non-Blocking寫法,會在WriteFile()傳入一個OVERLAPPED參數,該參數裡面有一個Event,用來告知是否已經處理完畢了。
Queue IRP流程:
1. InsertHeadList()
2. IoMarkIrpPending()
3. IoCompleteRequest(STATUS_PENDING)
4. IsListEmpty()
5. RemoveHeadList()
6. IoCompleteRequest(STATUS_SUCCESS)
main.c
#include <wdm.h> #define IOCTL_QUEUE CTL_CODE(FILE_DEVICE_UNKNOWN, 0x800, METHOD_BUFFERED, FILE_ANY_ACCESS) #define IOCTL_PROCESS CTL_CODE(FILE_DEVICE_UNKNOWN, 0x801, METHOD_BUFFERED, FILE_ANY_ACCESS) #define DEV_NAME L"\\Device\\MyDriver" #define SYM_NAME L"\\DosDevices\\MyDriver" LIST_ENTRY stQueue={0}; KDPC stTimeDPC={0}; KTIMER stTime={0}; VOID OnTimer(struct _KDPC *Dpc, PVOID DeferredContext, PVOID SystemArgument1, PVOID SystemArgument2) { PIRP pIrp; PLIST_ENTRY plist; if(IsListEmpty(&stQueue) == TRUE){ KeCancelTimer(&stTime); DbgPrint("Finish"); } else{ plist = RemoveHeadList(&stQueue); pIrp = CONTAINING_RECORD(plist, IRP, Tail.Overlay.ListEntry); pIrp->IoStatus.Status = STATUS_SUCCESS; pIrp->IoStatus.Information = 0; IoCompleteRequest(pIrp, IO_NO_INCREMENT); DbgPrint("Complete Irp"); } } void Unload(PDRIVER_OBJECT pOurDriver) { UNICODE_STRING usSymboName; RtlInitUnicodeString(&usSymboName, L"\\DosDevices\\MyDriver"); IoDeleteSymbolicLink(&usSymboName); IoDeleteDevice(pOurDriver->DeviceObject); } NTSTATUS IrpIOCTL(PDEVICE_OBJECT pOurDevice, PIRP pIrp) { LARGE_INTEGER stTimePeriod; PIO_STACK_LOCATION psk = IoGetCurrentIrpStackLocation(pIrp); switch(psk->Parameters.DeviceIoControl.IoControlCode){ case IOCTL_QUEUE: DbgPrint("IOCTL_QUEUE"); InsertHeadList(&stQueue, &pIrp->Tail.Overlay.ListEntry); IoMarkIrpPending(pIrp); return STATUS_PENDING; case IOCTL_PROCESS: DbgPrint("IOCTL_PROCESS"); stTimePeriod.HighPart|= -1; stTimePeriod.LowPart = -10000000; KeSetTimerEx(&stTime, stTimePeriod, 10, &stTimeDPC); break; } pIrp->IoStatus.Information = 0; pIrp->IoStatus.Status = STATUS_SUCCESS; IoCompleteRequest(pIrp, IO_NO_INCREMENT); return STATUS_SUCCESS; } NTSTATUS IrpFile(PDEVICE_OBJECT pOurDevice, PIRP pIrp) { PIO_STACK_LOCATION psk = IoGetCurrentIrpStackLocation(pIrp); switch(psk->MajorFunction){ case IRP_MJ_CREATE: DbgPrint("IRP_MJ_CREATE"); break; case IRP_MJ_CLOSE: DbgPrint("IRP_MJ_CLOSE"); break; } IoCompleteRequest(pIrp, IO_NO_INCREMENT); return STATUS_SUCCESS; } NTSTATUS DriverEntry(PDRIVER_OBJECT pOurDriver, PUNICODE_STRING pOurRegistry) { PDEVICE_OBJECT pOurDevice=NULL; UNICODE_STRING usDeviceName; UNICODE_STRING usSymboName; pOurDriver->MajorFunction[IRP_MJ_CREATE] = pOurDriver->MajorFunction[IRP_MJ_CLOSE] = IrpFile; pOurDriver->MajorFunction[IRP_MJ_DEVICE_CONTROL] = IrpIOCTL; pOurDriver->DriverUnload = Unload; RtlInitUnicodeString(&usDeviceName, L"\\Device\\MyDriver"); IoCreateDevice(pOurDriver, 0, &usDeviceName, FILE_DEVICE_UNKNOWN, 0, FALSE, &pOurDevice); RtlInitUnicodeString(&usSymboName, L"\\DosDevices\\MyDriver"); InitializeListHead(&stQueue); KeInitializeTimer(&stTime); KeInitializeDpc(&stTimeDPC, OnTimer, pOurDevice); IoCreateSymbolicLink(&usSymboName, &usDeviceName); pOurDevice->Flags&= ~DO_DEVICE_INITIALIZING; pOurDevice->Flags|= DO_BUFFERED_IO; return STATUS_SUCCESS; }
DriverEntry()初始List以及DPC Timer,DPC Timer用來定期確認List是否還有資料需要處理,當然,使用Thread檢查或許更恰當些
IrpIOCTL()IOCTL_QUEUE代表該IOCTL會被Queue起來,稍後處理,而當收到IOCTL_PROCESS時,則啟動DPC Timer開始處理那些被Queue起來的Irp
OnTimer()處理Queue裡面的Irp
app.c
#define INITGUID #include <windows.h> #include <winioctl.h> #include <strsafe.h> #include <setupapi.h> #include <stdio.h> #include <stdlib.h> #define IOCTL_QUEUE CTL_CODE(FILE_DEVICE_UNKNOWN, 0x800, METHOD_BUFFERED, FILE_ANY_ACCESS) #define IOCTL_PROCESS CTL_CODE(FILE_DEVICE_UNKNOWN, 0x801, METHOD_BUFFERED, FILE_ANY_ACCESS) int __cdecl main(int argc, char* argv[]) { int i=0; DWORD dwRet = 0; HANDLE hFile = NULL; OVERLAPPED ov[3]={0}; hFile = CreateFile("\\\\.\\MyDriver", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED | FILE_ATTRIBUTE_NORMAL, NULL); if (hFile == INVALID_HANDLE_VALUE) { printf("failed to open mydriver\n"); return -1; } for(i=0; i<3; i++){ memset(&ov[i], 0, sizeof(ov[i])); ov[i].hEvent = CreateEvent(NULL, TRUE, FALSE, NULL); printf("queue event\n"); DeviceIoControl(hFile, IOCTL_QUEUE, NULL, 0, NULL, 0, &dwRet, &ov[i]); } printf("process all of events\n"); DeviceIoControl(hFile, IOCTL_PROCESS, NULL, 0, NULL, 0, &dwRet, NULL); for(i=0; i<3; i++){ WaitForSingleObject(ov[i].hEvent, INFINITE); CloseHandle(ov[i].hEvent); printf("wait complete\n"); } CloseHandle(hFile); return 0; }
結果