Ｗin CE中流驱动支持临界区的问题！

只看该作者 · 2008-1-28 14:20

写了一个简单的流驱动，大体是这样的：
在DLL文件中，定义一个全局变量：
unsigned char chBuffer[BUFSIZE];

在XXX_Init中对其进行初始化为全０；
DWORD COM_Init(DWORD dwContext)

EnterCriticalSection(&(pDrv->InitCS));
memset (chBuffer, 0, BUFSIZE * sizeof(unsigned char));
LeaveCriticalSection(&(pDrv->InitCS));

在XXX_Write()中对其写入数据，例如一个固定的字符串；
DWORD COM_Write(HANDLE hOpenContext, LPCVOID pSourceBytes, DWORD NumberOfBytes)

    EnterCriticalSection(&(pDrv->WriteCS));
    dwRet = min(BUFSIZE, NumberOfBytes);
    memcpy(chBuffer, (PBYTE)pSourceBytes, dwRet);
    LeaveCriticalSection(&(pDrv->WriteCS));

在XXX_Read中把写入的数据读出；

DWORD COM_Read(HANDLE hOpenContext, LPVOID pBuffer, DWORD Count)

    EnterCriticalSection(&(pDrv->ReadCS));
    // Copy the smaller of buffer size or string size.
    DWORD dwcbBuffer = strlen((char *)chBuffer);
    dwRet = min(dwcbBuffer, Count);
    memcpy((unsigned char *)pBuffer, chBuffer, dwRet);
    LeaveCriticalSection(&(pDrv->ReadCS));

大体就是这个样子，我在初始化，读，写里面加了临界区保护数据，ＤＬＬ文件可以编译通过，但是生成ＮＫ文件，对流驱动进行操作时确同问题，调试口给出的信息是：
                                                                     Data Abort: Thread=8fe8b6d8 Proc=8e626160 'device.exe'
AKY=00000005 PC=03f92490(coredll.dll+0x00022490) RA=06039a38(device.exe+0x00029a
38) BVA=06039a39 FSR=00000003
RaiseException: Thread=8fe8b6d8 Proc=8e626160 'device.exe'
AKY=00000005 PC=03f8dff8(coredll.dll+0x0001dff8) RA=8c22a6d4(NK.EXE+0x0002a6d4)
BVA=00000001 FSR=00000001

但是我把监界区保护去掉，程序驱动可以正常加载和调用，只要一出现临界区保护：EnterCriticalSection();
LeaveCriticalSection();
就会出现上面的错误，会是那里的原因呢？

只看该作者 · 2008-1-28 14:21

// VirtualCom.cpp : Defines the entry point for the DLL application.
//

#include "stdafx.h"
#include "VirtualCom.h"

HANDLE g_hInstance;

#define BUFSIZE 2048
unsigned char chBuffer[BUFSIZE];

BOOL APIENTRY DllMain( HANDLE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
                     )
{
    switch (ul_reason_for_call)
    {
        case DLL_PROCESS_ATTACH:
            g_hInstance = hModule;
            RETAILMSG(1,(TEXT("VirtualCom: DLL_PROCESS_ATTACH\n")));
            DisableThreadLibraryCalls ((HMODULE)g_hInstance);
            break;
        //case DLL_THREAD_ATTACH:
        //    RETAILMSG(1,(TEXT("VirtualCom: DLL_THREAD_ATTACH\n")));
        //    break;
        //case DLL_THREAD_DETACH:
        //    RETAILMSG(1,(TEXT("VirtualCom: DLL_THREAD_DETACH\n")));
        //    break;
        case DLL_PROCESS_DETACH:
            RETAILMSG(1,(TEXT("VirtualCom: DLL_PROCESS_DETACH\n")));
            break;
    }
    return TRUE;
}

// This is an example of an exported variable
VirtualCom_API int nVirtualCom=0;

// This is an example of an exported function.
VirtualCom_API int fnVirtualCom(void)
{
    return 42;
}

// This is the constructor of a class that has been exported.
// see VirtualCom.h for the class definition
CVirtualCom::CVirtualCom()
{
    return;
}

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
DWORD COM_Init(DWORD dwContext)
{
    PDRVCONTEXT pDrv;
    DWORD dwRet = 0;
    RETAILMSG(1,(TEXT("VirtualCom: COM_Init\n")));

    //Allocate a driver instance struct
    pDrv = (PDRVCONTEXT)LocalAlloc(LPTR,sizeof(PDRVCONTEXT));
    //allocate driver instance struct failed
    if(pDrv == NULL)
    {
        RETAILMSG(1,(TEXT("COM_Init:Allocate driver instance struct failed!\n")));
        return 0;
    }
    //initialize driver instance struct
    memset((PBYTE)pDrv,0,sizeof(PDRVCONTEXT));
    pDrv->dwSize = sizeof(PDRVCONTEXT);

    //initialize critical section variable
    InitializeCriticalSection(&(pDrv->InitCS));
    InitializeCriticalSection(&(pDrv->CloseCS));
    InitializeCriticalSection(&(pDrv->ReadCS));
    InitializeCriticalSection(&(pDrv->WriteCS));

    // Initialize buffer to zero.
    EnterCriticalSection(&(pDrv->InitCS));
    RETAILMSG(1,(TEXT("COM_Init:EnterCriticalSection(&(pDrv->InitCS))\n")));
    memset (chBuffer, 0, BUFSIZE * sizeof(unsigned char));
    LeaveCriticalSection(&(pDrv->InitCS));
    RETAILMSG(1,(TEXT("COM_Init:LeaveCriticalSection(&(pDrv->InitCS))\n")));
    // Set return value to non-zero.
    dwRet = 1;
    return dwRet;
}

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
BOOL COM_Deinit(DWORD hDeviceContext)
{
    PDRVCONTEXT pDrv = (PDRVCONTEXT) hDeviceContext;
    BOOL bRet = TRUE;
    RETAILMSG(1,(TEXT("VirtualCom: COM_Deinit\n")));

    if(pDrv&&(pDrv->dwSize == sizeof(PDRVCONTEXT)))
    {
        LocalFree((PBYTE)pDrv);
        RETAILMSG(1,(TEXT("COM_Deinit:LocalFree((PBYTE)pDrv)\n")));
    }

    //Delete Critical Section
    //DeleteCriticalSection(&(pDrv->InitCS));
    DeleteCriticalSection(&(pDrv->CloseCS));
    DeleteCriticalSection(&(pDrv->ReadCS));
    DeleteCriticalSection(&(pDrv->WriteCS));
    return bRet;
}

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
DWORD COM_Open(HANDLE hDeviceContext, DWORD AccessCode, DWORD ShareMode)
{
    PDRVCONTEXT pDrv = (PDRVCONTEXT)hDeviceContext;
    DWORD dwRet = 0;
    RETAILMSG(1,(TEXT("VirtualCom: COM_Open\n")));
    //Verify that the context handle is valid
    //if(pDrv && (pDrv->dwSize != sizeof(PDRVCONTEXT)))
    //{
    //    RETAILMSG(1,(TEXT("COM_Open:context handle is invalid\n")));
    //    return 0;
    //}
    //count the number of opens
    RETAILMSG(1,(TEXT("COM_Open:Enter InterlockedIncrement\r\n")));
    //InterlockedIncrement((long *)&pDrv->nNumOpens);
    RETAILMSG(1,(TEXT("COM_Open:pDrv->nNumOpens++\n")));

    dwRet = 1; // Have to make non-zero for this call to succeed.
    return dwRet;
}

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
BOOL COM_Close(DWORD hOpenContext)
{
    PDRVCONTEXT pDrv = (PDRVCONTEXT)hOpenContext;
    BOOL bRet = TRUE;
    RETAILMSG(1,(TEXT("VirtualCom: COM_Close\n")));
    //Verify that the context handle is valid
    if(pDrv && (pDrv->dwSize != sizeof(PDRVCONTEXT)))
    {
        return FALSE;
    }
    //Close stream driver and increase counter.
    //if(pDrv->nNumOpens)
    //    pDrv->nNumOpens--;
    //Clear data buffer
    EnterCriticalSection(&(pDrv->CloseCS));
    memset(chBuffer,0,sizeof(unsigned char)*BUFSIZE);
    LeaveCriticalSection(&(pDrv->CloseCS));

    return bRet;
}

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
DWORD COM_Read(HANDLE hOpenContext, LPVOID pBuffer, DWORD Count)
{
    PDRVCONTEXT pDrv = (PDRVCONTEXT)hOpenContext;
    DWORD dwRet = 0;
    RETAILMSG(1,(TEXT("VirtualCom: COM_Read\n")));
    //Verify that the context handle is valid
    //if(pDrv && (pDrv->dwSize != sizeof(PDRVCONTEXT)))
    //{
    //    RETAILMSG(1,(TEXT("COM_Read:context handle is invalid\n")));
    //    return 0;
    //}
    RETAILMSG(1,(TEXT("VirtualCom: EnterCriticalSection(&(pDrv->ReadCS))\n")));
    EnterCriticalSection(&(pDrv->ReadCS));
    RETAILMSG(1,(TEXT("VirtualCom: Enter aleady CriticalSection(&(pDrv->ReadCS))\n")));
    // Copy the smaller of buffer size or string size.
    //DWORD cbBuffer = wcslen(chBuffer);
    DWORD dwcbBuffer = strlen((char *)chBuffer);
    dwRet = min(dwcbBuffer, Count);
    memcpy((unsigned char *)pBuffer, chBuffer, dwRet);
    LeaveCriticalSection(&(pDrv->ReadCS));
    RETAILMSG(1,(TEXT("VirtualCom: LeaveCriticalSection(&(pDrv->ReadCS))\n")));
    // Return number of bytes read.
    return dwRet;
}

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
DWORD COM_Write(HANDLE hOpenContext, LPCVOID pSourceBytes, DWORD NumberOfBytes)
{
    PDRVCONTEXT pDrv = (PDRVCONTEXT)hOpenContext;
    DWORD dwRet = 0;
    RETAILMSG(1,(TEXT("VirtualCom: COM_Write\n")));

    //Verify that the context handle is valid
    //if(pDrv && (pDrv->dwSize != sizeof(PDRVCONTEXT)))
    //{
    //    RETAILMSG(1,(TEXT("COM_Write:context handle is invalid\n")));
    //    return 0;
    //}
    RETAILMSG(1,(TEXT("COM_Write:EnterCriticalSection(&(pDrv->WriteCS))\n")));
    EnterCriticalSection(&(pDrv->WriteCS));
    RETAILMSG(1,(TEXT("VirtualCom: Enter aleady CriticalSection(&(pDrv->WriteCS))\n")));
    // Copy the smaller of buffer size or number of bytes they send us.
    dwRet = min(BUFSIZE, NumberOfBytes);
    memcpy(chBuffer, (PBYTE)pSourceBytes, dwRet);
    LeaveCriticalSection(&(pDrv->WriteCS));
    RETAILMSG(1,(TEXT("COM_Write:LeaveCriticalSection(&(pDrv->WriteCS))\n")));
    // Return number of bytes written.
    return dwRet;
}

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
BOOL COM_IOControl(DWORD hOpenContext,
    DWORD dwCode,
    PBYTE pBufIn,
    DWORD dwLenIn,
    PBYTE pBufOut,
    DWORD dwLenOut,
    PDWORD pdwActualOut)
{
    BOOL bRet = TRUE;
    RETAILMSG(1,(TEXT("VirtualCom: COM_IOControl\n")));
    return bRet;
}

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
void COM_PowerDown(DWORD hDeviceContext)
{
    RETAILMSG(1,(TEXT("VirtualCom: COM_PowerDown\n")));
}

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
void COM_PowerUp(DWORD hDeviceContext)
{
    RETAILMSG(1,(TEXT("VirtualCom: COM_PowerUp\n")));
}

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
DWORD COM_Seek(DWORD hOpenContext, long Amount, DWORD Type)
{
    DWORD dwRet = 0;
    RETAILMSG(1,(TEXT("VirtualCom: COM_Seek\n")));
    return dwRet;
}

只看该作者 · 2008-1-28 14:22

typedef struct {
    DWORD dwSize;
    INT nNumOpens;
    CRITICAL_SECTION InitCS;
    CRITICAL_SECTION ReadCS;
    CRITICAL_SECTION WriteCS;
    CRITICAL_SECTION CloseCS;
} DRVCONTEXT, *PDRVCONTEXT;