memory.c

WinCE5.0部分核心源码

//
// Copyright (c) Microsoft Corporation.  All rights reserved.
//
//
// This source code is licensed under Microsoft Shared Source License
// Version 1.0 for Windows CE.
// For a copy of the license visit http://go.microsoft.com/fwlink/?LinkId=3223.
//
/*****************************************************************************
* 
*
*   @doc EX_RAS
*   memory.c	NdisWan memory utilities
*
*   Date: 4/26/99
*
*/


//  Include Files

#include "windows.h"
#include "ndis.h"
#include "ras.h"
#include "raserror.h"
#include "cxport.h"
#include "protocol.h"
#include "ppp.h"
#include "macp.h"

#ifdef DEBUG
#define MAX_NODES	1000000
BOOLEAN
ListIsValid(
	IN	PLIST_ENTRY		pListHead,
	IN	PNDIS_SPIN_LOCK SpinLock	OPTIONAL)
{
	PLIST_ENTRY pPred, pCurr;
	DWORD		dwNumNodes = 0;
	BOOLEAN		bValid = TRUE;

	if (SpinLock)
		NdisAcquireSpinLock(SpinLock);

	pPred = pListHead;
	while (TRUE)
	{
		pCurr = pPred->Flink;
		if (pCurr->Blink != pPred)
		{
			DEBUGMSG(ZONE_ERROR, (TEXT("PPP: ERROR List %x Node %x Blink %x != pPred %x\n"), pListHead, pCurr, pCurr->Blink, pPred));
			bValid = FALSE;
			break;
		}

		if (pCurr == pListHead)
			break;

		if (dwNumNodes++ > MAX_NODES)
		{
			DEBUGMSG(ZONE_ERROR, (TEXT("PPP: ERROR List %x has more than %d nodes\n"), pListHead, MAX_NODES));
			bValid = FALSE;
			break;
		}

		pPred = pCurr;
	}

	if (SpinLock)
		NdisReleaseSpinLock(SpinLock);

	return bValid;
}
#endif
/*****************************************************************************
*
*
*	@func	BOOL | NdisWanAllocateSendResources
*		Allocate the required send resources
*
*	@rdesc	TRUE if successful, FALSE for error.
*
*	@parm	PMAC_CONTEXT	|	pMac	| Pointer to the Mac Context
*
*	@comm
*			This function will allocate the NDIS_WAN_PACKETs required for a
*			connection
*
*	@ex		No Example
*
*/
NDIS_STATUS
NdisWanAllocateSendResources(
	PMAC_CONTEXT	pMac)
{
	DWORD	dwBufferSize;
	DWORD	cPackets, n;
	DWORD	dwPacketMemorySize;
	PUCHAR	PacketMemory = NULL;
	PNDIS_WAN_PACKET	pWanPacket;

	// Allocate enough for the send window plus a spare for compression space
	cPackets = pMac->WanInfo.MaxTransmit + 1;

	// The compression code can actually wind up expanding the data size
	// (though when the frame expands the original is sent, not the expanded one).
	// The expansion can be up to 12.5% (1 extra bit per byte), so we reserve
	// 12.5% of the max frame size bytes for this possible expansion.
	//
	// The 8 bytes cover the 5 bytes left out at the bottom as well as whatever
	// bytes are lost to get DWORD alignment.
	//
	dwBufferSize = (pMac->WanInfo.MaxFrameSize * 9 + 7) / 8 +
				   pMac->WanInfo.HeaderPadding +
				   pMac->WanInfo.TailPadding +
				   8 + 
				   sizeof(PVOID);

	// Make size DWORD aligned
	dwBufferSize &= ~(sizeof(PVOID) - 1);
	
	dwPacketMemorySize = (dwBufferSize + sizeof(NDIS_WAN_PACKET)) * cPackets;

	PacketMemory = pppAllocateMemory(dwPacketMemorySize);

	if (NULL == PacketMemory)
	{
		DEBUGMSG(ZONE_ERROR, (TEXT("PPP: NdisWanAllocateSendResources: Allocation failed\r\n")));
		return NDIS_STATUS_RESOURCES;
	}
	

	pMac->PacketMemory = PacketMemory;
	pMac->PacketMemorySize = dwPacketMemorySize;
	pMac->BufferSize = dwBufferSize;
	NdisInitializeListHead (&pMac->PacketQueue);

	// Now setup all of the WAN_PACKET's
	for (n=0; n < cPackets; n++) {
		pWanPacket = (PNDIS_WAN_PACKET)PacketMemory;
		PacketMemory += sizeof(NDIS_WAN_PACKET);

		pWanPacket->StartBuffer = PacketMemory;
		PacketMemory += dwBufferSize;

		// Leave a little extra at the end.
		pWanPacket->EndBuffer = PacketMemory - 5;

		// Add it to the list.
		NdisInterlockedInsertHeadList (&pMac->PacketQueue, (PLIST_ENTRY)pWanPacket,
									   &pMac->PacketLock);
	}

	return NDIS_STATUS_SUCCESS;
}

NDIS_STATUS
NdisWanAllocatePacket (
	IN  OUT PMAC_CONTEXT         pMac,
	    OUT PNDIS_WAN_PACKET    *ppPacket)
//
//  Get a free packet from the PacketQueue.
//
{
	NDIS_STATUS Status = NDIS_STATUS_SUCCESS;

	ASSERT(ListIsValid(&pMac->PacketQueue, &pMac->PacketLock));
	*ppPacket = (PNDIS_WAN_PACKET)NdisInterlockedRemoveHeadList(&pMac->PacketQueue, &pMac->PacketLock);
	ASSERT(ListIsValid(&pMac->PacketQueue, &pMac->PacketLock));

	if (NULL == *ppPacket)
	{
		// If there are no transmit buffers left in the buffer pool maintained
		// by PPP, the a deadlock can occur if the thread that is responsible
		// for returning buffers to the pool blocks here.
		//
		// Currently this is known to happen when tcpstk "steals" the PPTP PacketWorkingThread
		// to send some unrelated packets which are destined for the PPTP adapter.
		//
		// So, we don't want to take a chance blocking sending to the PPTP adapter.
		//
		DEBUGMSG(ZONE_ERROR, (TEXT("PPP: All Xmit Packets in use\n")));
		Status = NDIS_STATUS_RESOURCES;
	}

	return Status;
}

NDIS_STATUS
NdisWanFreePacket (PMAC_CONTEXT	pMac, PNDIS_WAN_PACKET pPacket)
//
//  Return pPacket to the list of free packets.
//
{
	ASSERT(ListIsValid(&pMac->PacketQueue, &pMac->PacketLock));
	// Add it to the list.
	NdisInterlockedInsertHeadList(&pMac->PacketQueue, (PLIST_ENTRY)pPacket, &pMac->PacketLock);
	ASSERT(ListIsValid(&pMac->PacketQueue, &pMac->PacketLock));
	return NDIS_STATUS_SUCCESS;
}


/*****************************************************************************
*
*
*	@func	PNDIS_WAN_PACKET | pppMac_GetPacket
*		Get a packet to use internally
*
*	@rdesc	Pointer to the packet or NULL if error
*
*	@parm	PMAC_CONTEXT	|	pMac	| Pointer to the Mac Context
*
*	@comm
*			This function will allocate the NDIS_WAN_PACKET's required for a
*			connection
*
*	@ex		No Example
*
*/
PNDIS_WAN_PACKET 
pppMac_GetPacket (PMAC_CONTEXT	pMac)
{
	PNDIS_WAN_PACKET	pPacket;
	NDIS_STATUS			Status;

	Status = NdisWanAllocatePacket(pMac, &pPacket);
	if (NDIS_STATUS_SUCCESS != Status)
	{
		DEBUGMSG(ZONE_ERROR, (TEXT("pppMac_GetPacket: Error 0x%X from NdisWanAllocatePacket\n"), Status));
		return NULL;
	}

	// Initialize the packet.
	pPacket->CurrentBuffer = pPacket->StartBuffer + pMac->WanInfo.HeaderPadding;
	pPacket->CurrentLength = pPacket->EndBuffer - pPacket->CurrentBuffer -
							 pMac->WanInfo.TailPadding;

	DEBUGMSG (ZONE_MAC, (TEXT("pppMac_GetPacket: Have Packet Start=0x%X End=0x%X(%d) ")
				  TEXT("CBuf=0x%X CLen=%d HPad=%d TPad=%d\r\n"),
				  pPacket->StartBuffer, pPacket->EndBuffer,
				  pPacket->EndBuffer - pPacket->StartBuffer,
				  pPacket->CurrentBuffer, pPacket->CurrentLength,
				  pMac->WanInfo.HeaderPadding, pMac->WanInfo.TailPadding));
	
	pPacket->ProtocolReserved1 = pMac;
	
	pPacket->ProtocolReserved2 = pPacket->ProtocolReserved3 = pPacket->ProtocolReserved4 = NULL;

	return pPacket;		
}