Leaked source code of windows server 2003
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/*++
Copyright (c) 1997-2001 Microsoft Corporation
Module Name:
timer.c
Abstract:
Contains timer management structures.
Author:
Sanjay Anand (SanjayAn) 26-May-1997
ChunYe
Environment:
Kernel mode
Revision History:
--*/
#include "precomp.h"
#ifdef RUN_WPP
#include "timer.tmh"
#endif
#pragma hdrstop
BOOLEAN
IPSecInitTimer()
/*++
Routine Description:
Initialize the timer structures.
Arguments:
None
Return Value:
None
--*/
{
PIPSEC_TIMER_LIST pTimerList;
LONG i;
INIT_LOCK(&g_ipsec.TimerLock);
//
// Allocate timer structures
//
for (i = 0; i < IPSEC_CLASS_MAX; i++) {
pTimerList = &(g_ipsec.TimerList[i]);
#if DBG
pTimerList->atl_sig = atl_signature;
#endif
pTimerList->pTimers = IPSecAllocateMemory(
sizeof(IPSEC_TIMER) * IPSecTimerListSize[i],
IPSEC_TAG_TIMER);
if (pTimerList->pTimers == NULL_PIPSEC_TIMER) {
while (--i >= 0) {
pTimerList = &(g_ipsec.TimerList[i]);
IPSecFreeMemory(pTimerList->pTimers);
}
return FALSE;
}
}
//
// Initialize timer wheels.
//
for (i = 0; i < IPSEC_CLASS_MAX; i++) {
pTimerList = &(g_ipsec.TimerList[i]);
IPSecZeroMemory(pTimerList->pTimers,
sizeof(IPSEC_TIMER) * IPSecTimerListSize[i]);
pTimerList->MaxTimer = IPSecMaxTimerValue[i];
pTimerList->TimerPeriod = IPSecTimerPeriod[i];
pTimerList->TimerListSize = IPSecTimerListSize[i];
IPSEC_INIT_SYSTEM_TIMER(
&(pTimerList->NdisTimer),
IPSecTickHandler,
(PVOID)pTimerList);
}
return TRUE;
}
VOID
IPSecStartTimer(
IN PIPSEC_TIMER pTimer,
IN IPSEC_TIMEOUT_HANDLER TimeoutHandler,
IN ULONG SecondsToGo,
IN PVOID Context
)
/*++
Routine Description:
Start an IPSEC timer. Based on the length (SecondsToGo) of the
timer, we decide on whether to insert it in the short duration
timer list or in the long duration timer list in the Interface
structure.
NOTE: the caller is assumed to either hold a lock to the structure
that contains the timer, or ensure that it is safe to access the
timer structure.
Arguments:
pTimer - Pointer to IPSEC Timer structure
TimeoutHandler - Handler function to be called if this timer expires
SecondsToGo - When does this timer go off?
Context - To be passed to timeout handler if this timer expires
Return Value:
None
--*/
{
PIPSEC_TIMER_LIST pTimerList; // List to which this timer goes
PIPSEC_TIMER pTimerListHead; // Head of above list
ULONG Index; // Into timer wheel
ULONG TicksToGo = 1;
KIRQL kIrql;
INT i;
IPSEC_DEBUG(LL_A, DBF_TIMER,
("StartTimer: Secs %d, Handler %p, Ctxt %p, pTimer %p",
SecondsToGo, TimeoutHandler, Context, pTimer));
if (IPSEC_IS_TIMER_ACTIVE(pTimer)) {
IPSEC_DEBUG(LL_A, DBF_TIMER,
("Start timer: pTimer %p: is active (list %p, hnd %p), stopping it",
pTimer, pTimer->pTimerList, pTimer->TimeoutHandler));
if (!IPSecStopTimer(pTimer)) {
IPSEC_DEBUG(LL_A, DBF_TIMER, ("Couldnt stop prev timer - bail"));
return;
}
}
ACQUIRE_LOCK(&g_ipsec.TimerLock, &kIrql);
ASSERT(!IPSEC_IS_TIMER_ACTIVE(pTimer));
//
// Find the list to which this timer should go, and the
// offset (TicksToGo)
//
for (i = 0; i < IPSEC_CLASS_MAX; i++) {
pTimerList = &(g_ipsec.TimerList[i]);
if (SecondsToGo < pTimerList->MaxTimer) {
//
// Found it.
//
TicksToGo = SecondsToGo / (pTimerList->TimerPeriod);
break;
}
}
//
// Find the position in the list for this timer
//
Index = pTimerList->CurrentTick + TicksToGo;
if (Index >= pTimerList->TimerListSize) {
Index -= pTimerList->TimerListSize;
}
ASSERT(Index < pTimerList->TimerListSize);
pTimerListHead = &(pTimerList->pTimers[Index]);
//
// Fill in the timer
//
pTimer->pTimerList = pTimerList;
pTimer->LastRefreshTime = pTimerList->CurrentTick;
pTimer->Duration = TicksToGo;
pTimer->TimeoutHandler = TimeoutHandler;
pTimer->Context = Context;
//
// Insert this timer in the "ticking" list
//
pTimer->pPrevTimer = pTimerListHead;
pTimer->pNextTimer = pTimerListHead->pNextTimer;
if (pTimer->pNextTimer != NULL_PIPSEC_TIMER) {
pTimer->pNextTimer->pPrevTimer = pTimer;
}
pTimerListHead->pNextTimer = pTimer;
//
// Start off the system tick timer if necessary.
//
pTimerList->TimerCount++;
if (pTimerList->TimerCount == 1) {
IPSEC_DEBUG(LL_A, DBF_TIMER,
("StartTimer: Starting system timer %p, class %d",
&(pTimerList->NdisTimer), i));
IPSEC_START_SYSTEM_TIMER(&(pTimerList->NdisTimer), pTimerList->TimerPeriod);
}
RELEASE_LOCK(&g_ipsec.TimerLock, kIrql);
//
// We're done
//
IPSEC_DEBUG(LL_A, DBF_TIMER,
("Started timer %p, Secs %d, Index %d, Head %p",
pTimer,
SecondsToGo,
Index,
pTimerListHead));
IPSEC_INCREMENT(g_ipsec.NumTimers);
return;
}
BOOLEAN
IPSecStopTimer(
IN PIPSEC_TIMER pTimer
)
/*++
Routine Description:
Stop an IPSEC timer, if it is running. We remove this timer from
the active timer list and mark it so that we know it's not running.
NOTE: the caller is assumed to either hold a lock to the structure
that contains the timer, or ensure that it is safe to access the
timer structure.
SIDE EFFECT: If we happen to stop the last timer (of this "duration") on
the Interface, we also stop the appropriate Tick function.
Arguments:
pTimer - Pointer to IPSEC Timer structure
Return Value:
TRUE if the timer was running, FALSE otherwise.
--*/
{
PIPSEC_TIMER_LIST pTimerList; // Timer List to which this timer belongs
BOOLEAN WasRunning;
KIRQL kIrql;
IPSEC_DEBUG(LL_A, DBF_TIMER,
("Stopping Timer %p, List %p, Prev %p, Next %p",
pTimer,
pTimer->pTimerList,
pTimer->pPrevTimer,
pTimer->pNextTimer));
ACQUIRE_LOCK(&g_ipsec.TimerLock, &kIrql);
if (IPSEC_IS_TIMER_ACTIVE(pTimer)) {
WasRunning = TRUE;
//
// Unlink timer from the list
//
ASSERT(pTimer->pPrevTimer); // the list head always exists
if (pTimer->pPrevTimer) {
pTimer->pPrevTimer->pNextTimer = pTimer->pNextTimer;
}
if (pTimer->pNextTimer) {
pTimer->pNextTimer->pPrevTimer = pTimer->pPrevTimer;
}
pTimer->pNextTimer = pTimer->pPrevTimer = NULL_PIPSEC_TIMER;
//
// Update timer count on Interface, for this class of timers
//
pTimerList = pTimer->pTimerList;
pTimerList->TimerCount--;
//
// If all timers of this class are gone, stop the system tick timer
// for this class
//
if (pTimerList->TimerCount == 0) {
IPSEC_DEBUG(LL_A, DBF_TIMER, ("Stopping system timer %p, List %p",
&(pTimerList->NdisTimer),
pTimerList));
pTimerList->CurrentTick = 0;
IPSEC_STOP_SYSTEM_TIMER(&(pTimerList->NdisTimer));
}
//
// Mark stopped timer as not active
//
pTimer->pTimerList = (PIPSEC_TIMER_LIST)NULL;
IPSEC_DECREMENT(g_ipsec.NumTimers);
} else {
WasRunning = FALSE;
}
RELEASE_LOCK(&g_ipsec.TimerLock, kIrql);
return WasRunning;
}
VOID
IPSecTickHandler(
IN PVOID SystemSpecific1,
IN PVOID Context,
IN PVOID SystemSpecific2,
IN PVOID SystemSpecific3
)
/*++
Routine Description:
This is the handler we register with the system for processing each
Timer List. This is called every "tick" seconds, where "tick" is
determined by the granularity of the timer type.
Arguments:
Context - Actually a pointer to a Timer List structure
SystemSpecific[1-3] - Not used
Return Value:
None
--*/
{
PIPSEC_TIMER_LIST pTimerList;
PIPSEC_TIMER pExpiredTimer; // Start of list of expired timers
PIPSEC_TIMER pNextTimer; // for walking above list
PIPSEC_TIMER pTimer; // temp, for walking timer list
PIPSEC_TIMER pPrevExpiredTimer; // for creating expired timer list
ULONG Index; // into the timer wheel
ULONG NewIndex; // for refreshed timers
KIRQL kIrql;
pTimerList = (PIPSEC_TIMER_LIST)Context;
IPSEC_DEBUG(LL_A, DBF_TIMER, ("Tick: List %p, Count %d",
pTimerList, pTimerList->TimerCount));
pExpiredTimer = NULL_PIPSEC_TIMER;
ACQUIRE_LOCK(&g_ipsec.TimerLock, &kIrql);
if (TRUE) {
//
// Pick up the list of timers scheduled to have expired at the
// current tick. Some of these might have been refreshed.
//
Index = pTimerList->CurrentTick;
pExpiredTimer = (pTimerList->pTimers[Index]).pNextTimer;
(pTimerList->pTimers[Index]).pNextTimer = NULL_PIPSEC_TIMER;
//
// Go through the list of timers scheduled to expire at this tick.
// Prepare a list of expired timers, using the pNextExpiredTimer
// link to chain them together.
//
// Some timers may have been refreshed, in which case we reinsert
// them in the active timer list.
//
pPrevExpiredTimer = NULL_PIPSEC_TIMER;
for (pTimer = pExpiredTimer;
pTimer != NULL_PIPSEC_TIMER;
pTimer = pNextTimer) {
//
// Save a pointer to the next timer, for the next iteration.
//
pNextTimer = pTimer->pNextTimer;
IPSEC_DEBUG(LL_A, DBF_TIMER,
("Tick Handler: looking at timer %p, next %p",
pTimer, pNextTimer));
//
// Find out when this timer should actually expire.
//
NewIndex = pTimer->LastRefreshTime + pTimer->Duration;
if (NewIndex >= pTimerList->TimerListSize) {
NewIndex -= pTimerList->TimerListSize;
}
//
// Check if we are currently at the point of expiry.
//
if (NewIndex != Index) {
//
// This timer still has some way to go, so put it back.
//
IPSEC_DEBUG(LL_A, DBF_TIMER,
("Tick: Reinserting Timer %p: Hnd %p, Durn %d, Ind %d, NewInd %d",
pTimer, pTimer->TimeoutHandler, pTimer->Duration, Index, NewIndex));
//
// Remove it from the expired timer list. Note that we only
// need to update the forward (pNextExpiredTimer) links.
//
if (pPrevExpiredTimer == NULL_PIPSEC_TIMER) {
pExpiredTimer = pNextTimer;
} else {
pPrevExpiredTimer->pNextExpiredTimer = pNextTimer;
}
//
// And insert it back into the running timer list.
//
pTimer->pNextTimer = (pTimerList->pTimers[NewIndex]).pNextTimer;
if (pTimer->pNextTimer != NULL_PIPSEC_TIMER) {
pTimer->pNextTimer->pPrevTimer = pTimer;
}
pTimer->pPrevTimer = &(pTimerList->pTimers[NewIndex]);
(pTimerList->pTimers[NewIndex]).pNextTimer = pTimer;
} else {
//
// This one has expired. Keep it in the expired timer list.
//
pTimer->pNextExpiredTimer = pNextTimer;
if (pPrevExpiredTimer == NULL_PIPSEC_TIMER) {
pExpiredTimer = pTimer;
}
pPrevExpiredTimer = pTimer;
//
// Mark it as inactive.
//
ASSERT(pTimer->pTimerList == pTimerList);
pTimer->pTimerList = (PIPSEC_TIMER_LIST)NULL;
//
// Update the active timer count.
//
pTimerList->TimerCount--;
}
}
//
// Update current tick index in readiness for the next tick.
//
if (++Index == pTimerList->TimerListSize) {
pTimerList->CurrentTick = 0;
} else {
pTimerList->CurrentTick = Index;
}
if (pTimerList->TimerCount > 0) {
//
// Re-arm the tick handler
//
IPSEC_DEBUG(LL_A, DBF_TIMER, ("Tick[%d]: Starting system timer %p",
pTimerList->CurrentTick, &(pTimerList->NdisTimer)));
IPSEC_START_SYSTEM_TIMER(&(pTimerList->NdisTimer), pTimerList->TimerPeriod);
} else {
pTimerList->CurrentTick = 0;
}
}
RELEASE_LOCK(&g_ipsec.TimerLock, kIrql);
//
// Now pExpiredTimer is a list of expired timers.
// Walk through the list and call the timeout handlers
// for each timer.
//
while (pExpiredTimer != NULL_PIPSEC_TIMER) {
pNextTimer = pExpiredTimer->pNextExpiredTimer;
IPSEC_DEBUG(LL_A, DBF_TIMER,
("Expired timer %p: handler %p, next %p",
pExpiredTimer, pExpiredTimer->TimeoutHandler, pNextTimer));
(*(pExpiredTimer->TimeoutHandler))( pExpiredTimer,
pExpiredTimer->Context);
IPSEC_DECREMENT(g_ipsec.NumTimers);
pExpiredTimer = pNextTimer;
}
}