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- Fix locking bugs in guarded mutex implementation. In race conditions some operations were not re-attempted.

Browse source 
- Fix some other logic bugs, including a serious bug in KeTrytoAcquireGuardedMutex which inversed the result.

svn path=/trunk/; revision=25473
This commit is contained in:
Alex Ionescu 2007-01-15 21:34:36 +00:00
parent 2e03cf0bb5
commit 4f9b8acb4d
3 changed files with 46 additions and 47 deletions
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3
reactos/ntoskrnl/include/internal/ex.h
View file

@ -745,7 +745,8 @@ ExReleasePushLockExclusive(PEX_PUSH_LOCK PushLock)
ASSERT(PushLock->Waiting || PushLock->Shared == 0);
/* Unlock the pushlock */
OldValue.Value = InterlockedExchangeAddSizeT((PLONG)PushLock, -1);
OldValue.Value = InterlockedExchangeAddSizeT((PLONG)PushLock,
-EX_PUSH_LOCK_LOCK);
/* Sanity checks */
ASSERT(OldValue.Locked);

17
reactos/ntoskrnl/ke/gate.c
View file

@ -78,7 +78,7 @@ KeWaitForGate(IN PKGATE Gate,
/* Release the APC lock and return */
KiReleaseApcLock(&ApcLock);
return;
break;
}
/* Setup a Wait Block */
@ -122,8 +122,8 @@ KeWaitForGate(IN PKGATE Gate,
/* Find a new thread to run */
Status = KiSwapThread(Thread, KeGetCurrentPrcb());
/* Check if we were executing an APC */
if (Status != STATUS_KERNEL_APC) return;
/* Make sure we weren't executing an APC */
if (Status == STATUS_SUCCESS) return;
}
} while (TRUE);
}
@ -149,18 +149,14 @@ KeSignalGateBoostPriority(IN PKGATE Gate)
KiAcquireDispatcherObject(&Gate->Header);
/* Make sure we're not already signaled or that the list is empty */
if (Gate->Header.SignalState)
{
/* Lower IRQL and quit */
KeLowerIrql(OldIrql);
return;
}
if (Gate->Header.SignalState) break;
/* Check if our wait list is empty */
if (IsListEmpty(&Gate->Header.WaitListHead))
{
/* It is, so signal the event */
Gate->Header.SignalState = 1;
break;
}
else
{
@ -187,7 +183,7 @@ KeSignalGateBoostPriority(IN PKGATE Gate)
RemoveEntryList(&WaitBlock->WaitListEntry);
/* Clear wait status */
WaitThread->WaitStatus = 0;
WaitThread->WaitStatus = STATUS_SUCCESS;
/* Set state and CPU */
WaitThread->State = DeferredReady;
@ -223,6 +219,7 @@ KeSignalGateBoostPriority(IN PKGATE Gate)
/* Exit the dispatcher */
KiExitDispatcher(OldIrql);
return;
}
}

73
reactos/ntoskrnl/ke/gmutex.c
View file

@ -30,9 +30,6 @@ KiAcquireGuardedMutexContented(IN OUT PKGUARDED_MUTEX GuardedMutex)
BitsToRemove = GM_LOCK_BIT;
BitsToAdd = GM_LOCK_WAITER_INC;
/* Get the Count Bits */
OldValue = GuardedMutex->Count;
/* Start change loop */
for (;;)
{
@ -42,43 +39,47 @@ KiAcquireGuardedMutexContented(IN OUT PKGUARDED_MUTEX GuardedMutex)
ASSERT((BitsToAdd == GM_LOCK_WAITER_INC) ||
(BitsToAdd == GM_LOCK_WAITER_WOKEN));
/* Check if the Guarded Mutex is locked */
if (OldValue & GM_LOCK_BIT)
{
/* Sanity check */
ASSERT((BitsToRemove == GM_LOCK_BIT) ||
((OldValue & GM_LOCK_WAITER_WOKEN) != 0));
/* Get the Count Bits */
OldValue = GuardedMutex->Count;
/* Unlock it by removing the Lock Bit */
NewValue = InterlockedCompareExchange(&GuardedMutex->Count,
OldValue ^ BitsToRemove,
OldValue);
if (NewValue == OldValue) break;
/* Value got changed behind our backs, start over */
OldValue = NewValue;
}
else
/* Start internal bit change loop */
for (;;)
{
/* The Guarded Mutex isn't locked, so simply set the bits */
NewValue = InterlockedCompareExchange(&GuardedMutex->Count,
OldValue + BitsToAdd,
OldValue);
if (NewValue != OldValue)
/* Check if the Guarded Mutex is locked */
if (OldValue & GM_LOCK_BIT)
{
/* Value got changed behind our backs, start over */
OldValue = NewValue;
continue;
/* Sanity check */
ASSERT((BitsToRemove == GM_LOCK_BIT) ||
((OldValue & GM_LOCK_WAITER_WOKEN) != 0));
/* Unlock it by removing the Lock Bit */
NewValue = OldValue ^ BitsToRemove;
NewValue = InterlockedCompareExchange(&GuardedMutex->Count,
NewValue,
OldValue);
if (NewValue == OldValue) return;
}
else
{
/* The Guarded Mutex isn't locked, so simply set the bits */
NewValue = OldValue + BitsToAdd;
NewValue = InterlockedCompareExchange(&GuardedMutex->Count,
NewValue,
OldValue);
if (NewValue == OldValue) break;
}
/* Now we have to wait for it */
KeWaitForGate(&GuardedMutex->Gate, WrGuardedMutex, KernelMode);
ASSERT((GuardedMutex->Count & GM_LOCK_WAITER_WOKEN) != 0);
/* Old value changed, loop again */
OldValue = NewValue;
}
/* Ok, the wait is done, so set the new bits */
BitsToRemove = GM_LOCK_BIT | GM_LOCK_WAITER_WOKEN;
BitsToAdd = GM_LOCK_WAITER_WOKEN;
}
/* Now we have to wait for it */
KeWaitForGate(&GuardedMutex->Gate, WrGuardedMutex, KernelMode);
ASSERT((GuardedMutex->Count & GM_LOCK_WAITER_WOKEN) != 0);
/* Ok, the wait is done, so set the new bits */
BitsToRemove = GM_LOCK_BIT | GM_LOCK_WAITER_WOKEN;
BitsToAdd = GM_LOCK_WAITER_WOKEN;
}
}
@ -109,7 +110,7 @@ KiReleaseGuardedMutex(IN OUT PKGUARDED_MUTEX GuardedMutex)
GuardedMutex->Owner = NULL;
/* Add the Lock Bit */
OldValue = InterlockedExchangeAdd(&GuardedMutex->Count, 1);
OldValue = InterlockedExchangeAdd(&GuardedMutex->Count, GM_LOCK_BIT);
ASSERT((OldValue & GM_LOCK_BIT) == 0);
/* Check if it was already locked, but not woken */
@ -247,7 +248,7 @@ KeTryToAcquireGuardedMutex(IN OUT PKGUARDED_MUTEX GuardedMutex)
/* Remove the lock */
OldBit = InterlockedBitTestAndReset(&GuardedMutex->Count, GM_LOCK_BIT_V);
if (OldBit)
if (!OldBit)
{
/* Re-enable APCs */
KeLeaveGuardedRegion();