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Fix a race condition in quantum code. Spotted by Shmuel Baron.

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svn path=/trunk/; revision=16904
This commit is contained in:
Filip Navara 2005-07-30 23:06:46 +00:00
parent 46be8912e3
commit 34674d7646
1 changed files with 10 additions and 2 deletions
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12
reactos/ntoskrnl/ke/clock.c
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@ -305,14 +305,22 @@ KeUpdateRunTime(
/* FIXME: Do DPC rate adjustments */ /* FIXME: Do DPC rate adjustments */
/*
* RACE CONDITION WARNING. If one stays at DISPATCH_LEVEL for a long
* time the DPC routine which checks for quantum end will not be executed
* and decrementing the quantum here would result in overflow.
*/
if (CurrentThread->Quantum < 0)
return;
/* /*
* If we're at end of quantum request software interrupt. The rest * If we're at end of quantum request software interrupt. The rest
* is handled in KiDispatchInterrupt. * is handled in KiDispatchInterrupt.
*/ */
if ((CurrentThread->Quantum -= 3) <= 0) if ((CurrentThread->Quantum -= 3) <= 0)
{ {
Prcb->QuantumEnd = TRUE; Prcb->QuantumEnd = TRUE;
HalRequestSoftwareInterrupt(DISPATCH_LEVEL); HalRequestSoftwareInterrupt(DISPATCH_LEVEL);
} }
} }