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Fix APC problems. Thanks to Arty for finding this. This makes vncviewer work

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svn path=/trunk/; revision=13484
This commit is contained in:
Alex Ionescu 2005-02-10 05:13:43 +00:00
parent 73f1d215e0
commit ef53ccc2a8
1 changed files with 29 additions and 36 deletions
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65
reactos/ntoskrnl/ke/wait.c
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@ -1,4 +1,4 @@
/* $Id:$
/* $Id$
*
* COPYRIGHT: See COPYING in the top level directory
* PROJECT: ReactOS project
@ -489,6 +489,7 @@ KeWaitForMultipleObjects(ULONG Count,
NTSTATUS Status;
KIRQL OldIrql;
BOOLEAN Abandoned;
NTSTATUS WaitStatus;
DPRINT("Entering KeWaitForMultipleObjects(Count %lu Object[] %p) "
"PsGetCurrentThread() %x\n", Count, Object, PsGetCurrentThread());
@ -540,40 +541,32 @@ KeWaitForMultipleObjects(ULONG Count,
OldIrql = KeAcquireDispatcherDatabaseLock ();
}
/* Alertability 101
* ----------------
* A Wait can either be Alertable, or Non-Alertable.
* An Alertable Wait means that APCs can "Wake" the Thread, also called UnWaiting
* If an APC is Pending however, we must refuse an Alertable Wait. Such a wait would
* be pointless since an APC is just about to be delivered.
*
* There are many ways to check if it's safe to be alertable, and these are the ones
* that I could think of:
* - The Thread is already Alerted. So someone beat us to the punch and we bail out.
* - The Thread is Waiting in User-Mode, the APC Queue is not-empty.
* It's defintely clear that we have incoming APCs, so we need to bail out and let the system
* know that there are Pending User APCs (so they can be Delivered and maybe we can try again)
*
* Furthermore, wether or not we want to be Alertable, if the Thread is waiting in User-Mode, and there
* are Pending User APCs, we should bail out, since APCs will be delivered any second.
*/
if (Alertable) {
if (CurrentThread->Alerted[(int)WaitMode]) {
CurrentThread->Alerted[(int)WaitMode] = FALSE;
DPRINT("Alertability failed\n");
KeReleaseDispatcherDatabaseLock(OldIrql);
return (STATUS_ALERTED);
} else if ((!IsListEmpty(&CurrentThread->ApcState.ApcListHead[UserMode])) && (WaitMode == UserMode)) {
DPRINT1("Alertability failed\n");
CurrentThread->ApcState.UserApcPending = TRUE;
KeReleaseDispatcherDatabaseLock(OldIrql);
return (STATUS_USER_APC);
}
} else if ((CurrentThread->ApcState.UserApcPending) && (WaitMode != KernelMode)) {
DPRINT1("Alertability failed\n");
KeReleaseDispatcherDatabaseLock(OldIrql);
return (STATUS_USER_APC);
}
/* Get the current Wait Status */
WaitStatus = CurrentThread->WaitStatus;
if (Alertable) {
/* If the Thread is Alerted, set the Wait Status accordingly */
if (CurrentThread->Alerted[(int)WaitMode]) {
CurrentThread->Alerted[(int)WaitMode] = FALSE;
DPRINT("Thread was Alerted\n");
WaitStatus = STATUS_ALERTED;
/* If there are User APCs Pending, then we can't really be alertable */
} else if ((!IsListEmpty(&CurrentThread->ApcState.ApcListHead[UserMode])) &&
(WaitMode == UserMode)) {
DPRINT1("APCs are Pending\n");
CurrentThread->ApcState.UserApcPending = TRUE;
WaitStatus = STATUS_USER_APC;
}
/* If there are User APCs Pending and we are waiting in usermode, then we must notify the caller */
} else if ((CurrentThread->ApcState.UserApcPending) && (WaitMode == UserMode)) {
DPRINT1("APCs are Pending\n");
WaitStatus = STATUS_USER_APC;
}
/*
* Check if the wait is (already) satisfied
@ -659,7 +652,7 @@ KeWaitForMultipleObjects(ULONG Count,
/*
* Set up the wait
*/
CurrentThread->WaitStatus = STATUS_UNSUCCESSFUL;
CurrentThread->WaitStatus = WaitStatus;;
for (i = 0; i < Count; i++)
{