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Mutex support: Fix release ordering issue and current sync level.

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Fixes a problem where if multiple mutexes of the same sync level are
acquired but then not released in strict opposite order, the current
sync level becomes confused and can cause errors. ACPICA BZ 471.
This commit is contained in:
Robert Moore 2009-05-01 12:54:20 -07:00
parent 3fda08b9ad
commit 95b36bc38b
1 changed files with 19 additions and 1 deletions
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20
source/components/executer/exmutex.c
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@ -166,6 +166,15 @@ AcpiExUnlinkMutex (
if (ObjDesc->Mutex.Prev)
{
(ObjDesc->Mutex.Prev)->Mutex.Next = ObjDesc->Mutex.Next;
/*
* Migrate the previous sync level associated with this mutex to the
* previous mutex on the list so that it may be preserved. This handles
* the case where several mutexes have been acquired at the same level,
* but are not released in opposite order.
*/
(ObjDesc->Mutex.Prev)->Mutex.OriginalSyncLevel =
ObjDesc->Mutex.OriginalSyncLevel;
}
else
{
@ -461,6 +470,7 @@ AcpiExReleaseMutex (
ACPI_WALK_STATE *WalkState)
{
ACPI_STATUS Status = AE_OK;
UINT8 PreviousSyncLevel;
ACPI_FUNCTION_TRACE (ExReleaseMutex);
@ -517,13 +527,21 @@ AcpiExReleaseMutex (
return_ACPI_STATUS (AE_AML_MUTEX_ORDER);
}
/*
* Get the previous SyncLevel from the head of the acquired mutex list.
* This handles the case where several mutexes at the same level have been
* acquired, but are not released in reverse order.
*/
PreviousSyncLevel =
WalkState->Thread->AcquiredMutexList->Mutex.OriginalSyncLevel;
Status = AcpiExReleaseMutexObject (ObjDesc);
if (ObjDesc->Mutex.AcquisitionDepth == 0)
{
/* Restore the original SyncLevel */
WalkState->Thread->CurrentSyncLevel = ObjDesc->Mutex.OriginalSyncLevel;
WalkState->Thread->CurrentSyncLevel = PreviousSyncLevel;
}
return_ACPI_STATUS (Status);
}