153 lines
3.4 KiB
C
153 lines
3.4 KiB
C
/*++
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Copyright (c) 2000 Microsoft Corporation
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Module Name:
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obvutil.c
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Abstract:
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This module implements various utilities required to do driver verification.
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Author:
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Adrian J. Oney (adriao) 20-Apr-1998
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Environment:
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Kernel mode
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Revision History:
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AdriaO 06/15/2000 - Seperated out from ntos\io\flunkirp.c
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--*/
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#include "obp.h"
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#include "obvutil.h"
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//
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// When enabled, everything is locked down on demand...
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//
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text(PAGEVRFY, ObvUtilStartObRefMonitoring)
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#pragma alloc_text(PAGEVRFY, ObvUtilStopObRefMonitoring)
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#endif
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LONG
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ObvUtilStartObRefMonitoring(
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IN PDEVICE_OBJECT DeviceObject
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)
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/*++
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Description:
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Determines if ObRef has not been called between a call to this
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function and a subsequent call to ObvUtilStopObRefMonitoring.
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Arguments:
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Device object to monitor.
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Return Value:
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A start skew time to pass into ObvUtilStopObRefMonitoring.
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N.B. - A reference count is taken by this API and released
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by ObvUtilStopObRefMonitoring. That reference is not
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counted among the noticed calls to ObRef.
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--*/
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{
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#if DBG
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POBJECT_HEADER ObjectHeader;
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POBJECT_HEADER_NAME_INFO NameInfo;
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LONG startSkew, pointerCount ;
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ObReferenceObject(DeviceObject) ;
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ObjectHeader = OBJECT_TO_OBJECT_HEADER(DeviceObject);
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NameInfo = OBJECT_HEADER_TO_NAME_INFO( ObjectHeader );
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ASSERT(NameInfo) ;
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//
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// We will always decrement DbgDereferenceCount prior to PointerCount,
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// so any race conditions will look like an increment occured, which
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// is an allowable misread...
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//
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do {
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pointerCount = ObjectHeader->PointerCount ;
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startSkew = pointerCount - NameInfo->DbgDereferenceCount ;
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} while(pointerCount != ObjectHeader->PointerCount) ;
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return startSkew ;
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#else
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return 1;
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#endif
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}
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LONG
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ObvUtilStopObRefMonitoring(
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IN PDEVICE_OBJECT DeviceObject,
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IN LONG StartSkew
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)
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/*++
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Description:
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Determines if ObRef has not been called between a call to
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ObvUtilStartObRefMonitoring and a call to this API.
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In a race condition (say ObDereferenceObject is ran in-simo
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with this function), the return is gaurenteed to err on
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the side of a reference occuring.
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Arguments:
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Device Object and the skew returned by ObvUtilStartObRefMonitoring
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Return Value:
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Number of calls to ObRef that occured throughout the monitored timeframe.
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Note that the return could be positive even though the reference count
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actually dropped (ie, one ObRef and two ObDeref's).
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--*/
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{
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#if DBG
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POBJECT_HEADER ObjectHeader;
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POBJECT_HEADER_NAME_INFO NameInfo;
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LONG currentSkew, refDelta, pointerCount ;
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ObjectHeader = OBJECT_TO_OBJECT_HEADER(DeviceObject);
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NameInfo = OBJECT_HEADER_TO_NAME_INFO( ObjectHeader );
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ASSERT(NameInfo) ;
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//
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// We will always decrement DbgDereferenceCount prior to PointerCount,
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// so any race conditions will look like an increment occured, which
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// is an allowable misread...
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//
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do {
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pointerCount = ObjectHeader->PointerCount ;
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currentSkew = pointerCount - NameInfo->DbgDereferenceCount ;
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} while(pointerCount != ObjectHeader->PointerCount) ;
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refDelta = currentSkew - StartSkew ;
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ASSERT(refDelta>=0) ;
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ObDereferenceObject(DeviceObject) ;
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return refDelta ;
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#else
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return 1;
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#endif
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}
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