WDF Wait Lock Usage
in [Device Drivers]
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From: Murugesan on 10 Nov 2009 13:39 Hi all, From the WDF documentation, WdfWaitLock is the replacement for KEVENT(WDM). So if a thread calls wdfwaitlockacquire() will it be put in wait state eventhough the lock object is available. In other words, is wdfwaitlockacquire() & wdfwaitlockrelease() an exact replacement of Kewaitforsingleobject() & KeSetEvent() ? Thanks, Murugesan
From: Don Burn on 10 Nov 2009 13:49 I can't imagine why you would think it has anything to do with KEVENTS. Take a look at the various mutexs. Also, you are incorrect on KeWaitForSingleObject it does not put the thread into a wait state unless the object is not available. -- Don Burn (MVP, Windows DKD) Windows Filesystem and Driver Consulting Website: http://www.windrvr.com Blog: http://msmvps.com/blogs/WinDrvr Remove StopSpam to reply "Murugesan" <Murugesan(a)discussions.microsoft.com> wrote in message news:41EC25C5-EC76-4620-ACA5-13F236770BF3(a)microsoft.com... > Hi all, > From the WDF documentation, WdfWaitLock is the replacement for > KEVENT(WDM). > So if a thread calls wdfwaitlockacquire() will it be put in wait state > eventhough the lock object is available. > In other words, is wdfwaitlockacquire() & wdfwaitlockrelease() an exact > replacement of Kewaitforsingleobject() & KeSetEvent() ? > > Thanks, > Murugesan > > __________ Information from ESET NOD32 Antivirus, version of virus > signature database 4593 (20091110) __________ > > The message was checked by ESET NOD32 Antivirus. > > http://www.eset.com > > > __________ Information from ESET NOD32 Antivirus, version of virus signature database 4593 (20091110) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com
From: Murugesan on 11 Nov 2009 01:23 WdfWaitLockAcquire The sequence: KeEnterCriticalRegion KeWaitForSingleObject WdfWaitLockCreate KeInitializeEvent WdfWaitLockRelease The sequence: KeSetEvent KeLeaveCriticalRegion These are the WDM equivalents for WDF functionalities as per Microsoft's porting WDM to KMDF document. My earlier question might be incorrect. I agree that KeWaitForSingleObject() does not put the thread into wait state unless the object is not available, as for the KEVENT is considered it can be initialized with non signalled state so that the kewaitforsingleobject(event, NULL) puts a thread into wait state until some other thread moves the event into signalled state. So my question here is can we acheive this similar operation with WDFWAITLOCK. In other words, we have an option to configure initial value of an event using KeInitializeEvent so that we could make KeWaitForSingleObject to wait for the event when it encounters first time(after KeInitializeEvent). If WDFWAITLOCK is an equivalent of KEVENT, then could we initialize the state of lock object while creating lock using WdfWaitLockCreate so that WdfWaitLockAcquire waits for the lock object when it encounters for the first time. "Don Burn" wrote: > I can't imagine why you would think it has anything to do with KEVENTS. > Take a look at the various mutexs. Also, you are incorrect on > KeWaitForSingleObject it does not put the thread into a wait state unless > the object is not available. > > > -- > Don Burn (MVP, Windows DKD) > Windows Filesystem and Driver Consulting > Website: http://www.windrvr.com > Blog: http://msmvps.com/blogs/WinDrvr > Remove StopSpam to reply > > > > > "Murugesan" <Murugesan(a)discussions.microsoft.com> wrote in message > news:41EC25C5-EC76-4620-ACA5-13F236770BF3(a)microsoft.com... > > Hi all, > > From the WDF documentation, WdfWaitLock is the replacement for > > KEVENT(WDM). > > So if a thread calls wdfwaitlockacquire() will it be put in wait state > > eventhough the lock object is available. > > In other words, is wdfwaitlockacquire() & wdfwaitlockrelease() an exact > > replacement of Kewaitforsingleobject() & KeSetEvent() ? > > > > Thanks, > > Murugesan > > > > __________ Information from ESET NOD32 Antivirus, version of virus > > signature database 4593 (20091110) __________ > > > > The message was checked by ESET NOD32 Antivirus. > > > > http://www.eset.com > > > > > > > > > > __________ Information from ESET NOD32 Antivirus, version of virus signature database 4593 (20091110) __________ > > The message was checked by ESET NOD32 Antivirus. > > http://www.eset.com > > > > > . >
From: Doron Holan [MSFT] on 11 Nov 2009 16:00 just use a KEVENT if you want thread wake up semantics. a WDFWAITLOC is meant as a passive level synchonrization mechanism to synchronize access to a resource (like a list) d -- This posting is provided "AS IS" with no warranties, and confers no rights. "Murugesan" <Murugesan(a)discussions.microsoft.com> wrote in message news:333C145D-8881-4272-8C34-C666FCF958AD(a)microsoft.com... > WdfWaitLockAcquire The sequence: > KeEnterCriticalRegion > KeWaitForSingleObject > > WdfWaitLockCreate KeInitializeEvent > > WdfWaitLockRelease The sequence: > KeSetEvent > KeLeaveCriticalRegion > > These are the WDM equivalents for WDF functionalities as per Microsoft's > porting WDM to KMDF document. > My earlier question might be incorrect. I agree that > KeWaitForSingleObject() > does not put the thread into wait state unless the object is not > available, > as for the KEVENT is considered it can be initialized with non signalled > state so that the kewaitforsingleobject(event, NULL) puts a thread into > wait > state until some other thread moves the event into signalled state. So my > question here is can we acheive this similar operation with WDFWAITLOCK. > In other words, we have an option to configure initial value of an event > using KeInitializeEvent so that we could make KeWaitForSingleObject to > wait > for the event when it encounters first time(after KeInitializeEvent). If > WDFWAITLOCK is an equivalent of KEVENT, then could we initialize the state > of > lock object while creating lock using WdfWaitLockCreate so that > WdfWaitLockAcquire waits for the lock object when it encounters for the > first > time. > > "Don Burn" wrote: > >> I can't imagine why you would think it has anything to do with KEVENTS. >> Take a look at the various mutexs. Also, you are incorrect on >> KeWaitForSingleObject it does not put the thread into a wait state unless >> the object is not available. >> >> >> -- >> Don Burn (MVP, Windows DKD) >> Windows Filesystem and Driver Consulting >> Website: http://www.windrvr.com >> Blog: http://msmvps.com/blogs/WinDrvr >> Remove StopSpam to reply >> >> >> >> >> "Murugesan" <Murugesan(a)discussions.microsoft.com> wrote in message >> news:41EC25C5-EC76-4620-ACA5-13F236770BF3(a)microsoft.com... >> > Hi all, >> > From the WDF documentation, WdfWaitLock is the replacement for >> > KEVENT(WDM). >> > So if a thread calls wdfwaitlockacquire() will it be put in wait state >> > eventhough the lock object is available. >> > In other words, is wdfwaitlockacquire() & wdfwaitlockrelease() an exact >> > replacement of Kewaitforsingleobject() & KeSetEvent() ? >> > >> > Thanks, >> > Murugesan >> > >> > __________ Information from ESET NOD32 Antivirus, version of virus >> > signature database 4593 (20091110) __________ >> > >> > The message was checked by ESET NOD32 Antivirus. >> > >> > http://www.eset.com >> > >> > >> > >> >> >> >> __________ Information from ESET NOD32 Antivirus, version of virus >> signature database 4593 (20091110) __________ >> >> The message was checked by ESET NOD32 Antivirus. >> >> http://www.eset.com >> >> >> >> >> . >>
From: Murugesan on 13 Nov 2009 15:12
Hi Doron, I agree with your suggestion. But I have a query here. I think WDF doesn't encourage to create drivers which runs in its own thread context. Because WDF doesn't have framework functions for thread implementation, waiting for event & wakeup scenarios. I need to develop a driver which has a separate core thread which will be blocked while idle & unblocked while processing any requests queued to it. From the discussion, i think that this driver cannot be implemented as a framework based (using only WDF functions without any WDM functionalities).Is it true ? Murugesan. "Doron Holan [MSFT]" wrote: > just use a KEVENT if you want thread wake up semantics. a WDFWAITLOC is > meant as a passive level synchonrization mechanism to synchronize access to > a resource (like a list) > > d > > -- > > This posting is provided "AS IS" with no warranties, and confers no rights. > > > "Murugesan" <Murugesan(a)discussions.microsoft.com> wrote in message > news:333C145D-8881-4272-8C34-C666FCF958AD(a)microsoft.com... > > WdfWaitLockAcquire The sequence: > > KeEnterCriticalRegion > > KeWaitForSingleObject > > > > WdfWaitLockCreate KeInitializeEvent > > > > WdfWaitLockRelease The sequence: > > KeSetEvent > > KeLeaveCriticalRegion > > > > These are the WDM equivalents for WDF functionalities as per Microsoft's > > porting WDM to KMDF document. > > My earlier question might be incorrect. I agree that > > KeWaitForSingleObject() > > does not put the thread into wait state unless the object is not > > available, > > as for the KEVENT is considered it can be initialized with non signalled > > state so that the kewaitforsingleobject(event, NULL) puts a thread into > > wait > > state until some other thread moves the event into signalled state. So my > > question here is can we acheive this similar operation with WDFWAITLOCK. > > In other words, we have an option to configure initial value of an event > > using KeInitializeEvent so that we could make KeWaitForSingleObject to > > wait > > for the event when it encounters first time(after KeInitializeEvent). If > > WDFWAITLOCK is an equivalent of KEVENT, then could we initialize the state > > of > > lock object while creating lock using WdfWaitLockCreate so that > > WdfWaitLockAcquire waits for the lock object when it encounters for the > > first > > time. > > > > "Don Burn" wrote: > > > >> I can't imagine why you would think it has anything to do with KEVENTS. > >> Take a look at the various mutexs. Also, you are incorrect on > >> KeWaitForSingleObject it does not put the thread into a wait state unless > >> the object is not available. > >> > >> > >> -- > >> Don Burn (MVP, Windows DKD) > >> Windows Filesystem and Driver Consulting > >> Website: http://www.windrvr.com > >> Blog: http://msmvps.com/blogs/WinDrvr > >> Remove StopSpam to reply > >> > >> > >> > >> > >> "Murugesan" <Murugesan(a)discussions.microsoft.com> wrote in message > >> news:41EC25C5-EC76-4620-ACA5-13F236770BF3(a)microsoft.com... > >> > Hi all, > >> > From the WDF documentation, WdfWaitLock is the replacement for > >> > KEVENT(WDM). > >> > So if a thread calls wdfwaitlockacquire() will it be put in wait state > >> > eventhough the lock object is available. > >> > In other words, is wdfwaitlockacquire() & wdfwaitlockrelease() an exact > >> > replacement of Kewaitforsingleobject() & KeSetEvent() ? > >> > > >> > Thanks, > >> > Murugesan > >> > > >> > __________ Information from ESET NOD32 Antivirus, version of virus > >> > signature database 4593 (20091110) __________ > >> > > >> > The message was checked by ESET NOD32 Antivirus. > >> > > >> > http://www.eset.com > >> > > >> > > >> > > >> > >> > >> > >> __________ Information from ESET NOD32 Antivirus, version of virus > >> signature database 4593 (20091110) __________ > >> > >> The message was checked by ESET NOD32 Antivirus. > >> > >> http://www.eset.com > >> > >> > >> > >> > >> . > >> > . > |