KeWaitForSingleObject in Completion/Cancellation Routine
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From: eagersh on 20 Nov 2009 12:48 On Nov 19, 11:59 pm, Tim Roberts <t...(a)probo.com> wrote: > Prakash Manannavar <PrakashMananna...(a)discussions.microsoft.com> wrote: > The RIGHT way do to this is to queue up a work item with IoQueueWorkItem. > The callback will be called at PASSIVE_LEVEL. I would like to add that OP could move his KeWaitForSingleObject into work item or created system thread and synchronize the work item with a drivers Completion/Cancellation Routine. It is little bit complicated but it is safe for sure. Igor Sharovar
From: Doron Holan [MSFT] on 20 Nov 2009 18:42 lowering irql that you did not raise does not cause priority inversion. it causes deadlocks and strange undiagnosible errors. d -- This posting is provided "AS IS" with no warranties, and confers no rights. "David Craig" <drivers(a)noemail.noemail> wrote in message news:OkgjzUaaKHA.1592(a)TK2MSFTNGP06.phx.gbl... > NO!!! That will/can cause priority inversion. > > "Prakash Manannavar" <PrakashManannavar(a)discussions.microsoft.com> wrote > in message news:BAD738A5-ECE4-4D4B-8CA5-588A2232CD9D(a)microsoft.com... >> Thanks Scott, >> >> I have some issues, >> >> 1. If waiting with KeWaitForSingleObejct at IRQL <= DISPATCH_LEVEL, Is >> there >> any specific reason which has been supported by OS? >> >> 2. I read KeRaiseIrql and KeLowerIrql functions, As I read we can raise >> IRQL >> first and then we can lower it to the previous level. Is there any >> functions >> to lower the IRQL and then raise it to the previous level? >> >> -- >> ~~~~~ >> Prakash A Manannavar, >> Bangalore/Bengaluru. >> > >
From: Prakash Manannavar on 24 Nov 2009 01:36 Thanks guys, Now I have created WorkItem and queuing it. In DDK it has been told that "caller of KeWaitForSingleObject can be run at IRQL <= DISPATCH LEVEL" I wanted to know that, is there any specific scenarios we can wait there?? -- ~~~~~ Prakash A Manannavar, Bangalore/Bengaluru.
From: David Craig on 24 Nov 2009 02:19
I would take a class about driver development. I would also use the WDK and not a DDK. Version 7.0.0 A.K.A. 7600.16385.0 is the most recent and supports back to XP. The documentation describes how you can use KeWFSO. You can 'wait' at DISPATCH_LEVEL or lower, however the 'wait' at DISPATCH_LEVEL must be zero, which makes it a test and not a real wait. In the wrong context waiting at APC_LEVEL can cause a deadlock, though that is usually only in the file systems area. "Prakash Manannavar" <PrakashManannavar(a)discussions.microsoft.com> wrote in message news:D7855A81-20EA-4711-AD81-2AF55D27D0B3(a)microsoft.com... > Thanks guys, > > Now I have created WorkItem and queuing it. > > In DDK it has been told that "caller of KeWaitForSingleObject can be run > at > IRQL <= DISPATCH LEVEL" > > I wanted to know that, is there any specific scenarios we can wait there?? > > -- > ~~~~~ > Prakash A Manannavar, > Bangalore/Bengaluru. > > |