File Object Lock with WDK
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From: Asaf Shelly on 18 Aug 2010 21:38 Hi Doron, Thanks! This is exactly what I needed. Can you please go over the documentation and verify that this information is there? I spent a while searching for samples or this explanation but could not find any. Keep in mind that it is hard to search for this issue in a search engine. There are so many search results for "File", "Driver", "Object", "Lock", "Queue" which are not related to a Driver's File Object based Lock. Thanks again, Asaf "Doron Holan [MSFT]" wrote: > you can create your own set of queues per WDFFILEOBJECT. specify the > WDFFILEOBJECT as the parent when you create the queues in > EvtDeviceFileCreate. from your top level dispatching queue, you find the > WDFFILEOBJECT specific queue and forward the request to that queue. you can > then use queue level synchronization and each file object is separate from > each other. > > d > > "Asaf Shelly" wrote in message > news:EEF1F838-3A0A-4788-816C-DECC903FC106(a)microsoft.com... > > Hi Abhishek, > > I have a driver which is a higher level to the COM port, so it is using a > Serial Port as the lower driver. > My application opens my driver for communication and the driver can either > read, write, send periodic buffers, and manipulate data. Currently I need an > instance of the driver for every COM port so basically if I have 5 COM ports > on the machine then I also need 5 instances of my virtual device. > What I would like to do is open my device with the COM number so instead of > using \\?\MyDevice1 for COM1 and \\?\MyDevice2 for COM2, I would like to use > \\?\MyDevice\COM1 and \\?\MyDevice\COM2. > This is working, except that if my device is forwading a request in > transparent mode then it is possible that the lower level driver will block > to completion and my driver cannot handle any other request till completion. > I can solve this in many ways but am looking for a clean design with KMDF > support. > > From what I have seen there is some support for FOs in KMDF but fewer > samples than any other solution. Is FO support limited in this version of > KMDF? > > Thanks for the fast response. > > Regards, > Asaf > > > "Abhishek Ram [MSFT]" wrote: > > > Can you provide a little more information on what you are trying to > > accomplish? Which callbacks do you need to synchronize based on file > > object? > > > > "Asaf Shelly" <MSMediaForum(a)Shelly.co.il> wrote in message > > news:4578B801-0376-498D-8046-2B6DE6AE9122(a)microsoft.com... > > > Hi Pavel and Abhishek, > > > > > > Thanks for the answers. So basically if I need File-Object based > > > synchronization then I should not use Queue based synchronization and > > > instead > > > do this manually, correct? > > > > > > Is there any lock object attached to the File Object? > > > > > > TIA, > > > Asaf > > > > > > > > > "Pavel A." wrote: > > > > > >> "Asaf Shelly" <MSMediaForum(a)Shelly.co.il> wrote in message > > >> news:6D71B953-80CB-43AA-BA78-3955C288394C(a)microsoft.com... > > >> > Hi All, > > >> > > > >> > I know that it is possible to have an automatic synchronization that > > >> > is > > >> > based on File Object: > > >> > http://msdn.microsoft.com/en-us/library/ff544763(VS.85).aspx > > >> > > > >> > Can't find anywhere that says how. > > >> > > > >> > TIA, > > >> > Asaf > > >> > > >> Automatic synchronization is not _based_ on file objects. > > >> Rather, callbacks of a file object, that belongs to certain device > > >> object, > > >> can be synchronized with other callbacks of that file object, and with > > >> other callbacks of that device object. > > >> This is implemented by taking a lock in the device object. > > >> > > >> Call WdfDeviceInitSetFileObjectConfig > > >> with WDF_OBJECT_ATTRIBUTES where you specify SynchronizationScope > > >> and ExecutionLevel as needed. > > >> > > >> -- pa > > >> > > >> > > >> . > > >> > > . > > > > . >
From: Asaf Shelly on 18 Aug 2010 21:46 Hi Abhishek, My test application does not use FILE_FLAG_OVERLAPPED because my user is not used to it. The device might receive other requests, mainly Create File / Close Handle / Cleanup, and power, so basically I do need device level synchronization as well. Currently the synchronization scope is Queue level, but this without doron's solution is only device wide lock. Honestly I would expect WDF to forward the request to the File Object specific queue automatically. Thanks for all the help, Asaf "Abhishek Ram [MSFT]" wrote: > > This is working, except that if my device is forwading a request in > > transparent mode then it is possible that the lower level driver will > > block > > to completion and my driver cannot handle any other request till > > completion. > > Are you saying your driver does not receive any other request for that > device object? Or is it for that file object? > What synchronization scope did you set in the case that you observed this? > Also does the application use FILE_FLAG_OVERLAPPED when it opens the handle? > > "Asaf Shelly" <MSMediaForum(a)Shelly.co.il> wrote in message > news:EEF1F838-3A0A-4788-816C-DECC903FC106(a)microsoft.com... > > Hi Abhishek, > > > > I have a driver which is a higher level to the COM port, so it is using a > > Serial Port as the lower driver. > > My application opens my driver for communication and the driver can either > > read, write, send periodic buffers, and manipulate data. Currently I need > > an > > instance of the driver for every COM port so basically if I have 5 COM > > ports > > on the machine then I also need 5 instances of my virtual device. > > What I would like to do is open my device with the COM number so instead > > of > > using \\?\MyDevice1 for COM1 and \\?\MyDevice2 for COM2, I would like to > > use > > \\?\MyDevice\COM1 and \\?\MyDevice\COM2. > > This is working, except that if my device is forwading a request in > > transparent mode then it is possible that the lower level driver will > > block > > to completion and my driver cannot handle any other request till > > completion. > > I can solve this in many ways but am looking for a clean design with KMDF > > support. > > > > From what I have seen there is some support for FOs in KMDF but fewer > > samples than any other solution. Is FO support limited in this version of > > KMDF? > > > > Thanks for the fast response. > > > > Regards, > > Asaf > > > > > > "Abhishek Ram [MSFT]" wrote: > > > >> Can you provide a little more information on what you are trying to > >> accomplish? Which callbacks do you need to synchronize based on file > >> object? > >> > >> "Asaf Shelly" <MSMediaForum(a)Shelly.co.il> wrote in message > >> news:4578B801-0376-498D-8046-2B6DE6AE9122(a)microsoft.com... > >> > Hi Pavel and Abhishek, > >> > > >> > Thanks for the answers. So basically if I need File-Object based > >> > synchronization then I should not use Queue based synchronization and > >> > instead > >> > do this manually, correct? > >> > > >> > Is there any lock object attached to the File Object? > >> > > >> > TIA, > >> > Asaf > >> > > >> > > >> > "Pavel A." wrote: > >> > > >> >> "Asaf Shelly" <MSMediaForum(a)Shelly.co.il> wrote in message > >> >> news:6D71B953-80CB-43AA-BA78-3955C288394C(a)microsoft.com... > >> >> > Hi All, > >> >> > > >> >> > I know that it is possible to have an automatic synchronization that > >> >> > is > >> >> > based on File Object: > >> >> > http://msdn.microsoft.com/en-us/library/ff544763(VS.85).aspx > >> >> > > >> >> > Can't find anywhere that says how. > >> >> > > >> >> > TIA, > >> >> > Asaf > >> >> > >> >> Automatic synchronization is not _based_ on file objects. > >> >> Rather, callbacks of a file object, that belongs to certain device > >> >> object, > >> >> can be synchronized with other callbacks of that file object, and with > >> >> other callbacks of that device object. > >> >> This is implemented by taking a lock in the device object. > >> >> > >> >> Call WdfDeviceInitSetFileObjectConfig > >> >> with WDF_OBJECT_ATTRIBUTES where you specify SynchronizationScope > >> >> and ExecutionLevel as needed. > >> >> > >> >> -- pa > >> >> > >> >> > >> >> . > >> >> > >> . > >> > . >
From: Pavel A. on 19 Aug 2010 03:25 If you open \\?\MyDevice\COM1 and \\?\MyDevice\COM2, you get handles to different file objects, so synchronous requests to these run independently. However, the blocking on sync handles occurs in user mode. Drivers always complete requests and get out quickly, maybe with STATUS_PENDING. Windows is not Unix. --pa "Asaf Shelly" <MSMediaForum(a)Shelly.co.il> wrote in message news:50F8C3CA-EF1C-4AE0-81DE-0D56F9ACD884(a)microsoft.com... > Hi Doron, > > Thanks! This is exactly what I needed. Can you please go over the > documentation and verify that this information is there? I spent a while > searching for samples or this explanation but could not find any. Keep in > mind that it is hard to search for this issue in a search engine. There > are > so many search results for "File", "Driver", "Object", "Lock", "Queue" > which > are not related to a Driver's File Object based Lock. > > Thanks again, > Asaf > > > "Doron Holan [MSFT]" wrote: > >> you can create your own set of queues per WDFFILEOBJECT. specify the >> WDFFILEOBJECT as the parent when you create the queues in >> EvtDeviceFileCreate. from your top level dispatching queue, you find the >> WDFFILEOBJECT specific queue and forward the request to that queue. you >> can >> then use queue level synchronization and each file object is separate >> from >> each other. >> >> d >> >> "Asaf Shelly" wrote in message >> news:EEF1F838-3A0A-4788-816C-DECC903FC106(a)microsoft.com... >> >> Hi Abhishek, >> >> I have a driver which is a higher level to the COM port, so it is using a >> Serial Port as the lower driver. >> My application opens my driver for communication and the driver can >> either >> read, write, send periodic buffers, and manipulate data. Currently I need >> an >> instance of the driver for every COM port so basically if I have 5 COM >> ports >> on the machine then I also need 5 instances of my virtual device. >> What I would like to do is open my device with the COM number so instead >> of >> using \\?\MyDevice1 for COM1 and \\?\MyDevice2 for COM2, I would like to >> use >> \\?\MyDevice\COM1 and \\?\MyDevice\COM2. >> This is working, except that if my device is forwading a request in >> transparent mode then it is possible that the lower level driver will >> block >> to completion and my driver cannot handle any other request till >> completion. >> I can solve this in many ways but am looking for a clean design with KMDF >> support. >> >> From what I have seen there is some support for FOs in KMDF but fewer >> samples than any other solution. Is FO support limited in this version of >> KMDF? >> >> Thanks for the fast response. >> >> Regards, >> Asaf >> >> >> "Abhishek Ram [MSFT]" wrote: >> >> > Can you provide a little more information on what you are trying to >> > accomplish? Which callbacks do you need to synchronize based on file >> > object? >> > >> > "Asaf Shelly" <MSMediaForum(a)Shelly.co.il> wrote in message >> > news:4578B801-0376-498D-8046-2B6DE6AE9122(a)microsoft.com... >> > > Hi Pavel and Abhishek, >> > > >> > > Thanks for the answers. So basically if I need File-Object based >> > > synchronization then I should not use Queue based synchronization and >> > > instead >> > > do this manually, correct? >> > > >> > > Is there any lock object attached to the File Object? >> > > >> > > TIA, >> > > Asaf >> > > >> > > >> > > "Pavel A." wrote: >> > > >> > >> "Asaf Shelly" <MSMediaForum(a)Shelly.co.il> wrote in message >> > >> news:6D71B953-80CB-43AA-BA78-3955C288394C(a)microsoft.com... >> > >> > Hi All, >> > >> > >> > >> > I know that it is possible to have an automatic synchronization >> > >> > that >> > >> > is >> > >> > based on File Object: >> > >> > http://msdn.microsoft.com/en-us/library/ff544763(VS.85).aspx >> > >> > >> > >> > Can't find anywhere that says how. >> > >> > >> > >> > TIA, >> > >> > Asaf >> > >> >> > >> Automatic synchronization is not _based_ on file objects. >> > >> Rather, callbacks of a file object, that belongs to certain device >> > >> object, >> > >> can be synchronized with other callbacks of that file object, and >> > >> with >> > >> other callbacks of that device object. >> > >> This is implemented by taking a lock in the device object. >> > >> >> > >> Call WdfDeviceInitSetFileObjectConfig >> > >> with WDF_OBJECT_ATTRIBUTES where you specify SynchronizationScope >> > >> and ExecutionLevel as needed. >> > >> >> > >> -- pa >> > >>
From: Maxim S. Shatskih on 19 Aug 2010 06:38 > However, the blocking on sync handles occurs in user mode. In kernel mode in IopSynchronousServiceTail -- Maxim S. Shatskih Windows DDK MVP maxim(a)storagecraft.com http://www.storagecraft.com
From: Maxim S. Shatskih on 19 Aug 2010 06:51
> My test application does not use FILE_FLAG_OVERLAPPED because my user is not > used to it. > The device might receive other requests, mainly Create File / Close Handle / > Cleanup, and power, so basically I do need device level synchronization as > well. > Currently the synchronization scope is Queue level, but this without doron's > solution is only device wide lock. So what? You need delice-level synchronization, and the KMDF queue gives you this. All is OK. And, if you need file-level synchronization, then just never use FILE_FLAG_OVERLAPPED, and all IRPs sent to this file object will be serialized by IO. -- Maxim S. Shatskih Windows DDK MVP maxim(a)storagecraft.com http://www.storagecraft.com |