OSROSBFX2 WDF Sample driver contains EvtUsbTargetPipeReadComplete callback. From function notes: “This can called concurrently on multiprocessor system if there are more than one readers configured. So make sure to protect access to global resources.”
I understand that this driver is 100% correct because there is only one reader. Assuming that there are more than one readers, how should I protect the global data?
My guess is that “Global data” is device context structure, and I should add WDFWAITLOCK member to it. When I want to access device context members, I need to acquire lock before.
Is this right, can I get some details about synchronization?
Thank you.
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You have to define global as the scope of the functions which touch that data. 99.99% of the time, yes, the data will be in your device context. You will need to protect your data with a spinlock (KSPINLOCK or WDFSPINLOCK) since completion routines can run at IRQL == DISPATCH_LEVEL, while a WDFWAITLOCK can only be synchronously waited on at IRQL == PASSIVE_LVEL.
d
From: xxxxx@lists.osr.com [mailto:xxxxx@lists.osr.com] On Behalf Of Alex Farber
Sent: Tuesday, February 28, 2006 1:59 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] EvtUsbTargetPipeReadComplete callback and global resources
OSROSBFX2 WDF Sample driver contains EvtUsbTargetPipeReadComplete callback. From function notes: “This can called concurrently on multiprocessor system if there are more than one readers configured. So make sure to protect access to global resources.”
I understand that this driver is 100% correct because there is only one reader. Assuming that there are more than one readers, how should I protect the global data?
My guess is that “Global data” is device context structure, and I should add WDFWAITLOCK member to it. When I want to access device context members, I need to acquire lock before.
Is this right, can I get some details about synchronization?
??? Thank you.
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Thank you.
Doron Holan wrote: You have to define global as the scope of the functions which touch that data. 99.99% of the time, yes, the data will be in your device context. You will need to protect your data with a spinlock (KSPINLOCK or WDFSPINLOCK) since completion routines can run at IRQL == DISPATCH_LEVEL, while a WDFWAITLOCK can only be synchronously waited on at IRQL == PASSIVE_LVEL.
d
From: xxxxx@lists.osr.com [mailto:xxxxx@lists.osr.com] On Behalf Of Alex Farber
Sent: Tuesday, February 28, 2006 1:59 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] EvtUsbTargetPipeReadComplete callback and global resources
OSROSBFX2 WDF Sample driver contains EvtUsbTargetPipeReadComplete callback. From function notes: “This can called concurrently on multiprocessor system if there are more than one readers configured. So make sure to protect access to global resources.”
I understand that this driver is 100% correct because there is only one reader. Assuming that there are more than one readers, how should I protect the global data?
My guess is that “Global data” is device context structure, and I should add WDFWAITLOCK member to it. When I want to access device context members, I need to acquire lock before.
Is this right, can I get some details about synchronization?
Thank you.
Yahoo! Mail
Use Photomail to share photos without annoying attachments. — Questions? First check the Kernel Driver FAQ at http://www.osronline.com/article.cfm?id=256 To unsubscribe, visit the List Server section of OSR Online at http://www.osronline.com/page.cfm?name=ListServer
—
Questions? First check the Kernel Driver FAQ at http://www.osronline.com/article.cfm?id=256
To unsubscribe, visit the List Server section of OSR Online at http://www.osronline.com/page.cfm?name=ListServer
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