IWDFInterrupt::AcquireInterruptLock method

[Warning: UMDF 2 is the latest version of UMDF and supersedes UMDF 1. All new UMDF drivers should be written using UMDF 2. No new features are being added to UMDF 1 and there is limited support for UMDF 1 on newer versions of Windows 10. Universal Windows drivers must use UMDF 2. For more info, see Getting Started with UMDF.]

The AcquireInterruptLock method begins a code sequence that executes while holding an interrupt object's lock.

Syntax


void AcquireInterruptLock();

Parameters

This method has no parameters.

Return value

This method does not return a value.

Remarks

When a driver calls AcquireInterruptLock, the system acquires the framework's interrupt lock.

When the driver calls ReleaseInterruptLock, the system releases the interrupt lock.

You can use AcquireInterruptLock and ReleaseInterruptLock if your driver must execute a few lines of code without being preempted and with interrupt servicing disabled.

Your driver cannot call AcquireInterruptLock before the framework has called the driver's OnInterruptEnable callback function or after the framework has called the driver's OnInterruptDisable callback function. After your driver calls AcquireInterruptLock, it must not call the method again for the same interrupt object before calling ReleaseInterruptLock.

When running in an arbitrary thread, such as an I/O queue callback method, drivers must call IWDFInterrupt::TryToAcquireInterruptLock instead of IWDFInterrupt::AcquireInterruptLock. For example, the driver calls IWDFInterrupt::TryToAcquireInterruptLock from IQueueCallbackRead::OnRead.

Doing so avoids the possibility of deadlock, as described in the following scenario.

  1. In order to determine if its device interrupted, a UMDF sends I/O to its bus from within its ISR, with the interrupt lock held.
  2. The bus driver completes a second request in the same thread in which it received the above request.
  3. The completion routine of the second request sends a request to the UMDF driver.
  4. The UMDF driver's I/O dispatch routine calls IWDFInterrupt::AcquireInterruptLock, which then deadlocks attempting to acquire the interrupt lock.

The driver must not attempt to acquire the lock recursively. If connected to the debugger, the framework introduces a breakpoint in this scenario.

For more information about manual interrupt locking, see Synchronizing Interrupt Code.

For more information about handling interrupts in UMDF drivers, see Accessing Hardware and Handling Interrupts.

Requirements

Target platform

Desktop

End of support

Unavailable in UMDF 2.0 and later.

Minimum UMDF version

1.11

Header

Wudfddi.h

DLL

WUDFx.dll

See also

IWDFInterrupt
IWDFInterrupt::ReleaseInterruptLock
WdfInterruptAcquireLock

 

 

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