NdisDprAcquireSpinLock macro (ndis.h)

The NdisDprAcquireSpinLock function acquires a spin lock so the caller can synchronize access to resources shared among non-ISR driver functions in a multiprocessor-safe way.


void NdisDprAcquireSpinLock(
  [in]  _SpinLock


[in] _SpinLock

Pointer to an opaque spin lock, already initialized by the caller.

Return value



The miniport driver must initialize a variable of type NDIS_SPIN_LOCK with NdisAllocateSpinLock before it calls any other Ndis..SpinLock function. The driver must provide resident storage for the spin lock(s) it uses.

NdisDprAcquireSpinLock is an optimized version of NdisAcquireSpinLock that a miniport driver can call only while running at IRQL = DISPATCH_LEVEL.

After acquiring a spin lock with NdisDprAcquireSpinLock, the caller must release that lock with a call to NdisDprReleaseSpinLock. A miniport driver must call NdisDprReleaseSpinLock following each call to NdisDprAcquireSpinLock. Otherwise, a deadlock occurs, hanging the driver.

A spin lock acquired with NdisDprAcquireSpinLock must be released with NdisDprReleaseSpinLock. A spin lock acquired with NdisAcquireSpinLock must be released with NdisReleaseSpinLock.

A driver should never hold a spin lock for an extended period (more than a few instructions). Holding a spin lock for longer than 25 microseconds degrades both system and driver performance.

A miniport driver cannot use a spin lock to protect resources that its other functions share with the MiniportInterrupt and/or MiniportDisableInterruptEx functions. Instead, a miniport driver must call NdisMSynchronizeWithInterruptEx so that its MiniportSynchronizeInterrupt function accesses such shared resources at the same DIRQL at which its
MiniportInterrupt and/or MiniportDisableInterruptEx functions do.

For more information about acquiring and releasing NDIS spin locks, see Synchronization and Notification in Network Drivers.


Minimum supported client Supported for NDIS 6.0 and NDIS 5.1 drivers (see NdisDprAcquireSpinLock (NDIS 5.1)) in Windows Vista. Supported for NDIS 5.1 drivers (see NdisDprAcquireSpinLock (NDIS 5.1)) in Windows XP.
Target Platform Universal
Header ndis.h (include Ndis.h)
Library Ndis.lib
DDI compliance rules Irql_Synch_Function(ndis), SpinLock(ndis), SpinLockBalanced(ndis), SpinLockDpr(ndis), SpinLockDprRelease(ndis), SpinlockRelease(ndis)

See also