KeAcquireSpinLockAtDpcLevel macro (wdm.h)

Article
02/22/2024

The KeAcquireSpinLockAtDpcLevel routine acquires a spin lock when the caller is already running at IRQL >= DISPATCH_LEVEL.

Syntax

void KeAcquireSpinLockAtDpcLevel(
  [in, out] PKSPIN_LOCK SpinLock
);

Parameters

[in, out] SpinLock

Pointer to an initialized KSPIN_LOCK spin lock for which the caller must provide the storage. The spin lock must be from non-paged pool.

Return value

None

Remarks

Drivers call KeAcquireSpinLockAtDpcLevel instead of KeAcquireSpinLock for better driver performance if and only if they are already running at an IRQL of DISPATCH_LEVEL or above.

If a driver is running at IRQL <= APC_LEVEL, it should call KeAcquireSpinLock to have IRQL raised by that routine. KeAcquireSpinLockAtDpcLevel assumes the caller is already running at IRQL >= DISPATCH_LEVEL, so no raise is necessary.

The caller should release the spin lock with KeReleaseSpinLockFromDpcLevel as quickly as possible.

For more information about spin locks, see Spin Locks.

Requirements

Requirement	Value
Target Platform	Universal
Header	wdm.h (include Wdm.h, Ntddk.h, Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	See Remarks section.
DDI compliance rules	HwStorPortProhibitedDDIs(storport), IrqlDispatch(storport), SpinLockSafe(storport)