InterlockedExchangePointer function (wdm.h)

Article
02/22/2024

The InterlockedExchangePointer routine performs an atomic operation that sets a pointer to a new value.

Syntax

PVOID InterlockedExchangePointer(
  [in, out]      PVOID volatile *Target,
  [in, optional] PVOID          Value
);

Parameters

[in, out] Target

A pointer to a PVOID value. The routine sets (*Target) to Value.

[in, optional] Value

Specifies the PVOID value to set (*Target) to.

Return value

InterlockedExchangePointer returns the original value of the pointer at *Target (that is, the value of this pointer at entry to the routine).

Remarks

InterlockedExchangePointer provides a fast, atomic way to synchronize updating a pointer variable that is shared by multiple threads.

InterlockedExchangePointer is designed for speed and, typically, is implemented inline by a compiler. InterlockedExchangePointer is atomic only with respect to other InterlockedXxx calls. It does not use a spin lock and can be safely used on pageable data.

The Target parameter should be aligned on either a 32-bit or 64-bit boundary, depending on the system type, for better performance.

A call to InterlockedExchangePointer is atomic only with respect to other InterlockedXxx calls.

Interlocked operations cannot be used on non-cached memory.

Requirements

Requirement	Value
Minimum supported client	Available starting with Windows 2000.
Target Platform	Desktop
Header	wdm.h (include Wdm.h, Ntddk.h, Ntifs.h, Miniport.h)
IRQL	Any level