KSYNCHRONIZE_ROUTINE callback function (wdm.h)

Article
02/22/2024

The SynchCritSection routine is used to access hardware resources or driver data that are shared with a driver's InterruptService routine.

Syntax

KSYNCHRONIZE_ROUTINE KsynchronizeRoutine;

BOOLEAN KsynchronizeRoutine(
  [in] PVOID SynchronizeContext
)
{...}

Parameters

[in] SynchronizeContext

Caller-supplied context information, specified by the driver's call to KeSynchronizeExecution.

Return value

If the routine's operation succeeds, the routine should return TRUE; otherwise, it should return FALSE. (Success and failure of this routine are driver-defined.) The specified return value becomes the return value for KeSynchronizeExecution.

Remarks

Drivers must use SynchCritSection routines to access hardware resources or driver data that can also be accessed by an InterruptService routine (ISR).

The system calls a driver's SynchCritSection routine when the driver calls KeSynchronizeExecution. When a driver calls KeSynchronizeExecution, it specifies the address of a SynchCritSection routine, context information for the routine, and an interrupt object pointer. The KeSynchronizeExecution routine acquires the interrupt object's spin lock, then calls the SynchCritSection routine.

A driver's SynchCritSection routine executes at the same IRQL as the ISR with which it is associated. Specifically, it executes at some system-assigned DIRQL, as specified by the SynchronizeIrql parameter to IoConnectInterrupt. (Other devices, with higher DIRQL values, can interrupt a SynchCritSection routine.)

Examples

To define a SynchCritSection callback routine, you must first provide a function declaration that identifies the type of callback routine you're defining. Windows provides a set of callback function types for drivers. Declaring a function using the callback function types helps Code Analysis for Drivers, Static Driver Verifier (SDV), and other verification tools find errors, and it's a requirement for writing drivers for the Windows operating system.

For example, to define a SynchCritSection callback routine that is named MySynchCritSection, use the KSYNCHRONIZE_ROUTINE type as shown in this code example:

KSYNCHRONIZE_ROUTINE MySynchCritSection;

Then, implement your callback routine as follows:

_Use_decl_annotations_
BOOLEAN
  MySynchCritSection(
    PVOID  SynchronizeContext
    )
  {
      // Function body
  }

The KSYNCHRONIZE_ROUTINE function type is defined in the Wdm.h header file. To more accurately identify errors when you run the code analysis tools, be sure to add the _Use_decl_annotations_ annotation to your function definition. The _Use_decl_annotations_ annotation ensures that the annotations that are applied to the KSYNCHRONIZE_ROUTINE function type in the header file are used. For more information about the requirements for function declarations, see Declaring Functions by Using Function Role Types for WDM Drivers. For information about _Use_decl_annotations_, see Annotating Function Behavior.

Requirements

Requirement	Value
Target Platform	Desktop
Header	wdm.h (include Wdm.h, Ntddk.h, Ntifs.h)
IRQL	Called at DIRQL (see Remarks section).

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