---
description: "Learn more about: C26130"
title: C26130
ms.date: 11/04/2016
ms.topic: reference
f1_keywords: ["C26130"]
helpviewer_keywords: ["C26130"]
ms.assetid: 535e2356-bc84-4549-983d-7d29aee2249c
---
# C26130

> warning C26130: Missing annotation \_Requires\_lock\_held\_(\<lock>) or \_No\_competing\_thread\_ at function \<func>. Otherwise it could be a race condition. Variable \<var> should be protected by lock \<lock>.

Warning C26130 is issued when the analyzer detects a potential race condition but infers that the function is likely to be run in a single threaded mode, for example, when the function is in the initialization stage based on certain heuristics.

## Examples

In the following example, warning C26130 is generated because a `_Guarded_by_` member is being modified without a lock.

```cpp
typedef struct _DATA
{
    CRITICAL_SECTION cs;
    _Guarded_by_(cs) int data;
} DATA;

void Init(DATA* p)
{
    p->data = 0; // Warning C26130
}
```

If the previous code is guaranteed to be operated in a single threaded mode, annotate the function by using `_No_competing_thread_`, as shown in the following example.

```cpp
typedef struct _DATA
{
    CRITICAL_SECTION cs;
    _Guarded_by_(cs) int data;
} DATA;

_No_competing_thread_ void Init(DATA* p)
{
    p->data = 0; // Warning C26130 will be resolved
}
```

Alternatively, you can annotate a code fragment by using `_No_competing_thread_begin_` and `_No_competing_thread_end_`, as follows.

```cpp
typedef struct _DATA
{
    CRITICAL_SECTION cs;
    _Guarded_by_(cs) int data;
} DATA;

void Init(DATA* p)
{
    _No_competing_thread_begin_
    p->data = 0; // Warning C26130 will be resolved
    _No_competing_thread_end_
}
```