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The latest version of this topic can be found at C26110.

warning C26110: Caller failing to hold lock <lock> before calling function <func>.

When a lock is required, make sure to clarify whether the function itself or its caller should acquire the lock. Warning C26110 is issued when there is a violation of the _Requires_lock_held_ annotation.

In the following example, warning C26110 is generated because the annotation _Requires_lock_held_ on function LockRequired states that the caller of LockRequired must acquire the lock before it calls LockRequired. Without this annotation, LockRequired has to acquire the lock before it accesses any shared data protected by the lock.

typedef struct _DATA   
    int d;  
} DATA;  
void LockRequired(DATA* p)  
    p->d = 0;  
void LockNotHeld(DATA* p)   
    LockRequired(p); // Warning C26110