InitializeListHead - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers
#ifndef _NTRTL_H

// Linked lists

FORCEINLINE VOID InitializeListHead(
    _Out_ PLIST_ENTRY ListHead
    )
{
    ListHead->Flink = ListHead->Blink = ListHead;
}

#endif

View code on GitHub

This function is documented in Windows Driver Kit.