Mutex Held Across co_await

Load windbg-diagnostic-method first if it is not already loaded in this conversation, and apply it throughout for evidence ranking, hypothesis testing, confidence calibration, independent review, and report validation. This skill adds the bug-family-specific commands and evidence requirements.

Detection

This pattern can occur in native application, service, or user-mode driver code, including UMDF components that use C++ coroutines. Look for a lock acquired before co_await and released after resumption or coroutine destruction. Mutex ownership belongs to the acquiring thread, not the coroutine frame. A resumption on another thread can violate that contract. Even same-thread resumption can create reentrancy or progress problems when the awaited operation needs a lock the coroutine still holds.

Workflow