core: Fix data race in mission transfer WorkItem dtor#2792
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Use unregister_all_blocking() instead of unregister_all() in WorkItem destructors to wait for any in-flight message handler callbacks to complete before destroying the object. The non-blocking variant uses try_to_lock which can fail if a callback is executing, causing use-after-free when the destructor proceeds to deallocate members.
JonasVautherin
previously approved these changes
Mar 11, 2026
Defer WorkItem destruction to after releasing the LockedQueue mutex. The WorkItem destructor calls unregister_all_blocking() which acquires the message handler mutex, while process_message() holds the message handler mutex and can push_back() to the queue - causing a deadlock cycle.
Add mutex to protect _system_ids unordered_set which was being concurrently read by has_system_id() (work thread) and written to by receive_message() (UDP receive thread).
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Use unregister_all_blocking() instead of unregister_all() in WorkItem destructors to wait for any in-flight message handler callbacks to complete before destroying the object. The non-blocking variant uses try_to_lock which can fail if a callback is executing, causing use-after-free when the destructor proceeds to deallocate members.
Should fix thread sanitizer issue which happened in https://github.com/mavlink/MAVSDK/actions/runs/22841268305/job/66247808660?pr=2790.