The code is here https://source.winehq.org/source/dlls/ntdll/sync.c#0474 https://source.winehq.org/source/dlls/ntdll/sync.c#0474 and it uses compare exchange op

The code is here https://source.winehq.org/source/dlls/ntdll/sync.c#0474 https://source.winehq.org/source/dlls/ntdll/sync.c#0474 and it uses compare exchange operations throughout, so it should be unaffected. The ReactOS implementation is more involved https://doxygen.reactos.org/d1/db8/srw_8c_source.html https://doxygen.reactos.org/d1/db8/srw_8c_source.html but still, it uses mostly CAS operations both for the shared and the exclusive case. So it should be largely free from issues.