Re: [Qemu-devel] [PATCH v4 06/10] qemu-ga: Add Windows VSS provider to quiesce applications on fsfreeze

[Laszlo Ersek]

>>>>> +STDAPI DllCanUnloadNow()
>>>>> +{
>>>>> +    return g_nComObjsInUse == 0 ? S_OK : S_FALSE;
>>>>> +}
>>
>> Don't you need some kind of atomic or locked read here? We could read a
>> stale value here. Granted, most stale values would err on the safe side
>> (ie. read >0 instead of ==0), but in theory the other mistake is
>> possible, no?
> 
> MSDN says "Simple reads and writes to properly-aligned 32bit variables
> are atomic", and I couldn't find a function to atomic read provided.
> (Maybe InterlockedCompareExchange(&g_nComObjsInUse, 0, 0)...?)

Alright then. Thanks!
Laszlo