Re: Recent testsuite/winsup.api/pthread/cancel2 failure

On 14/12/2025 07:39, Takashi Yano via Cygwin wrote:
> On Sun, 14 Dec 2025 16:26:37 +0900
> Takashi Yano via Cygwin <[email protected]> wrote:
> 
>> Recently, I have concerned that testsuite winsup.api/pthread/cancel2 fails
>> consistently.
>>
>> https://github.com/cygwin/cygwin/actions/runs/19926408142/job/57127200619

Thanks very much for looking into this!

I have the vague idea that this problem started showing up (more?) when 
the CI VM was upgraded from Windows Server 2022 to Windows Server 2025, 
but I guess that's maybe just timings...

>>
>> I'm not sure why this happens, but it also falis in my local environment.
>> I looked into this issue a bit, and found that access violation happnes
>> in CloseHandle() in _cygtls::remove().
>>
>> And I am also not sure why at all, cancel2 works if CloseHandle()'s are
>> replaced with NtClose() as follows.

I think this is just the difference between the two calls: CloseHandle 
generates an exception whereas NtClose returns an error code if the 
handle is invalid.

Doesn't really explain whats wrong with the handle, though.

>>
>> diff --git a/winsup/cygwin/cygtls.cc b/winsup/cygwin/cygtls.cc
>> index 13d133f47..249c8cb18 100644
>> --- a/winsup/cygwin/cygtls.cc
>> +++ b/winsup/cygwin/cygtls.cc
>> @@ -118,7 +118,7 @@ _cygtls::remove (DWORD wait)
>>       {
>>         HANDLE h = signal_arrived;
>>         signal_arrived = NULL;
>> -      CloseHandle (h);
>> +      NtClose (h);
>>       }
>>   
>>     if (locals.drivemappings)
>> @@ -148,7 +148,7 @@ _cygtls::remove (DWORD wait)
>>     if (mutex)
>>       {
>>         ReleaseMutex (mutex);
>> -      CloseHandle (mutex);
>> +      NtClose (mutex);
>>       }
>>   }
>>   
>>
>> Any idea?
> 
> I forgot to mention that the thread crashes when canceled with
> PTHREAD_CANCEL_ASYNCHRONOUS.
> 
> PTHREAD_CANCEL_DEFERRED works without the problem.

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