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Subject: Re: Recent testsuite/winsup.api/pthread/cancel2 failure
To: cygwin@cygwin.com
References: <20251214162637.1ee05b084788ba073fe94670@nifty.ne.jp>
 <20251214163936.6841fc62145d8f54cfa31fe7@nifty.ne.jp>
 <9d058204-fb3f-43b4-9e32-6adc7af12ff4@dronecode.org.uk>
Organization: WiseMo A/S
Message-ID: <77acb030-e983-6841-b475-f360ad90be48@wisemo.com>
Date: Tue, 16 Dec 2025 16:48:09 +0100
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From: Jakob Bohm via Cygwin <cygwin@cygwin.com>
Reply-To: Jakob Bohm <jb-cygwin@wisemo.com>
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On 16/12/2025 14:11, Jon Turney via Cygwin wrote:
> On 14/12/2025 07:39, Takashi Yano via Cygwin wrote:
>> On Sun, 14 Dec 2025 16:26:37 +0900
>> Takashi Yano via Cygwin <cygwin@cygwin.com> 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.
>
Historically, CloseHandle() would simply return FALSE (0) for bad 
handles.  If this changed, it is a regression in Windows itself. 
Debug/Checked builds of Windows might report the bad handle to the 
debugger, but the Release/Free builds would not throw an exception, BSOD 
or other kind of assert().

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

Jakob
-- 
Jakob Bohm, CIO, Partner, WiseMo A/S.  https://www.wisemo.com
Transformervej 29, 2860 Søborg, Denmark.  Direct +45 31 13 16 10
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