X-Recipient:	archive-cygwin AT delorie DOT com
DomainKey-Signature:	a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:subject:to:references:from:message-id:date
	:mime-version:in-reply-to:content-type; q=dns; s=default; b=XWhx
	wkJ/6oS1aTlTYsRt0ioOnawLCn4dwxDjHHOMrs2tBwWyeIWbdEFMk3KWzzbt+bSE
	Ggx/Q9BM28MnKbxl2KqW0rf8dWJiUPAQutYMWfYin5EvpGwVJiY7V3L2IrgeckcV
	c2e5evP4TBcEA+rjtNrSHSoGhYyYwQVNWsRA5wY=
DKIM-Signature:	v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:subject:to:references:from:message-id:date
	:mime-version:in-reply-to:content-type; s=default; bh=SMuUOgdsLa
	oEgyklL0HiUn4Hk08=; b=O9qcjSo6cpXZgSOvCEnngDFx1CK/sXIwjmvAem4mLw
	5wJoDKzMudNPtGsxBNsGqMjm9oP6CHa3aCQb+J7h/usVLLMYo7AIYxHF74XGBxaa
	wpu21F2Xh1fUgKxwrN9m6fVxLA6lB0NXzjwIyfui3NvmX0bSEOI4v04xgiHOz2jA
	g=
Mailing-List:	contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id:	<cygwin.cygwin.com>
List-Subscribe:	<mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive:	<http://sourceware.org/ml/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender:	cygwin-owner AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
Delivered-To:	mailing list cygwin AT cygwin DOT com
Authentication-Results:	sourceware.org; auth=none
X-Spam-SWARE-Status:	No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_PASS autolearn=ham version=3.3.1 spammy=principal, DOES, expires
X-HELO:	mx1.redhat.com
Subject:	Re: Is async-signal-safety applicable to Cygwin?
To:	cygwin AT cygwin DOT com
References:	<f80444ec-69b9-0177-dd75-c994092380fd AT gmail DOT com>
From:	Eric Blake <eblake AT redhat DOT com>
Openpgp:	preference=signencrypt
Message-ID:	<9e5ce156-19c2-8379-6e29-8997c1700d5b@redhat.com>
Date:	Tue, 19 Mar 2019 09:35:19 -0500
User-Agent:	Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1
MIME-Version:	1.0
In-Reply-To:	<f80444ec-69b9-0177-dd75-c994092380fd@gmail.com>
X-IsSubscribed:	yes

--7V9SnJ5MdHGL2Mu7723BekRxN10c6iJI5
Content-Type: multipart/mixed; boundary="BIemsF0heglGvAWvjVab8Ih3xZ3pT2odR";
 protected-headers="v1"
From: Eric Blake <eblake AT redhat DOT com>
To: cygwin AT cygwin DOT com
Message-ID: <9e5ce156-19c2-8379-6e29-8997c1700d5b AT redhat DOT com>
Subject: Re: Is async-signal-safety applicable to Cygwin?
References: <f80444ec-69b9-0177-dd75-c994092380fd AT gmail DOT com>
In-Reply-To: <f80444ec-69b9-0177-dd75-c994092380fd AT gmail DOT com>


--BIemsF0heglGvAWvjVab8Ih3xZ3pT2odR
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: quoted-printable

On 3/19/19 9:28 AM, LRN wrote:
> ASS[0] is documented for Linux (and for POSIX) but i'm failing to find any
> information on how this applies to Cygwin. I assume, since there are no "=
real"
> signals on Cygwin, that it's not possible for a signal handler to break t=
he
> state of some function that happened to be executed when the signal handl=
er was
> triggered. But i could be wrong.

You are wrong. It IS applicable. Cygwin has signals and signal handlers;
although Windows may not have POSIX signals as such, it DOES have the
ability to interrupt a process mid-function when a timer expires, and
cygwin's implementation of signals on top of the semantics that windows
provides can indeed result in interrupting the middle of a
non-async-safe function.  Hence, a signal handler that calls a
non-async-safe function at the same time that the signal has interrupted
another non-async-safe function is indeed observable on Cygwin and can
indeed result in deadlocks (a classic example being the case if you
malloc() from a signal handler that interrupted an ongoing malloc() call).

--=20
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org


--BIemsF0heglGvAWvjVab8Ih3xZ3pT2odR--

--7V9SnJ5MdHGL2Mu7723BekRxN10c6iJI5
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"

-----BEGIN PGP SIGNATURE-----

iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAlyQ/icACgkQp6FrSiUn
Q2pSVQgAj2HYJjXqfmgL+BZnT/hpBr0RD1N0Vd+u4mofGq8k1n8aCSa5P8Qyf6Op
o8S/kQ5hAo6VCsQuxW+pW4zWvxO10wPzN9b3C410Ao3PPUsStqhAzSDP60T+b2Nx
nPDd9BhiQjNNXyYCHWkt2Q3x5gkO2i51jKVIDJ6DAp/L+m0Yn/7zVV5CpY1w+fZ9
nf8ZSlOsezbV9m4EcVR0p4VCLA9qTitfGUNK+zZNbQeZLXcyVCXZ9NgH/ZeTo41w
lqr4x/idcokR31EnYJHmwuC89SzXwkgtv8+L4Fy7VWkvl2JqeEE1vGR5oEK89ZO2
Dk64YTCwAXOvfugN7Tg72agogyDe5A==
=LeYy
-----END PGP SIGNATURE-----

--7V9SnJ5MdHGL2Mu7723BekRxN10c6iJI5--

- Raw text -