From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34503) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z5FUn-0006Kj-JC for qemu-devel@nongnu.org; Wed, 17 Jun 2015 11:43:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z5FUg-0000nw-JF for qemu-devel@nongnu.org; Wed, 17 Jun 2015 11:43:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48674) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z5FUg-0000nm-Dx for qemu-devel@nongnu.org; Wed, 17 Jun 2015 11:43:14 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (Postfix) with ESMTPS id F2B4C33E7F2 for ; Wed, 17 Jun 2015 15:43:13 +0000 (UTC) Message-ID: <5581951F.9050802@redhat.com> Date: Wed, 17 Jun 2015 09:41:19 -0600 From: Eric Blake MIME-Version: 1.0 References: <1434525861-21768-1-git-send-email-mst@redhat.com> <1434525861-21768-2-git-send-email-mst@redhat.com> In-Reply-To: <1434525861-21768-2-git-send-email-mst@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="AaW45VVA4mbMO1SpNaLQH9X822ULi8JEi" Subject: Re: [Qemu-devel] [PATCH v2 1/3] error: don't rely on pointer comparisons List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" , qemu-devel@nongnu.org Cc: kwolf@redhat.com, armbru@redhat.com, dgilbert@redhat.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --AaW45VVA4mbMO1SpNaLQH9X822ULi8JEi Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 06/17/2015 01:24 AM, Michael S. Tsirkin wrote: > makes it possible to copy error_abort pointers, > not just pass them on directly. >=20 > @@ -168,7 +175,7 @@ void error_free(Error *err) > =20 > void error_propagate(Error **dst_errp, Error *local_err) > { > - if (local_err && dst_errp =3D=3D &error_abort) { > + if (local_err && error_is_abort(dst_errp)) { > error_report_err(local_err); > abort(); > } else if (dst_errp && !*dst_errp) { As I pointed out on 3/3, this breaks code that does: if (local_err) { error_propagate(errp, local_err); ... } now that local_err is non-NULL when errp is error_abort. But what if you alter the semantics, and have error_propagate return a bool (true if an error was propagated, false if no error or caller didn't care): bool error_propagate(Error **dst_errp, Error *local_err) { if (error_is_abort(&local_err)) { assert(error_is_abort(dst_errp); return false; } if (local_err && error_is_abort(dst_errp)) { error_report_err(local_err); abort(); } if (dst_errp && !*dst_errp) { *dst_errp =3D local_err; return true; } if (local_err) { error_free(local_err); } return false; } then callers can be modified to this idiom (also has the benefit of being one line shorter): if (error_propagate(errp, local_err)) { ... } --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --AaW45VVA4mbMO1SpNaLQH9X822ULi8JEi Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJVgZUgAAoJEKeha0olJ0NqF/4H+QGtoZGotKdx8MjDfnLMuB5H +6SIiFHKsNK7x4HukDxEnKYTicecjfEeO+3Y2SBn7lOI54wHZo3JP4HCPnaQIsH8 iW5frVVO2l2UZiVjA5WK/yNxrlVxN9hugHKPbcatNtkseNc5+S/lYLShSDL8X/6x 3dl3beScgR2hIiiEG0I14rWm1ePwI5lcmzh7I9u39WzjBBJ5BX0lU50JMmIongcn moJhcyCTUOSfMWFkScftOZf8N5HgSXM8CM+WbYg6cJR/fIpJemV6Y3FhGQlKzhIc PWfHkjc8JHp8Jg8/yVzOZMxKCn6kD0qYN8rj2aIuh5JSA+aMi20adisF7lbKtR0= =zbTn -----END PGP SIGNATURE----- --AaW45VVA4mbMO1SpNaLQH9X822ULi8JEi--