From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50337) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dKnLR-0002uK-02 for qemu-devel@nongnu.org; Tue, 13 Jun 2017 11:03:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dKnLP-0002eJ-Ft for qemu-devel@nongnu.org; Tue, 13 Jun 2017 11:03:01 -0400 Date: Tue, 13 Jun 2017 22:55:00 +0800 From: David Gibson Message-ID: <20170613145500.GB13420@umbus> References: <20170608040857.GV13397@umbus.fritz.box> <20170608115410.2e7a2511@bahia.ttt.fr.ibm.com> <20170612142456.GJ18542@umbus> <20170613093359.4567ba94@bahia.ttt.fr.ibm.com> <20170613080631.GB30171@umbus> <20170613104003.233e21d5@bahia.ttt.fr.ibm.com> <20170613090002.GA2096@work-vm> <20170613112150.7f64171c@bahia.ttt.fr.ibm.com> <20170613095549.GC2096@work-vm> <20170613120552.44c1c58e@bahia.ttt.fr.ibm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="KFztAG8eRSV9hGtP" Content-Disposition: inline In-Reply-To: <20170613120552.44c1c58e@bahia.ttt.fr.ibm.com> Subject: Re: [Qemu-devel] [PATCH v3 5/5] spapr: fix migration of ICPState objects from/to older QEMU List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz Cc: "Dr. David Alan Gilbert" , qemu-devel@nongnu.org, qemu-ppc@nongnu.org, Cedric Le Goater , Juan Quintela --KFztAG8eRSV9hGtP Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jun 13, 2017 at 12:05:52PM +0200, Greg Kurz wrote: > On Tue, 13 Jun 2017 10:55:50 +0100 > "Dr. David Alan Gilbert" wrote: >=20 > > * Greg Kurz (groug@kaod.org) wrote: > > > On Tue, 13 Jun 2017 10:00:03 +0100 > > > "Dr. David Alan Gilbert" wrote: > > > =20 > > > > * Greg Kurz (groug@kaod.org) wrote: =20 > > > > > On Tue, 13 Jun 2017 16:06:31 +0800 > > > > > David Gibson wrote: > > > > > =20 > > > > > > On Tue, Jun 13, 2017 at 09:33:59AM +0200, Greg Kurz wrote: = =20 > > > > > [...] =20 > > > > > > > > > > > +static void pre_2_10_vmstate_register_dummy_icp(sPAP= RMachineState *spapr, int i) > > > > > > > > > > > +{ > > > > > > > > > > > + bool *flag =3D &spapr->pre_2_10_ignore_icp[i]; > > > > > > > > > > > + > > > > > > > > > > > + g_assert(!*flag); =20 > > > > > > > > > >=20 > > > > > > > > > > Apart from this assert(), you never seem to test the va= lues in the > > > > > > > > > > pre_2_10_ignore_icp() array, so it seems a bit pointles= s. > > > > > > > > > > =20 > > > > > > > > >=20 > > > > > > > > > There's the opposite check in pre_2_10_vmstate_unregister= _dummy_icp(). > > > > > > > > > But I agree it isn't really useful... but more because of= paranoia :) =20 > > > > > > > >=20 > > > > > > > > I'm all for paranoid assert()s if they can be made using da= ta readily > > > > > > > > to hand. Adding a data structure just for the purpose of m= aking an > > > > > > > > assert() later, not so much. > > > > > > > > =20 > > > > > > >=20 > > > > > > > It is also passed as opaque argument to vmstate_register(), w= here it is > > > > > > > used as a key when calling vmstate_unregister(). I could poss= ibly pass > > > > > > > (void *) i instead, but I'm not a big fan of hijacking pointe= r arguments > > > > > > > to pass numbers. =20 > > > > > >=20 > > > > > > Ah, I see your point. Creating an array, purely to generate ar= bitrary > > > > > > pointers is also kind of ugly, though. Really the cpu_index / = XICS > > > > > > server number makes sense to identify the vmstate, but it looks= like > > > > > > vmstate_unregister() doesn't take that. > > > > > > =20 > > > > >=20 > > > > > Indeed... what about adding a vmstate_unregister_by_instance_id()= then ? > > > > >=20 > > > > > Cc'ing Juan and David. =20 > > > >=20 > > > > So what's the problem with a (void *)i ? =20 > > >=20 > > > https://stackoverflow.com/questions/8618637/what-does-it-mean-to-conv= ert-int-to-void-or-vice-versa > > > =20 > > > > It's simple, as long as you're > > > > not actually using the opaque anywhere it's easy. > > > > =20 > > >=20 > > > but as you say, since the opaque isn't used anywhere, it is probably > > > okay to pass (void *) i. =20 > >=20 > > Yes, I don't think we're ever casting back from the (void *) to an int > > so it feels pretty safe to me. > >=20 >=20 > Just one nit, gcc doesn't like it on 64-bit hosts: >=20 > hw/ppc/spapr.c: In function =E2=80=98pre_2_10_vmstate_register_dummy_icp= =E2=80=99: > hw/ppc/spapr.c:148:60: error: cast to pointer from integer of different > size [-Werror=3Dint-to-pointer-cast] > vmstate_register(NULL, i, &pre_2_10_vmstate_dummy_icp, (void *) i); >=20 > I need to cast to (long) first. No, you need to cast to uintptr_t first. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --KFztAG8eRSV9hGtP Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJZP/zBAAoJEGw4ysog2bOSPDkQAM/QEVJgd7mt2qh1NuH5Ap2/ p2oD3t1OwikVoDHM58T2d54cN/DEOXPUWS2xd9ALnl+lOq3qNfmRiLgG5vWvOH06 E3Dc4Avuac0MzwZk1UdwRNLfMCrsnG2L8gss2UavATyPYUHkskOq8hg2vcAZWSm1 FHZlWAAUpDAsVUWsusKWEeQuuxRZSerECVpUuFHurY41s7tISOJDzVlwdPxHMBud TAnuKesEel+VSYoZOy7TReJk2akjwHFjLiY1AfhANLXK5JjcXst/TJ0d1Z034Ymy 2ZIxkR9HPO8XjucEzY2F5Gdma/ikEv29Jo8niI03sDR9LpWoYTmTlqaFNuy6qfAh mpo8sieFaig5crieoYEV3rU1YZUkY8dHporDJh4+D0Y3lx/Rc4Q1RueCWmnVQ9V6 BGnPZhpFC+/HtMaAeREpPFYWgWbJuQo+UehCP6PVKMcSLBbEPbbTHJrBVQqapVMe jAERGjiIvAuwcXbNvGE5ZvPSJRCDh6FyiiaMmtnTEza2mxAZaIzh3BUpUFQQ0BVi mQo4w6ZIHIqcOKTZOjWfhiL6lEFsIpgX0/GDmxPqTs4ADfjKYSSYYqO4QEZ1tkQ5 psMN5gd6pDMMOb4kpGBGRIrSbjiiFnw9Wrg4dwtf+FNB2fbpL6ruxnU7IL6/WPoC GwwJkHq57IeT4RdmSVeE =THhf -----END PGP SIGNATURE----- --KFztAG8eRSV9hGtP--