From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46169) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dKn8M-0006DN-BJ for qemu-devel@nongnu.org; Tue, 13 Jun 2017 10:49:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dKn8I-0006CW-Vz for qemu-devel@nongnu.org; Tue, 13 Jun 2017 10:49:30 -0400 Date: Tue, 13 Jun 2017 18:01:46 +0800 From: David Gibson Message-ID: <20170613100146.GA13420@umbus> References: <149685579678.12025.9278446121024037161.stgit@bahia.lan> <149685584629.12025.14875914798241845062.stgit@bahia.lan> <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> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="UlVJffcvxoiEqYs2" Content-Disposition: inline In-Reply-To: <20170613112150.7f64171c@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 --UlVJffcvxoiEqYs2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jun 13, 2017 at 11:21:50AM +0200, Greg Kurz wrote: > On Tue, 13 Jun 2017 10:00:03 +0100 > "Dr. David Alan Gilbert" wrote: >=20 > > * Greg Kurz (groug@kaod.org) wrote: > > > 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(sPAPRMac= hineState *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 values= in the > > > > > > > > pre_2_10_ignore_icp() array, so it seems a bit pointless. > > > > > > > > =20 > > > > > > >=20 > > > > > > > There's the opposite check in pre_2_10_vmstate_unregister_dum= my_icp(). > > > > > > > But I agree it isn't really useful... but more because of par= anoia :) =20 > > > > > >=20 > > > > > > I'm all for paranoid assert()s if they can be made using data r= eadily > > > > > > to hand. Adding a data structure just for the purpose of makin= g an > > > > > > assert() later, not so much. > > > > > > =20 > > > > >=20 > > > > > It is also passed as opaque argument to vmstate_register(), where= it is > > > > > used as a key when calling vmstate_unregister(). I could possibly= pass > > > > > (void *) i instead, but I'm not a big fan of hijacking pointer ar= guments > > > > > to pass numbers. =20 > > > >=20 > > > > Ah, I see your point. Creating an array, purely to generate arbitr= ary > > > > 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() the= n ? > > >=20 > > > Cc'ing Juan and David. =20 > >=20 > > So what's the problem with a (void *)i ? >=20 > https://stackoverflow.com/questions/8618637/what-does-it-mean-to-convert-= 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. Right, that's probably the right short term approach. Incidentally, for a somewhat safer-than-standard approach to this common problem, see https://ccodearchive.net/info/ptrint.html --=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 --UlVJffcvxoiEqYs2 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJZP7gIAAoJEGw4ysog2bOSE68QAKT2HZsHi0QZ99G6e2Wo7HVO EItgsKxrnh30BY8dDgnZMSrvEPCAtTZxWZDYxKWsXsBtnlaj/1dQ/tdczgfokYZg lMlrD6e2BC3Hg5tKVb3zHdHIe1lUWPPPxe4uzMCdvDWjEcgVvoEWlwYaRhooqGvU Fa8bweI3PTzr68QKtdfBT3y+REYmqE03e9ti/gLhWn0fA1lOibwOOQb3QDketxFp e81qlnYFe3CamwonB9Nw4NgA1WwMhKaS6hZsGpEBWnlKNY6HPGcb1HPiqPXl3MFg naPlbNP8TTAtAYkBH6xvMX7qJqoWA8ODmz3vRq/IhDcPpVZ87w0DWPfA7ho46Ik8 v2ZAU5qf5X4c12+P1f0Gk+Rdd+4IT3ErXnJcB8N/DbZZjTxtg5Ss1En1RQb/K/HJ 7ivF/aktWeQznEq9HUTVmUDTdhPvrpCqlwNHRoxjtsSOaTOT5bYFsmMWFiPH4P/X /pDl1U0DQ1kOol1J6TpAqCM1ipCnYEatfKt9zE1sR6qtqVFi9OXD0lGiz4w2p+sE bpsUXSeu4oVfjHz0Q2i4mNiGL2Mgl/RB/qLpZ880K/n4HgtE7qPudeBdfkVpjhjj 8jZII5VB2qKW73uQgpkks125ej0Y1b0gSr77eMNYvSVFZWzOZpaBWyprraj/sUqN b8fLzTOhXbrdDEIP0Niw =wVjS -----END PGP SIGNATURE----- --UlVJffcvxoiEqYs2--