From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37200) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1frn9s-0007s1-Lf for qemu-devel@nongnu.org; Mon, 20 Aug 2018 12:36:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1frn9r-0001FR-R2 for qemu-devel@nongnu.org; Mon, 20 Aug 2018 12:36:00 -0400 References: <1b072083-700b-9853-e525-e2726bf17476@virtuozzo.com> <20180817180440.49687-1-vsementsov@virtuozzo.com> <4d266435-855b-7900-0ad0-d677a568ebf7@redhat.com> <8ce95ada-2162-d22f-6925-a97309d8c48a@virtuozzo.com> <7cd836ad-7270-fe65-d0bd-32b0423d07be@redhat.com> From: Max Reitz Message-ID: Date: Mon, 20 Aug 2018 18:35:44 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="qBa1HKmKF0aamZoUAyp21VUVjUydvBkXm" Subject: Re: [Qemu-devel] [PATCH v2 1/3] qapi: add x-query-block-graph List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladimir Sementsov-Ogievskiy , Eric Blake , qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: crosa@redhat.com, ehabkost@redhat.com, armbru@redhat.com, kwolf@redhat.com, famz@redhat.com, jsnow@redhat.com, den@openvz.org, stefanha@redhat.com, pbonzini@redhat.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --qBa1HKmKF0aamZoUAyp21VUVjUydvBkXm From: Max Reitz To: Vladimir Sementsov-Ogievskiy , Eric Blake , qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: crosa@redhat.com, ehabkost@redhat.com, armbru@redhat.com, kwolf@redhat.com, famz@redhat.com, jsnow@redhat.com, den@openvz.org, stefanha@redhat.com, pbonzini@redhat.com Message-ID: Subject: Re: [PATCH v2 1/3] qapi: add x-query-block-graph References: <1b072083-700b-9853-e525-e2726bf17476@virtuozzo.com> <20180817180440.49687-1-vsementsov@virtuozzo.com> <4d266435-855b-7900-0ad0-d677a568ebf7@redhat.com> <8ce95ada-2162-d22f-6925-a97309d8c48a@virtuozzo.com> <7cd836ad-7270-fe65-d0bd-32b0423d07be@redhat.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 2018-08-20 17:13, Vladimir Sementsov-Ogievskiy wrote: > 20.08.2018 16:44, Max Reitz wrote: >> On 2018-08-20 12:20, Vladimir Sementsov-Ogievskiy wrote: [...] >>> My goal is to get graphviz representation of block graph with all the= >>> parents for debugging. And I'm absolutely ok to do it with x-debug-. >>> Then we shouldn't care about enum for role type now. So, it the patch= ok >>> for you with x-debug- prefix? >> Actually, no, because I'm not sure whether using points for the IDs is= a >> good idea.=C2=A0 That may defeat ASLR, and that would be a problem eve= n with >> x-debug-. >=20 > Good point, agree. >=20 >> >> So I'd prefer using e.g. a hash map to map pointers to freshly generat= ed >> IDs (just incrementing integers). (By the way, that would also improve the speed of checking whether a certain node needs to be added to the @nodes list still.) >> In any case, I'll take a further look at the patch later, but another >> thing that I've just seen is that using the opaque pointers to identif= y >> a parent is something that doesn't look like it's guaranteed to work. >=20 > Hm, isn't it a bug? Can you point to an example? Ah, no, it's OK. Well, kind of. It's OK in the sense that it is unique when set. I didn't notice that you only use it for the non-node parents, sorry. Still, it probably would be better to just use the BdrvChild object, as that should be unique as well, and it is obviously non-NULL. (BdrvChild.opaque may be NULL, even though it isn't in practice.) Max --qBa1HKmKF0aamZoUAyp21VUVjUydvBkXm Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAlt67eAACgkQ9AfbAGHV z0BA8wgAkZQipyubdl+AehqhlRNgHaJUWfkM+sxcuHbFIuYZepzG9sQLj/0NAldR cjZZ2IWRxlHEx//84vg2bgOCBdoaqKeQ3vyHlqB8LirT12x4/jkSATMr65h1U2iq wtadJrsaQca3OUjyS0xvwplodIMq1/StHoLtrLvPYAtaxLaVHY6HImte7DcAagre bRyq051B393x0p8MnzW4tu/ObKo3l5BVDBASIUgj1ZJsp56L07PYuyGlcUa+Xn60 N1/PMCx7yPFV+g7+gYIskQNTI3o7sHg8IYTUwQr+HK/d5CBgyTH7xO3DcZr8kNUI G3JW1QaZ7hsI54Xx0MVSUD0Ytzqxqg== =AO4K -----END PGP SIGNATURE----- --qBa1HKmKF0aamZoUAyp21VUVjUydvBkXm--