From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:46745) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TkjbD-00015K-Er for qemu-devel@nongnu.org; Mon, 17 Dec 2012 17:55:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TkjbA-0000WA-Pv for qemu-devel@nongnu.org; Mon, 17 Dec 2012 17:55:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:6360) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TkjbA-0000W6-Gk for qemu-devel@nongnu.org; Mon, 17 Dec 2012 17:55:48 -0500 Date: Tue, 18 Dec 2012 00:58:52 +0200 From: "Michael S. Tsirkin" Message-ID: <20121217225852.GA12661@redhat.com> References: <20121217154521.GA28674@redhat.com> <50CF5CA2.7060800@suse.de> <50CF629A.4090005@redhat.com> <50CF6384.9040809@suse.de> <20121217204811.GB30842@redhat.com> <50CF8AE7.1090803@suse.de> <20121217211831.GA11153@redhat.com> <50CF97EB.9070200@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <50CF97EB.9070200@suse.de> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] virtio: make bindings typesafe List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Andreas =?iso-8859-1?Q?F=E4rber?= Cc: Anthony Liguori , Jan Kiszka , qemu-devel@nongnu.org, Alexander Graf , Christian Borntraeger , Paolo Bonzini , fred.konrad@greensocs.com On Mon, Dec 17, 2012 at 11:08:43PM +0100, Andreas F=E4rber wrote: > Am 17.12.2012 22:18, schrieb Michael S. Tsirkin: > > On Mon, Dec 17, 2012 at 10:13:11PM +0100, Andreas F=E4rber wrote: > >> Am 17.12.2012 21:48, schrieb Michael S. Tsirkin: > >>> On Mon, Dec 17, 2012 at 07:25:08PM +0100, Andreas F=E4rber wrote: > >>>> Am 17.12.2012 19:21, schrieb Paolo Bonzini: > >>>>> Il 17/12/2012 18:55, Andreas F=E4rber ha scritto: > >>>>>> Am 17.12.2012 16:45, schrieb Michael S. Tsirkin: > >>>>>>> diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c > >>>>>>> index 3ea4140..63ae888 100644 > >>>>>>> --- a/hw/virtio-pci.c > >>>>>>> +++ b/hw/virtio-pci.c > >>>>>>> @@ -98,34 +98,34 @@ bool virtio_is_big_endian(void); > >>>>>>> =20 > >>>>>>> /* virtio device */ > >>>>>>> =20 > >>>>>>> -static void virtio_pci_notify(void *opaque, uint16_t vector) > >>>>>>> +static void virtio_pci_notify(DeviceState *d, uint16_t vector) > >>>>>>> { > >>>>>>> - VirtIOPCIProxy *proxy =3D opaque; > >>>>>>> + VirtIOPCIProxy *proxy =3D container_of(d, VirtIOPCIProxy, = pci_dev.qdev); > >>>>>> > >>>>>> Nack. This is going the wrong direction QOM-wise and you among a= ll > >>>>>> others know that from PCI host bridges! > >>>>> > >>>>> Well, that's just a difference of VIRTIO_PCI_PROXY(d) vs. contain= er_of. > >>>> > >>>> VIRTIO_PCI_PROXY(d) would be acceptable, sure. But as-is this patc= h just > >>>> pushes unnecessary work on Fred, me, you or anyone else who works = with QOM. > >>> > >>> What's VIRTIO_PCI_PROXY? Note this is data path we do not want extr= a > >>> code. > >> > >> My complaint is the direct access of pci_dev, qdev, etc. parent fiel= ds > >> in many places as the main change of this patch. Those mean more pla= ces > >> to touch in a future patch. > >> > >> Use of any new-style macro hiding these - wherever the particular on= e > >> suggested may be defined or whether it needs to be added - is better. > >> > >> If performance of dynamic_cast is an issue - something I'd leave you= to > >> discuss with Anthony - you can just do a C cast directly. Just don't > >> spread this qdev paradigm further please. > >=20 > > OK so just > >=20 > > #define VIRTIO_PCI_PROXY(d) container_of(d, VirtIOPCIProxy, pci_dev.q= dev) > >=20 > > is OK with you? >=20 > Well, at least it's better than inlining it... >=20 > I would've expected to see VIRTIO_PCI_PROXY(obj) defined as > OBJECT_CHECK(VirtIOPCIProxy, (obj), TYPE_something) somewhere. >=20 > If, as you imply with "data path", this were a problem, you could just > do VirtIOPCIProxy *proxy =3D (VirtIOPCIProxy *)d inline to allow for > VIRTIO_PCI_PROXY() to be used in the QOM sense elsewhere. >=20 > Andreas I don't get it - where? Since we don't do runtime checks we need container_of - safer than a plain cast. Anyway, when you start doing your QOM conversions it will be easy to do what you like. > --=20 > SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg, Germany > GF: Jeff Hawn, Jennifer Guild, Felix Imend=F6rffer; HRB 16746 AG N=FCrn= berg