From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:38572) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tkl1f-0004df-Qn for qemu-devel@nongnu.org; Mon, 17 Dec 2012 19:27:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Tkl1d-0007eB-1P for qemu-devel@nongnu.org; Mon, 17 Dec 2012 19:27:15 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41990) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tkl1c-0007e6-Q1 for qemu-devel@nongnu.org; Mon, 17 Dec 2012 19:27:12 -0500 Date: Tue, 18 Dec 2012 02:30:16 +0200 From: "Michael S. Tsirkin" Message-ID: <20121218003016.GA15241@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> <20121217225852.GA12661@redhat.com> <50CFB51E.5030108@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <50CFB51E.5030108@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 Tue, Dec 18, 2012 at 01:13:18AM +0100, Andreas F=E4rber wrote: > Am 17.12.2012 23:58, schrieb Michael S. Tsirkin: > > 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 vecto= r) > >>>>>>>>> { > >>>>>>>>> - 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= all > >>>>>>>> others know that from PCI host bridges! > >>>>>>> > >>>>>>> Well, that's just a difference of VIRTIO_PCI_PROXY(d) vs. conta= iner_of. > >>>>>> > >>>>>> VIRTIO_PCI_PROXY(d) would be acceptable, sure. But as-is this pa= tch just > >>>>>> pushes unnecessary work on Fred, me, you or anyone else who work= s with QOM. > >>>>> > >>>>> What's VIRTIO_PCI_PROXY? Note this is data path we do not want ex= tra > >>>>> code. > >>>> > >>>> My complaint is the direct access of pci_dev, qdev, etc. parent fi= elds > >>>> in many places as the main change of this patch. Those mean more p= laces > >>>> to touch in a future patch. > >>>> > >>>> Use of any new-style macro hiding these - wherever the particular = one > >>>> suggested may be defined or whether it needs to be added - is bett= er. > >>>> > >>>> If performance of dynamic_cast is an issue - something I'd leave y= ou to > >>>> discuss with Anthony - you can just do a C cast directly. Just don= 't > >>>> spread this qdev paradigm further please. > >>> > >>> OK so just > >>> > >>> #define VIRTIO_PCI_PROXY(d) container_of(d, VirtIOPCIProxy, pci_dev= .qdev) > >>> > >>> is OK with you? > >> > >> Well, at least it's better than inlining it... > >> > >> I would've expected to see VIRTIO_PCI_PROXY(obj) defined as > >> OBJECT_CHECK(VirtIOPCIProxy, (obj), TYPE_something) somewhere. > >> > >> If, as you imply with "data path", this were a problem, you could ju= st > >> do VirtIOPCIProxy *proxy =3D (VirtIOPCIProxy *)d inline to allow for > >> VIRTIO_PCI_PROXY() to be used in the QOM sense elsewhere. > >=20 > > 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 > I don't get what you don't get Wha'ts the QOM way to get virtio pci proxy from devicestate? C cast is not what I am looking for.