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Re: [PATCH 51/55] qdev: Make qdev_realize() support bus-less devices
From: |
Markus Armbruster |
Subject: |
Re: [PATCH 51/55] qdev: Make qdev_realize() support bus-less devices |
Date: |
Wed, 20 May 2020 17:02:47 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) |
Paolo Bonzini <address@hidden> writes:
> On 19/05/20 16:55, Markus Armbruster wrote:
>> So far, qdev_realize() supports only devices that plug into a bus:
>> argument @bus cannot be null. Extend it to support bus-less devices,
>> too.
>>
>> qdev_realize_and_unref() remains restricted, because its reference
>> counting would become rather confusing for bus-less devices.
>
> I think it would be fine, you would just rely on the reference held by
> the QOM parent (via the child property).
I took one look at the contract I wrote for it, and balked :)
qdev_realize()'s contract before this patch:
/*
* Realize @dev.
* @dev must not be plugged into a bus.
* Plug @dev into @bus. This takes a reference to @dev.
* If @dev has no QOM parent, make one up, taking another reference.
* On success, return true.
* On failure, store an error through @errp and return false.
*/
bool qdev_realize(DeviceState *dev, BusState *bus, Error **errp)
Simple enough.
This patch merely adds "If @bus, " before "plug". Still simple enough.
qdev_realize_and_unref()'s contract:
/*
* Realize @dev and drop a reference.
* This is like qdev_realize(), except it steals a reference rather
* than take one to plug @dev into @bus. On failure, it drops that
* reference instead. @bus must not be null. Intended use:
* dev = qdev_new();
* [...]
* qdev_realize_and_unref(dev, bus, errp);
* Now @dev can go away without further ado.
*/
bool qdev_realize_and_unref(DeviceState *dev, BusState *bus, Error **errp)
If @bus is null, who gets to hold the stolen reference?
You seem to suggest the QOM parent. What if @dev already has a parent?
Oh, sod it, let's go shopping.
- [PATCH 15/55] pci: Convert uses of pci_create() etc. manually, (continued)
- [PATCH 15/55] pci: Convert uses of pci_create() etc. manually, Markus Armbruster, 2020/05/19
- [PATCH 54/55] qdev: qdev_init_nofail() is now unused, drop, Markus Armbruster, 2020/05/19
- [PATCH 17/55] isa: New isa_new(), isa_realize_and_unref() etc., Markus Armbruster, 2020/05/19
- [PATCH 52/55] qdev: Use qdev_realize() in qdev_device_add(), Markus Armbruster, 2020/05/19
- [PATCH 37/55] sysbus: Drop useless OBJECT() in sysbus_init_child_obj() calls, Markus Armbruster, 2020/05/19
- [PATCH 25/55] usb: New usb_new(), usb_realize_and_unref(), Markus Armbruster, 2020/05/19
- [PATCH 51/55] qdev: Make qdev_realize() support bus-less devices, Markus Armbruster, 2020/05/19
- Re: [PATCH 51/55] qdev: Make qdev_realize() support bus-less devices, Paolo Bonzini, 2020/05/20
- Re: [PATCH 51/55] qdev: Make qdev_realize() support bus-less devices,
Markus Armbruster <=
- Re: [PATCH 51/55] qdev: Make qdev_realize() support bus-less devices, Paolo Bonzini, 2020/05/20
- Re: [PATCH 51/55] qdev: Make qdev_realize() support bus-less devices, Markus Armbruster, 2020/05/25
- Re: [PATCH 51/55] qdev: Make qdev_realize() support bus-less devices, Paolo Bonzini, 2020/05/25
- Re: [PATCH 51/55] qdev: Make qdev_realize() support bus-less devices, Markus Armbruster, 2020/05/26
- Re: [PATCH 51/55] qdev: Make qdev_realize() support bus-less devices, Paolo Bonzini, 2020/05/26
[PATCH 47/55] sysbus: Convert qdev_set_parent_bus() use with Coccinelle, part 3, Markus Armbruster, 2020/05/19
[PATCH 26/55] usb: Convert uses of usb_create(), Markus Armbruster, 2020/05/19
[PATCH 35/55] macio: Convert use of qdev_set_parent_bus(), Markus Armbruster, 2020/05/19
[PATCH 36/55] macio: Eliminate macio_init_child_obj(), Markus Armbruster, 2020/05/19