Re: [Qemu-devel] [PATCH for-1.5 4/4] virtio-scsi: fix the command line compatibility.

["KONRAD Frédéric" <fred.konrad@greensocs.com>]

On 29/04/2013 19:55, Andreas Färber wrote:
> Am 29.04.2013 19:39, schrieb KONRAD Frédéric:
>> On 29/04/2013 18:32, Paolo Bonzini wrote:
>>> Il 29/04/2013 18:28, KONRAD Frédéric ha scritto:
>>>>> Could this be simply a qdev property?
>>>> Yes, that can be a good idea.
>>>>
>>>> What about adding a qdev property bus_name and using it in qbus_realize?
>>>>
>>>> Like this:
>>>>
>>>> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
>>>> index 4eb0134..c5d5407 100644
>>>> --- a/hw/core/qdev.c
>>>> +++ b/hw/core/qdev.c
>>>> @@ -421,6 +421,13 @@ static void qbus_realize(BusState *bus, DeviceState
>>>> *parent, const char *name)
>>>>
>>>>        if (name) {
>>>>            bus->name = g_strdup(name);
>>>> +    } else if (bus->parent && bus->parent->bus_name) {
>>>> +        /* parent device has bus_name -> use it for bus name */
>>>> +        len = strlen(bus->parent->bus_name) + 16;
>>>> +        buf = g_malloc(len);
>>>> +        snprintf(buf, len, "%s.%d", bus->parent->bus_name,
>>>> +                 bus->parent->num_child_bus);
>>>> +        bus->name = buf;
>>>>        } else if (bus->parent && bus->parent->id) {
>>>>            /* parent device has id -> use it for bus name */
>>>>            len = strlen(bus->parent->id) + 16;
>>>>
>>>> If so, change to scsi_bus_new is not needed and the two new functions
>>>> are
>>>> not needed.
>>>>
>>>> Is that making sense?
>>> Ah, that's a bit more extreme. :)
>>>
>>> I think I like it, but I need more input.
>>>
>>> Paolo
>> Well, just for virtio-scsi-pci, something like that:
>>
>> ---
>>   hw/core/qdev.c         | 14 ++++++++++++++
>>   hw/virtio/virtio-pci.c |  9 +++++++++
>>   include/hw/qdev-core.h |  4 ++++
>>   3 files changed, 27 insertions(+)
>>
>> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
>> index 4eb0134..3aa0082 100644
>> --- a/hw/core/qdev.c
>> +++ b/hw/core/qdev.c
>> @@ -342,6 +342,13 @@ BusState *qdev_get_child_bus(DeviceState *dev,
>> const char *name)
>>       return NULL;
>>   }
>>
>> +void qdev_set_bus_name(DeviceState *dev, const char *bus_name)
> device_... for new functions please. :)
>
>> +{
>
> Might be called multiple times, so better insert:
>
> if (dev->bus_name) {
>      g_free(dev->bus_name);
>      dev->bus_name = NULL;
> }
>
>> +    if (bus_name) {
>> +        dev->bus_name = g_strdup(bus_name);
>> +    }
>> +}
>> +
>>   int qbus_walk_children(BusState *bus, qdev_walkerfn *devfn,
>>                          qbus_walkerfn *busfn, void *opaque)
>>   {
>> @@ -421,6 +428,13 @@ static void qbus_realize(BusState *bus, DeviceState
>> *parent, const char *name)
>>
>>       if (name) {
>>           bus->name = g_strdup(name);
>> +    } else if (bus->parent && bus->parent->bus_name) {
>> +        /* parent device has bus_name -> use it for bus name */
> This seems backwards to me. qdev had made sure to have a 1:n
> relationship between device and bus, whereas you are making the name
> template 1:1 here. Don't you rather want a qbus_set_name() mechanism
> operating on the bus?

What do you mean with the relationship 1:n / 1:1 I don't understand?

Note: I did that quickly to ask Paolo if it was worth doing like that or 
like the original
          series.
>
>> +        len = strlen(bus->parent->bus_name) + 16;
> Why 15 decimal digits? Is there any constant we could reuse?
>
>> +        buf = g_malloc(len);
>> +        snprintf(buf, len, "%s.%d", bus->parent->bus_name,
>> +                 bus->parent->num_child_bus);
>> +        bus->name = buf;
>>       } else if (bus->parent && bus->parent->id) {
>>           /* parent device has id -> use it for bus name */
>>           len = strlen(bus->parent->id) + 16;
>> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
>> index 070df44..8d5d146 100644
>> --- a/hw/virtio/virtio-pci.c
>> +++ b/hw/virtio/virtio-pci.c
>> @@ -1106,11 +1106,20 @@ static int
>> virtio_scsi_pci_init_pci(VirtIOPCIProxy *vpci_dev)
>>       VirtIOSCSIPCI *dev = VIRTIO_SCSI_PCI(vpci_dev);
>>       DeviceState *vdev = DEVICE(&dev->vdev);
>>       VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
>> +    DeviceState *proxy = DEVICE(dev);
>>
>>       if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) {
>>           vpci_dev->nvectors = vs->conf.num_queues + 3;
>>       }
>>
>> +    /*
>> +     * For command line compatibility, this set the virtio-scsi-device bus
> "sets"
>
>> +     * name as before.
>> +     */
>> +    if (proxy->id) {
>> +        qdev_set_bus_name(vdev, proxy->id);
>> +    }
>> +
>>       qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus));
>>       if (qdev_init(vdev) < 0) {
>>           return -1;
>> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
>> index cf83d54..332e11f 100644
>> --- a/include/hw/qdev-core.h
>> +++ b/include/hw/qdev-core.h
>> @@ -125,6 +125,7 @@ struct DeviceState {
>>       int num_child_bus;
>>       int instance_id_alias;
>>       int alias_required_for_version;
>> +    const char *bus_name;
>>   };
>>
>>   #define TYPE_BUS "bus"
>> @@ -224,6 +225,9 @@ BusState *qdev_get_child_bus(DeviceState *dev, const
>> char *name);
>>   void qdev_init_gpio_in(DeviceState *dev, qemu_irq_handler handler, int n);
>>   void qdev_init_gpio_out(DeviceState *dev, qemu_irq *pins, int n);
>>
>> +/* Set the bus_name property. */
>> +void qdev_set_bus_name(DeviceState *dev, const char *bus_name);
>> +
>>   BusState *qdev_get_parent_bus(DeviceState *dev);
>>
>>   /*** BUS API. ***/
> Andreas
>