Re: [Qemu-devel] [PATCH 10/13] Implement scsi device destruction

[Gerd Hoffmann <kraxel@redhat.com>]

   Hi,

> If I understand this correctly, SCSI devices "overwrite": if you add a
> new one with an existing SCSI ID, the old one gets disconnected
> automatically.  Isn't that inconsistent with other buses?  PCI,
> specifically.  Question applies before your patch already.

Yes, this is correct.
I've just maintained current behavior.

To extend that question:  While playing with that I've noticed linux 
does not automagically find the a scsi disk hot-plugged in.  After 
reboot (and the scsi bus rescan triggered by that) it finds the disk. 
Reloading the driver module probably would have worked too.  We don't 
signal the guest in any way it got a new disk, so this isn't exactly 
surprising.  Is this just a emulation limitation?  Or a limitation of 
the emulated scsi host adapters?

>> +static int scsi_qdev_exit(DeviceState *qdev)
>> +{
>> +    SCSIDevice *dev = DO_UPCAST(SCSIDevice, qdev, qdev);
>> +    SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, dev->qdev.parent_bus);
>> +
>> +    assert(bus->devs[dev->id] != NULL);
>> +    if (bus->devs[dev->id]->info->destroy) {
>> +        bus->devs[dev->id]->info->destroy(bus->devs[dev->id]);
>> +    }
>> +    bus->devs[dev->id] = NULL;
>> +    return 0;
>>   }
>
> You have scsi_qdev_exit() as qdev callback exit().  It does the generic
> stuff, then runs the SCSIDevice callback destroy() for the specific
> stuff.  Shouldn't the two callbacks be named the same, to make their
> relation more obvious?

I'm just using the existing callbacks and windup stuff correctly in the 
qdev_free() paths.  Make the naming more consistent would be useful 
indeed, but that is IMHO a job for a separate patch.  And we should 
agree on a naming convention first ;)

cheers,
   Gerd