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Re: [Qemu-devel] [PATCH v3 4/9] ide: Drop redundant IDEState member bs


From: Markus Armbruster
Subject: Re: [Qemu-devel] [PATCH v3 4/9] ide: Drop redundant IDEState member bs
Date: Wed, 05 Feb 2014 15:07:06 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.2 (gnu/linux)

[Note cc: Stefano]

Kevin Wolf <address@hidden> writes:

> Am 30.01.2014 um 13:16 hat Markus Armbruster geschrieben:
>> It's a copy of dev->conf.bs.  The copy was needed for non-qdevified
>> controllers, which lacked dev.
>> 
>> Note how pci_piix3_xen_ide_unplug() cleared the copy.  We'll get back
>> to that in the next few commits.
>> 
>> Signed-off-by: Markus Armbruster <address@hidden>
>
> So this pci_piix3_xen_ide_unplug() is what happens here:
>
>> --- a/hw/ide/piix.c
>> +++ b/hw/ide/piix.c
>> @@ -169,12 +169,9 @@ static int pci_piix_ide_initfn(PCIDevice *dev)
>>  
>>  static int pci_piix3_xen_ide_unplug(DeviceState *dev)
>>  {
>> -    PCIIDEState *pci_ide;
>>      DriveInfo *di;
>>      int i = 0;
>>  
>> -    pci_ide = PCI_IDE(dev);
>> -
>>      for (; i < 3; i++) {
>>          di = drive_get_by_index(IF_IDE, i);
>>          if (di != NULL && !di->media_cd) {
>> @@ -183,7 +180,6 @@ static int pci_piix3_xen_ide_unplug(DeviceState *dev)
>>                  bdrv_detach_dev(di->bdrv, ds);
>>              }
>>              bdrv_close(di->bdrv);
>> -            pci_ide->bus[di->bus].ifs[di->unit].bs = NULL;
>>              drive_put_ref(di);
>>          }
>>      }
>
> Probably I'm just missing the obvious, but it seems to me that the
> copy was cleared here, while the original was left around. This was
> no problem because the original was unused anyway after device
> initialisation.
>
> Now that the copy doesn't exist any more, we can't clear it, obviously,
> but why don't we have to clear the original? Won't we still run the
> "device is attached" code branches even though the device is really
> unplugged?

It's been a while since I wrote this.  Almost 14 months, in fact.

No other IDE controller implements DeviceClass method unplug().  I can't
remember why the normal code to detach the backend (release_drive())
doesn't do here.  Stefano, can you help?



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