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

[Stefano Stabellini]

On Thu, 6 Feb 2014, Markus Armbruster wrote:
> Stefano Stabellini <address@hidden> writes:
> 
> > On Wed, 5 Feb 2014, Markus Armbruster wrote:
> >> [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?
> >
> > Too long to be able to remember the exact details :-/
> > However if you point me to a branch I can give it a try and tell you if
> > the unplug still works as it used to.
> 
> Series trivially rebased to current master available at
> git://repo.or.cz/qemu/armbru.git branch kill-non-qdev-ide

Unfortunately it doesn't work: I can see both sda and xvda being present
after the system has booted.