On Thu, 16 Feb 2006 19:56:52 +0100
Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx> wrote:
> Randy Dunlap wrote:
> > On Thu, 16 Feb 2006 09:58:33 +0100
> > Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx> wrote:
> >>Why are you calling these from SCSI? Wouldn't ahci_pci_driver.remove()
> >>and piix_pci_driver.remove() be a proper place to perform what you are
> >>doing in ata_device_shutdown?
> >
> > Mostly to have the scsi_device pointers available.
>
> Note that roughly as long a scsi_device exists, SCSI high-level drivers
> expect to be able to send commands to them. In particular, when
> scsi_remove_device is called, (or scsi_remove_host, which calls
> scsi_remove_device for all still existing devices of a host), the SCSI
> high-level drivers' shutdwon methods get executed. Some of them send
> SCSI commands. The upshot is, a SCSI low-level driver has to be able to
> handle newly enqueued command while it is calling
> scsi_remove_{device,host}. Moreover it must not block a SCSI host at
> this moment.
>
> IOW the most natural order for layers to shut down would be first SCSI,
> then ATA. (But then, I don't really comprehend whether your shutdown
> code would actually collide with that of the SCSI subsystem at all.)
OK, now it seems like you just told me why I shouldn't use
the pci_driver.remove() interface. But thanks for your comments,
I do appreciate them and will dig deeper [into a twisty maze :].
anyone else care to comment on this?
---
~Randy
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