On Sun, 2005-08-07 at 14:43 -0400, Alan Stern wrote:
> What host device release method? scsi_host_template->release is marked
> OBSOLETE and for use only with old-style drivers. scsi_host_dev_release
^^^^^
This is the one I was thinking of adding to.
> is the only release method for hosts, and it doesn't notify the LLD in any
> way.
>
> Anyhow, I'm not so concerned about releasing resources associated with the
> host. The LLD can handle that easily enough by first flagging the HBA
> as not accessible, then waiting for current I/O to terminate, then
> calling scsi_remove_host. The resources can be released any time after
> the current I/O is finished; it doesn't matter whether the host is removed
> before or after.
>
> The only resource that matters for this discussion is associated with the
> LLD itself, not with any of its hosts: the host template. Once the SCSI
> core has released all references to the template, it can't call the LLD
> any more. The problem is that the LLD has no way to know when all the
> references have been dropped. This suggests that the entire problem could
> be solved by adding a kref to struct scsi_host_template.
>
> Would you agree to a patch adding such a kref?
Well, not really. The host template usually exists as a variable in the
module, so its lifetime is tied to the lifetime of the module. Adding a
kref wouldn't help because it will still be freed when the module is
removed. If there's a case where the template is being freed
prematurely because the module is being removed, then we have the module
refcounting wrong somewhere. Have you run across such a case?
James
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