Alex Chiang wrote:
* Kenji Kaneshige <kaneshige.kenji@xxxxxxxxxxxxxx>:
I'm sorry, but I forgot to tell you one important thing. Now we
are trying to change pci slot management API to setup
pci_slot->hotplug. We must consider how to implement the
counterpart to clean up pci_slot->hotplug at the same time. My
current idea is adding hotplug arg to pci_destroy_slot(), but
it seems a little ugly...
Ugh, I'm not sure which is worse, an unbalanced API vs passing a
hotplug_slot to pci_destroy_slot.
pci_destroy_slot should never touch the pci_slot->hotplug
argument, I think, because it is possible for non-hotplug callers
to call pci_create_slot.
I think the rule should just be:
- all hotplug drivers must use pci_hp_register/deregister
- hotplug drivers must pass a valid hotplug_slot argument
- all detection drivers must use pci_create/destroy_slot
- detection drivers must pass NULL for hotplug_slot
I'm still concerned about one thing. Now that we added hotplug
arg to pci_create_slot(), pci_bus_sem could be used for changing
pci_slot->hotplug. But if there is no generic API to clean up
pci_slot->hotplug, we can't use pci_bus_sem because pci hotplug
core cannot hold pci_bus_sem. As a result, we need to add the
following rule in addition to the above rules.
- hotplug core driver must hold some mutex/semaphore when
calling pci_create_slot()
- hotplug core driver must hold the same mutex/semaphore
when cleaning up pci_slot->hotplug.
That is, even though pci_create_slot provides the interface to
setup pci_slot->hotplug, caller needs to pay attention to race
condition about pci_slot->hotplug. I think it's a little strange.
But I might be overcareful...
Thanks,
Kenji Kaneshige
If you prefer, we could wrap pci_create_slot for detection
drivers:
struct pci_slot *pci_slot_register(struct pci_bus *parent, int slot_nr,
const char *name)
{
return pci_create_slot(parent, slot_nr, name, NULL);
}
EXPORT_SYMBOL_GPL(pci_slot_register);
And then do not export pci_create_slot().
Hm?
/ac
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