Clean up in the pci host generic driver

[andrew]

Summary

Add clean up on failure and a detach function to the pci host generic
driver.

[imp]

sys/dev/pci/pci_host_generic.c

169

Is there any reason that you went with this style over what other drivers do with testing pointers, etc in a generic release routine?

[andrew]

sys/dev/pci/pci_host_generic.c

169

rman_fini is dangerous as it locks rm->rm_mtx. This is allocated via malloc so may be a NULL pointer dereference if rman_init hasn't been called. We could check on rm->rm_mtx, but that feels like it's too much knowledge of the internals that may change.

[jhb]

sys/dev/pci/pci_host_generic.c

566

Given that this driver has no probe method, I assume it's used as a base class for other drivers and not instantiated directly. In that case, are these attach/detach methods ever used or do child classes always define custom methods that call these routines? (For example, I see now calls to bus_generic_attach or bus_generic_detach, so it seems unlikely these routines can be used for attach/detach as-is). If they are always used in custom methods, I think it makes sense to not define device_attach and device_detach in this method list at all.