> > it's better to distinguish them from normal specfs operations.
> > ie. another REQ_xxx, rather than using NULL/NODEV.
> 
> Oh, in that case, I can revert the previous change; though you'll have
> to help a bit with that as I'm unfamiliar with them.

i'm not familiar with details of each drivers either...
let's ask authers. :)  it seems that ad@ wrore or ported many of them.

> What requests are we looking at? IIUC you can't really tell what kind
> of request it is, so we should probably have a single request to
> identify these, or do you have a better idea?

i think that a single request with dev_t of a controller as a context
can cover the most cases.

YAMAMOTO Takashi