> > > > Would proc still be NULL if the IOCTL is called from a kernel thread ?
> > > 
> > > We're making the semantics of such a call up as we go along. However I 
> > > think that passing proc == NULL if the secondary addresses are in kernel 
> > > space is reasonable.
> > 
> > Won't this cause problems if the ioctl wants to sleep ?
> 
> Hmm.... Yes.

what's a problem if it sleeps?

YAMAMOTO Takashi