Re: getiobuf(x, false) can sleep ?

[Andrew Doran <ad%NetBSD.org@localhost>]

On Fri, Apr 02, 2010 at 03:45:21PM +0200, Manuel Bouyer wrote:
> On Fri, Apr 02, 2010 at 01:01:12PM +0000, Andrew Doran wrote:
> > > - that buffer queue manipulations are done at splbio() with the
> > >   kernel_lock held in dkstart() and dkstrategy():
> > >     KASSERT(curcpu()->ci_biglock_count > 0);
> > >     KASSERT(curcpu()->ci_ilevel >= IPL_BIO);
> > >     KASSERT(curlwp->l_blcnt > 0); 
> > > - that the buffer doesn't change under us in dkstart():
> > >   KASSERT(BUFQ_GET(sc->sc_bufq) == bp);
> > 
> > Should this not be bufq_peek()?
> 
> No, the bufq_peek() has been done earlier, this is where bp comes from.
> At this point we really want to dequeue the buffer (because we know we can
> handle it); I just changed
>       BUFQ_GET(sc->sc_bufq);
> to
>       KASSERT(BUFQ_GET(sc->sc_bufq) == bp);
> 
> > 
> > Hmm, it shouldn't be doing dkiodone -> dkstart -> VOP_STRATEGY.
> > VOP_STRATEGY should be called with process context (kthread, user).
> > Anyhow that's unlikely to fix your problem.
> 
> dkiodone() is always called from thread or software interrupt context, isn't
> that enough ?

Conceptually VOP_STRATEGY is file system code which always runs with
process context.