Re: serialize access to ide device

[Jens Axboe <axboe@suse.de>]

On Mon, Aug 23 2004, Bartlomiej Zolnierkiewicz wrote:
> On Monday 23 August 2004 14:15, Jens Axboe wrote:
> > On Sat, Aug 21 2004, Bartlomiej Zolnierkiewicz wrote:
> > > On Saturday 21 August 2004 18:21, Jens Axboe wrote:
> > > > On Sat, Aug 21 2004, Bartlomiej Zolnierkiewicz wrote:
> > > > > On Saturday 21 August 2004 12:32, Jens Axboe wrote:
> > > > > > > What about adding new kind of REQ_SPECIAL request and converting
> > > > > > > set_using_dma(), set_xfer_rate(), ..., to be callback functions
> > > > > > > for this request?
> > > > > > >
> > > > > > > This should be a lot cleaner and will cover 100% cases.
> > > > > >
> > > > > > That will still only serialize per-channel. But yes, a lot cleaner.
> > > > >
> > > > > per hwgroup not per channel
> > > > > (serializing per host device will be better but requires even more
> > > > > work)
> > > >
> > > > Sorry yes hwgroup, that's what I meant. The case I worried about in my
> > > > patch (and noted) is that it doesn't cover per-hwif and neither would a
> > > > special request.
> > >
> > > I guess you meant 'per-host' because hwif == channel.
> > >
> > > [ You are of course right for about 'per-host' case. ]
> >
> > Yep, per host. So REQ_SPECIAL-like approach is cleaner, but doesn't
> > cover more cases than a simple hwif pinning would anyways. You'd need
> > some code to quisce the host in any case.
> 
> No, REQ_SPECIAL-like approach would serialize per ide_hwgroup_t and 
> ide_hwgroup_t may serialize more then one ide_hwif_t.  See ide-probe.c.

I see, that would work. So you would need to doctor some message type
system for these requests. Are you going to do this?

-- 
Jens Axboe