On Tue, May 04, 2021 at 11:36:36AM +0200, Christoph Hellwig wrote:
> On Wed, Apr 28, 2021 at 11:00:05AM -0300, Jason Gunthorpe wrote:
> > I thought about doing it like that, it is generally a good idea,
> > however, if I add new API surface to the driver core I really want to
> > get rid of device_bind_driver(), or at least most of its users.
> >
> > I'm pretty sure Greg will ask for it too.
> >
> > So, I need a way to sequence that which doesn't mean I have to shelf
> > the mdev stuff for ages while I try to get acks from lots of places.
> >
> > Leave this alone and fix it after? Export device_driver_attach() and
> > say to try and fix the rest after?
>
> Maybe. Or convert one or two samples.
The conversions are easy I just can't test them or completely tell if
they are correct..
> > I think this will still need the ugly errno capture though..
>
> Why?
Several of the mdev drivers are checking some predicate during their
new probe function, like total # of devices. So if userspace exceeds
that then the old behavior was to fail the sysfs create operation. eg:
static int vfio_ccw_mdev_probe(struct mdev_device *mdev)
{
if (private->state == VFIO_CCW_STATE_NOT_OPER)
return -ENODEV;
if (atomic_dec_if_positive(&private->avail) < 0)
return -EPERM;
Without the errno capture this doesn't work anymore and things end
succeeding to create a device and but failing to attach a driver.
It could be changed to loose the errno and just return with some
generic -EINVAL if no driver bound, but that seems pretty ugly too.
Returning the probe error from some device_driver_attach() also make
some sense, but revising the code to do that is a big touch and this
is so strange I don't know if it is worth it.
Jason
