On 30.10.2012, at 15:00, Cornelia Huck <cornelia.huck@xxxxxxxxxx> wrote: > On Tue, 30 Oct 2012 14:41:46 +0100 > Alexander Graf <agraf@xxxxxxx> wrote: > >> On 10/30/2012 02:03 PM, Cornelia Huck wrote: >>> On Mon, 29 Oct 2012 19:37:10 +0100 >>> Alexander Graf<agraf@xxxxxxx> wrote: >>> >>>> On 29.10.2012, at 19:34, Cornelia Huck wrote: >>>> >>>>> On Mon, 29 Oct 2012 19:12:54 +0100 >>>>> Alexander Graf<agraf@xxxxxxx> wrote: >>>>> >>>>>> On 29.10.2012, at 14:07, Cornelia Huck wrote: >>>>>>> +static void virtio_ccw_kvm_notify(struct virtqueue *vq) >>>>>>> +{ >>>>>>> + struct virtio_ccw_vq_info *info = vq->priv; >>>>>>> + struct virtio_ccw_device *vcdev; >>>>>>> + struct subchannel_id schid; >>>>>>> + __u32 reg2; >>>>>>> + >>>>>>> + vcdev = to_vc_device(info->vq->vdev); >>>>>>> + ccw_device_get_schid(vcdev->cdev,&schid); >>>>>>> + reg2 = *(__u32 *)&schid; >>>>>> That cast looks quite ugly. Can't you just access the field in there you need? Or if it's multiple fields do a union over them? Or assemble them by hand in C? >>>>> I think the cast looks less ugly than using a union to morph it around. >>>>> I want the schid with all fields filled out anyway, since this is what >>>>> identifies the subchannel. >>>> How about a helper function that returns a u32 for a struct subchannel_id in arch/s390/include/asm/schid.h then? >>> This would just move the cast around, no? I don't think that would >>> improve readability. >> >> It would take it from the user of that struct close to the definition of >> the struct. The fact that it's an ugly cast by then is an implementation >> detail. This way it's a public API. > > But API-wise, returning a struct subchannel_id is cleaner - we don't > want "u32 associated with that device", but "subchannel identifier for > that device". The fact that we want to stuff it into an integer for the > hypercall is the implementaton detail. The subchannel id is not an implementation detail ;) Alex -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html