Re: [PATCH 3/5] s390: Add a mechanism to get the subchannel id.

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Sun, 9 Dec 2012 13:12:37 +0100
Alexander Graf <agraf@suse.de> wrote:

> 
> On 07.12.2012, at 13:29, Cornelia Huck wrote:
> 
> > This will be needed by the new virtio-ccw transport.
> > 
> > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
> > ---
> > arch/s390/include/asm/ccwdev.h |  5 +++++
> > drivers/s390/cio/device_ops.c  | 12 ++++++++++++
> > 2 files changed, 17 insertions(+)
> > 
> > diff --git a/arch/s390/include/asm/ccwdev.h b/arch/s390/include/asm/ccwdev.h
> > index 1cb4bb3..9ad79f7 100644
> > --- a/arch/s390/include/asm/ccwdev.h
> > +++ b/arch/s390/include/asm/ccwdev.h
> > @@ -18,6 +18,9 @@ struct irb;
> > struct ccw1;
> > struct ccw_dev_id;
> > 
> > +/* from asm/schid.h */
> > +struct subchannel_id;
> > +
> > /* simplified initializers for struct ccw_device:
> >  * CCW_DEVICE and CCW_DEVICE_DEVTYPE initialize one
> >  * entry in your MODULE_DEVICE_TABLE and set the match_flag correctly */
> > @@ -226,5 +229,7 @@ int ccw_device_siosl(struct ccw_device *);
> > // FIXME: these have to go
> > extern int _ccw_device_get_subchannel_number(struct ccw_device *);
> > 
> > +extern void ccw_device_get_schid(struct ccw_device *, struct subchannel_id *);
> > +
> > extern void *ccw_device_get_chp_desc(struct ccw_device *, int);
> > #endif /* _S390_CCWDEV_H_ */
> > diff --git a/drivers/s390/cio/device_ops.c b/drivers/s390/cio/device_ops.c
> > index ec7fb6d..2ad832f 100644
> > --- a/drivers/s390/cio/device_ops.c
> > +++ b/drivers/s390/cio/device_ops.c
> > @@ -763,6 +763,18 @@ _ccw_device_get_subchannel_number(struct ccw_device *cdev)
> > 	return cdev->private->schid.sch_no;
> > }
> > 
> > +/**
> > + * ccw_device_get_schid - obtain a subchannel id
> > + * @cdev: device to obtain the id for
> > + * @schid: where to fill in the values
> > + */
> > +void ccw_device_get_schid(struct ccw_device *cdev, struct subchannel_id *schid)
> 
> If you make this
> 
> u32 ccw_device_get_schid(struct ccw_device *cdev)
> 
> and you return the u32 (architected) value of the schid, not the internal struct, then you can save yourself the struct export (patch 2/5) and the ugly cast in patch 4/5 to get the u32 value.

I really prefer using the structure instead.

Moreover, there's a patch based on this that switches non-kvm users to
this new interface (getting rid of an old, broken interface) already
queued in the linux-s390 tree AFAIK.

> 
> 
> Alex
> 
> > +{
> > +	struct subchannel *sch = to_subchannel(cdev->dev.parent);
> > +
> > +	*schid = sch->schid;
> > +}
> > +EXPORT_SYMBOL_GPL(ccw_device_get_schid);
> > 
> > MODULE_LICENSE("GPL");
> > EXPORT_SYMBOL(ccw_device_set_options_mask);
> > -- 
> > 1.7.12.4
> > 
>