Messages in this thread | | | Subject | Re: [RFC 05/19] s390/zcrypt: base implementation of AP matrix device driver | From | Tony Krowiak <> | Date | Tue, 14 Nov 2017 13:15:27 -0500 |
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On 11/14/2017 12:00 PM, Cornelia Huck wrote: > On Tue, 14 Nov 2017 11:37:05 -0500 > Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote: > >> On 11/14/2017 07:40 AM, Cornelia Huck wrote: >>> On Fri, 13 Oct 2017 13:38:50 -0400 >>> Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote: >>>> diff --git a/drivers/s390/crypto/ap_matrix_bus.c b/drivers/s390/crypto/ap_matrix_bus.c >>>> index 4eb1e3c..66bfa54 100644 >>>> --- a/drivers/s390/crypto/ap_matrix_bus.c >>>> +++ b/drivers/s390/crypto/ap_matrix_bus.c >>>> @@ -75,10 +75,18 @@ static int ap_matrix_dev_create(void) >>>> return 0; >>>> } >>>> >>>> +struct ap_matrix *ap_matrix_get_device(void) >>>> +{ >>>> + return matrix; >>> See the comments I had for the previous patch. In particular, I think >>> it is better to retrieve a pointer to the matrix device via driver core >>> methods. >> I got some objections to creating a new bus and since there will only ever >> be a single AP matrix device, I decided there really wasn't a need for an >> AP matrix bus and got rid of it. I opted instead to create the matrix >> device >> in the init function of the vfio_ap_matrix driver. Rather than passing >> around a >> pointer, I put the following in vfio_ap_matrix_private.h: >> >> struct ap_matrix { >> struct device device; >> spinlock_t qlock; >> struct list_head queues; >> }; >> >> extern struct ap_matrix ap_matrix; >> >> ... and declared the ap_matrix in the driver (vfio_ap_matrix_drv.c) >> file as: >> >> struct ap_matrix ap_matrix; >> >> Does this seem like a reasonable approach? > Getting rid of the bus as overhead is not unreasonable. > > I'm feeling a bit queasy about the extern, however. I'd prefer a getter > function (that also makes sure refcounting rules are followed). I now think I can avoid having to reference the ap_matrix device from multiple places. The reason the device is referenced in vfio_ap_matrix_ops.c is because there is a need for information about the AP queues that have been bound to the vfio_ap_matrix device driver. If interfaces are provided by the vfio_ap_matrix device driver to access the needed information, it won't be necessary to reference the ap_matrix device directly in vfio_ap_matrix_ops. I think this would be a better solution, don't you? > > We can't get around referencing this device from multiple files, can we? The only way would be to roll up vfio_ap_matrix_ops.c into vfio_ap_matrix_drv.c. I followed the pattern established by the vfio_ccw >
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