Messages in this thread | | | Subject | Re: [PATCH v3 4/9] s390: ap: tools to find a queue with a specific APQN | From | Tony Krowiak <> | Date | Fri, 15 Feb 2019 17:13:21 -0500 |
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On 2/14/19 8:51 AM, Pierre Morel wrote: > We need to find the queue with a specific APQN during the > handling of the interception of the PQAP/AQIC instruction. > > To handle the AP associated device reference count we keep > track of it in the vfio_ap_queue until we put the device. > > Signed-off-by: Pierre Morel <pmorel@linux.ibm.com> > --- > drivers/s390/crypto/vfio_ap_ops.c | 54 +++++++++++++++++++++++++++++++++++ > drivers/s390/crypto/vfio_ap_private.h | 1 + > 2 files changed, 55 insertions(+) > > diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c > index 900b9cf..2a52c9b 100644 > --- a/drivers/s390/crypto/vfio_ap_ops.c > +++ b/drivers/s390/crypto/vfio_ap_ops.c > @@ -24,6 +24,60 @@ > #define VFIO_AP_MDEV_TYPE_HWVIRT "passthrough" > #define VFIO_AP_MDEV_NAME_HWVIRT "VFIO AP Passthrough Device" > > +/** > + * vfio_ap_check_apqn: check if a ap_queue is of a given APQN > + * > + * Returns 1 if we have a match. > + * Otherwise returns 0. > + */ > +static int vfio_ap_check_apqn(struct device *dev, void *data) > +{ > + struct vfio_ap_queue *q = dev_get_drvdata(dev); > + > + return (q->apqn == *(int *)data); > +} > + > +/** > + * vfio_ap_get_queue: Retrieve a queue with a specific APQN > + * @apqn: The queue APQN > + * > + * Retrieve a queue with a specific APQN from the list of the > + * devices associated to the vfio_ap_driver. > + * > + * The vfio_ap_queue has been already associated with the device > + * during the probe. > + * Store the associated device for reference counting > + * > + * Returns the pointer to the associated vfio_ap_queue > + */ > +static __attribute__((unused)) > + struct vfio_ap_queue *vfio_ap_get_queue(int apqn)
I think you should change this signature for the reasons I stated below:
struct device *vfio_ap_get_queue_dev(int apqn)
> +{ > + struct device *dev; > + struct vfio_ap_queue *q; > + > + dev = driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL, &apqn, > + vfio_ap_check_apqn); > + if (!dev) > + return NULL; > + q = dev_get_drvdata(dev); > + q->dev = dev;
Why store the device with the vfio_ap_queue object? Why not just return the device. The caller can get the vfio_ap_queue from the device's driver data. It seems the only reason for the 'dev' field is to temporarily hold a ref to the device so it can be put later. Why not just put the device.
> + return q; > +} > + > +/** > + * vfio_ap_put_queue: lower device reference count for a queue > + * @q: The queue > + * > + * put the associated device > + * > + */ > +static __attribute__((unused)) void vfio_ap_put_queue(struct vfio_ap_queue *q) > +{ > + put_device(q->dev); > + q->dev = NULL; > +}
I would get rid of this function. If you take my suggestion above, you can just call the put_device() directly. There will be no need for this superfluous 'dev' field.
> + > static void vfio_ap_matrix_init(struct ap_config_info *info, > struct ap_matrix *matrix) > { > diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h > index 8836f01..081f0d7 100644 > --- a/drivers/s390/crypto/vfio_ap_private.h > +++ b/drivers/s390/crypto/vfio_ap_private.h > @@ -87,6 +87,7 @@ extern int vfio_ap_mdev_register(void); > extern void vfio_ap_mdev_unregister(void); > > struct vfio_ap_queue { > + struct device *dev;
No need for this as per my comments above.
> int apqn; > }; > #endif /* _VFIO_AP_PRIVATE_H_ */ >
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