From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Krowiak Subject: Re: [PATCH v3 4/9] s390: ap: tools to find a queue with a specific APQN Date: Fri, 15 Feb 2019 17:13:21 -0500 Message-ID: <56f583e7-fb41-ec54-ccf9-585a3e51b1c4@linux.ibm.com> References: <1550152269-6317-1-git-send-email-pmorel@linux.ibm.com> <1550152269-6317-5-git-send-email-pmorel@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1550152269-6317-5-git-send-email-pmorel@linux.ibm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Pierre Morel , borntraeger@de.ibm.com Cc: alex.williamson@redhat.com, cohuck@redhat.com, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, frankja@linux.ibm.com, pasic@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, freude@linux.ibm.com, mimu@linux.ibm.com List-ID: 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 > --- > 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_ */ >