Messages in this thread | | | Subject | Re: [PATCH v7 01/15] s390/vfio-ap: store queue struct in hash table for quick access | From | Tony Krowiak <> | Date | Wed, 8 Apr 2020 12:34:15 -0400 |
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On 4/8/20 12:27 PM, Cornelia Huck wrote: > On Wed, 8 Apr 2020 11:38:07 -0400 > Tony Krowiak <akrowiak@linux.ibm.com> wrote: > >> On 4/8/20 6:48 AM, Cornelia Huck wrote: >>> On Tue, 7 Apr 2020 15:20:01 -0400 >>> Tony Krowiak <akrowiak@linux.ibm.com> wrote: >>> >>>> Rather than looping over potentially 65535 objects, let's store the >>>> structures for caching information about queue devices bound to the >>>> vfio_ap device driver in a hash table keyed by APQN. >>> This also looks like a nice code simplification. >>> >>>> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com> >>>> --- >>>> drivers/s390/crypto/vfio_ap_drv.c | 28 +++------ >>>> drivers/s390/crypto/vfio_ap_ops.c | 90 ++++++++++++++------------- >>>> drivers/s390/crypto/vfio_ap_private.h | 10 ++- >>>> 3 files changed, 60 insertions(+), 68 deletions(-) >>>> >>> (...) >>>> - */ >>>> -static struct vfio_ap_queue *vfio_ap_get_queue( >>>> - struct ap_matrix_mdev *matrix_mdev, >>>> - int apqn) >>>> +struct vfio_ap_queue *vfio_ap_get_queue(unsigned long apqn) >>>> { >>>> struct vfio_ap_queue *q; >>>> - struct device *dev; >>>> - >>>> - if (!test_bit_inv(AP_QID_CARD(apqn), matrix_mdev->matrix.apm)) >>>> - return NULL; >>>> - if (!test_bit_inv(AP_QID_QUEUE(apqn), matrix_mdev->matrix.aqm)) >>>> - return NULL; >>> These were just optimizations and therefore can be dropped now? >> The purpose of this function has changed from its previous incarnation. >> This function was originally called from the handle_pqap() function and >> served two purposes: It retrieved the struct vfio_ap_queue as driver data >> and linked the matrix_mdev to the vfio_ap_queue. The linking of the >> matrix_mdev and the vfio_ap_queue are now done when queue devices >> are probed and when adapters and domains are assigned; so now, the >> handle_pqap() function calls this function to retrieve both the >> vfio_ap_queue as well as the matrix_mdev to which it is linked. >> Consequently, >> the above code is no longer needed. > Thanks for the explanation, that makes sense. > >>> >>>> - >>>> - dev = driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL, >>>> - &apqn, match_apqn); >>>> - if (!dev) >>>> - return NULL; >>>> - q = dev_get_drvdata(dev); >>>> - q->matrix_mdev = matrix_mdev; >>>> - put_device(dev); >>>> >>>> - return q; >>>> + hash_for_each_possible(matrix_dev->qtable, q, qnode, apqn) { >>>> + if (q && (apqn == q->apqn)) >>>> + return q; >>>> + } >>> Do we need any serialization here? Previously, the driver core made >>> sure we could get a reference only if the device was still registered; >>> not sure if we need any further guarantees now. >> The vfio_ap_queue structs are created when the queue device is >> probed and removed when the queue device is removed. > Ok, so anything further is not needed. > >>> >>>> + >>>> + return NULL; >>>> } >>>> >>>> /** >>> (...) >>> > Looks good to me, then. With vfio_ap_get_queue made static and the > kerneldoc restored/updated:
Already done, thanks for the review.
> > Reviewed-by: Cornelia Huck <cohuck@redhat.com> >
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