From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:32252 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728279AbgDHKsP (ORCPT ); Wed, 8 Apr 2020 06:48:15 -0400 Date: Wed, 8 Apr 2020 12:48:01 +0200 From: Cornelia Huck Subject: Re: [PATCH v7 01/15] s390/vfio-ap: store queue struct in hash table for quick access Message-ID: <20200408124801.2d61bc5b.cohuck@redhat.com> In-Reply-To: <20200407192015.19887-2-akrowiak@linux.ibm.com> References: <20200407192015.19887-1-akrowiak@linux.ibm.com> <20200407192015.19887-2-akrowiak@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Tony Krowiak Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, freude@linux.ibm.com, borntraeger@de.ibm.com, mjrosato@linux.ibm.com, pmorel@linux.ibm.com, pasic@linux.ibm.com, alex.williamson@redhat.com, kwankhede@nvidia.com, jjherne@linux.ibm.com, fiuczy@linux.ibm.com On Tue, 7 Apr 2020 15:20:01 -0400 Tony Krowiak 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 > --- > 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(-) > (...) > diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c > index 5c0f53c6dde7..134860934fe7 100644 > --- a/drivers/s390/crypto/vfio_ap_ops.c > +++ b/drivers/s390/crypto/vfio_ap_ops.c > @@ -26,45 +26,16 @@ > > static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev); > > -static int match_apqn(struct device *dev, const void *data) > -{ > - struct vfio_ap_queue *q = dev_get_drvdata(dev); > - > - return (q->apqn == *(int *)(data)) ? 1 : 0; > -} > - > -/** > - * vfio_ap_get_queue: Retrieve a queue with a specific APQN from a list > - * @matrix_mdev: the associated mediated matrix > - * @apqn: The queue APQN > - * > - * Retrieve a queue with a specific APQN from the list of the > - * devices of the vfio_ap_drv. > - * Verify that the APID and the APQI are set in the matrix. > - * > - * Returns the pointer to the associated vfio_ap_queue Any reason you're killing this comment, instead of adapting it? The function is even no longer static... > - */ > -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? > - > - 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. > + > + return NULL; > } > > /** (...)