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Wed, 08 Apr 2020 16:34:19 +0000 Received: from b01ledav005.gho.pok.ibm.com (b01ledav005.gho.pok.ibm.com [9.57.199.110]) by b01cxnp23032.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 038GYHxr54198728 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 8 Apr 2020 16:34:17 GMT Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4ABC6AE060; Wed, 8 Apr 2020 16:34:17 +0000 (GMT) Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7B144AE05C; Wed, 8 Apr 2020 16:34:16 +0000 (GMT) Received: from cpe-172-100-173-215.stny.res.rr.com (unknown [9.85.151.56]) by b01ledav005.gho.pok.ibm.com (Postfix) with ESMTP; Wed, 8 Apr 2020 16:34:16 +0000 (GMT) Subject: Re: [PATCH v7 01/15] s390/vfio-ap: store queue struct in hash table for quick access To: Cornelia Huck 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 References: <20200407192015.19887-1-akrowiak@linux.ibm.com> <20200407192015.19887-2-akrowiak@linux.ibm.com> <20200408124801.2d61bc5b.cohuck@redhat.com> <20200408182750.6d9443f6.cohuck@redhat.com> From: Tony Krowiak Message-ID: Date: Wed, 8 Apr 2020 12:34:15 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200408182750.6d9443f6.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.676 definitions=2020-04-07_10:2020-04-07,2020-04-07 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 spamscore=0 clxscore=1015 mlxscore=0 suspectscore=3 bulkscore=0 adultscore=0 phishscore=0 priorityscore=1501 impostorscore=0 mlxlogscore=999 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004080127 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/8/20 12:27 PM, Cornelia Huck wrote: > On Wed, 8 Apr 2020 11:38:07 -0400 > Tony Krowiak wrote: > >> On 4/8/20 6:48 AM, Cornelia Huck wrote: >>> 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(-) >>>> >>> (...) >>>> - */ >>>> -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 >