From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:14994 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726255AbgIYJ3u (ORCPT ); Fri, 25 Sep 2020 05:29:50 -0400 Date: Fri, 25 Sep 2020 11:29:41 +0200 From: Halil Pasic Subject: Re: [PATCH v10 05/16] s390/vfio-ap: implement in-use callback for vfio_ap driver Message-ID: <20200925112941.71589591.pasic@linux.ibm.com> In-Reply-To: <20200821195616.13554-6-akrowiak@linux.ibm.com> References: <20200821195616.13554-1-akrowiak@linux.ibm.com> <20200821195616.13554-6-akrowiak@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit 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, cohuck@redhat.com, mjrosato@linux.ibm.com, alex.williamson@redhat.com, kwankhede@nvidia.com, fiuczy@linux.ibm.com, frankja@linux.ibm.com, david@redhat.com, imbrenda@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com On Fri, 21 Aug 2020 15:56:05 -0400 Tony Krowiak wrote: > + > +bool vfio_ap_mdev_resource_in_use(unsigned long *apm, unsigned long *aqm) > +{ > + bool in_use; > + > + mutex_lock(&matrix_dev->lock); > + in_use = !!vfio_ap_mdev_verify_no_sharing(NULL, apm, aqm); > + mutex_unlock(&matrix_dev->lock); See also my comment for patch 4. AFAIU as soon as you release the lock the in_use may become outdated in any moment. > + > + return in_use; > +}