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Tue, 28 Jul 2026 02:08:24 +0000 (GMT) Received: from [9.61.157.32] (unknown [9.61.157.32]) by smtpav04.dal12v.mail.ibm.com (Postfix) with ESMTP; Tue, 28 Jul 2026 02:08:24 +0000 (GMT) Message-ID: <3048391c-003a-4bde-84c9-e1eca0063766@linux.ibm.com> Date: Mon, 27 Jul 2026 22:08:23 -0400 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 08/10] s390/vfio_ccw: move cp cleanup out of not operational To: Eric Farman , linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Halil Pasic , Christian Borntraeger , stable@vger.kernel.org References: <20260728013509.1551753-1-farman@linux.ibm.com> <20260728013509.1551753-9-farman@linux.ibm.com> Content-Language: en-US From: Matthew Rosato In-Reply-To: <20260728013509.1551753-9-farman@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzI4MDAxNCBTYWx0ZWRfX/W1tT7q4vRmH uKokzOdrIBdRcJnIwQm1pZGZ44qQwOY87jpWL+XdDD8xr1APCxOt+efVpAWC0nPIgt4Rhf/F25v 52j/4PXuhvampD1LRfo22O0VI+Nk5aM= X-Proofpoint-GUID: 92P_GnRWfZe9VQmJhuk8IjmWzBK7rN4D X-Proofpoint-ORIG-GUID: 92P_GnRWfZe9VQmJhuk8IjmWzBK7rN4D X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI4MDAxNCBTYWx0ZWRfX/ob26IHYgE/B FS8h3rmpdYqqzPV7eCpObK1G0z+jynCwJX/fcLXqMSWOQtO+L9ldbwQEFnomSDzDY7rBazhLKi8 WSvgFDIwMEE6YMDAidIXfzVK81d0PK9Yr7US0raGDBeevwIr5IA6q+dQYxpA+qD2aay9T1Dmyrf eX1y1w4L8/EcpH8zu31LO7+Tf69VGUKo8/uaRLT/WO/LYtCpcB3y6Lz7koORqrQ2/djcDOqFsrY ZLrBVnzFUJsslM9hnR3uxsYB9BCkMCjObw1V93MDaqXXJHtQOUKFJQQ/qxNLp3yBBMNTNJAW7ow DA78zuNpmTuoXfit1q+O5Cnrj1r9FNO8X/eiIG/UADnlbDjwu7Prf3vi6QTZrjkLYkO5u9ZnED1 KT4l6pDri7LFHbAHrF7x+vzhPHDXTwtgCKlMmfc298ytjGTzs/8Zz61gUl/hd0aD7XCGRLxqjD5 mZHs0RzDizQQ5NiyhbA== X-Authority-Analysis: v=2.4 cv=X5Vi7mTe c=1 sm=1 tr=0 ts=6a680f1b cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=2CkcZuEoo9mvoDp0OvwA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-27_07,2026-07-27_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 phishscore=0 priorityscore=1501 malwarescore=0 spamscore=0 suspectscore=0 bulkscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607280014 On 7/27/26 9:35 PM, Eric Farman wrote: > The fsm_notoper() routine is called when the device has been > lost, and is (by definition) no longer operational. Since this > can happen asynchronously from the normal behavior of the > driver, the cleanup may happen when holding other locks > in the calling sequence (notably, the cio subchannel lock). > > Push the cleanup of the private->cp resources to a workqueue, > where it can be done out from under that lock sequence and > safely under a common locking mechanism. Nit: you mention 'safely under a common locking mechanism' but that doesn't actually happen until next patch. Maybe add something like 'so a subsequent patch can...' > > Fixes: 204b394a23ad ("vfio/ccw: Move FSM open/close to MDEV open/close") > Cc: stable@vger.kernel.org > Signed-off-by: Eric Farman > --- > drivers/s390/cio/vfio_ccw_drv.c | 9 +++++++++ > drivers/s390/cio/vfio_ccw_fsm.c | 3 +-- > drivers/s390/cio/vfio_ccw_ops.c | 6 +++++- > drivers/s390/cio/vfio_ccw_private.h | 3 +++ > 4 files changed, 18 insertions(+), 3 deletions(-) > > diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c > index 1a095085bc72..c197ad5ab580 100644 > --- a/drivers/s390/cio/vfio_ccw_drv.c > +++ b/drivers/s390/cio/vfio_ccw_drv.c > @@ -125,6 +125,15 @@ void vfio_ccw_crw_todo(struct work_struct *work) > eventfd_signal(private->crw_trigger); > } > > +void vfio_ccw_notoper_todo(struct work_struct *work) > +{ > + struct vfio_ccw_private *private; > + > + private = container_of(work, struct vfio_ccw_private, notoper_work); > + > + cp_free(&private->cp); > +} > + > /* > * Css driver callbacks > */ > diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c > index 4d7988ea47ef..4d47a3c7b9a0 100644 > --- a/drivers/s390/cio/vfio_ccw_fsm.c > +++ b/drivers/s390/cio/vfio_ccw_fsm.c > @@ -170,8 +170,7 @@ static void fsm_notoper(struct vfio_ccw_private *private, > css_sched_sch_todo(sch, SCH_TODO_UNREG); > private->state = VFIO_CCW_STATE_NOT_OPER; > > - /* This is usually handled during CLOSE event */ > - cp_free(&private->cp); > + queue_work(vfio_ccw_work_q, &private->notoper_work); > } > > /* > diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c > index bc8eb485d03f..1cca3ecdae45 100644 > --- a/drivers/s390/cio/vfio_ccw_ops.c > +++ b/drivers/s390/cio/vfio_ccw_ops.c > @@ -54,6 +54,7 @@ static int vfio_ccw_mdev_init_dev(struct vfio_device *vdev) > INIT_LIST_HEAD(&private->crw); > INIT_WORK(&private->io_work, vfio_ccw_sch_io_todo); > INIT_WORK(&private->crw_work, vfio_ccw_crw_todo); > + INIT_WORK(&private->notoper_work, vfio_ccw_notoper_todo); > > private->cp.guest_cp = kzalloc_objs(struct ccw1, CCWCHAIN_LEN_MAX); > if (!private->cp.guest_cp) > @@ -133,7 +134,9 @@ static void vfio_ccw_mdev_release_dev(struct vfio_device *vdev) > > /* > * Ensure these work items are fully drained, so none can > - * fire after being released. > + * fire after being released. The notoper_work struct is > + * only meaningful if the device had been opened, which > + * means it would have been cleaned in an earlier close. > */ > cancel_work_sync(&private->io_work); > cancel_work_sync(&private->crw_work); > @@ -216,6 +219,7 @@ static void vfio_ccw_mdev_close_device(struct vfio_device *vdev) > */ > cancel_work_sync(&private->io_work); > cancel_work_sync(&private->crw_work); > + flush_work(&private->notoper_work); Sashiko found a path where you might never open/close, so I guess we need to flush in both close and release after all? I still think flush vs cancel to ensure that we process the cp_free() work if it's pending else we risk leaking the cp resources. I think this is the last issue of note, so this series is very close as far as I'm concerned. Thanks, Matt > > vfio_ccw_unregister_dev_regions(private); > } > diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h > index 0501d4bbcdbd..e2256402b089 100644 > --- a/drivers/s390/cio/vfio_ccw_private.h > +++ b/drivers/s390/cio/vfio_ccw_private.h > @@ -102,6 +102,7 @@ struct vfio_ccw_parent { > * @req_trigger: eventfd ctx for signaling userspace to return device > * @io_work: work for deferral process of I/O handling > * @crw_work: work for deferral process of CRW handling > + * @notoper_work: work for deferred processing in not-operational state > */ > struct vfio_ccw_private { > struct vfio_device vdev; > @@ -125,11 +126,13 @@ struct vfio_ccw_private { > struct eventfd_ctx *req_trigger; > struct work_struct io_work; > struct work_struct crw_work; > + struct work_struct notoper_work; > } __aligned(8); > > int vfio_ccw_sch_quiesce(struct subchannel *sch); > void vfio_ccw_sch_io_todo(struct work_struct *work); > void vfio_ccw_crw_todo(struct work_struct *work); > +void vfio_ccw_notoper_todo(struct work_struct *work); > > extern struct mdev_driver vfio_ccw_mdev_driver; >