linux-kernel - [PATCH v3 5/7] vfio/ccw: remove release completion

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Date:   Fri,  4 Nov 2022 15:20:05 +0100
From:   Eric Farman <farman@...ux.ibm.com>
To:     Matthew Rosato <mjrosato@...ux.ibm.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Kevin Tian <kevin.tian@...el.com>, Yi Liu <yi.l.liu@...el.com>
Cc:     Zhenyu Wang <zhenyuw@...ux.intel.com>,
        Zhi Wang <zhi.a.wang@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Halil Pasic <pasic@...ux.ibm.com>,
        Vineeth Vijayan <vneethv@...ux.ibm.com>,
        Peter Oberparleiter <oberpar@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Tony Krowiak <akrowiak@...ux.ibm.com>,
        Jason Herne <jjherne@...ux.ibm.com>,
        Harald Freudenberger <freude@...ux.ibm.com>,
        Diana Craciun <diana.craciun@....nxp.com>,
        Eric Auger <eric.auger@...hat.com>,
        Kirti Wankhede <kwankhede@...dia.com>,
        Abhishek Sahu <abhsahu@...dia.com>,
        Yishai Hadas <yishaih@...dia.com>,
        intel-gvt-dev@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        kvm@...r.kernel.org, Eric Farman <farman@...ux.ibm.com>
Subject: [PATCH v3 5/7] vfio/ccw: remove release completion

There's enough separation between the parent and private structs now,
that it is fine to remove the release completion hack.

Signed-off-by: Eric Farman <farman@...ux.ibm.com>
Reviewed-by: Kevin Tian <kevin.tian@...el.com>
Reviewed-by: Matthew Rosato <mjrosato@...ux.ibm.com>
---
 drivers/s390/cio/vfio_ccw_ops.c     | 14 +-------------
 drivers/s390/cio/vfio_ccw_private.h |  3 ---
 2 files changed, 1 insertion(+), 16 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index e45d4acb109b..8a929a9cf3c6 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -54,7 +54,6 @@ 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_completion(&private->release_comp);
 
 	private->cp.guest_cp = kcalloc(CCWCHAIN_LEN_MAX, sizeof(struct ccw1),
 				       GFP_KERNEL);
@@ -137,7 +136,7 @@ static void vfio_ccw_mdev_release_dev(struct vfio_device *vdev)
 	struct vfio_ccw_private *private =
 		container_of(vdev, struct vfio_ccw_private, vdev);
 
-	complete(&private->release_comp);
+	vfio_ccw_free_private(private);
 }
 
 static void vfio_ccw_mdev_remove(struct mdev_device *mdev)
@@ -155,17 +154,6 @@ static void vfio_ccw_mdev_remove(struct mdev_device *mdev)
 
 	dev_set_drvdata(&parent->dev, NULL);
 	vfio_put_device(&private->vdev);
-	/*
-	 * Wait for all active references on mdev are released so it
-	 * is safe to defer kfree() to a later point.
-	 *
-	 * TODO: the clean fix is to split parent/mdev info from ccw
-	 * private structure so each can be managed in its own life
-	 * cycle.
-	 */
-	wait_for_completion(&private->release_comp);
-
-	vfio_ccw_free_private(private);
 }
 
 static int vfio_ccw_mdev_open_device(struct vfio_device *vdev)
diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index 747aba5f5272..2278fd38d34e 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -102,7 +102,6 @@ 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
- * @release_comp: synchronization helper for vfio device release
  */
 struct vfio_ccw_private {
 	struct vfio_device vdev;
@@ -126,8 +125,6 @@ struct vfio_ccw_private {
 	struct eventfd_ctx	*req_trigger;
 	struct work_struct	io_work;
 	struct work_struct	crw_work;
-
-	struct completion	release_comp;
 } __aligned(8);
 
 int vfio_ccw_sch_quiesce(struct subchannel *sch);
-- 
2.34.1