[PATCH 6.1.y 1/4] s390/vfio_ccw: Cancel existing workqueues

[Sasha Levin <sashal@kernel.org>]

From: Eric Farman <farman@linux.ibm.com>

[ Upstream commit 79c60b2c61105368dcc8444eb45847e21734f7c4 ]

The initialization of the io_work and crw_work workqueues begs the
question of whether they should be un-initialized. Add the corresponding
cleanup tags in _release_dev to ensure work isn't dispatched after
the private struct is free'd.

Suggested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Fixes: e5f84dbaea59 ("vfio: ccw: return I/O results asynchronously")
Fixes: 3f02cb2fd9d2 ("vfio-ccw: Wire up the CRW irq and CRW region")
Cc: stable@vger.kernel.org
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Stable-dep-of: 16b0798024c0 ("s390/vfio_ccw: Implement a crw lock")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/s390/cio/vfio_ccw_ops.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 5af74d3142492..c73f675ae29a1 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -86,6 +86,13 @@ static void vfio_ccw_mdev_release_dev(struct vfio_device *vdev)
 	struct vfio_ccw_private *private =
 		container_of(vdev, struct vfio_ccw_private, vdev);
 
+	/*
+	 * Ensure these work items are fully drained, so none can
+	 * fire after being released.
+	 */
+	cancel_work_sync(&private->io_work);
+	cancel_work_sync(&private->crw_work);
+
 	/*
 	 * We cannot free vfio_ccw_private here because it includes
 	 * parent info which must be free'ed by css driver.
@@ -162,6 +169,14 @@ static void vfio_ccw_mdev_close_device(struct vfio_device *vdev)
 		container_of(vdev, struct vfio_ccw_private, vdev);
 
 	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_CLOSE);
+
+	/*
+	 * Ensure these work items are drained, in the event the
+	 * device is re-opened instead of released.
+	 */
+	cancel_work_sync(&private->io_work);
+	cancel_work_sync(&private->crw_work);
+
 	vfio_ccw_unregister_dev_regions(private);
 }
 
-- 
2.53.0