[RFC V1 08/13] vduse: flush workers on suspend

[Steve Sistare <steven.sistare@oracle.com>]

To pass ownership of a live vdpa device to a new process, the user
suspends the device, calls VHOST_NEW_OWNER to change the mm, and calls
VHOST_IOTLB_REMAP to change the user virtual addresses to match the new
mm.  Flush workers in suspend to guarantee that no worker sees the new
mm and old VA in between.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 drivers/vdpa/vdpa_user/vduse_dev.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 0ddd4b8abecb..6b25457a037d 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -472,6 +472,18 @@ static void vduse_dev_reset(struct vduse_dev *dev)
 	up_write(&dev->rwsem);
 }
 
+static void vduse_flush_work(struct vduse_dev *dev)
+{
+	flush_work(&dev->inject);
+
+	for (int i = 0; i < dev->vq_num; i++) {
+		struct vduse_virtqueue *vq = dev->vqs[i];
+
+		flush_work(&vq->inject);
+		flush_work(&vq->kick);
+	}
+}
+
 static int vduse_vdpa_set_vq_address(struct vdpa_device *vdpa, u16 idx,
 				u64 desc_area, u64 driver_area,
 				u64 device_area)
@@ -713,6 +725,17 @@ static int vduse_vdpa_reset(struct vdpa_device *vdpa)
 	return ret;
 }
 
+static int vduse_vdpa_suspend(struct vdpa_device *vdpa)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	down_write(&dev->rwsem);
+	vduse_flush_work(dev);
+	up_write(&dev->rwsem);
+
+	return 0;
+}
+
 static u32 vduse_vdpa_get_generation(struct vdpa_device *vdpa)
 {
 	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
@@ -794,6 +817,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
 	.set_vq_affinity	= vduse_vdpa_set_vq_affinity,
 	.get_vq_affinity	= vduse_vdpa_get_vq_affinity,
 	.reset			= vduse_vdpa_reset,
+	.suspend		= vduse_vdpa_suspend,
 	.set_map		= vduse_vdpa_set_map,
 	.free			= vduse_vdpa_free,
 };
-- 
2.39.3