[PATCH v5 08/22] virtio_ring: queue_reset: add vring_release_virtqueue()

[Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>]

Added vring_release_virtqueue() to release the ring of the vq.

In this process, vq is removed from the vdev->vqs queue. And the memory
of the ring is released

Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
 drivers/virtio/virtio_ring.c | 18 +++++++++++++++++-
 include/linux/virtio.h       | 12 ++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index c5dd17c7dd4a..b37753bdbbc4 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1730,6 +1730,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	vq->vq.vdev = vdev;
 	vq->vq.num_free = num;
 	vq->vq.index = index;
+	vq->vq.reset = VIRTQUEUE_RESET_STAGE_NONE;
 	vq->we_own_ring = true;
 	vq->notify = notify;
 	vq->weak_barriers = weak_barriers;
@@ -2218,6 +2219,7 @@ static int __vring_init_virtqueue(struct virtqueue *_vq,
 	vq->vq.vdev = vdev;
 	vq->vq.num_free = vring.num;
 	vq->vq.index = index;
+	vq->vq.reset = VIRTQUEUE_RESET_STAGE_NONE;
 	vq->we_own_ring = false;
 	vq->notify = notify;
 	vq->weak_barriers = weak_barriers;
@@ -2397,11 +2399,25 @@ void vring_del_virtqueue(struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
-	__vring_del_virtqueue(vq);
+	if (_vq->reset != VIRTQUEUE_RESET_STAGE_RELEASE)
+		__vring_del_virtqueue(vq);
 	kfree(vq);
 }
 EXPORT_SYMBOL_GPL(vring_del_virtqueue);
 
+void vring_release_virtqueue(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	if (_vq->reset != VIRTQUEUE_RESET_STAGE_DEVICE)
+		return;
+
+	__vring_del_virtqueue(vq);
+
+	_vq->reset = VIRTQUEUE_RESET_STAGE_RELEASE;
+}
+EXPORT_SYMBOL_GPL(vring_release_virtqueue);
+
 /* Manipulates transport-specific feature bits. */
 void vring_transport_features(struct virtio_device *vdev)
 {
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 72292a62cd90..cdb2a551257c 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -10,6 +10,12 @@
 #include <linux/mod_devicetable.h>
 #include <linux/gfp.h>
 
+enum virtqueue_reset_stage {
+	VIRTQUEUE_RESET_STAGE_NONE,
+	VIRTQUEUE_RESET_STAGE_DEVICE,
+	VIRTQUEUE_RESET_STAGE_RELEASE,
+};
+
 /**
  * virtqueue - a queue to register buffers for sending or receiving.
  * @list: the chain of virtqueues for this device
@@ -32,6 +38,7 @@ struct virtqueue {
 	unsigned int index;
 	unsigned int num_free;
 	void *priv;
+	enum virtqueue_reset_stage reset;
 };
 
 int virtqueue_add_outbuf(struct virtqueue *vq,
@@ -196,4 +203,9 @@ void unregister_virtio_driver(struct virtio_driver *drv);
 #define module_virtio_driver(__virtio_driver) \
 	module_driver(__virtio_driver, register_virtio_driver, \
 			unregister_virtio_driver)
+/*
+ * Resets a virtqueue. Just frees the ring, not free vq.
+ * This function must be called after reset_vq().
+ */
+void vring_release_virtqueue(struct virtqueue *vq);
 #endif /* _LINUX_VIRTIO_H */
-- 
2.31.0