Re: [PATCH 06/33] virtio_ring: introduce virtqueue_reset()

On Fri, 3 Feb 2023 04:05:38 -0500, "Michael S. Tsirkin" [off-list ref] wrote:

On Thu, Feb 02, 2023 at 07:00:31PM +0800, Xuan Zhuo wrote:

quoted

Introduce virtqueue_reset() to release all buffer inside vq.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 50 ++++++++++++++++++++++++++++++++++++
 include/linux/virtio.h       |  2 ++
 2 files changed, 52 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index e32046fd15a5..7dfce7001f9f 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c

@@ -2735,6 +2735,56 @@ int virtqueue_resize(struct virtqueue *_vq, u32 num,
 }
 EXPORT_SYMBOL_GPL(virtqueue_resize);

+/**
+ * virtqueue_reset - reset the vring of vq

..., detach and recycle all unused buffers

	after all this is why we are doing this reset, right?

quoted

+ * @_vq: the struct virtqueue we're talking about.
+ * @recycle: callback for recycle the useless buffer

not useless :) unused:

	callback to recycle unused buffers

I agree. Will fix.

Thanks.

I know we have the same confusion in virtqueue_resize, I will fix
that.

quoted

+ *
+ * Caller must ensure we don't call this with other virtqueue operations
+ * at the same time (except where noted).
+ *
+ * Returns zero or a negative error.
+ * 0: success.
+ * -EBUSY: Failed to sync with device, vq may not work properly
+ * -ENOENT: Transport or device not supported
+ * -EPERM: Operation not permitted
+ */
+int virtqueue_reset(struct virtqueue *_vq,
+		    void (*recycle)(struct virtqueue *vq, void *buf))
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	struct virtio_device *vdev = vq->vq.vdev;
+	void *buf;
+	int err;
+
+	if (!vq->we_own_ring)
+		return -EPERM;
+
+	if (!vdev->config->disable_vq_and_reset)
+		return -ENOENT;
+
+	if (!vdev->config->enable_vq_after_reset)
+		return -ENOENT;
+
+	err = vdev->config->disable_vq_and_reset(_vq);
+	if (err)
+		return err;
+
+	while ((buf = virtqueue_detach_unused_buf(_vq)) != NULL)
+		recycle(_vq, buf);
+
+	if (vq->packed_ring)
+		virtqueue_reinit_packed(vq);
+	else
+		virtqueue_reinit_split(vq);
+
+	if (vdev->config->enable_vq_after_reset(_vq))
+		return -EBUSY;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtqueue_reset);
+
 /* Only available for split ring */
 struct virtqueue *vring_new_virtqueue(unsigned int index,
 				      unsigned int num,

diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 3ebb346ebb7c..3ca2edb1aef3 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h

@@ -105,6 +105,8 @@ dma_addr_t virtqueue_get_used_addr(struct virtqueue *vq);

 int virtqueue_resize(struct virtqueue *vq, u32 num,
 		     void (*recycle)(struct virtqueue *vq, void *buf));
+int virtqueue_reset(struct virtqueue *vq,
+		    void (*recycle)(struct virtqueue *vq, void *buf));

 /**
  * struct virtio_device - representation of a device using virtio
--

2.32.0.3.g01195cf9f

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