Re: [PATCH v7 14/26] virtio: add helper for queue reset

Add helper for virtio queue reset.

* virtio_reset_vq(): reset a queue individually
* virtio_enable_resetq(): enable a reset queue

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
  include/linux/virtio_config.h | 40 +++++++++++++++++++++++++++++++++++
  1 file changed, 40 insertions(+)

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index d51906b1389f..0b81fbe17c85 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h

@@ -230,6 +230,46 @@ int virtio_find_vqs_ctx(struct virtio_device *vdev, unsigned nvqs,
  				      desc);
  }
  
+/**
+ * virtio_reset_vq - reset a queue individually
+ * @vq: the virtqueue
+ *
+ * returns 0 on success or error status
+ *
+ * The api process of reset under normal circumstances:
+ *	1. virtio_reset_vq()              - notify the device to reset the queue
+ *	2. virtqueue_detach_unused_buf()  - recycle the buffer submitted
+ *	3. virtqueue_reset_vring()        - reset the vring (may re-alloc)
+ *	4. virtio_enable_resetq()         - mmap vring to device, and enable the queue
+ *
+ * Caller should guarantee that the vring is not accessed by any functions
+ * of virtqueue.
+ */
+static inline
+int virtio_reset_vq(struct virtqueue *vq)
+{

+	if (!vq->vdev->config->reset_vq)
+		return -ENOENT;
+
+	return vq->vdev->config->reset_vq(vq);
+}
+
+/**
+ * virtio_enable_resetq - enable a reset queue
+ * @vq: the virtqueue
+ *
+ * returns 0 on success or error status
+ *
+ */
+static inline
+int virtio_enable_resetq(struct virtqueue *vq)
+{
+	if (!vq->vdev->config->enable_reset_vq)
+		return -ENOENT;
+
+	return vq->vdev->config->enable_reset_vq(vq);
+}
+
  /**
   * virtio_device_ready - enable vq use in probe function
   * @vdev: the device