Re: [PATCH v7 13/26] virtio: queue_reset: struct virtio_config_ops add callbacks for queue_reset

Jason Wang
2022-03-09T08:47:38Z

在 2022/3/8 下午8:35, Xuan Zhuo 写道:
> Performing reset on a queue is divided into four steps:
>
> 1. 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. enable_reset_vq() - mmap vring to device, and enable the queue
>
> So add two callbacks reset_vq, enable_reset_vq to struct
> virtio_config_ops.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
> include/linux/virtio_config.h | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> index 4d107ad31149..d51906b1389f 100644
> --- a/include/linux/virtio_config.h
> +++ b/include/linux/virtio_config.h
> @@ -74,6 +74,15 @@ struct virtio_shm_region {
> * @set_vq_affinity: set the affinity for a virtqueue (optional).
> * @get_vq_affinity: get the affinity for a virtqueue (optional).
> * @get_shm_region: get a shared memory region based on the index.
> + * @reset_vq: reset a queue individually (optional).
> + * vq: the virtqueue
> + * Returns 0 on success or error status
> + * Caller should guarantee that the vring is not accessed by any functions
> + * of virtqueue.

We probably need to be more accurate here:

1) reset_vq will guarantee that the callbacks are disabled or synchronized
2) except for the callback, the caller should guarantee ...

Thanks

> + * @enable_reset_vq: enable a reset queue
> + * vq: the virtqueue
> + * Returns 0 on success or error status
> + * If reset_vq is set, then enable_reset_vq must also be set.
> */
> typedef void vq_callback_t(struct virtqueue *);
> struct virtio_config_ops {
> @@ -100,6 +109,8 @@ struct virtio_config_ops {
> int index);
> bool (*get_shm_region)(struct virtio_device *vdev,
> struct virtio_shm_region *region, u8 id);
> + int (*reset_vq)(struct virtqueue *vq);
> + int (*enable_reset_vq)(struct virtqueue *vq);
> };
>
> /* If driver didn't advertise the feature, it will never appear. */