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

[Xuan Zhuo]

On Wed, 9 Mar 2022 16:47:11 +0800, Jason Wang <jasowang at redhat.com> wrote:
>
> 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 at 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 ...

OK.

Thanks.

>
> 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. */
>