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

From: "Michael S. Tsirkin" <[email-masked]>
Date: Mon, 13 Feb 2023 07:15:02 -0500

On Fri, Feb 03, 2023 at 05:09:12PM +0800, Xuan Zhuo wrote:
> On Fri, 3 Feb 2023 04:05:38 -0500, "Michael S. Tsirkin" <[email-masked]> wrote:
> > On Thu, Feb 02, 2023 at 07:00:31PM +0800, Xuan Zhuo wrote:
> > > Introduce virtqueue_reset() to release all buffer inside vq.
> > >
> > > Signed-off-by: Xuan Zhuo <[email-masked]>
> > > ---
> > >  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?
> >
> > > + * @_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.

Probably too late for this merge cycle then. Oh well.

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