Re: [PATCH v9 12/32] virtio_ring: packed: extract the logic of alloc queue

Jason Wang
2022-04-14T09:19:07Z

On Wed, Apr 13, 2022 at 11:26 AM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
>
> On Tue, 12 Apr 2022 14:28:24 +0800, Jason Wang <jasowang@redhat.com> wrote:
> >
> > 在 2022/4/6 上午11:43, Xuan Zhuo 写道:
> > > Separate the logic of packed to create vring queue.
> > >
> > > For the convenience of passing parameters, add a structure
> > > vring_packed.
> > >
> > > This feature is required for subsequent virtuqueue reset vring.
> > >
> > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > > ---
> > > drivers/virtio/virtio_ring.c | 70 ++++++++++++++++++++++++++++--------
> > > 1 file changed, 56 insertions(+), 14 deletions(-)
> > >
> > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > > index 33864134a744..ea451ae2aaef 100644
> > > --- a/drivers/virtio/virtio_ring.c
> > > +++ b/drivers/virtio/virtio_ring.c
> > > @@ -1817,19 +1817,17 @@ static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num)
> > > return desc_extra;
> > > }
> > >
> > > -static struct virtqueue *vring_create_virtqueue_packed(
> > > - unsigned int index,
> > > - unsigned int num,
> > > - unsigned int vring_align,
> > > - struct virtio_device *vdev,
> > > - bool weak_barriers,
> > > - bool may_reduce_num,
> > > - bool context,
> > > - bool (*notify)(struct virtqueue *),
> > > - void (*callback)(struct virtqueue *),
> > > - const char *name)
> > > +static int vring_alloc_queue_packed(struct virtio_device *vdev,
> > > + u32 num,
> > > + struct vring_packed_desc **_ring,
> > > + struct vring_packed_desc_event **_driver,
> > > + struct vring_packed_desc_event **_device,
> > > + dma_addr_t *_ring_dma_addr,
> > > + dma_addr_t *_driver_event_dma_addr,
> > > + dma_addr_t *_device_event_dma_addr,
> > > + size_t *_ring_size_in_bytes,
> > > + size_t *_event_size_in_bytes)
> > > {
> > > - struct vring_virtqueue *vq;
> > > struct vring_packed_desc *ring;
> > > struct vring_packed_desc_event *driver, *device;
> > > dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
> > > @@ -1857,6 +1855,52 @@ static struct virtqueue *vring_create_virtqueue_packed(
> > > if (!device)
> > > goto err_device;
> > >
> > > + *_ring = ring;
> > > + *_driver = driver;
> > > + *_device = device;
> > > + *_ring_dma_addr = ring_dma_addr;
> > > + *_driver_event_dma_addr = driver_event_dma_addr;
> > > + *_device_event_dma_addr = device_event_dma_addr;
> > > + *_ring_size_in_bytes = ring_size_in_bytes;
> > > + *_event_size_in_bytes = event_size_in_bytes;
> >
> >
> > I wonder if we can simply factor out split and packed from struct
> > vring_virtqueue:
> >
> > struct vring_virtqueue {
> > union {
> > struct {} split;
> > struct {} packed;
> > };
> > };
> >
> > to
> >
> > struct vring_virtqueue_split {};
> > struct vring_virtqueue_packed {};
> >
> > Then we can do things like:
> >
> > vring_create_virtqueue_packed(struct virtio_device *vdev, u32 num,
> > struct vring_virtqueue_packed *packed);
> >
> > and
> >
> > vring_vritqueue_attach_packed(struct vring_virtqueue *vq, struct
> > vring_virtqueue_packed packed);
>
> This idea is very similar to my previous idea, just without introducing a new
> structure.

Yes, it's better to not introduce new structures if it's possible.

>
> I'd be more than happy to revise this.

Good to know this.

Thanks

>
> Thanks.
>
>
> >
> > Thanks
> >
> >
> > > +
> > > + return 0;
> > > +
> > > +err_device:
> > > + vring_free_queue(vdev, event_size_in_bytes, driver, driver_event_dma_addr);
> > > +
> > > +err_driver:
> > > + vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
> > > +
> > > +err_ring:
> > > + return -ENOMEM;
> > > +}
> > > +
> > > +static struct virtqueue *vring_create_virtqueue_packed(
> > > + unsigned int index,
> > > + unsigned int num,
> > > + unsigned int vring_align,
> > > + struct virtio_device *vdev,
> > > + bool weak_barriers,
> > > + bool may_reduce_num,
> > > + bool context,
> > > + bool (*notify)(struct virtqueue *),
> > > + void (*callback)(struct virtqueue *),
> > > + const char *name)
> > > +{
> > > + dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
> > > + struct vring_packed_desc_event *driver, *device;
> > > + size_t ring_size_in_bytes, event_size_in_bytes;
> > > + struct vring_packed_desc *ring;
> > > + struct vring_virtqueue *vq;
> > > +
> > > + if (vring_alloc_queue_packed(vdev, num, &ring, &driver, &device,
> > > + &ring_dma_addr, &driver_event_dma_addr,
> > > + &device_event_dma_addr,
> > > + &ring_size_in_bytes,
> > > + &event_size_in_bytes))
> > > + goto err_ring;
> > > +
> > > vq = kmalloc(sizeof(*vq), GFP_KERNEL);
> > > if (!vq)
> > > goto err_vq;
> > > @@ -1939,9 +1983,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
> > > kfree(vq);
> > > err_vq:
> > > vring_free_queue(vdev, event_size_in_bytes, device, device_event_dma_addr);
> > > -err_device:
> > > vring_free_queue(vdev, event_size_in_bytes, driver, driver_event_dma_addr);
> > > -err_driver:
> > > vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
> > > err_ring:
> > > return NULL;
> >
>