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

[Jason Wang]

On Wed, Apr 13, 2022 at 11:26 AM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote:
>
> On Tue, 12 Apr 2022 14:28:24 +0800, Jason Wang <jasowang at 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 at 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;
> >
>