On Sat, Aug 27, 2011 at 05:52:02PM +0800, Wang Sheng-Hui wrote:
> On 2011年08月27日 17:34, Wang Sheng-Hui wrote:
> > On 2011年08月27日 10:49, Wanlong Gao wrote:
> >> On Sat, 2011-08-27 at 09:07 +0800, Wang Sheng-Hui wrote:
> >>> The patch is against 3.1-rc3.
> >>>
> >>> struct vring_used has two __u16 fields plus array of struct vring_used_elem.
> >>> Current vring_size counts the __u16 fields to 3. Fix it to 2 in the patch.
> >>>
> >>> Signed-off-by: Wang Sheng-Hui <shhuiw@xxxxxxxxx>
> >>> ---
> >>> include/linux/virtio_ring.h | 2 +-
> >>> 1 files changed, 1 insertions(+), 1 deletions(-)
> >>>
> >>> diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
> >>> index 4a32cb6..fcda152 100644
> >>> --- a/include/linux/virtio_ring.h
> >>> +++ b/include/linux/virtio_ring.h
> >>> @@ -143,7 +143,7 @@ static inline unsigned vring_size(unsigned int num, unsigned long align)
> >>> {
> >>> return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num)
> >>> + align - 1) & ~(align - 1))
> >>> - + sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num;
> >>> + + sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num;
> >>> }
> >>>
> >>> /* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */
> >>
> >> Hi:
> >> I'm not deep into it, but I think you can see this:
> >> http://marc.info/?l=git-commits-head&m=130687915816130&w=2
> >>
> >> Thanks
> >> -Wanlong Gao
> >>
> >
> > Thanks.
> >
> > I checked the comments, and think we should patch vring_init
> > and vring_size according to the layout description in the comments.
> > Right?
>
> New patch generated. Please check it. Thanks,
> [PATCH] virtio: modify vring_init and vring_size to take account of the layout containing *_event_idx
>
> The patch is against 3.1-rc3.
>
> Based on the layout description in the comments, take account of
> the *_event_idx in functions vring_init and vring_size.
>
> Signed-off-by: Wang Sheng-Hui <shhuiw@xxxxxxxxx>
Is this a bugfix or just a cleanup?
Alignment makes us get the same values with and without, right?
> ---
> include/linux/virtio_ring.h | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
> index 4a32cb6..300af76 100644
> --- a/include/linux/virtio_ring.h
> +++ b/include/linux/virtio_ring.h
> @@ -135,13 +135,13 @@ static inline void vring_init(struct vring *vr, unsigned int num, void *p,
> vr->num = num;
> vr->desc = p;
> vr->avail = p + num*sizeof(struct vring_desc);
> - vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + align-1)
> - & ~(align - 1));
> + vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + 16
> + + align-1) & ~(align - 1));
> }
>
> static inline unsigned vring_size(unsigned int num, unsigned long align)
> {
> - return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num)
> + return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (3 + num)
> + align - 1) & ~(align - 1))
> + sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num;
> }
> --
> 1.7.1
>
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