[dpdk-dev] vring_init bug

[dpdk-dev] vring_init bug

[Xie, Huawei]

static inline void
vring_init(struct vring *vr, unsigned int num, uint8_t *p,
    unsigned long align)
{
    vr->num = num;
    vr->desc = (struct vring_desc *) p;
    vr->avail = (struct vring_avail *) (p +
        num * sizeof(struct vring_desc));
    vr->used = (void *)
        RTE_ALIGN_CEIL((uintptr_t)(&vr->avail->ring[num]), align);
}

There is a bug in vr->used calculation. 2 bytes of used_event_idx isn't
considered. Would submit a fix.
__u16 available[num];
__u16 used_event_idx;

Re: [dpdk-dev] vring_init bug

[Ouyang, Changchun]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Xie, Huawei
> Sent: Wednesday, September 9, 2015 11:00 AM
> To: dev@dpdk.org
> Subject: [dpdk-dev] vring_init bug
> 
> static inline void
> vring_init(struct vring *vr, unsigned int num, uint8_t *p,
>     unsigned long align)
> {
>     vr->num = num;
>     vr->desc = (struct vring_desc *) p;
>     vr->avail = (struct vring_avail *) (p +
>         num * sizeof(struct vring_desc));
>     vr->used = (void *)
>         RTE_ALIGN_CEIL((uintptr_t)(&vr->avail->ring[num]), align); }
> 
> There is a bug in vr->used calculation. 2 bytes of used_event_idx isn't
> considered. Would submit a fix.
> __u16 available[num];
> __u16 used_event_idx;

For vring_used ring, it also misses avail_event.

struct vring_used {
u16 flags ;
u16 idx ;
struct vring_used_elem r ing [qsz] ;
u16 avail_event ;  // this one missed in dpdk
} ;

It doesn't affect the offset calculation, but it will be great if you can add it together.

Re: [dpdk-dev] vring_init bug

[Xie, Huawei]

> -----Original Message-----
> From: Ouyang, Changchun
> Sent: Wednesday, September 09, 2015 11:18 AM
> To: Xie, Huawei; dev@dpdk.org
> Cc: Ouyang, Changchun
> Subject: RE: vring_init bug
> 
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Xie, Huawei
> > Sent: Wednesday, September 9, 2015 11:00 AM
> > To: dev@dpdk.org
> > Subject: [dpdk-dev] vring_init bug
> >
> > static inline void
> > vring_init(struct vring *vr, unsigned int num, uint8_t *p,
> >     unsigned long align)
> > {
> >     vr->num = num;
> >     vr->desc = (struct vring_desc *) p;
> >     vr->avail = (struct vring_avail *) (p +
> >         num * sizeof(struct vring_desc));
> >     vr->used = (void *)
> >         RTE_ALIGN_CEIL((uintptr_t)(&vr->avail->ring[num]), align); }
> >
> > There is a bug in vr->used calculation. 2 bytes of used_event_idx isn't
> > considered. Would submit a fix.
> > __u16 available[num];
> > __u16 used_event_idx;
> 
> For vring_used ring, it also misses avail_event.
> 
> struct vring_used {
> u16 flags ;
> u16 idx ;
> struct vring_used_elem r ing [qsz] ;
> u16 avail_event ;  // this one missed in dpdk
> } ;
> 
> It doesn't affect the offset calculation, but it will be great if you can add it
> together.

No need to add this field for use vring and you couldn't because previous array is variable length.