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From: Stephen Hemminger <stephen@networkplumber.org>
To: "Xie, Huawei" <huawei.xie@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] virtio: fix used ring address calculation
Date: Thu, 24 Sep 2015 14:01:50 -0700	[thread overview]
Message-ID: <20150924140150.5941e4a6@urahara> (raw)
In-Reply-To: <C37D651A908B024F974696C65296B57B40F2E435@SHSMSX101.ccr.corp.intel.com>

On Thu, 24 Sep 2015 18:35:37 +0000
"Xie, Huawei" <huawei.xie@intel.com> wrote:

> On 9/25/2015 12:36 AM, Stephen Hemminger wrote:
> > On Thu, 24 Sep 2015 07:30:41 +0000
> > "Xie, Huawei" <huawei.xie@intel.com> wrote:
> >
> >> On 9/21/2015 11:39 AM, Xie, Huawei wrote:
> >> vring_size calculation should consider both used_event_idx at the tail
> >> of avail ring and avail_event_idx at the tail of used ring.
> >> Will merge those two fixes and send a new patch.
> >>> used event idx is put at the end of available ring. It isn't taken into account
> >>> when we calculate the address of used ring. Fortunately, it doesn't introduce
> >>> the bug with fixed queue number 256 and 4KB alignment.
> >>>
> >>> Signed-off-by: hxie5 <huawei.xie@intel.com>
> >>> ---
> >>>  drivers/net/virtio/virtio_ring.h | 2 +-
> >>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/net/virtio/virtio_ring.h b/drivers/net/virtio/virtio_ring.h
> >>> index a16c499..92e430d 100644
> >>> --- a/drivers/net/virtio/virtio_ring.h
> >>> +++ b/drivers/net/virtio/virtio_ring.h
> >>> @@ -145,7 +145,7 @@ vring_init(struct vring *vr, unsigned int num, uint8_t *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);
> >>> +		RTE_ALIGN_CEIL((uintptr_t)(&vr->avail->ring[num + 1]), align);
> >>>  }
> >>>  
> >>>  /*
> > Why aren't we just using the standard Linux includes for this?
> > See <linux/virtio_ring.h> and the function vring_init()
> >
> > Keeping parallel copies of headers is prone to failures.
> Agree.
> Using standard Linux includes then at least we don't need to redefine
> the feature and other related MACRO.
> This applies to vhost as well.
> For vring, vring_init, we could also reuse the linux implementation
> unless we have strong reason to define our own structure.
> One reason was to support both FreeBSD and Linux. FreeBSD should have
> its own header file. To avoid the case they have different vring
> structure or VIRTIO_F_xx macro name, they are redefined here.
> 
> >
> 

The Linux headers for virtio are explictly BSD licensed.
You could at least just have a local copy of same code.

  reply	other threads:[~2015-09-24 21:01 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-21  3:39 Huawei Xie
2015-09-21  9:19 ` Tan, Jianfeng
2015-09-24  7:30 ` Xie, Huawei
2015-09-24 16:36   ` Stephen Hemminger
2015-09-24 18:35     ` Xie, Huawei
2015-09-24 21:01       ` Stephen Hemminger [this message]
2015-09-25 15:46         ` Xie, Huawei
2015-09-25 17:48           ` Stephen Hemminger

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