* [PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size
@ 2011-08-27 1:07 Wang Sheng-Hui
2011-08-27 2:49 ` Wanlong Gao
0 siblings, 1 reply; 10+ messages in thread
From: Wang Sheng-Hui @ 2011-08-27 1:07 UTC (permalink / raw)
To: rusty, mst, virtualization, linux-kernel
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@gmail.com>
---
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 */
--
1.7.1
crossover@crossover-plinux:~/dev/patchwork$
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size
2011-08-27 1:07 [PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size Wang Sheng-Hui
@ 2011-08-27 2:49 ` Wanlong Gao
2011-08-27 9:34 ` Wang Sheng-Hui
0 siblings, 1 reply; 10+ messages in thread
From: Wanlong Gao @ 2011-08-27 2:49 UTC (permalink / raw)
To: Wang Sheng-Hui; +Cc: rusty, mst, virtualization, linux-kernel
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@gmail.com>
> ---
> 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
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size
2011-08-27 2:49 ` Wanlong Gao
@ 2011-08-27 9:34 ` Wang Sheng-Hui
2011-08-27 9:52 ` Wang Sheng-Hui
0 siblings, 1 reply; 10+ messages in thread
From: Wang Sheng-Hui @ 2011-08-27 9:34 UTC (permalink / raw)
To: wanlong.gao; +Cc: rusty, mst, virtualization, linux-kernel
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@gmail.com>
>> ---
>> 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?
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size
2011-08-27 9:34 ` Wang Sheng-Hui
@ 2011-08-27 9:52 ` Wang Sheng-Hui
2011-08-28 11:31 ` Michael S. Tsirkin
2011-08-29 2:53 ` Rusty Russell
0 siblings, 2 replies; 10+ messages in thread
From: Wang Sheng-Hui @ 2011-08-27 9:52 UTC (permalink / raw)
To: wanlong.gao; +Cc: rusty, mst, virtualization, linux-kernel
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@gmail.com>
>>> ---
>>> 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@gmail.com>
---
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
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size
2011-08-27 9:52 ` Wang Sheng-Hui
@ 2011-08-28 11:31 ` Michael S. Tsirkin
2011-08-28 12:48 ` Wang Sheng-Hui
2011-08-29 2:53 ` Rusty Russell
1 sibling, 1 reply; 10+ messages in thread
From: Michael S. Tsirkin @ 2011-08-28 11:31 UTC (permalink / raw)
To: Wang Sheng-Hui; +Cc: wanlong.gao, rusty, virtualization, linux-kernel
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@gmail.com>
> >>> ---
> >>> 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@gmail.com>
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
>
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size
2011-08-28 11:31 ` Michael S. Tsirkin
@ 2011-08-28 12:48 ` Wang Sheng-Hui
0 siblings, 0 replies; 10+ messages in thread
From: Wang Sheng-Hui @ 2011-08-28 12:48 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: wanlong.gao, rusty, virtualization, linux-kernel
On 2011年08月28日 19:31, Michael S. Tsirkin wrote:
> 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@gmail.com>
>>>>> ---
>>>>> 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@gmail.com>
>
> Is this a bugfix or just a cleanup?
> Alignment makes us get the same values with and without, right?
It's just a cleanup.
For normal case, the value 16 is too small compared with
the alignment, I think.
>
>> ---
>> 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
>>
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size
2011-08-27 9:52 ` Wang Sheng-Hui
2011-08-28 11:31 ` Michael S. Tsirkin
@ 2011-08-29 2:53 ` Rusty Russell
2011-08-29 6:51 ` Wang Sheng-Hui
2011-08-29 7:55 ` Wang Sheng-Hui
1 sibling, 2 replies; 10+ messages in thread
From: Rusty Russell @ 2011-08-29 2:53 UTC (permalink / raw)
To: Wang Sheng-Hui, wanlong.gao; +Cc: mst, virtualization, linux-kernel
On Sat, 27 Aug 2011 17:52:02 +0800, Wang Sheng-Hui <shhuiw@gmail.com> wrote:
> On 2011年08月27日 17:34, Wang Sheng-Hui wrote:
> 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));
> }
This + 16 should be + sizeof(__u16), right? It's just the
used_event_idx which has been added:
* __u16 available[num];
* __u16 used_event_idx;
*
* // Padding to the next align boundary.
* char pad[];
*
* [USED]
> 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;
This is correct.
And, yes, since align is always 4096, it's currently just a cleanup, but
it makes things much less confusing!
Thanks,
Rusty.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size
2011-08-29 2:53 ` Rusty Russell
@ 2011-08-29 6:51 ` Wang Sheng-Hui
2011-08-29 7:55 ` Wang Sheng-Hui
1 sibling, 0 replies; 10+ messages in thread
From: Wang Sheng-Hui @ 2011-08-29 6:51 UTC (permalink / raw)
To: Rusty Russell; +Cc: wanlong.gao, mst, virtualization, linux-kernel
On 2011年08月29日 10:53, Rusty Russell wrote:
> On Sat, 27 Aug 2011 17:52:02 +0800, Wang Sheng-Hui <shhuiw@gmail.com> wrote:
>> On 2011年08月27日 17:34, Wang Sheng-Hui wrote:
>> 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));
>> }
>
> This + 16 should be + sizeof(__u16), right? It's just the
> used_event_idx which has been added:
Yes.
>
> * __u16 available[num];
> * __u16 used_event_idx;
> *
> * // Padding to the next align boundary.
> * char pad[];
> *
> * [USED]
>
>> 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;
>
> This is correct.
>
> And, yes, since align is always 4096, it's currently just a cleanup, but
> it makes things much less confusing!
>
> Thanks,
> Rusty.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size
2011-08-29 2:53 ` Rusty Russell
2011-08-29 6:51 ` Wang Sheng-Hui
@ 2011-08-29 7:55 ` Wang Sheng-Hui
2011-08-30 0:12 ` Rusty Russell
1 sibling, 1 reply; 10+ messages in thread
From: Wang Sheng-Hui @ 2011-08-29 7:55 UTC (permalink / raw)
To: Rusty Russell; +Cc: wanlong.gao, mst, virtualization, linux-kernel
On 2011年08月29日 10:53, Rusty Russell wrote:
> On Sat, 27 Aug 2011 17:52:02 +0800, Wang Sheng-Hui <shhuiw@gmail.com> wrote:
>> On 2011年08月27日 17:34, Wang Sheng-Hui wrote:
>> 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));
>> }
>
> This + 16 should be + sizeof(__u16), right? It's just the
> used_event_idx which has been added:
>
> * __u16 available[num];
> * __u16 used_event_idx;
> *
> * // Padding to the next align boundary.
> * char pad[];
> *
> * [USED]
>
>> 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;
>
> This is correct.
>
> And, yes, since align is always 4096, it's currently just a cleanup, but
> it makes things much less confusing!
>
> Thanks,
> Rusty.
Patch regerated to use sizeof(__u16) instead of 16 in vring_init.
Please check it.
[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@gmail.com>
---
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..2a731bd 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] + sizeof(__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
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size
2011-08-29 7:55 ` Wang Sheng-Hui
@ 2011-08-30 0:12 ` Rusty Russell
0 siblings, 0 replies; 10+ messages in thread
From: Rusty Russell @ 2011-08-30 0:12 UTC (permalink / raw)
To: Wang Sheng-Hui; +Cc: wanlong.gao, mst, virtualization, linux-kernel
On Mon, 29 Aug 2011 15:55:59 +0800, Wang Sheng-Hui <shhuiw@gmail.com> wrote:
> Patch regerated to use sizeof(__u16) instead of 16 in vring_init.
> Please check it.
Applied.
Thanks,
Rusty.
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2011-08-30 0:27 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-08-27 1:07 [PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size Wang Sheng-Hui
2011-08-27 2:49 ` Wanlong Gao
2011-08-27 9:34 ` Wang Sheng-Hui
2011-08-27 9:52 ` Wang Sheng-Hui
2011-08-28 11:31 ` Michael S. Tsirkin
2011-08-28 12:48 ` Wang Sheng-Hui
2011-08-29 2:53 ` Rusty Russell
2011-08-29 6:51 ` Wang Sheng-Hui
2011-08-29 7:55 ` Wang Sheng-Hui
2011-08-30 0:12 ` Rusty Russell
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