Re: [PATCH 4/14] drivers/media/v4l2-core/videobuf2-core.c: fix error return code
Hi Peter,
On 10/10/2012 06:47 PM, Peter Senna Tschudin wrote:
>>> diff --git a/drivers/media/v4l2-core/videobuf2-core.c
>>> b/drivers/media/v4l2-core/videobuf2-core.c
>>> index 4da3df6..f6bc240 100644
>>> --- a/drivers/media/v4l2-core/videobuf2-core.c
>>> +++ b/drivers/media/v4l2-core/videobuf2-core.c
>>> @@ -1876,8 +1876,10 @@ static int __vb2_init_fileio(struct vb2_queue *q,
>>> int read)
>>>*/
>>> for (i = 0; i < q->num_buffers; i++) {
>>> fileio->bufs[i].vaddr = vb2_plane_vaddr(q->bufs[i], 0);
>>> - if (fileio->bufs[i].vaddr == NULL)
>>> + if (fileio->bufs[i].vaddr == NULL) {
>>> + ret = -EFAULT;
>>> goto err_reqbufs;
>>> + }
>>
>> Had you test this patch? I suspect it breaks the driver, as there are
>> failures under
>> streaming handling that are acceptable, as it may indicate that userspace
>> was not
>> able to handle all queued frames in time. On such cases, what the Kernel
>> does is to
>> just discard the frame. Userspace is able to detect it, by looking inside
>> the timestamp
>> added on each frame.
>
> No, I have not tested it. This was the only place the function was
> returning non negative value for error path, so looked as a bug to me.
> May I add a comment about returning non-negative value is intended
> there?
There are several drivers depending on core modules like videobuf2. By making
random changes for something that _looks like_ a bug to you and not verifying
it by testing with at least one driver you are potentially causing trouble to
developers that are already busy fixing real bugs or working on new features.
I appreciate your help but I also don't want to see _any_ untested, not trivial
patches for core modules like videobuf2 being applied.
--
Thanks,
Sylwester
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Re: [PATCH 4/14] drivers/media/v4l2-core/videobuf2-core.c: fix error return code
On Sat, Oct 6, 2012 at 1:17 PM, Mauro Carvalho Chehab
wrote:
> Em Thu, 6 Sep 2012 17:23:57 +0200
> Peter Senna Tschudin escreveu:
>
>> From: Peter Senna Tschudin
>>
>> Convert a nonnegative error return code to a negative one, as returned
>> elsewhere in the function.
>>
>> A simplified version of the semantic match that finds this problem is as
>> follows: (http://coccinelle.lip6.fr/)
>>
>> //
>> (
>> if@p1 (\(ret < 0\|ret != 0\))
>> { ... return ret; }
>> |
>> ret@p1 = 0
>> )
>> ... when != ret = e1
>> when != &ret
>> *if(...)
>> {
>> ... when != ret = e2
>> when forall
>> return ret;
>> }
>>
>> //
>>
>> Signed-off-by: Peter Senna Tschudin
>>
>> ---
>> drivers/media/v4l2-core/videobuf2-core.c |4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/media/v4l2-core/videobuf2-core.c
>> b/drivers/media/v4l2-core/videobuf2-core.c
>> index 4da3df6..f6bc240 100644
>> --- a/drivers/media/v4l2-core/videobuf2-core.c
>> +++ b/drivers/media/v4l2-core/videobuf2-core.c
>> @@ -1876,8 +1876,10 @@ static int __vb2_init_fileio(struct vb2_queue *q, int
>> read)
>>*/
>> for (i = 0; i < q->num_buffers; i++) {
>> fileio->bufs[i].vaddr = vb2_plane_vaddr(q->bufs[i], 0);
>> - if (fileio->bufs[i].vaddr == NULL)
>> + if (fileio->bufs[i].vaddr == NULL) {
>> + ret = -EFAULT;
>> goto err_reqbufs;
>> + }
>
> Had you test this patch? I suspect it breaks the driver, as there are
> failures under
> streaming handling that are acceptable, as it may indicate that userspace was
> not
> able to handle all queued frames in time. On such cases, what the Kernel does
> is to
> just discard the frame. Userspace is able to detect it, by looking inside the
> timestamp
> added on each frame.
No, I have not tested it. This was the only place the function was
returning non negative value for error path, so looked as a bug to me.
May I add a comment about returning non-negative value is intended
there?
>
>> fileio->bufs[i].size = vb2_plane_size(q->bufs[i], 0);
>> }
>>
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-media" in
>> the body of a message to majord...@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
>
>
>
> Cheers,
> Mauro
--
Peter
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Re: [PATCH 4/14] drivers/media/v4l2-core/videobuf2-core.c: fix error return code
Em Thu, 6 Sep 2012 17:23:57 +0200
Peter Senna Tschudin escreveu:
> From: Peter Senna Tschudin
>
> Convert a nonnegative error return code to a negative one, as returned
> elsewhere in the function.
>
> A simplified version of the semantic match that finds this problem is as
> follows: (http://coccinelle.lip6.fr/)
>
> //
> (
> if@p1 (\(ret < 0\|ret != 0\))
> { ... return ret; }
> |
> ret@p1 = 0
> )
> ... when != ret = e1
> when != &ret
> *if(...)
> {
> ... when != ret = e2
> when forall
> return ret;
> }
>
> //
>
> Signed-off-by: Peter Senna Tschudin
>
> ---
> drivers/media/v4l2-core/videobuf2-core.c |4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c
> b/drivers/media/v4l2-core/videobuf2-core.c
> index 4da3df6..f6bc240 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -1876,8 +1876,10 @@ static int __vb2_init_fileio(struct vb2_queue *q, int
> read)
>*/
> for (i = 0; i < q->num_buffers; i++) {
> fileio->bufs[i].vaddr = vb2_plane_vaddr(q->bufs[i], 0);
> - if (fileio->bufs[i].vaddr == NULL)
> + if (fileio->bufs[i].vaddr == NULL) {
> + ret = -EFAULT;
> goto err_reqbufs;
> + }
Had you test this patch? I suspect it breaks the driver, as there are failures
under
streaming handling that are acceptable, as it may indicate that userspace was
not
able to handle all queued frames in time. On such cases, what the Kernel does
is to
just discard the frame. Userspace is able to detect it, by looking inside the
timestamp
added on each frame.
> fileio->bufs[i].size = vb2_plane_size(q->bufs[i], 0);
> }
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-media" in
> the body of a message to majord...@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
Cheers,
Mauro
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[PATCH 4/14] drivers/media/v4l2-core/videobuf2-core.c: fix error return code
From: Peter Senna Tschudin
Convert a nonnegative error return code to a negative one, as returned
elsewhere in the function.
A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)
//
(
if@p1 (\(ret < 0\|ret != 0\))
{ ... return ret; }
|
ret@p1 = 0
)
... when != ret = e1
when != &ret
*if(...)
{
... when != ret = e2
when forall
return ret;
}
//
Signed-off-by: Peter Senna Tschudin
---
drivers/media/v4l2-core/videobuf2-core.c |4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/media/v4l2-core/videobuf2-core.c
b/drivers/media/v4l2-core/videobuf2-core.c
index 4da3df6..f6bc240 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1876,8 +1876,10 @@ static int __vb2_init_fileio(struct vb2_queue *q, int
read)
*/
for (i = 0; i < q->num_buffers; i++) {
fileio->bufs[i].vaddr = vb2_plane_vaddr(q->bufs[i], 0);
- if (fileio->bufs[i].vaddr == NULL)
+ if (fileio->bufs[i].vaddr == NULL) {
+ ret = -EFAULT;
goto err_reqbufs;
+ }
fileio->bufs[i].size = vb2_plane_size(q->bufs[i], 0);
}
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