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SubjectRe: [PATCH v5 6/8] media: v4l2-core: fix v4l2_buffer handling for time64 ABI
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On 12/13/19 4:08 PM, Arnd Bergmann wrote:
> On Thu, Dec 12, 2019 at 4:43 PM Hans Verkuil <hverkuil@xs4all.nl> wrote:
>>
>> On 11/26/19 5:18 PM, Arnd Bergmann wrote:
>>>
>>> switch (cmd) {
>>> +#ifdef COMPAT_32BIT_TIME
>>
>> COMPAT_32BIT_TIME -> CONFIG_COMPAT_32BIT_TIME
>
> Fixed.
>
>>> + *vb = (struct v4l2_buffer) {
>>> + .index = vb32.index,
>>> + .type = vb32.type,
>>> + .bytesused = vb32.bytesused,
>>> + .flags = vb32.flags,
>>> + .field = vb32.field,
>>> + .timestamp.tv_sec = vb32.timestamp.tv_sec,
>>> + .timestamp.tv_usec = vb32.timestamp.tv_usec,
>>> + .timecode = vb32.timecode,
>>
>> You forgot to copy sequence.
>>
>>> + .memory = vb32.memory,
>>> + .m.userptr = vb32.m.usercopy,
>>
>> usercopy -> userptr
>
> Fixed.
>
>>> + .length = vb32.length,
>>> + .request_fd = vb32.request_fd,
>>> + };
>>> +
>>> + if (cmd == VIDIOC_QUERYBUF_TIME32)
>>> + memset(&vb->length, 0, sizeof(*vb) -
>>> + offsetof(struct v4l2_buffer, length));
>>
>> It's from the field AFTER vb->length that this needs to be zeroed. It's best to
>> use the CLEAR_AFTER_FIELD macro here.
>
> I'm a bit lost about this one: the fields that are not explicitly
> uninitialized here are already set to zero by the assignment
> above. Should this simply be a
>
> if (cmd == VIDIOC_QUERYBUF_TIME32)
> vb->request_fd = 0;

Yes, you are correct. That's much simpler.

>
> then? I don't remember where that memset() originally came
> from or why request_fd has to be cleared here.
>
>>> @@ -3100,6 +3141,30 @@ static int video_put_user(void __user *arg, void *parg, unsigned int cmd)
>>> return -EFAULT;
>>> break;
>>> }
>>> + case VIDIOC_QUERYBUF_TIME32:
>>> + case VIDIOC_QBUF_TIME32:
>>> + case VIDIOC_DQBUF_TIME32:
>>> + case VIDIOC_PREPARE_BUF_TIME32: {
>>> + struct v4l2_buffer *vb = parg;
>>> + struct v4l2_buffer_time32 vb32 = {
>>> + .index = vb->index,
>>> + .type = vb->type,
>>> + .bytesused = vb->bytesused,
>>> + .flags = vb->flags,
>>> + .field = vb->field,
>>> + .timestamp.tv_sec = vb->timestamp.tv_sec,
>>> + .timestamp.tv_usec = vb->timestamp.tv_usec,
>>> + .timecode = vb->timecode,
>>
>> You forgot to copy sequence.
>
> Fixed.
>
>> With these changes this patch series passed both the 64 and 32 bit compliance
>> tests (in fact, all the issues mentioned above were found with these compliance
>> tests).
>
> Yay compliance tests!
>
>> I am unable to test with musl since v4l2-ctl and v4l2-compliance are C++ programs,
>> and there doesn't appear to be an easy way to compile a C++ program with musl.
>>
>> If you happen to have a test environment where you can compile C++ with musl,
>> then let me know and I can give instructions on how to run the compliance tests.
>>
>> If you can't test that, then I can merge this regardless, and hope for the best
>> once the Y2038 fixes end up in glibc. But ideally I'd like to have this tested.
>
> I've heard good things about the prebuilt toolchains from http://musl.cc/.
> These seems to come with a libstdc++, but I have not tried that myself.

I'll see if I can give those a spin, but if I can't get it to work quickly,
then I don't plan on spending much time on it.

Regards,

Hans

>
> I've folded the change below into this patch in my y2038-v4l2-v6 branch
> but have not been able to update the copy on git.kernel.org yet because of
> server-side issues today.
>
> Arnd
>
> 8<-----
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c
> b/drivers/media/v4l2-core/v4l2-ioctl.c
> index c416870a3166..667225712343 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -3055,7 +3055,7 @@ static int video_get_user(void __user *arg, void
> *parg, unsigned int cmd,
> }
>
> switch (cmd) {
> -#ifdef COMPAT_32BIT_TIME
> +#ifdef CONFIG_COMPAT_32BIT_TIME
> case VIDIOC_QUERYBUF_TIME32:
> case VIDIOC_QBUF_TIME32:
> case VIDIOC_DQBUF_TIME32:
> @@ -3075,15 +3075,15 @@ static int video_get_user(void __user *arg,
> void *parg, unsigned int cmd,
> .timestamp.tv_sec = vb32.timestamp.tv_sec,
> .timestamp.tv_usec = vb32.timestamp.tv_usec,
> .timecode = vb32.timecode,
> + .sequence = vb32.sequence,
> .memory = vb32.memory,
> - .m.userptr = vb32.m.usercopy,
> + .m.userptr = vb32.m.userptr,
> .length = vb32.length,
> .request_fd = vb32.request_fd,
> };
>
> if (cmd == VIDIOC_QUERYBUF_TIME32)
> - memset(&vb->length, 0, sizeof(*vb) -
> - offsetof(struct v4l2_buffer, length));
> + vb->request_fd = 0;
>
> break;
> }
> @@ -3155,6 +3155,7 @@ static int video_put_user(void __user *arg, void
> *parg, unsigned int cmd)
> .timestamp.tv_sec = vb->timestamp.tv_sec,
> .timestamp.tv_usec = vb->timestamp.tv_usec,
> .timecode = vb->timecode,
> + .sequence = vb->sequence,
> .memory = vb->memory,
> .m.userptr = vb->m.userptr,
> .length = vb->length,
>

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