VB2 will returning -ERESTARTSYS to userland

VB2 will returning -ERESTARTSYS to userland

[Chetan Nanda]

Hi,

I am working on V4L2 base videodecoder,
I have two threads say A and B. Thread A is for configuration and
Thread B for queuing/de-queuing buffers.

In one usecase,
- Thread B is blocked on VIDIOC_DQBUF,
- and at same time Thread A do the flush and do, STREAMOFF, QBUF, STREAMON.

Once thread A do this, Thread B waked up (as a result of STREAMOFF)
and return -ERESTARTSYS (from wait_interrupt_interruptible) from
DQBUF.

ERESTARTSYS is for kernel internal and should not be passed to
userside, and even ERESTARTSYS is not available at user side.

Shouldn't VB2 catch ERESTARTSYS and return -RESTART or some other error?

Thanks,
Chetan Nanda

Re: VB2 will returning -ERESTARTSYS to userland

[Mauro Carvalho Chehab]

Em Fri, 9 Oct 2015 10:00:39 +0530
Chetan Nanda <chetannanda@gmail.com> escreveu:

> Hi,
> 
> I am working on V4L2 base videodecoder,
> I have two threads say A and B. Thread A is for configuration and
> Thread B for queuing/de-queuing buffers.
> 
> In one usecase,
> - Thread B is blocked on VIDIOC_DQBUF,
> - and at same time Thread A do the flush and do, STREAMOFF, QBUF, STREAMON.
> 
> Once thread A do this, Thread B waked up (as a result of STREAMOFF)
> and return -ERESTARTSYS (from wait_interrupt_interruptible) from
> DQBUF.
> 
> ERESTARTSYS is for kernel internal and should not be passed to
> userside, and even ERESTARTSYS is not available at user side.
> 
> Shouldn't VB2 catch ERESTARTSYS and return -RESTART or some other error?

In thesis, the ioctl core should be handling -ERESTARTSYS. Are you
sure that you're seeing ERESTARTSYS on userspace?

> 
> Thanks,
> Chetan Nanda
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