Re: [PATCH v5 0/5] Make sure .device_run is always called in non-atomic context

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On Thu, 2018-10-18 at 15:02 -0300, Ezequiel Garcia wrote:
> This series goal is to avoid drivers from having ad-hoc code
> to call .device_run in non-atomic context. Currently, .device_run
> can be called via v4l2_m2m_job_finish(), not only running
> in interrupt context, but also creating a nasty re-entrant
> path into mem2mem drivers.
> 
> The proposed solution is to add a per-device worker that is scheduled
> by v4l2_m2m_job_finish, which replaces drivers having a threaded interrupt
> or similar.
> 
> This change allows v4l2_m2m_job_finish() to be called in interrupt
> context, separating .device_run and v4l2_m2m_job_finish() contexts.
> 
> It's worth mentioning that v4l2_m2m_cancel_job() doesn't need
> to flush or cancel the new worker, because the job_spinlock
> synchronizes both and also because the core prevents simultaneous
> jobs. Either v4l2_m2m_cancel_job() will wait for the worker, or the
> worker will be unable to run a new job.
> 
> Patches apply on top of Request API and the Cedrus VPU
> driver.
> 
> Tested with cedrus driver using v4l2-request-test and
> vicodec driver using gstreamer.
> 
> Ezequiel Garcia (4):
>   mem2mem: Require capture and output mutexes to match
>   v4l2-ioctl.c: Simplify locking for m2m devices
>   v4l2-mem2mem: Avoid calling .device_run in v4l2_m2m_job_finish
>   media: cedrus: Get rid of interrupt bottom-half
> 
> Sakari Ailus (1):
>   v4l2-mem2mem: Simplify exiting the function in __v4l2_m2m_try_schedule
> 
>  drivers/media/v4l2-core/v4l2-ioctl.c          | 47 +------------
>  drivers/media/v4l2-core/v4l2-mem2mem.c        | 66 ++++++++++++-------
>  .../staging/media/sunxi/cedrus/cedrus_hw.c    | 26 ++------
>  3 files changed, 51 insertions(+), 88 deletions(-)
> 

Hans, Maxime:

Any feedback for this?

Thanks,
Eze




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