On 09/26/2018 10:09 AM, Sakari Ailus wrote:
> Sometimes it may be necessary to grab a control while holding the control
> handler's lock. Provide an unlocked variant of v4l2_ctrl_grab for the
> purpose --- it's called __v4l2_ctrl_grab.
>
> Signed-off-by: Sakari Ailus <sakari.ai...@linux.intel.com>
Acked-by: Hans Verkuil <hans.verk...@cisco.com>
Regards,
Hans
> ---
> drivers/media/v4l2-core/v4l2-ctrls.c | 8 ++++----
> include/media/v4l2-ctrls.h | 26 +++++++++++++++++++++++++-
> 2 files changed, 29 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c
> b/drivers/media/v4l2-core/v4l2-ctrls.c
> index ab393adf51eb..4c0ecf29d278 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> @@ -2511,14 +2511,15 @@ void v4l2_ctrl_activate(struct v4l2_ctrl *ctrl, bool
> active)
> }
> EXPORT_SYMBOL(v4l2_ctrl_activate);
>
> -void v4l2_ctrl_grab(struct v4l2_ctrl *ctrl, bool grabbed)
> +void __v4l2_ctrl_grab(struct v4l2_ctrl *ctrl, bool grabbed)
> {
> bool old;
>
> if (ctrl == NULL)
> return;
>
> - v4l2_ctrl_lock(ctrl);
> + lockdep_assert_held(ctrl->handler->lock);
> +
> if (grabbed)
> /* set V4L2_CTRL_FLAG_GRABBED */
> old = test_and_set_bit(1, &ctrl->flags);
> @@ -2527,9 +2528,8 @@ void v4l2_ctrl_grab(struct v4l2_ctrl *ctrl, bool
> grabbed)
> old = test_and_clear_bit(1, &ctrl->flags);
> if (old != grabbed)
> send_event(NULL, ctrl, V4L2_EVENT_CTRL_CH_FLAGS);
> - v4l2_ctrl_unlock(ctrl);
> }
> -EXPORT_SYMBOL(v4l2_ctrl_grab);
> +EXPORT_SYMBOL(__v4l2_ctrl_grab);
>
> /* Log the control name and value */
> static void log_ctrl(const struct v4l2_ctrl *ctrl,
> diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
> index f615ba1b29dd..ff89df428f79 100644
> --- a/include/media/v4l2-ctrls.h
> +++ b/include/media/v4l2-ctrls.h
> @@ -729,6 +729,22 @@ struct v4l2_ctrl *v4l2_ctrl_find(struct
> v4l2_ctrl_handler *hdl, u32 id);
> void v4l2_ctrl_activate(struct v4l2_ctrl *ctrl, bool active);
>
> /**
> + * __v4l2_ctrl_grab() - Unlocked variant of v4l2_ctrl_grab.
> + *
> + * @ctrl: The control to (de)activate.
> + * @grabbed: True if the control should become grabbed.
> + *
> + * This sets or clears the V4L2_CTRL_FLAG_GRABBED flag atomically.
> + * Does nothing if @ctrl == NULL.
> + * The V4L2_EVENT_CTRL event will be generated afterwards.
> + * This will usually be called when starting or stopping streaming in the
> + * driver.
> + *
> + * This function assumes that the control handler is locked by the caller.
> + */
> +void __v4l2_ctrl_grab(struct v4l2_ctrl *ctrl, bool grabbed);
> +
> +/**
> * v4l2_ctrl_grab() - Mark the control as grabbed or not grabbed.
> *
> * @ctrl: The control to (de)activate.
> @@ -743,7 +759,15 @@ void v4l2_ctrl_activate(struct v4l2_ctrl *ctrl, bool
> active);
> * This function assumes that the control handler is not locked and will
> * take the lock itself.
> */
> -void v4l2_ctrl_grab(struct v4l2_ctrl *ctrl, bool grabbed);
> +static inline void v4l2_ctrl_grab(struct v4l2_ctrl *ctrl, bool grabbed)
> +{
> + if (!ctrl)
> + return;
> +
> + v4l2_ctrl_lock(ctrl);
> + __v4l2_ctrl_grab(ctrl, grabbed);
> + v4l2_ctrl_unlock(ctrl);
> +}
>
> /**
> *__v4l2_ctrl_modify_range() - Unlocked variant of v4l2_ctrl_modify_range()
>
