Re: [RFC v2 4/4] v4l: events: Don't sleep in dequeue if none are subscribed

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sakari,

On Wednesday 02 October 2013 16:45:16 Sakari Ailus wrote:
> Dequeueing events was is entirely possible even if none are subscribed,

was or is ? :-)

> leading to sleeping indefinitely. Fix this by returning -ENOENT when no
> events are subscribed.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  drivers/media/v4l2-core/v4l2-event.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-event.c
> b/drivers/media/v4l2-core/v4l2-event.c index b53897e..553a800 100644
> --- a/drivers/media/v4l2-core/v4l2-event.c
> +++ b/drivers/media/v4l2-core/v4l2-event.c
> @@ -77,10 +77,17 @@ int v4l2_event_dequeue(struct v4l2_fh *fh, struct
> v4l2_event *event, mutex_unlock(fh->vdev->lock);
> 
>  	do {
> -		ret = wait_event_interruptible(fh->wait,
> -					       fh->navailable != 0);
> +		bool subscribed;
> +		ret = wait_event_interruptible(
> +			fh->wait,
> +			fh->navailable != 0 ||
> +			!(subscribed = v4l2_event_has_subscribed(fh)));
>  		if (ret < 0)
>  			break;
> +		if (!subscribed) {
> +			ret = -EIO;
> +			break;
> +		}
> 
>  		ret = __v4l2_event_dequeue(fh, event);
>  	} while (ret == -ENOENT);
-- 
Regards,

Laurent Pinchart