Hi Hans, Thanks for your comments. Hans Verkuil wrote:
On 10/02/13 15:45, Sakari Ailus wrote:The current implementation allowed polling for events even if none were subscribed. This may be troublesome in multi-threaded applications where the thread handling the subscription is different from the one that handles the events. Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> --- drivers/media/v4l2-core/videobuf2-core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c index 79acf5e..c5dc903 100644 --- a/drivers/media/v4l2-core/videobuf2-core.c +++ b/drivers/media/v4l2-core/videobuf2-core.c @@ -2011,6 +2011,9 @@ unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait) if (v4l2_event_pending(fh)) res = POLLPRI; + + if (!v4l2_event_has_subscribed(fh)) + return POLLERR | POLLPRI;What should happen if you poll for both POLLPRI and POLLIN and one of the two would normally return POLLERR? Should that error condition be ignored? I'm not sure, frankly.
I think you just need to go to see what does VIDIOC_DQBUF / VIDIOC_DQEVENT return. If you're using select(2) you won't know about POLLERR explicitly anyway: there's a bit for read, write and exceptions but not for errors.
-- Kind regards, Sakari Ailus sakari.ailus@xxxxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
