| Message ID | 1380721516-488-4-git-send-email-sakari.ailus@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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@linux.intel.com> > --- > 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. Regards, Hans > } > > if (!V4L2_TYPE_IS_OUTPUT(q->type) && !(req_events & (POLLIN | POLLRDNORM))) > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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@linux.intel.com> >> --- >> 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.
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; } if (!V4L2_TYPE_IS_OUTPUT(q->type) && !(req_events & (POLLIN | POLLRDNORM)))
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@linux.intel.com> --- drivers/media/v4l2-core/videobuf2-core.c | 3 +++ 1 file changed, 3 insertions(+)