From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp-vbr11.xs4all.nl ([194.109.24.31]:1364 "EHLO smtp-vbr11.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751977Ab3JBOFh (ORCPT ); Wed, 2 Oct 2013 10:05:37 -0400 Message-ID: <524C2826.6030902@xs4all.nl> Date: Wed, 02 Oct 2013 16:05:26 +0200 From: Hans Verkuil MIME-Version: 1.0 To: Sakari Ailus CC: linux-media@vger.kernel.org, laurent.pinchart@ideasonboard.com, teemux.tuominen@intel.com Subject: Re: [RFC v2 1/4] v4l: return POLLERR on V4L2 sub-devices if no events are subscribed References: <1380721516-488-1-git-send-email-sakari.ailus@linux.intel.com> <1380721516-488-2-git-send-email-sakari.ailus@linux.intel.com> In-Reply-To: <1380721516-488-2-git-send-email-sakari.ailus@linux.intel.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 10/02/13 15:45, Sakari Ailus wrote: > From: Teemu Tuominen > > Add check and return POLLERR from subdev_poll() in case of no events > subscribed and wakeup once the last event subscription is removed. > > This change is essentially done to add possibility to wakeup polling > with concurrent unsubscribe. > > Signed-off-by: Teemu Tuominen > > Move the check after calling poll_wait(). Otherwise it's possible that we go > to sleep without getting notified if the subscription went away between the > two. > > Signed-off-by: Sakari Ailus > Tested-by: Teemu Tuominen Acked-by: Hans Verkuil Regards, Hans > --- > drivers/media/v4l2-core/v4l2-event.c | 15 +++++++++++++++ > drivers/media/v4l2-core/v4l2-subdev.c | 3 +++ > include/media/v4l2-event.h | 1 + > 3 files changed, 19 insertions(+) > > diff --git a/drivers/media/v4l2-core/v4l2-event.c b/drivers/media/v4l2-core/v4l2-event.c > index 86dcb54..b53897e 100644 > --- a/drivers/media/v4l2-core/v4l2-event.c > +++ b/drivers/media/v4l2-core/v4l2-event.c > @@ -107,6 +107,19 @@ static struct v4l2_subscribed_event *v4l2_event_subscribed( > return NULL; > } > > +bool v4l2_event_has_subscribed(struct v4l2_fh *fh) > +{ > + unsigned long flags; > + bool rval; > + > + spin_lock_irqsave(&fh->vdev->fh_lock, flags); > + rval = !list_empty(&fh->subscribed); > + spin_unlock_irqrestore(&fh->vdev->fh_lock, flags); > + > + return rval; > +} > +EXPORT_SYMBOL(v4l2_event_has_subscribed); > + > static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev, > const struct timespec *ts) > { > @@ -299,6 +312,8 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh, > fh->navailable--; > } > list_del(&sev->list); > + if (list_empty(&fh->subscribed)) > + wake_up_all(&fh->wait); > } > > spin_unlock_irqrestore(&fh->vdev->fh_lock, flags); > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c > index 996c248..7d72389 100644 > --- a/drivers/media/v4l2-core/v4l2-subdev.c > +++ b/drivers/media/v4l2-core/v4l2-subdev.c > @@ -382,6 +382,9 @@ static unsigned int subdev_poll(struct file *file, poll_table *wait) > if (v4l2_event_pending(fh)) > return POLLPRI; > > + if (!v4l2_event_has_subscribed(fh)) > + return POLLERR | POLLPRI; > + > return 0; > } > > diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h > index be05d01..a9ca2b5 100644 > --- a/include/media/v4l2-event.h > +++ b/include/media/v4l2-event.h > @@ -121,6 +121,7 @@ struct v4l2_subscribed_event { > > int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event, > int nonblocking); > +bool v4l2_event_has_subscribed(struct v4l2_fh *fh); > void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev); > void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev); > int v4l2_event_pending(struct v4l2_fh *fh); >