From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from perceval.ideasonboard.com ([95.142.166.194]:39700 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753406Ab3JBSMN (ORCPT ); Wed, 2 Oct 2013 14:12:13 -0400 From: Laurent Pinchart To: Sakari Ailus Cc: linux-media@vger.kernel.org, hverkuil@xs4all.nl, teemux.tuominen@intel.com Subject: Re: [RFC v2 4/4] v4l: events: Don't sleep in dequeue if none are subscribed Date: Wed, 02 Oct 2013 20:12:17 +0200 Message-ID: <2284638.0TjbNMnX7g@avalon> In-Reply-To: <1380721516-488-5-git-send-email-sakari.ailus@linux.intel.com> References: <1380721516-488-1-git-send-email-sakari.ailus@linux.intel.com> <1380721516-488-5-git-send-email-sakari.ailus@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-media-owner@vger.kernel.org List-ID: 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 > --- > 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