linux-kernel - [RFCv4 PATCH 3/6] videobuf2: only start streaming in poll() if so requested by the poll mask.

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Message-Id: <47dc03d0de07b08b43188d0ef3a53f431aa6b955.1317281827.git.hans.verkuil@cisco.com>
Date:	Thu, 29 Sep 2011 09:44:09 +0200
From:	Hans Verkuil <hverkuil@...all.nl>
To:	linux-media@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	viro@...iv.linux.org.uk, Jonathan Corbet <corbet@....net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hans Verkuil <hans.verkuil@...co.com>
Subject: [RFCv4 PATCH 3/6] videobuf2: only start streaming in poll() if so requested by the poll mask.

From: Hans Verkuil <hans.verkuil@...co.com>

Signed-off-by: Hans Verkuil <hans.verkuil@...co.com>
---
 drivers/media/video/videobuf2-core.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/media/video/videobuf2-core.c b/drivers/media/video/videobuf2-core.c
index 6687ac3..a921638 100644
--- a/drivers/media/video/videobuf2-core.c
+++ b/drivers/media/video/videobuf2-core.c
@@ -1368,6 +1368,7 @@ static int __vb2_cleanup_fileio(struct vb2_queue *q);
  */
 unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait)
 {
+	unsigned long req_events = poll_requested_events(wait);
 	unsigned long flags;
 	unsigned int ret;
 	struct vb2_buffer *vb = NULL;
@@ -1376,12 +1377,14 @@ unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait)
 	 * Start file I/O emulator only if streaming API has not been used yet.
 	 */
 	if (q->num_buffers == 0 && q->fileio == NULL) {
-		if (!V4L2_TYPE_IS_OUTPUT(q->type) && (q->io_modes & VB2_READ)) {
+		if (!V4L2_TYPE_IS_OUTPUT(q->type) && (q->io_modes & VB2_READ) &&
+				(req_events & (POLLIN | POLLRDNORM))) {
 			ret = __vb2_init_fileio(q, 1);
 			if (ret)
 				return POLLERR;
 		}
-		if (V4L2_TYPE_IS_OUTPUT(q->type) && (q->io_modes & VB2_WRITE)) {
+		if (V4L2_TYPE_IS_OUTPUT(q->type) && (q->io_modes & VB2_WRITE) &&
+				(req_events & (POLLOUT | POLLWRNORM))) {
 			ret = __vb2_init_fileio(q, 0);
 			if (ret)
 				return POLLERR;
-- 
1.7.5.4

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