media: v4l2-ctrls.c: fix epoll() by calling poll_wait first

The epoll function expects that whenever the poll file op is
called, the poll_wait function is also called. That didn't
always happen in v4l2_ctrl_poll(). Fix this, otherwise epoll()
would timeout when it shouldn't.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
index 99308da..b79d3bb 100644 (file)
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -4166,9 +4166,9 @@ __poll_t v4l2_ctrl_poll(struct file *file, struct poll_table_struct *wait)
 {
        struct v4l2_fh *fh = file->private_data;
 
+       poll_wait(file, &fh->wait, wait);
        if (v4l2_event_pending(fh))
                return EPOLLPRI;
-       poll_wait(file, &fh->wait, wait);
        return 0;
 }
 EXPORT_SYMBOL(v4l2_ctrl_poll);