[RFC PATCH 1/9] [media] v4l2-core: add v4l2_is_v4l2_file function

[Alexandre Courbot <acourbot@chromium.org>]

Add a function that checks whether a given open file is a v4l2 device
instance. This will be useful for job queue creation as we are passed a
set of FDs and we need to make this check.

Signed-off-by: Alexandre Courbot <acourbot@chromium.org>
---
 drivers/media/v4l2-core/v4l2-dev.c | 6 ++++++
 include/media/v4l2-dev.h           | 9 +++++++++
 2 files changed, 15 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index c647ba648805..5a7063886c93 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -470,6 +470,12 @@ static const struct file_operations v4l2_fops = {
 	.llseek = no_llseek,
 };
 
+bool v4l2_is_v4l2_file(struct file *filp)
+{
+	return filp->f_op == &v4l2_fops;
+}
+EXPORT_SYMBOL(v4l2_is_v4l2_file);
+
 /**
  * get_index - assign stream index number based on v4l2_dev
  * @vdev: video_device to assign index number to, vdev->v4l2_dev should be assigned
diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index e657614521e3..b73d646980da 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -395,6 +395,15 @@ void video_device_release(struct video_device *vdev);
  */
 void video_device_release_empty(struct video_device *vdev);
 
+/**
+ * v4l2_is_v4l2_file - Check whether a file describes a V4L2 device
+ *
+ * @filp: opened file to check
+ *
+ * Returns true of the file is a V4L2 device, false otherwise.
+ */
+bool v4l2_is_v4l2_file(struct file *filp);
+
 /**
  * v4l2_is_known_ioctl - Checks if a given cmd is a known V4L ioctl
  *
-- 
2.14.2.822.g60be5d43e6-goog