media: Wrap file->private_data access with a helper function

Accessing file->private_data manually to retrieve the v4l2_fh pointer is
error-prone, as the field is a void * and will happily convert
implicitly to any pointer type. To avoid direct access to
file->private_data, introduce a new inline function that retrieves the
v4l2_fh pointer, and use it to replace common access patterns through
the kernel.

Changes to drivers have been generated with the following coccinelle
semantic patch:

@@
struct file *filp;
identifier fh;
@@

-       struct v4l2_fh *fh = filp->private_data;
+       struct v4l2_fh *fh = file_to_v4l2_fh(filp);

Manual changes have been applied to Documentation/ to update the usage
patterns, and to include/media/v4l2-fh.h to add the new function.

While at it, fix a typo in the title of v4l2-fh.rst: the file describes
the "file handles" API, not "file handlers".

No functional change is intended, this only paves the way to remove
direct accesses to file->private_data and make V4L2 drivers safer.
Other accesses to the field will be addressed separately.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/drivers/media/platform/renesas/vsp1/vsp1_video.c b/drivers/media/platform/renesas/vsp1/vsp1_video.c
index bc66fbdde3cc..656fb5e6cb30 100644
--- a/drivers/media/platform/renesas/vsp1/vsp1_video.c
+++ b/drivers/media/platform/renesas/vsp1/vsp1_video.c
@@ -896,7 +896,7 @@ static const struct vb2_ops vsp1_video_queue_qops = {
 static int
 vsp1_video_querycap(struct file *file, void *fh, struct v4l2_capability *cap)
 {
-	struct v4l2_fh *vfh = file->private_data;
+	struct v4l2_fh *vfh = file_to_v4l2_fh(file);
 	struct vsp1_video *video = to_vsp1_video(vfh->vdev);
 
 	cap->capabilities = V4L2_CAP_DEVICE_CAPS | V4L2_CAP_STREAMING
@@ -912,7 +912,7 @@ vsp1_video_querycap(struct file *file, void *fh, struct v4l2_capability *cap)
 static int vsp1_video_enum_format(struct file *file, void *fh,
 				  struct v4l2_fmtdesc *f)
 {
-	struct v4l2_fh *vfh = file->private_data;
+	struct v4l2_fh *vfh = file_to_v4l2_fh(file);
 	struct vsp1_video *video = to_vsp1_video(vfh->vdev);
 	const struct vsp1_format_info *info;
 
@@ -933,7 +933,7 @@ static int vsp1_video_enum_format(struct file *file, void *fh,
 static int
 vsp1_video_get_format(struct file *file, void *fh, struct v4l2_format *format)
 {
-	struct v4l2_fh *vfh = file->private_data;
+	struct v4l2_fh *vfh = file_to_v4l2_fh(file);
 	struct vsp1_video *video = to_vsp1_video(vfh->vdev);
 
 	if (format->type != video->queue.type)
@@ -949,7 +949,7 @@ vsp1_video_get_format(struct file *file, void *fh, struct v4l2_format *format)
 static int
 vsp1_video_try_format(struct file *file, void *fh, struct v4l2_format *format)
 {
-	struct v4l2_fh *vfh = file->private_data;
+	struct v4l2_fh *vfh = file_to_v4l2_fh(file);
 	struct vsp1_video *video = to_vsp1_video(vfh->vdev);
 
 	if (format->type != video->queue.type)
@@ -961,7 +961,7 @@ vsp1_video_try_format(struct file *file, void *fh, struct v4l2_format *format)
 static int
 vsp1_video_set_format(struct file *file, void *fh, struct v4l2_format *format)
 {
-	struct v4l2_fh *vfh = file->private_data;
+	struct v4l2_fh *vfh = file_to_v4l2_fh(file);
 	struct vsp1_video *video = to_vsp1_video(vfh->vdev);
 	const struct vsp1_format_info *info;
 	int ret;
@@ -991,7 +991,7 @@ done:
 static int
 vsp1_video_streamon(struct file *file, void *fh, enum v4l2_buf_type type)
 {
-	struct v4l2_fh *vfh = file->private_data;
+	struct v4l2_fh *vfh = file_to_v4l2_fh(file);
 	struct vsp1_video *video = to_vsp1_video(vfh->vdev);
 	struct media_device *mdev = &video->vsp1->media_dev;
 	struct vsp1_pipeline *pipe;