media: Replace file->private_data access with custom functions

Accessing file->private_data manually to retrieve the v4l2_fh pointer is
error-prone, as the field is a void * and will happily cast implicitly
to any pointer type.

Replace all remaining locations that read the v4l2_fh pointer directly
from file->private_data and cast it to driver-specific file handle
structures with driver-specific functions that use file_to_v4l2_fh() and
perform the same cast.

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, 1 deletions

diff --git a/drivers/media/platform/allegro-dvt/allegro-core.c b/drivers/media/platform/allegro-dvt/allegro-core.c
index 1f134e08923a..74977f3ae484 100644
--- a/drivers/media/platform/allegro-dvt/allegro-core.c
+++ b/drivers/media/platform/allegro-dvt/allegro-core.c
@@ -302,6 +302,11 @@ struct allegro_channel {
 	unsigned int error;
 };
 
+static inline struct allegro_channel *file_to_channel(struct file *filp)
+{
+	return container_of(file_to_v4l2_fh(filp), struct allegro_channel, fh);
+}
+
 static inline int
 allegro_channel_get_i_frame_qp(struct allegro_channel *channel)
 {
@@ -3229,7 +3234,7 @@ error:
 
 static int allegro_release(struct file *file)
 {
-	struct allegro_channel *channel = fh_to_channel(file->private_data);
+	struct allegro_channel *channel = file_to_channel(file);
 
 	v4l2_m2m_ctx_release(channel->fh.m2m_ctx);