diff mbox series

media: subdev: Fix backward compatibility with the new 'stream' field

Message ID 20230215135523.357332-1-tomi.valkeinen@ideasonboard.com (mailing list archive)
State New, archived
Headers show
Series media: subdev: Fix backward compatibility with the new 'stream' field | expand

Commit Message

Tomi Valkeinen Feb. 15, 2023, 1:55 p.m. UTC 
The new 'stream' field in many v4l2 structs was taken from reserved
fields. The assumption was that the userspace is always required to zero
initialize the whole struct.

However, what happens in real life is that the apps only zero initialize
the reserved fields/arrays. When such an app is compiled with new
headers, the 'stream' field will be uninitialized, causing the kernel to
(most likely) return an error.

The streams API is still experimental and behind a compile-time flag,
'v4l2_subdev_enable_streams_api', and disabled by default. As a quick
fix always set the 'stream' field to zero when that flag is not set.
This keeps the backward compatibility when streams API is not enabled.

A proper fix when streams support is enabled is something else. Somehow
the userspace needs to signal the kernel that it actually intializes the
'stream' field.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/media/v4l2-core/v4l2-subdev.c | 33 +++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
diff mbox series

Patch

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 1bebcda2bd20..efa0a7f770cf 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -609,6 +609,9 @@  static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 	case VIDIOC_SUBDEV_G_FMT: {
 		struct v4l2_subdev_format *format = arg;
 
+		if (!v4l2_subdev_enable_streams_api)
+			format->stream = 0;
+
 		memset(format->reserved, 0, sizeof(format->reserved));
 		memset(format->format.reserved, 0, sizeof(format->format.reserved));
 		return v4l2_subdev_call(sd, pad, get_fmt, state, format);
@@ -620,6 +623,9 @@  static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 		if (format->which != V4L2_SUBDEV_FORMAT_TRY && ro_subdev)
 			return -EPERM;
 
+		if (!v4l2_subdev_enable_streams_api)
+			format->stream = 0;
+
 		memset(format->reserved, 0, sizeof(format->reserved));
 		memset(format->format.reserved, 0, sizeof(format->format.reserved));
 		return v4l2_subdev_call(sd, pad, set_fmt, state, format);
@@ -629,6 +635,9 @@  static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 		struct v4l2_subdev_crop *crop = arg;
 		struct v4l2_subdev_selection sel;
 
+		if (!v4l2_subdev_enable_streams_api)
+			crop->stream = 0;
+
 		memset(crop->reserved, 0, sizeof(crop->reserved));
 		memset(&sel, 0, sizeof(sel));
 		sel.which = crop->which;
@@ -650,6 +659,9 @@  static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 		if (crop->which != V4L2_SUBDEV_FORMAT_TRY && ro_subdev)
 			return -EPERM;
 
+		if (!v4l2_subdev_enable_streams_api)
+			crop->stream = 0;
+
 		memset(crop->reserved, 0, sizeof(crop->reserved));
 		memset(&sel, 0, sizeof(sel));
 		sel.which = crop->which;
@@ -668,6 +680,9 @@  static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 	case VIDIOC_SUBDEV_ENUM_MBUS_CODE: {
 		struct v4l2_subdev_mbus_code_enum *code = arg;
 
+		if (!v4l2_subdev_enable_streams_api)
+			code->stream = 0;
+
 		memset(code->reserved, 0, sizeof(code->reserved));
 		return v4l2_subdev_call(sd, pad, enum_mbus_code, state,
 					code);
@@ -676,6 +691,9 @@  static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 	case VIDIOC_SUBDEV_ENUM_FRAME_SIZE: {
 		struct v4l2_subdev_frame_size_enum *fse = arg;
 
+		if (!v4l2_subdev_enable_streams_api)
+			fse->stream = 0;
+
 		memset(fse->reserved, 0, sizeof(fse->reserved));
 		return v4l2_subdev_call(sd, pad, enum_frame_size, state,
 					fse);
@@ -684,6 +702,9 @@  static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 	case VIDIOC_SUBDEV_G_FRAME_INTERVAL: {
 		struct v4l2_subdev_frame_interval *fi = arg;
 
+		if (!v4l2_subdev_enable_streams_api)
+			fi->stream = 0;
+
 		memset(fi->reserved, 0, sizeof(fi->reserved));
 		return v4l2_subdev_call(sd, video, g_frame_interval, arg);
 	}
@@ -694,6 +715,9 @@  static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 		if (ro_subdev)
 			return -EPERM;
 
+		if (!v4l2_subdev_enable_streams_api)
+			fi->stream = 0;
+
 		memset(fi->reserved, 0, sizeof(fi->reserved));
 		return v4l2_subdev_call(sd, video, s_frame_interval, arg);
 	}
@@ -701,6 +725,9 @@  static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 	case VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL: {
 		struct v4l2_subdev_frame_interval_enum *fie = arg;
 
+		if (!v4l2_subdev_enable_streams_api)
+			fie->stream = 0;
+
 		memset(fie->reserved, 0, sizeof(fie->reserved));
 		return v4l2_subdev_call(sd, pad, enum_frame_interval, state,
 					fie);
@@ -709,6 +736,9 @@  static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 	case VIDIOC_SUBDEV_G_SELECTION: {
 		struct v4l2_subdev_selection *sel = arg;
 
+		if (!v4l2_subdev_enable_streams_api)
+			sel->stream = 0;
+
 		memset(sel->reserved, 0, sizeof(sel->reserved));
 		return v4l2_subdev_call(
 			sd, pad, get_selection, state, sel);
@@ -720,6 +750,9 @@  static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
 		if (sel->which != V4L2_SUBDEV_FORMAT_TRY && ro_subdev)
 			return -EPERM;
 
+		if (!v4l2_subdev_enable_streams_api)
+			sel->stream = 0;
+
 		memset(sel->reserved, 0, sizeof(sel->reserved));
 		return v4l2_subdev_call(
 			sd, pad, set_selection, state, sel);