media: Zero-initialize all structures passed to subdev pad operations

Several drivers call subdev pad operations, passing structures that are
not fully zeroed. While the drivers initialize the fields they care
about explicitly, this results in reserved fields having uninitialized
values. Future kernel API changes that make use of those fields thus
risk breaking proper driver operation in ways that could be hard to
detect.

To avoid this, make the code more robust by zero-initializing all the
structures passed to subdev pad operation. Maintain a consistent coding
style by preferring designated initializers (which zero-initialize all
the fields that are not specified) over memset() where possible, and
make variable declarations local to inner scopes where applicable. One
notable exception to this rule is in the ipu3 driver, where a memset()
is needed as the structure is not a local variable but a function
parameter provided by the caller.

Not all fields of those structures can be initialized when declaring the
variables, as the values for those fields are computed later in the
code. Initialize the 'which' field in all cases, and other fields when
the variable declaration is so close to the v4l2_subdev_call() call that
it keeps all the context easily visible when reading the code, to avoid
hindering readability.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org> # For vimc
Reviewed-by: Lad Prabhakar <prabhakar.csengg@gmail.com> # For am437x
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de> # For drivers/staging/media/imx/
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

5 files changed, 26 insertions, 14 deletions

diff --git a/drivers/media/platform/samsung/exynos4-is/fimc-capture.c b/drivers/media/platform/samsung/exynos4-is/fimc-capture.c
index e3b95a2b7e04..4800751a401c 100644
--- a/drivers/media/platform/samsung/exynos4-is/fimc-capture.c
+++ b/drivers/media/platform/samsung/exynos4-is/fimc-capture.c
@@ -854,7 +854,7 @@ static int fimc_get_sensor_frame_desc(struct v4l2_subdev *sensor,
 				      struct v4l2_plane_pix_format *plane_fmt,
 				      unsigned int num_planes, bool try)
 {
-	struct v4l2_mbus_frame_desc fd;
+	struct v4l2_mbus_frame_desc fd = { };
 	int i, ret;
 	int pad;
 
@@ -1095,7 +1095,12 @@ static int fimc_cap_g_input(struct file *file, void *priv, unsigned int *i)
  */
 static int fimc_pipeline_validate(struct fimc_dev *fimc)
 {
-	struct v4l2_subdev_format sink_fmt, src_fmt;
+	struct v4l2_subdev_format sink_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
+	struct v4l2_subdev_format src_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct fimc_vid_cap *vc = &fimc->vid_cap;
 	struct v4l2_subdev *sd = &vc->subdev;
 	struct fimc_pipeline *p = to_fimc_pipeline(vc->ve.pipe);
@@ -1132,7 +1137,6 @@ static int fimc_pipeline_validate(struct fimc_dev *fimc)
 			sink_fmt.format.code = ff->fmt ? ff->fmt->mbus_code : 0;
 		} else {
 			sink_fmt.pad = sink_pad->index;
-			sink_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 			ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &sink_fmt);
 			if (ret < 0 && ret != -ENOIOCTLCMD)
 				return -EPIPE;
@@ -1141,7 +1145,6 @@ static int fimc_pipeline_validate(struct fimc_dev *fimc)
 		/* Retrieve format at the source pad */
 		sd = media_entity_to_v4l2_subdev(src_pad->entity);
 		src_fmt.pad = src_pad->index;
-		src_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 		ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &src_fmt);
 		if (ret < 0 && ret != -ENOIOCTLCMD)
 			return -EPIPE;
diff --git a/drivers/media/platform/samsung/exynos4-is/fimc-isp-video.c b/drivers/media/platform/samsung/exynos4-is/fimc-isp-video.c
index f6a302fa8d37..8fa26969c411 100644
--- a/drivers/media/platform/samsung/exynos4-is/fimc-isp-video.c
+++ b/drivers/media/platform/samsung/exynos4-is/fimc-isp-video.c
@@ -449,17 +449,22 @@ static int isp_video_s_fmt_mplane(struct file *file, void *priv,
 static int isp_video_pipeline_validate(struct fimc_isp *isp)
 {
 	struct v4l2_subdev *sd = &isp->subdev;
-	struct v4l2_subdev_format sink_fmt, src_fmt;
 	struct media_pad *pad;
 	int ret;
 
 	while (1) {
+		struct v4l2_subdev_format sink_fmt = {
+			.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		};
+		struct v4l2_subdev_format src_fmt = {
+			.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		};
+
 		/* Retrieve format at the sink pad */
 		pad = &sd->entity.pads[0];
 		if (!(pad->flags & MEDIA_PAD_FL_SINK))
 			break;
 		sink_fmt.pad = pad->index;
-		sink_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 		ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &sink_fmt);
 		if (ret < 0 && ret != -ENOIOCTLCMD)
 			return -EPIPE;
@@ -471,7 +476,6 @@ static int isp_video_pipeline_validate(struct fimc_isp *isp)
 
 		sd = media_entity_to_v4l2_subdev(pad->entity);
 		src_fmt.pad = pad->index;
-		src_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 		ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &src_fmt);
 		if (ret < 0 && ret != -ENOIOCTLCMD)
 			return -EPIPE;
diff --git a/drivers/media/platform/samsung/exynos4-is/fimc-lite.c b/drivers/media/platform/samsung/exynos4-is/fimc-lite.c
index 2fadb18560d7..24b3dda26714 100644
--- a/drivers/media/platform/samsung/exynos4-is/fimc-lite.c
+++ b/drivers/media/platform/samsung/exynos4-is/fimc-lite.c
@@ -765,7 +765,12 @@ static int fimc_lite_s_fmt_mplane(struct file *file, void *priv,
 static int fimc_pipeline_validate(struct fimc_lite *fimc)
 {
 	struct v4l2_subdev *sd = &fimc->subdev;
-	struct v4l2_subdev_format sink_fmt, src_fmt;
+	struct v4l2_subdev_format sink_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
+	struct v4l2_subdev_format src_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct media_pad *pad;
 	int ret;
 
@@ -782,7 +787,6 @@ static int fimc_pipeline_validate(struct fimc_lite *fimc)
 			sink_fmt.format.code = fimc->inp_frame.fmt->mbus_code;
 		} else {
 			sink_fmt.pad = pad->index;
-			sink_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 			ret = v4l2_subdev_call(sd, pad, get_fmt, NULL,
 					       &sink_fmt);
 			if (ret < 0 && ret != -ENOIOCTLCMD)
@@ -795,7 +799,6 @@ static int fimc_pipeline_validate(struct fimc_lite *fimc)
 
 		sd = media_entity_to_v4l2_subdev(pad->entity);
 		src_fmt.pad = pad->index;
-		src_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 		ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &src_fmt);
 		if (ret < 0 && ret != -ENOIOCTLCMD)
 			return -EPIPE;
diff --git a/drivers/media/platform/samsung/s3c-camif/camif-capture.c b/drivers/media/platform/samsung/s3c-camif/camif-capture.c
index db106ebdf870..76634d242b10 100644
--- a/drivers/media/platform/samsung/s3c-camif/camif-capture.c
+++ b/drivers/media/platform/samsung/s3c-camif/camif-capture.c
@@ -806,7 +806,9 @@ static int s3c_camif_vidioc_s_fmt(struct file *file, void *priv,
 /* Only check pixel formats at the sensor and the camif subdev pads */
 static int camif_pipeline_validate(struct camif_dev *camif)
 {
-	struct v4l2_subdev_format src_fmt;
+	struct v4l2_subdev_format src_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct media_pad *pad;
 	int ret;
 
@@ -816,7 +818,6 @@ static int camif_pipeline_validate(struct camif_dev *camif)
 		return -EPIPE;
 
 	src_fmt.pad = pad->index;
-	src_fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(camif->sensor.sd, pad, get_fmt, NULL, &src_fmt);
 	if (ret < 0 && ret != -ENOIOCTLCMD)
 		return -EPIPE;
diff --git a/drivers/media/platform/samsung/s3c-camif/camif-core.c b/drivers/media/platform/samsung/s3c-camif/camif-core.c
index 0b50183d9230..afe1fcc37354 100644
--- a/drivers/media/platform/samsung/s3c-camif/camif-core.c
+++ b/drivers/media/platform/samsung/s3c-camif/camif-core.c
@@ -190,7 +190,9 @@ static int camif_register_sensor(struct camif_dev *camif)
 	struct s3c_camif_sensor_info *sensor = &camif->pdata.sensor;
 	struct v4l2_device *v4l2_dev = &camif->v4l2_dev;
 	struct i2c_adapter *adapter;
-	struct v4l2_subdev_format format;
+	struct v4l2_subdev_format format = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+	};
 	struct v4l2_subdev *sd;
 	int ret;
 
@@ -220,7 +222,6 @@ static int camif_register_sensor(struct camif_dev *camif)
 
 	/* Get initial pixel format and set it at the camif sink pad */
 	format.pad = 0;
-	format.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &format);
 
 	if (ret < 0)