imx258_open(), imx258_enum_mbus_code(), and imx258_enum_frame_size()
call imx258_get_format_code() without holding imx258->mutex. However,
imx258_get_format_code() has lockdep_assert_held(&imx258->mutex)
indicating that callers must hold this lock.

All other callers of imx258_get_format_code() properly acquire the mutex:
- imx258_set_pad_format() acquires mutex at imx258.c:918
- imx258_get_pad_format() acquires mutex at imx258.c:896

The mutex is needed to protect access to imx258->vflip->val and
imx258->hflip->val which are used to calculate the bayer format code.

Add mutex_lock()/mutex_unlock() around the imx258_get_format_code()
calls in the affected functions to fix the missing lock protection.

Signed-off-by: Ziyi Guo <n7l8m4@u.northwestern.edu>
---
 drivers/media/i2c/imx258.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/media/i2c/imx258.c b/drivers/media/i2c/imx258.c
index e50dcfd830f5..bc9ee449a87c 100644
--- a/drivers/media/i2c/imx258.c
+++ b/drivers/media/i2c/imx258.c
@@ -709,12 +709,16 @@ static int imx258_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
 		v4l2_subdev_state_get_format(fh->state, 0);
 	struct v4l2_rect *try_crop;
 
+	mutex_lock(&imx258->mutex);
+
 	/* Initialize try_fmt */
 	try_fmt->width = supported_modes[0].width;
 	try_fmt->height = supported_modes[0].height;
 	try_fmt->code = imx258_get_format_code(imx258);
 	try_fmt->field = V4L2_FIELD_NONE;
 
+	mutex_unlock(&imx258->mutex);
+
 	/* Initialize try_crop */
 	try_crop = v4l2_subdev_state_get_crop(fh->state, 0);
 	try_crop->left = IMX258_PIXEL_ARRAY_LEFT;
@@ -839,7 +843,9 @@ static int imx258_enum_mbus_code(struct v4l2_subdev *sd,
 	if (code->index > 0)
 		return -EINVAL;
 
+	mutex_lock(&imx258->mutex);
 	code->code = imx258_get_format_code(imx258);
+	mutex_unlock(&imx258->mutex);
 
 	return 0;
 }
@@ -849,10 +855,16 @@ static int imx258_enum_frame_size(struct v4l2_subdev *sd,
 				  struct v4l2_subdev_frame_size_enum *fse)
 {
 	struct imx258 *imx258 = to_imx258(sd);
+	u32 code;
+
 	if (fse->index >= ARRAY_SIZE(supported_modes))
 		return -EINVAL;
 
-	if (fse->code != imx258_get_format_code(imx258))
+	mutex_lock(&imx258->mutex);
+	code = imx258_get_format_code(imx258);
+	mutex_unlock(&imx258->mutex);
+
+	if (fse->code != code)
 		return -EINVAL;
 
 	fse->min_width = supported_modes[fse->index].width;
-- 
2.34.1