media: ipu3-cio2: Serialise access to pad format

commit 55a6c6b upstream.

Pad format can be accessed from user space. Serialise access to it.

Fixes: c2a6a07 ("media: intel-ipu3: cio2: add new MIPI-CSI2 driver")
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Bingbu Cao <bingbu.cao@intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: stable@vger.kernel.org # v4.16 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/media/pci/intel/ipu3/ipu3-cio2.c

@@ -1245,11 +1245,15 @@ static int cio2_subdev_get_fmt(struct v4l2_subdev *sd,
 {
 	struct cio2_queue *q = container_of(sd, struct cio2_queue, subdev);
 
+	mutex_lock(&q->subdev_lock);
+
 	if (fmt->which == V4L2_SUBDEV_FORMAT_TRY)
 		fmt->format = *v4l2_subdev_get_try_format(sd, cfg, fmt->pad);
 	else
 		fmt->format = q->subdev_fmt;
 
+	mutex_unlock(&q->subdev_lock);
+
 	return 0;
 }
 
@@ -1273,6 +1277,8 @@ static int cio2_subdev_set_fmt(struct v4l2_subdev *sd,
 	if (fmt->pad == CIO2_PAD_SOURCE)
 		return cio2_subdev_get_fmt(sd, cfg, fmt);
 
+	mutex_lock(&q->subdev_lock);
+
 	if (fmt->which == V4L2_SUBDEV_FORMAT_TRY) {
 		*v4l2_subdev_get_try_format(sd, cfg, fmt->pad) = fmt->format;
 	} else {
@@ -1283,6 +1289,8 @@ static int cio2_subdev_set_fmt(struct v4l2_subdev *sd,
 		fmt->format = q->subdev_fmt;
 	}
 
+	mutex_unlock(&q->subdev_lock);
+
 	return 0;
 }
 
@@ -1541,6 +1549,7 @@ static int cio2_queue_init(struct cio2_device *cio2, struct cio2_queue *q)
 
 	/* Initialize miscellaneous variables */
 	mutex_init(&q->lock);
+	mutex_init(&q->subdev_lock);
 
 	/* Initialize formats to default values */
 	fmt = &q->subdev_fmt;
@@ -1659,6 +1668,7 @@ static int cio2_queue_init(struct cio2_device *cio2, struct cio2_queue *q)
 fail_subdev_media_entity:
 	cio2_fbpt_exit(q, &cio2->pci_dev->dev);
 fail_fbpt:
+	mutex_destroy(&q->subdev_lock);
 	mutex_destroy(&q->lock);
 
 	return r;
@@ -1672,6 +1682,7 @@ static void cio2_queue_exit(struct cio2_device *cio2, struct cio2_queue *q)
 	v4l2_device_unregister_subdev(&q->subdev);
 	media_entity_cleanup(&q->subdev.entity);
 	cio2_fbpt_exit(q, &cio2->pci_dev->dev);
+	mutex_destroy(&q->subdev_lock);
 	mutex_destroy(&q->lock);
 }
 

drivers/media/pci/intel/ipu3/ipu3-cio2.h

@@ -332,6 +332,7 @@ struct cio2_queue {
 
 	/* Subdev, /dev/v4l-subdevX */
 	struct v4l2_subdev subdev;
+	struct mutex subdev_lock; /* Serialise acces to subdev_fmt field */
 	struct media_pad subdev_pads[CIO2_PADS];
 	struct v4l2_mbus_framefmt subdev_fmt;
 	atomic_t frame_sequence;