[PATCH v8 9/9] media: v4l: subdev: Return NULL from pad access functions on error

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Return NULL from sub-device pad state access functions
(v4l2_subdev_state_get_{format,crop,compose}) for non-existent pads. While
this behaviour differs from older set of pad state information access
functions, we've had a WARN_ON() there for a long time and callers also do
validate the pad index nowadays. Therefore problems are not expected.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/v4l2-core/v4l2-subdev.c | 36 +++++----------------------
 1 file changed, 6 insertions(+), 30 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index eb57a2582124..efb39172b20f 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -1538,16 +1538,8 @@ __v4l2_subdev_state_get_format(struct v4l2_subdev_state *state,
 		if (stream)
 			return NULL;
 
-		/*
-		 * Set the pad to 0 on error as this is aligned with the
-		 * behaviour of the pad state information access functions. The
-		 * purpose of setting pad to 0 here is to avoid accessing memory
-		 * outside the pads array, but still issuing warning of the
-		 * invalid access while making the caller's error handling
-		 * easier.
-		 */
-		if (WARN_ON_ONCE(pad >= state->sd->entity.num_pads))
-			pad = 0;
+		if (pad >= state->sd->entity.num_pads)
+			return NULL;
 
 		return &state->pads[pad].format;
 	}
@@ -1580,16 +1572,8 @@ __v4l2_subdev_state_get_crop(struct v4l2_subdev_state *state, unsigned int pad,
 		if (stream)
 			return NULL;
 
-		/*
-		 * Set the pad to 0 on error as this is aligned with the
-		 * behaviour of the pad state information access functions. The
-		 * purpose of setting pad to 0 here is to avoid accessing memory
-		 * outside the pads array, but still issuing warning of the
-		 * invalid access while making the caller's error handling
-		 * easier.
-		 */
-		if (WARN_ON_ONCE(pad >= state->sd->entity.num_pads))
-			pad = 0;
+		if (pad >= state->sd->entity.num_pads)
+			return NULL;
 
 		return &state->pads[pad].crop;
 	}
@@ -1622,16 +1606,8 @@ __v4l2_subdev_state_get_compose(struct v4l2_subdev_state *state,
 		if (stream)
 			return NULL;
 
-		/*
-		 * Set the pad to 0 on error as this is aligned with the
-		 * behaviour of the pad state information access functions. The
-		 * purpose of setting pad to 0 here is to avoid accessing memory
-		 * outside the pads array, but still issuing warning of the
-		 * invalid access while making the caller's error handling
-		 * easier.
-		 */
-		if (WARN_ON_ONCE(pad >= state->sd->entity.num_pads))
-			pad = 0;
+		if (pad >= state->sd->entity.num_pads)
+			return NULL;
 
 		return &state->pads[pad].compose;
 	}
-- 
2.39.2