[PATCH 2/3] media: iris: Document difference in size during allocation

[Ricardo Ribalda]

As we get ready for kzalloc checking for invalid sizes, let's add
documentation for the cases where the size is different but valid.

This patch fixes this cocci warning:
./platform/qcom/iris/iris_hfi_gen2_command.c:1215:9-25: WARNING: casting value returned by memory allocation function to (struct iris_inst *) is useless.

Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
---
 drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c b/drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c
index f9129553209922fda548ca320494ae6ae797854c..ab91afd0597045bd876d0411b08b5a3421b12c70 100644
--- a/drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c
+++ b/drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c
@@ -1212,5 +1212,13 @@ void iris_hfi_gen2_command_ops_init(struct iris_core *core)
 
 struct iris_inst *iris_hfi_gen2_get_instance(void)
 {
-	return (struct iris_inst *)kzalloc(sizeof(struct iris_inst_hfi_gen2), GFP_KERNEL);
+	struct iris_inst_hfi_gen2 *out;
+
+	/*
+	 * The allocation is intentionally larger. The first member of
+	 * struct iris_hfi_gen2 is struct iris_inst.
+	 */
+	out = kzalloc(sizeof(*out), GFP_KERNEL);
+
+	return (struct iris_inst *)out;
 }

-- 
2.52.0.158.g65b55ccf14-goog