# Re: \[PATCH RFC 05/20\] ctlv: Prepare message input handling

- From: Jiri Pirko \<jiri@resnulli.us\>
- Date: 2026-10-27 10:17:32 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2026/10/17809565
- Thread: https://ratatoskr.run/linux-coco/2026/10/17748473/t/2.md

```text
Mon, Oct 26, 2026 at 03:07:54PM +0100, jgg@nvidia.com wrote:
>> [ ... 38 lines skipped ... ]
>> --- /dev/null
>> +++ b/drivers/ctlv/Kconfig
>> @@ -0,0 +1,12 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +menuconfig CTLV
>> +	tristate "CTLV character device TLV UAPI"
>> +	help
>> +	  CTLV provides character device UAPIs described by a checked-in YAML
>> +	  specification. It owns the character device lifetime, the strict TLV
>> +	  message format, request validation, reply serialization, the large
>> +	  payloads a request describes rather than carries, per-open event
>> +	  queues and runtime schema introspection, so families only implement
>> +	  semantics.
>> +
>> +	  If you don't know what to do here, say N.
>
>This should probably just be a simple selectable config instead of a
>full blown menuconfig. ie one with no description. Since this is
>really just a tool for subsystems to use every subsystem that uses it
>should just select it.
>
>So:
>
>config CTLV
>   bool

Makes sense.


>
>
>> [ ... 159 lines skipped ... ]
>> +static bool ctlv_message_nest_index_ok(const struct ctlv_cursor *nest)
>> +{
>> +	const struct ctlv_message_input_index *index = nest->msg->index;
>> +	const struct ctlv_message_input_nest *indexed;
>> +	const struct ctlv_message_input_scope *scope;
>> +	const struct ctlv_attr *attr;
>> +
>> +	if (WARN_ON_ONCE(!nest->msg->request || !index ||
>> +			 nest->index_nest_scope >= index->scopes_count))
>> +		return false;
>> +	scope = &index->scopes[nest->index_nest_scope];
>> +	if (WARN_ON_ONCE(scope->nest >= index->nests_count))
>> +		return false;
>> +	indexed = &index->nests[scope->nest];
>> +	attr = (const void *)((const u8 *)nest->msg->root + indexed->offset);
>> +	if (WARN_ON_ONCE(attr != nest->attr))
>> +		return false;
>> +	return !WARN_ON_ONCE(scope->tree != nest->tree || scope->node != nest->node);
>
>Maybe wrap these invariant assertions in a helper and we can compile
>them out?
>
>  #ifdef CONFIG_CTLV_DEBUG
>  #define CTLV_ASSERT(xxx) WARN_ON_ONCE(xxx)
>  #endif

Well, yeah, that would probably make sense.


>
>It helps manage expectations around WARN_ON. I assume these have all
>been checked to guarentee they cannot be triggered by users space?

Sure.

>
>-- 
>Jason
```