Re: [PATCH v3 3/4] tracing/remotes: Add REMOTE_EVENT_CUSTOM_PRINTK() helper

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] tracing/remotes: invalid unquoted print fmt string breaks libtraceevent
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commit c1fe85ccb9998d0f07df828f87f45a8f874da608
Author: Vincent Donnefort <vdonnefort@google.com>

tracing/remotes: Add REMOTE_EVENT_CUSTOM_PRINTK() helper

The current REMOTE_EVENT() takes as a __printk argument a string format
and a list of arguments. Add a REMOTE_EVENT_CUSTOM_PRINTK() where the
__printk argument can be a function. This intends to support the creation
of a "printk" event for the arm64 nVHE/pKVM hypervisor with a dynamic
prototype and by extension a dynamic print format.

> diff --git a/include/trace/define_remote_events.h b/include/trace/define_remote_events.h
> index 676e803dc144d..4f4d58e37b84b 100644
> --- a/include/trace/define_remote_events.h
> +++ b/include/trace/define_remote_events.h

[ ... ]

> @@ -70,4 +79,8 @@ do {											\
>  		.print_fmt	= remote_event_print_fmt_##__name,			\
>  		.print		= remote_event_print_##__name,				\
>  	}
> +
> +#define REMOTE_EVENT_CUSTOM_PRINTK(__name, __id, __struct, __printk)			\
> +	REMOTE_EVENT(__name, __id, RE_STRUCT(__struct), "Unknown")

[Severity: Medium]
Does this unquoted print fmt string break libtraceevent parsing?

This macro assigns the literal "Unknown" directly to the event's print_fmt
field. The tracefs format file outputs this field directly, which results in
print fmt: Unknown instead of the expected print fmt: "Unknown".

The standard libtraceevent parser expects the format string to be enclosed
in double quotes. Encountering an unquoted string causes it to be misparsed
as a field variable (which does not exist) rather than a literal string,
preventing userspace tools like perf and trace-cmd from parsing the event
format correctly.

Should this be escaped as "\"Unknown\"" to preserve UAPI formatting
expectations?

> +
>  #include REMOTE_EVENT_INCLUDE(REMOTE_EVENT_INCLUDE_FILE)

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Sashiko AI review · https://sashiko.dev/#/patchset/20260930153505.2144559-1-vdonnefort@google.com?part=3