Re: [PATCH] ring-buffer: report header_page overwrite as signed char

Steven Rostedt
2026-04-06T16:44:21Z

On Tue, 7 Apr 2026 00:28:43 +0800
CaoRuichuang <create0818@163.com> wrote:

> The header_page tracefs metadata currently reports overwrite as an
> int field with size 1. That makes parsers warn about a type and
> size mismatch even though the field is only used as a one-byte flag
> within commit.
>
> Keep the shared offset with commit as-is, but report overwrite as
> signed char so the declared type matches the hardcoded size and the
> emitted signedness.
>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=216999
> Signed-off-by: CaoRuichuang <create0818@163.com>
> ---
> kernel/trace/ring_buffer.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> index 170170bd8..c4c2361b0 100644
> --- a/kernel/trace/ring_buffer.c
> +++ b/kernel/trace/ring_buffer.c
> @@ -627,11 +627,11 @@ int ring_buffer_print_page_header(struct trace_buffer *buffer, struct trace_seq
> (unsigned int)sizeof(field.commit),
> (unsigned int)is_signed_type(long));
>
> - trace_seq_printf(s, "\tfield: int overwrite;\t"
> + trace_seq_printf(s, "\tfield: signed char overwrite;\t"

From the Bugzilla, the issue was with the rust parser. Would this still not
cause a warning if the "int" was switched to "char" and not "signed char".
The signed is redundant as it is already specified in the fields.

-- Steve

> "offset:%u;\tsize:%u;\tsigned:%u;\n",
> (unsigned int)offsetof(typeof(field), commit),
> 1,
> - (unsigned int)is_signed_type(long));
> + (unsigned int)is_signed_type(signed char));
>
> trace_seq_printf(s, "\tfield: char data;\t"
> "offset:%u;\tsize:%u;\tsigned:%u;\n",