Re: [PATCH RESEND 2/2] ring-buffer/selftest: Handle meta-page bigger than the system

From: Steven Rostedt
Date: Tue Sep 10 2024 - 12:46:03 EST



Shuah,

Can you take this through your tree?

Acked-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>

-- Steve

On Tue, 10 Sep 2024 17:23:35 +0100
Vincent Donnefort <vdonnefort@xxxxxxxxxx> wrote:

> Handle the case where the meta-page content is bigger than the system
> page-size. This prepares the ground for extending features covered by
> the meta-page.
>
> Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
> Cc: linux-kselftest@xxxxxxxxxxxxxxx
> Signed-off-by: Vincent Donnefort <vdonnefort@xxxxxxxxxx>
>
> diff --git a/tools/testing/selftests/ring-buffer/map_test.c b/tools/testing/selftests/ring-buffer/map_test.c
> index ba12fd31de87..d10a847130fb 100644
> --- a/tools/testing/selftests/ring-buffer/map_test.c
> +++ b/tools/testing/selftests/ring-buffer/map_test.c
> @@ -92,12 +92,22 @@ int tracefs_cpu_map(struct tracefs_cpu_map_desc *desc, int cpu)
> if (desc->cpu_fd < 0)
> return -ENODEV;
>
> +again:
> map = mmap(NULL, page_size, PROT_READ, MAP_SHARED, desc->cpu_fd, 0);
> if (map == MAP_FAILED)
> return -errno;
>
> desc->meta = (struct trace_buffer_meta *)map;
>
> + /* the meta-page is bigger than the original mapping */
> + if (page_size < desc->meta->meta_struct_len) {
> + int meta_page_size = desc->meta->meta_page_size;
> +
> + munmap(desc->meta, page_size);
> + page_size = meta_page_size;
> + goto again;
> + }
> +
> return 0;
> }
>