Re: [PATCH 1/6] ring-buffer: Prevent resizing of persistent ring buffer

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Thu,  6 Aug 2026 22:13:01 +0100
Vincent Donnefort <vdonnefort@google.com> wrote:

> Dynamically resizing a persistent ring buffer is not possible. Disable
> the feature.

Is it true? Of course there is meaningless to resize the persistent
ring buffer (because it makes the buffer none-persistent), we are currently
allows user to resize it (like for resizing unused persistent ring buffer)

Thank you,

> 
> Fixes: be68d63a139b ("ring-buffer: Add ring_buffer_alloc_range()")
> Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
> 
> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> index 8e2485bb3aa8..afe75ad2bbf2 100644
> --- a/kernel/trace/ring_buffer.c
> +++ b/kernel/trace/ring_buffer.c
> @@ -2528,6 +2528,8 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu)
>  		if (cpu_buffer->ring_meta->head_buffer)
>  			rb_meta_buffer_update(cpu_buffer, bpage);
>  		bpage->range = 1;
> +
> +		atomic_inc(&cpu_buffer->resize_disabled);
>  	} else if (buffer->remote) {
>  		struct ring_buffer_desc *desc = ring_buffer_desc(buffer->remote->desc, cpu);
>  
> -- 
> 2.55.0.654.g21b8a5bc05-goog
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>