linux-kernel - Re: [PATCH] ring-buffer: Unlock resize on mmap error

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Message-Id: <20250214091031.fc31a81a5e86148655998e4a@kernel.org>
Date: Fri, 14 Feb 2025 09:10:31 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Linux Trace Kernel
 <linux-trace-kernel@...r.kernel.org>, Masami Hiramatsu
 <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Vincent Donnefort <vdonnefort@...gle.com>
Subject: Re: [PATCH] ring-buffer: Unlock resize on mmap error

On Thu, 13 Feb 2025 13:19:57 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

> From: Steven Rostedt <rostedt@...dmis.org>
> 
> Memory mapping the tracing ring buffer will disable resizing the buffer.
> But if there's an error in the memory mapping like an invalid parameter,
> the function exits out without re-enabling the resizing of the ring
> buffer, preventing the ring buffer from being resized after that.
> 

Looks good to me.

Reveiewed-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Thank you,

> Cc: stable@...r.kernel.org
> Fixes: 117c39200d9d7 ("ring-buffer: Introducing ring-buffer mapping functions")
> Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
> ---
>  kernel/trace/ring_buffer.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> index b8e0ae15ca5b..07b421115692 100644
> --- a/kernel/trace/ring_buffer.c
> +++ b/kernel/trace/ring_buffer.c
> @@ -7126,6 +7126,7 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu,
>  		kfree(cpu_buffer->subbuf_ids);
>  		cpu_buffer->subbuf_ids = NULL;
>  		rb_free_meta_page(cpu_buffer);
> +		atomic_dec(&cpu_buffer->resize_disabled);
>  	}
>  
>  unlock:
> -- 
> 2.47.2
> 


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