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Date:   Mon, 22 May 2023 10:32:24 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     sunliming <sunliming@kylinos.cn>
Cc:     mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Beau Belgrave <beaub@linux.microsoft.com>
Subject: Re: [PATCH] racing/user_events: Prevent same address and bit per
 process
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In-Reply-To: <20230519081035.228891-1-sunliming@kylinos.cn>
References: <20230519081035.228891-1-sunliming@kylinos.cn>
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Is the subject a Freudian slip?

Added Beau. I need to add him to the maintainers file for user events ;-)

On Fri, 19 May 2023 16:10:35 +0800
sunliming <sunliming@kylinos.cn> wrote:

> User processes register name_args for events. If the same name are registered
> multiple times in the same process, it can cause undefined behavior. Because
> the same name may be used for a diffrent event. If this event has the same
> format as the original event, it is impossible to distinguish the trace output
> of these two events. If the event has a different format from the original event,
> the trace output of the new event is incorrect.
> 
> Return EADDRINUSE back to the user process if the same event has being registered
> in the same process.

I'll let Beau ack this or not.

-- Steve

> 
> Signed-off-by: sunliming <sunliming@kylinos.cn>
> ---
>  kernel/trace/trace_events_user.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
> index b1ecd7677642..4ef6bdb5c07c 100644
> --- a/kernel/trace/trace_events_user.c
> +++ b/kernel/trace/trace_events_user.c
> @@ -1996,7 +1996,7 @@ static int user_events_ref_add(struct user_event_file_info *info,
>  
>  		for (i = 0; i < count; ++i)
>  			if (refs->events[i] == user)
> -				return i;
> +				return -EADDRINUSE;
>  	}
>  
>  	size = struct_size(refs, events, count + 1);