linux-kernel - Re: [PATCH] tracing: Fix trace_event_raw_event

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Date:   Wed, 1 Feb 2023 00:36:33 +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>,
        Tom Zanussi <zanussi@...nel.org>,
        kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] tracing: Fix trace_event_raw_event_synth() if else
 statement

On Tue, 31 Jan 2023 09:52:37 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

> From: "Steven Rostedt (Google)" <rostedt@...dmis.org>
> 
> The test to check if the field is a stack is to be done if it is not a
> string. But the code had:
> 
>     } if (event->fields[i]->is_stack) {
> 
> and not
> 
>    } else if (event->fields[i]->is_stack) {
> 
> which would cause it to always be tested. Worse yet, this also included an
> "else" statement that was only to be called if the field was not a string
> and a stack, but this code allows it to be called if it was a string (and
> not a stack).
> 
> Also fixed some whitespace issues.
> 

Looks good to me.

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

Hmm, I need to add more tests for syntax events...

Thanks!


> Link: https://lore.kernel.org/all/202301302110.mEtNwkBD-lkp@intel.com/
> 
> Fixes: 00cf3d672a9d ("tracing: Allow synthetic events to pass around stacktraces")
> Reported-by: kernel test robot <lkp@...el.com>
> Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
> ---
>  kernel/trace/trace_events_synth.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
> index adb630633f31..306c89e0ce55 100644
> --- a/kernel/trace/trace_events_synth.c
> +++ b/kernel/trace/trace_events_synth.c
> @@ -564,8 +564,8 @@ static notrace void trace_event_raw_event_synth(void *__data,
>  					   event->fields[i]->is_dynamic,
>  					   data_size, &n_u64);
>  			data_size += len; /* only dynamic string increments */
> -		} if (event->fields[i]->is_stack) {
> -		        long *stack = (long *)(long)var_ref_vals[val_idx];
> +		} else if (event->fields[i]->is_stack) {
> +			long *stack = (long *)(long)var_ref_vals[val_idx];
>  
>  			len = trace_stack(entry, event, stack,
>  					   data_size, &n_u64);
> -- 
> 2.39.0
> 


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