linux-kernel - Re: [PATCH v2] tracing/kprobes: 'nmissed' not showed correctly for kretprobe

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Date:   Sat, 8 Jan 2022 13:11:18 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Xiangyang Zhang <xyz.sun.ok@...il.com>
Cc:     rostedt@...dmis.org, mingo@...hat.com, mhiramat@...nel.org,
        oleg@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] tracing/kprobes: 'nmissed' not showed correctly for
 kretprobe

On Fri,  7 Jan 2022 23:02:42 +0800
Xiangyang Zhang <xyz.sun.ok@...il.com> wrote:

> The 'nmissed' column of the 'kprobe_profile' file for kretprobe is
> not showed correctly, kretprobe can be skipped by two reasons,
> shortage of kretprobe_instance which is counted by tk->rp.nmissed,
> and kprobe itself is missed by some reason, so to show the sum.
> 

Thanks! This looks good to me.

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

> Fixes: 4a846b443b4e ("tracing/kprobes: Cleanup kprobe tracer code")
> Signed-off-by: Xiangyang Zhang <xyz.sun.ok@...il.com>
> ---
>  kernel/trace/trace_kprobe.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index f8c26ee72de3..3d85323278ed 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -1170,15 +1170,18 @@ static int probes_profile_seq_show(struct seq_file *m, void *v)
>  {
>  	struct dyn_event *ev = v;
>  	struct trace_kprobe *tk;
> +	unsigned long nmissed;
>  
>  	if (!is_trace_kprobe(ev))
>  		return 0;
>  
>  	tk = to_trace_kprobe(ev);
> +	nmissed = trace_kprobe_is_return(tk) ?
> +		tk->rp.kp.nmissed + tk->rp.nmissed : tk->rp.kp.nmissed;
>  	seq_printf(m, "  %-44s %15lu %15lu\n",
>  		   trace_probe_name(&tk->tp),
>  		   trace_kprobe_nhit(tk),
> -		   tk->rp.kp.nmissed);
> +		   nmissed);
>  
>  	return 0;
>  }
> -- 
> 2.25.1
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>