linux-kernel - Re: [PATCH] perf/probe: Skip same probe address

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Message-ID: <20190920182646.GC4865@kernel.org>
Date:   Fri, 20 Sep 2019 15:26:46 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Wang Nan <wangnan0@...wei.com>, Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf/probe: Skip same probe address

Em Thu, Sep 19, 2019 at 12:41:10PM +0900, Masami Hiramatsu escreveu:
> Fix to skip making a same probe address on given line.
> 
> Since dwarf line info contains several entries for one line
> with different column, perf probe will make a different
> probe on same address if user specifies a probe point by
> "function:line" or "file:line".
> 
> e.g.
>  $ perf probe -D kernel_read:8
>  p:probe/kernel_read_L8 kernel_read+39
>  p:probe/kernel_read_L8_1 kernel_read+39
> 
> This skips such duplicated probe address.

Thanks, applied to perf/urgent.

- Arnaldo
 
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> ---
>  tools/perf/util/probe-finder.c |   19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index 025fc4491993..02ca95deaf2c 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -1244,6 +1244,17 @@ static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,
>  	return n;
>  }
>  
> +static bool trace_event_finder_overlap(struct trace_event_finder *tf)
> +{
> +	int i;
> +
> +	for (i = 0; i < tf->ntevs; i++) {
> +		if (tf->pf.addr == tf->tevs[i].point.address)
> +			return true;
> +	}
> +	return false;
> +}
> +
>  /* Add a found probe point into trace event list */
>  static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
>  {
> @@ -1254,6 +1265,14 @@ static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
>  	struct perf_probe_arg *args = NULL;
>  	int ret, i;
>  
> +	/*
> +	 * For some reason (e.g. different column assigned to same address)
> +	 * This callback can be called with the address which already passed.
> +	 * Ignore it first.
> +	 */
> +	if (trace_event_finder_overlap(tf))
> +		return 0;
> +
>  	/* Check number of tevs */
>  	if (tf->ntevs == tf->max_tevs) {
>  		pr_warning("Too many( > %d) probe point found.\n",

-- 

- Arnaldo