linux-kernel - Re: [PATCH v2 05/15] perf ftrace: factor out function write_tracing_file

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Date:   Tue, 7 Jul 2020 12:09:23 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Changbin Du <changbin.du@...il.com>
Cc:     Jiri Olsa <jolsa@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 05/15] perf ftrace: factor out function
 write_tracing_file_int()

On Sat, 27 Jun 2020 21:36:44 +0800
Changbin Du <changbin.du@...il.com> wrote:

> We will reuse this function later.
> 

BTW, trace-cmd.git now has a libtracefs.so library, which I'm hoping
within a month to have as a stand alone (probably along with
libtraceevent and even a libtracecmd).

  https://git.kernel.org/pub/scm/utils/trace-cmd/trace-cmd.git/tree/lib/tracefs

This is a library made to interact with the tracefs directory to remove
reimplementing it all over the place.

-- Steve



> Signed-off-by: Changbin Du <changbin.du@...il.com>
> ---
>  tools/perf/builtin-ftrace.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> index dceae70c3a22..003efa756322 100644
> --- a/tools/perf/builtin-ftrace.c
> +++ b/tools/perf/builtin-ftrace.c
> @@ -166,6 +166,17 @@ static int read_tracing_file_to_stdout(const char *name)
>  	return ret;
>  }
>  
> +static int write_tracing_file_int(const char *name, int value)
> +{
> +	char buf[16];
> +
> +	snprintf(buf, sizeof(buf), "%d", value);
> +	if (write_tracing_file(name, buf) < 0)
> +		return -1;
> +
> +	return 0;
> +}
> +
>  static int reset_tracing_cpu(void);
>  static void reset_tracing_filters(void);
>  
> @@ -296,8 +307,6 @@ static void reset_tracing_filters(void)
>  
>  static int set_tracing_depth(struct perf_ftrace *ftrace)
>  {
> -	char buf[16];
> -
>  	if (ftrace->graph_depth == 0)
>  		return 0;
>  
> @@ -306,9 +315,7 @@ static int set_tracing_depth(struct perf_ftrace *ftrace)
>  		return -1;
>  	}
>  
> -	snprintf(buf, sizeof(buf), "%d", ftrace->graph_depth);
> -
> -	if (write_tracing_file("max_graph_depth", buf) < 0)
> +	if (write_tracing_file_int("max_graph_depth", ftrace->graph_depth) < 0)
>  		return -1;
>  
>  	return 0;