linux-kernel - Re: [PATCH 07/12] perf script: Pad dso name for --call-trace

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Message-ID: <20190507081350.GA17416@krava>
Date:   Tue, 7 May 2019 10:13:50 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Song Liu <songliubraving@...com>
Cc:     Jiri Olsa <jolsa@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Stanislav Fomichev <sdf@...ichev.me>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 07/12] perf script: Pad dso name for --call-trace

On Mon, May 06, 2019 at 09:38:55PM +0000, Song Liu wrote:

SNIP

> > 
> > Link: http://lkml.kernel.org/n/tip-99g9rg4p20a1o99vr0nkjhq8@git.kernel.org
> > Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> > ---
> > tools/include/linux/kernel.h  |  1 +
> > tools/lib/vsprintf.c          | 19 +++++++++++++++++++
> > tools/perf/builtin-script.c   |  1 +
> > tools/perf/util/map.c         |  6 ++++++
> > tools/perf/util/symbol_conf.h |  1 +
> > 5 files changed, 28 insertions(+)
> > 
> > diff --git a/tools/include/linux/kernel.h b/tools/include/linux/kernel.h
> > index 857d9e22826e..cba226948a0c 100644
> > --- a/tools/include/linux/kernel.h
> > +++ b/tools/include/linux/kernel.h
> > @@ -102,6 +102,7 @@
> > 
> > int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
> > int scnprintf(char * buf, size_t size, const char * fmt, ...);
> > +int scnprintf_pad(char * buf, size_t size, const char * fmt, ...);
> > 
> > #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
> > 
> > diff --git a/tools/lib/vsprintf.c b/tools/lib/vsprintf.c
> > index e08ee147eab4..149a15013b23 100644
> > --- a/tools/lib/vsprintf.c
> > +++ b/tools/lib/vsprintf.c
> > @@ -23,3 +23,22 @@ int scnprintf(char * buf, size_t size, const char * fmt, ...)
> > 
> >        return (i >= ssize) ? (ssize - 1) : i;
> > }
> > +
> > +int scnprintf_pad(char * buf, size_t size, const char * fmt, ...)
> > +{
> > +	ssize_t ssize = size;
> > +	va_list args;
> > +	int i;
> 
> nit: I guess we can avoid mixing int, ssize_t and size_t here?

I copied that from scnprintf ;-)

the thing is that at the end we call vsnprintf, which takes size_t
as size param and returns int, so there will be casting at some
point in any case..

I guess the ssize_t was introduced to compare the size_t value with int

> 
> 
> > +
> > +	va_start(args, fmt);
> > +	i = vsnprintf(buf, size, fmt, args);
> > +	va_end(args);
> > +
> > +	if (i < (int) size) {
> > +		for (; i < (int) size; i++)
> > +			buf[i] = ' ';
> > +		buf[i] = 0x0;
> > +	}
> > +
> > +	return (i >= ssize) ? (ssize - 1) : i;
> > +}
> > diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
> > index 61cfd8f70989..7adaa6c63a0b 100644
> > --- a/tools/perf/builtin-script.c
> > +++ b/tools/perf/builtin-script.c
> > @@ -3297,6 +3297,7 @@ static int parse_call_trace(const struct option *opt __maybe_unused,
> > 	parse_output_fields(NULL, "-ip,-addr,-event,-period,+callindent", 0);
> > 	itrace_parse_synth_opts(opt, "cewp", 0);
> > 	symbol_conf.nanosecs = true;
> > +	symbol_conf.pad_output_len_dso = 50;
> > 	return 0;
> > }
> > 
> > diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
> > index ee71efb9db62..c3fbd6e556b0 100644
> > --- a/tools/perf/util/map.c
> > +++ b/tools/perf/util/map.c
> > @@ -405,6 +405,7 @@ size_t map__fprintf(struct map *map, FILE *fp)
> > 
> > size_t map__fprintf_dsoname(struct map *map, FILE *fp)
> > {
> > +	char buf[PATH_MAX];
> 
> nit: PATH_MAX vs. 50 is a little weird. 

right, the "staying on the safe side" is too big here, will change 

thanks,
jirka