netdev - Re: [PATCH 1/2] perf trace: Use pr_debug() instead of fprintf() for logging

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Date:   Tue, 18 Jun 2019 14:24:23 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [PATCH 1/2] perf trace: Use pr_debug() instead of fprintf() for
 logging

On Mon, Jun 17, 2019 at 12:24:12PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Jun 17, 2019 at 05:11:39PM +0800, Leo Yan escreveu:
> > In the function trace__syscall_info(), it explicitly checks verbose
> > level and print out log with fprintf().  Actually, we can use
> > pr_debug() to do the same thing for debug logging.
> > 
> > This patch uses pr_debug() instead of fprintf() for debug logging; it
> > includes a minor fixing for 'space before tab in indent', which
> > dismisses git warning when apply it.
> 
> But those are not fprintf(stdout,), they explicitely redirect to the
> output file that the user may have specified using 'perf trace --output
> filename.trace' :-)

Thanks for pointing out, sorry for noise. Please drop this patch.

Thanks,
Leo Yan

> > Signed-off-by: Leo Yan <leo.yan@...aro.org>
> > ---
> >  tools/perf/builtin-trace.c | 21 +++++++++------------
> >  1 file changed, 9 insertions(+), 12 deletions(-)
> > 
> > diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> > index bd1f00e7a2eb..5cd74651db4c 100644
> > --- a/tools/perf/builtin-trace.c
> > +++ b/tools/perf/builtin-trace.c
> > @@ -1760,12 +1760,11 @@ static struct syscall *trace__syscall_info(struct trace *trace,
> >  		 * grep "NR -1 " /t/trace_pipe
> >  		 *
> >  		 * After generating some load on the machine.
> > - 		 */
> > -		if (verbose > 1) {
> > -			static u64 n;
> > -			fprintf(trace->output, "Invalid syscall %d id, skipping (%s, %" PRIu64 ") ...\n",
> > -				id, perf_evsel__name(evsel), ++n);
> > -		}
> > +		 */
> > +		static u64 n;
> > +
> > +		pr_debug("Invalid syscall %d id, skipping (%s, %" PRIu64 ")\n",
> > +			 id, perf_evsel__name(evsel), ++n);
> >  		return NULL;
> >  	}
> >  
> > @@ -1779,12 +1778,10 @@ static struct syscall *trace__syscall_info(struct trace *trace,
> >  	return &trace->syscalls.table[id];
> >  
> >  out_cant_read:
> > -	if (verbose > 0) {
> > -		fprintf(trace->output, "Problems reading syscall %d", id);
> > -		if (id <= trace->syscalls.max && trace->syscalls.table[id].name != NULL)
> > -			fprintf(trace->output, "(%s)", trace->syscalls.table[id].name);
> > -		fputs(" information\n", trace->output);
> > -	}
> > +	pr_debug("Problems reading syscall %d", id);
> > +	if (id <= trace->syscalls.max && trace->syscalls.table[id].name != NULL)
> > +		pr_debug("(%s)", trace->syscalls.table[id].name);
> > +	pr_debug(" information\n");
> >  	return NULL;
> >  }
> >  
> > -- 
> > 2.17.1
> 
> -- 
> 
> - Arnaldo