linux-kernel - Re: [PATCH] perf tool: Add event name to error message for filters

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Date:	Tue, 24 Mar 2015 18:57:37 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	David Ahern <david.ahern@...cle.com>
Cc:	linux-kernel@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH] perf tool: Add event name to error message for filters

Em Tue, Mar 24, 2015 at 06:29:56PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Tue, Mar 24, 2015 at 12:10:17PM -0400, David Ahern escreveu:
> > Use of a bad filter currently generates the message:
> >  Error: failed to set filter with 22 (Invalid argument)
> > 
> > Add the event name to make it clear to which event the filter
> > failed to apply:
> >   Error: Failed to set filter on event sched:sg_lb_stats: 22: Invalid argument
> > 
> > Signed-off-by: David Ahern <david.ahern@...cle.com>
> > Cc: Jiri Olsa <jolsa@...nel.org>
> > Cc: Namhyung Kim <namhyung@...nel.org>
> 
> 
> > +++ b/tools/perf/util/evsel.c
> > @@ -807,9 +807,19 @@ static int perf_evsel__run_ioctl(struct perf_evsel *evsel, int ncpus, int nthrea
> >  int perf_evsel__set_filter(struct perf_evsel *evsel, int ncpus, int nthreads,
> >  			   const char *filter)
> >  {
> > -	return perf_evsel__run_ioctl(evsel, ncpus, nthreads,
> > -				     PERF_EVENT_IOC_SET_FILTER,
> > -				     (void *)filter);
> > +	int err;
> > +	char msg[512];
> > +
> > +	err = perf_evsel__run_ioctl(evsel, ncpus, nthreads,
> > +				    PERF_EVENT_IOC_SET_FILTER,
> > +				    (void *)filter);
> > +	if (err) {
> > +		error("Failed to set filter on event %s: %d: %s\n",
> > +		      perf_evsel__name(evsel), errno,
> > +		      strerror_r(errno, msg, sizeof(msg)));
> 
> Humm, probably this will be the only call to error() from evsel.c,
> making it require the error() routine, which in turn will break the
> python binding, lemme check...
> 
> If that is the case we'll have to somehow propagate to the caller of
> perf_evlist__apply_filters what was the evsel that had a filter that
> caused the problem.

With the patch below, that leaves printing something, using whatever UI, to the
tool, acceptable?

[root@...andy linux]# perf record -e sched:sched_switch -e sched:*fork --filter parent_pid==1 -e sched:*wait* --filter bla usleep 1
  Error: failed to set filter "bla" on event sched:sched_stat_iowait with 22 (Invalid argument)

[root@...andy linux]# 

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 091868288d29..15670aa986b9 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -161,8 +161,9 @@ try_again:
 		}
 	}
 
-	if (perf_evlist__apply_filters(evlist)) {
-		error("failed to set filter with %d (%s)\n", errno,
+	if (perf_evlist__apply_filters(evlist, &pos)) {
+		error("failed to set filter \"%s\" on event %s with %d (%s)\n",
+			pos->filter, perf_evsel__name(pos), errno,
 			strerror_r(errno, msg, sizeof(msg)));
 		rc = -1;
 		goto out;
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index d4d1b77da0bd..f7b8218785f6 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -684,8 +684,9 @@ static int __run_perf_stat(int argc, const char **argv)
 			unit_width = l;
 	}
 
-	if (perf_evlist__apply_filters(evsel_list)) {
-		error("failed to set filter with %d (%s)\n", errno,
+	if (perf_evlist__apply_filters(evsel_list, &counter)) {
+		error("failed to set filter \"%s\" on event %s with %d (%s)\n",
+			counter->filter, perf_evsel__name(counter), errno,
 			strerror_r(errno, msg, sizeof(msg)));
 		return -1;
 	}
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 8d0b62361129..82bf224bbee9 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1050,7 +1050,7 @@ out_delete_threads:
 	return -1;
 }
 
-int perf_evlist__apply_filters(struct perf_evlist *evlist)
+int perf_evlist__apply_filters(struct perf_evlist *evlist, struct perf_evsel **err_evsel)
 {
 	struct perf_evsel *evsel;
 	int err = 0;
@@ -1062,8 +1062,10 @@ int perf_evlist__apply_filters(struct perf_evlist *evlist)
 			continue;
 
 		err = perf_evsel__set_filter(evsel, ncpus, nthreads, evsel->filter);
-		if (err)
+		if (err) {
+			*err_evsel = evsel;
 			break;
+		}
 	}
 
 	return err;
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index f07c984465f0..fb19c47b8aac 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -152,7 +152,7 @@ static inline void perf_evlist__set_maps(struct perf_evlist *evlist,
 }
 
 int perf_evlist__create_maps(struct perf_evlist *evlist, struct target *target);
-int perf_evlist__apply_filters(struct perf_evlist *evlist);
+int perf_evlist__apply_filters(struct perf_evlist *evlist, struct perf_evsel **err_evsel);
 
 void __perf_evlist__set_leader(struct list_head *list);
 void perf_evlist__set_leader(struct perf_evlist *evlist);
--
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