perf probe: List probes in stdout

Since commit 5e17b28f1e24 ("perf probe: Add --quiet option to
suppress output result message") have replaced printf with pr_info,
perf probe -l outputs its result in stderr. However, that is not
what the commit expected.

E.g.:

# perf probe -l > /dev/null
probe:vfs_read (on vfs_read@ksrc/linux-3/fs/read_write.c)

With this fix:

# perf probe -l > list
# cat list
probe:vfs_read (on vfs_read@ksrc/linux-3/fs/read_write.c)

Of course, --quiet(-q) still works on --add/--del.

# perf probe -q vfs_write
# perf probe -l
probe:vfs_read (on vfs_read@ksrc/linux-3/fs/read_write.c)
probe:vfs_write (on vfs_write@ksrc/linux-3/fs/read_write.c)
-----

Reported-by: Naohiro Aota <[e-mail]>
Signed-off-by: Masami Hiramatsu <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Naohiro Aota <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/probe-event.c

···
 	return NULL;
 }
 
-/* Show an event */
-static int show_perf_probe_event(struct perf_probe_event *pev,
-				 const char *module)
+static int perf_probe_event__sprintf(struct perf_probe_event *pev,
+				     const char *module,
+				     struct strbuf *result)
 {
 	int i, ret;
 	char buf[128];
···
 
 	ret = e_snprintf(buf, 128, "%s:%s", pev->group, pev->event);
 	if (ret < 0)
-		return ret;
+		goto out;
 
-	pr_info("  %-20s (on %s", buf, place);
+	strbuf_addf(result, "  %-20s (on %s", buf, place);
 	if (module)
-		pr_info(" in %s", module);
+		strbuf_addf(result, " in %s", module);
 
 	if (pev->nargs > 0) {
-		pr_info(" with");
+		strbuf_addstr(result, " with");
 		for (i = 0; i < pev->nargs; i++) {
 			ret = synthesize_perf_probe_arg(&pev->args[i],
 							buf, 128);
 			if (ret < 0)
-				break;
-			pr_info(" %s", buf);
+				goto out;
+			strbuf_addf(result, " %s", buf);
 		}
 	}
-	pr_info(")\n");
+	strbuf_addch(result, ')');
+out:
 	free(place);
+	return ret;
+}
+
+/* Show an event */
+static int show_perf_probe_event(struct perf_probe_event *pev,
+				 const char *module, bool use_stdout)
+{
+	struct strbuf buf = STRBUF_INIT;
+	int ret;
+
+	ret = perf_probe_event__sprintf(pev, module, &buf);
+	if (ret >= 0) {
+		if (use_stdout)
+			printf("%s\n", buf.buf);
+		else
+			pr_info("%s\n", buf.buf);
+	}
+	strbuf_release(&buf);
+
 	return ret;
 }
 
···
 				goto next;
 			ret = convert_to_perf_probe_event(&tev, &pev,
 								is_kprobe);
-			if (ret >= 0)
-				ret = show_perf_probe_event(&pev,
-							    tev.point.module);
+			if (ret < 0)
+				goto next;
+			ret = show_perf_probe_event(&pev, tev.point.module,
+						    true);
 		}
 next:
 		clear_perf_probe_event(&pev);
···
 		group = pev->group;
 		pev->event = tev->event;
 		pev->group = tev->group;
-		show_perf_probe_event(pev, tev->point.module);
+		show_perf_probe_event(pev, tev->point.module, false);
 		/* Trick here - restore current event/group */
 		pev->event = (char *)event;
 		pev->group = (char *)group;