perf utils: Add perf_quiet_option()

The perf_quiet_option() is to suppress all messages.  It's intended to
be called just after parsing options.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: kernel-team@lge.com
Link: http://lkml.kernel.org/r/20170217081742.17417-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/debug.c

@@ -203,11 +203,28 @@ int perf_debug_option(const char *str)
 		v = (v < 0) || (v > 10) ? 0 : v;
 	}
 
+	if (quiet)
+		v = -1;
+
 	*var->ptr = v;
 	free(s);
 	return 0;
 }
 
+int perf_quiet_option(void)
+{
+	struct debug_variable *var = &debug_variables[0];
+
+	/* disable all debug messages */
+	while (var->name) {
+		*var->ptr = -1;
+		var++;
+	}
+
+	quiet = true;
+	return 0;
+}
+
 #define DEBUG_WRAPPER(__n, __l)				\
 static int pr_ ## __n ## _wrapper(const char *fmt, ...)	\
 {							\

tools/perf/util/debug.h

@@ -54,5 +54,6 @@ int veprintf(int level, int var, const char *fmt, va_list args);
 
 int perf_debug_option(const char *str);
 void perf_debug_setup(void);
+int perf_quiet_option(void);
 
 #endif	/* __PERF_DEBUG_H */