perf trace: Validate target task/user/cpu argument

Those target options are mutually exclusive so check it before setting
up target thread/cpu maps.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1349413336-26936-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -323,14 +323,21 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
 	OPT_END()
 	};
 	int err;
+	char bf[BUFSIZ];
 
 	argc = parse_options(argc, argv, trace_options, trace_usage, 0);
 	if (argc)
 		usage_with_options(trace_usage, trace_options);
 
+	err = perf_target__validate(&trace.opts.target);
+	if (err) {
+		perf_target__strerror(&trace.opts.target, err, bf, sizeof(bf));
+		printf("%s", bf);
+		return err;
+	}
+
 	err = perf_target__parse_uid(&trace.opts.target);
 	if (err) {
-		char bf[BUFSIZ];
 		perf_target__strerror(&trace.opts.target, err, bf, sizeof(bf));
 		printf("%s", bf);
 		return err;