perf test: Fix 'perf test BPF' when it fails to find a suitable vmlinux

Two bugs in 'perf test BPF' are found when testing BPF prologue without
vmlinux:

 # mv /lib/modules/4.3.0-rc4+/build/vmlinux{,.bak}
 # ./perf test BPF
 37: Test BPF filter             :Failed to find the path for kernel: No such file or directory
 Ok

Test BPF should fail in this case.

After this patch:

 # ./perf test BPF
 37: Test BPF filter             :Failed to find the path for kernel: No such file or directory
  FAILED!
 # mv /lib/modules/4.3.0-rc4+/build/vmlinux{.bak,}
 # ./perf test BPF
 37: Test BPF filter             : Ok

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1447749170-175898-2-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/bpf.c

@@ -102,8 +102,7 @@ static int do_test(struct bpf_object *obj, int (*func)(void),
 	err = parse_events_load_bpf_obj(&parse_evlist, &parse_evlist.list, obj);
 	if (err || list_empty(&parse_evlist.list)) {
 		pr_debug("Failed to add events selected by BPF\n");
-		if (!err)
-			return TEST_FAIL;
+		return TEST_FAIL;
 	}
 
 	snprintf(pid, sizeof(pid), "%d", getpid());
@@ -157,8 +156,10 @@ static int do_test(struct bpf_object *obj, int (*func)(void),
 		}
 	}
 
-	if (count != expect)
+	if (count != expect) {
 		pr_debug("BPF filter result incorrect\n");
+		goto out_delete_evlist;
+	}
 
 	ret = TEST_OK;