selftests/bpf: Avoid errno clobbering

Print a message when the returned error is about a program type being not supported or because of permission problems. These messages are expected if the program to test was actually executed. Cc: Krzesimir Nowak <krzesimir@kinvolk.io> Signed-off-by: Florian Lehner <dev@der-flo.net>

Author: florianl

tools/testing/selftests/bpf/test_verifier.c

@@ -875,19 +875,36 @@ static int do_prog_test_run(int fd_prog, bool unpriv, uint32_t expected_val,
 __u8 tmp[TEST_DATA_LEN << 2];
 __u32 size_tmp = sizeof(tmp);
 uint32_t retval;
-int err;
+int err, saved_errno;
 
 if (unpriv)
 set_admin(true);
 err = bpf_prog_test_run(fd_prog, 1, data, size_data,
 tmp, &size_tmp, &retval, NULL);
+saved_errno = errno;
+
 if (unpriv)
 set_admin(false);
-if (err && errno != 524/*ENOTSUPP*/ && errno != EPERM) {
-printf("Unexpected bpf_prog_test_run error ");
-return err;
+
+if (err) {
+switch (saved_errno) {
+case 524/*ENOTSUPP*/:
+printf("Did not run the program (not supported) ");
+return 0;
+case EPERM:
+if (unpriv) {
+printf("Did not run the program (no permission) ");
+return 0;
+}
+/* fallthrough; */
+default:
+printf("FAIL: Unexpected bpf_prog_test_run error (%s) ",
+strerror(saved_errno));
+return err;
+}
 }
-if (!err && retval != expected_val &&
+
+if (retval != expected_val &&
  expected_val != POINTER_VALUE) {
 printf("FAIL retval %d != %d ", retval, expected_val);
 return 1;