bpftool: Check argc first before "file" in do_batch()

If the parameters for batch are more than 2, check argc first can
return immediately, no need to use is_prefix() to check "file" with
a little overhead and then check argc, it is better to check "file"
only when the parameters for batch are 2.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Acked-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/r/1668517207-11822-1-git-send-email-yangtiezhu@loongson.cnSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/bpf/bpftool/main.c

@@ -337,12 +337,12 @@ static int do_batch(int argc, char **argv)
 	if (argc < 2) {
 		p_err("too few parameters for batch");
 		return -1;
-	} else if (!is_prefix(*argv, "file")) {
-		p_err("expected 'file', got: %s", *argv);
-		return -1;
 	} else if (argc > 2) {
 		p_err("too many parameters for batch");
 		return -1;
+	} else if (!is_prefix(*argv, "file")) {
+		p_err("expected 'file', got: %s", *argv);
+		return -1;
 	}
 	NEXT_ARG();