From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E5C65CD37B4 for ; Sun, 17 Sep 2023 05:55:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231910AbjIQFuk (ORCPT ); Sun, 17 Sep 2023 01:50:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48144 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230222AbjIQFuI (ORCPT ); Sun, 17 Sep 2023 01:50:08 -0400 Received: from todd.t-8ch.de (todd.t-8ch.de [IPv6:2a01:4f8:c010:41de::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17BE310B; Sat, 16 Sep 2023 22:50:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=weissschuh.net; s=mail; t=1694929799; bh=I2ORHDPmzg8IMQkgZSGbyhmTUn7nAixQxkusYZXX9Ow=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bNhvK9COLyxFXqsSZoncbm4ouWx+Xn1gh6p+fU6V31arYi8oIbkEOyMxEv8YtTaM4 9JuXFJ7xrV8X8uhdb/ZrUvtuG054Xa4X5b66PsE+uDraTemleD4RBH9PezFqXpHXYh jgb+n3iwz/+Ck3NN2n1YjPHOM/2fLBWGlxMJLLTw= Date: Sun, 17 Sep 2023 07:49:57 +0200 From: Thomas =?utf-8?Q?Wei=C3=9Fschuh?= To: Willy Tarreau Cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , Shuah Khan , linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH 2/4] tools/nolibc: avoid unused parameter warnings for ENOSYS fallbacks Message-ID: <2bd688b7-5f1b-44ca-a41b-6e90dc3e8557@t-8ch.de> References: <20230914-nolibc-syscall-nr-v1-0-e50df410da11@weissschuh.net> <20230914-nolibc-syscall-nr-v1-2-e50df410da11@weissschuh.net> <20230917025851.GE9646@1wt.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20230917025851.GE9646@1wt.eu> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023-09-17 04:58:51+0200, Willy Tarreau wrote: > On Thu, Sep 14, 2023 at 06:01:18PM +0200, Thomas Weißschuh wrote: > > The ENOSYS fallback code does not use its functions parameters. > > This can lead to compiler warnings about unused parameters. > > > > Explicitly avoid these warnings. > > Just out of curiosity, did you find a valid case for enabling this > warning or were you trying various combinations ? I'm asking because > I've never seen it enabled anywhere given that it's probably the most > useless and unusable warning: as soon as you're dealing with function > pointers, you start to have multiple functions with a similar > prototype, some of which just don't need certain arguments, and the > only way to shut the warning is to significantly uglify the code. nolibc-test uses it currently and I also used it in some projects. > If really needed, I'm wondering if instead we shouldn't have an > "no_syscall*" set of macros, that would have the same signature > as my_syscall* to just consume all args in the same order and > return -ENOSYS. E.g, consider the following: > > @@ -934,6 +960,11 @@ int sys_select(int nfds, fd_set *rfds, fd_set *wfds, fd_set *efds, struct timeva > #endif > return my_syscall5(__NR__newselect, nfds, rfds, wfds, efds, timeout); > #else > + (void)nfds; > + (void)rfds; > + (void)wfds; > + (void)efds; > + (void)timeout; > return -ENOSYS; > #endif > > It would become: > > @@ -934,6 +960,11 @@ int sys_select(int nfds, fd_set *rfds, fd_set *wfds, fd_set *efds, struct timeva > #endif > return my_syscall5(__NR__newselect, nfds, rfds, wfds, efds, timeout); > #else > + return no_syscall5(nfds, rfds, wfds, efds, timeout); > - return -ENOSYS; > #endif > > What do you think ? The idea sounds good. But "no_syscall5" sounds a bit non-obvious to me. Maybe the macro-equivalent of this? static inline int __nolibc_enosys(...) { return -ENOSYS; } The only-vararg function unfortunately needs C23 so we can't use it. It's clear to the users that this is about ENOSYS and we don't need a bunch of new macros similar. I'll check if it is cleaner to implement a generic macro or a few numbered ones. Thomas