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 A92ADC433F5 for ; Mon, 29 Nov 2021 08:57:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243517AbhK2JAr (ORCPT ); Mon, 29 Nov 2021 04:00:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244372AbhK2I6n (ORCPT ); Mon, 29 Nov 2021 03:58:43 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 08536C06139C; Mon, 29 Nov 2021 00:44:15 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id C9042B80E2E; Mon, 29 Nov 2021 08:44:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 990D0C004E1; Mon, 29 Nov 2021 08:44:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1638175452; bh=3pcEGhFOVWdIckCjXvTNwGTmdnLfc9cuV4zeOS6jxtQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=bBcTPSbYBtH8V1BYLlyfjzrqDJlXOHL/FfVLpcppL0fwwOuVnepFt+IKYgF8iuin9 8A4Gl298WzYihOdIcgsXP5QnQod5W3wwEsey3UVkybnQbL8uGxcQx+nv6zGn4KnjWP Fb0uhLHqdR55R5fRbyNhHls4rVLcmn4XMKoK6nhPc8FXsH3D2ogLskOiH5BAYZw6Xz 770vPuNFSBBvpjnpScxtPNbzzrotWTHbe2UFnc/iw2K45cqSNFTrLdW4n+abVhI5m6 PIzgSIVCRRt29zkEm12FK4wp5q2S5hIWaKa6/aTaDmhKNSZyBgsmD37d76ZoaggaEN b4F7PLMRUtpwA== Date: Mon, 29 Nov 2021 09:44:06 +0100 From: Mauro Carvalho Chehab To: Nathan Chancellor Cc: linuxarm@huawei.com, mauro.chehab@huawei.com, Andrey Utkin , Anton Sviridenko , Bluecherry Maintainers , Ismael Luceno , Mauro Carvalho Chehab , Nick Desaulniers , linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH 08/20] media: solo6x10: add _maybe_unused to currently unused functions Message-ID: <20211129094406.39904314@coco.lan> In-Reply-To: References: <18daa194878d8815beef39d6fed2a838e1c2cb68.1637781097.git.mchehab+huawei@kernel.org> X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.30; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Fri, 26 Nov 2021 12:58:33 -0700 Nathan Chancellor escreveu: > On Wed, Nov 24, 2021 at 08:13:11PM +0100, Mauro Carvalho Chehab wrote: > > There are several unused helper macros there, meant to parse some > > fields. > > > > While there's not wrong with that, it generates clang warnings > > with W=1, causing build to break with CONFIG_WERROR. > > > > So, add __maybe_unused to fix such warnings. > > > > Signed-off-by: Mauro Carvalho Chehab > > I'll comment on this one patch but my opinion applies for all the > patches adding '__maybe_unused' to truly unused functions. > > I agree with Laurent's comment [1]: unless this code is going to be used > soon, it should be deleted and resurrected when it is actually needed. > We have git for a reason and by adding this attribute, you are making it > harder to catch and eliminate unused functions, as no compiler will > catch them with an unused attribute (it is possible other static > analysis tools will but I doubt those are run as frequently as compilers > with W=1). In this specific case (and on a few other patches on this series), those macros are used to document a field. That's why I opted to keep it. > > However, you are the maintainer so if you really want to keep these > around, I would recommend adding '__always_unused' instead of > '__maybe_unused' for documentation and auditing purposes, even though > they evaluate to the same thing: > > $ rg __always_unused | wc -l > 337 > > $ rg __maybe_unused | wc -l > 4335 Good point. I'll use __always_unused on such patches. > > [1]: https://lore.kernel.org/r/YZtpnjPcGxVwhe61@pendragon.ideasonboard.com/ > > Cheers, > Nathan > > > --- > > > > To avoid mailbombing on a large number of people, only mailing lists were C/C on the cover. > > See [PATCH 00/20] at: https://lore.kernel.org/all/cover.1637781097.git.mchehab+huawei@kernel.org/ > > > > drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c | 12 ++++++------ > > 1 file changed, 6 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c b/drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c > > index 0abcad4e84fa..85eaf5d00e9b 100644 > > --- a/drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c > > +++ b/drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c > > @@ -391,12 +391,12 @@ static int solo_send_desc(struct solo_enc_dev *solo_enc, int skip, > > } > > > > /* Extract values from VOP header - VE_STATUSxx */ > > -static inline int vop_interlaced(const vop_header *vh) > > +static inline __maybe_unused int vop_interlaced(const vop_header *vh) > > { > > return (__le32_to_cpu((*vh)[0]) >> 30) & 1; > > } > > > > -static inline u8 vop_channel(const vop_header *vh) > > +static inline __maybe_unused u8 vop_channel(const vop_header *vh) > > { > > return (__le32_to_cpu((*vh)[0]) >> 24) & 0x1F; > > } > > @@ -411,12 +411,12 @@ static inline u32 vop_mpeg_size(const vop_header *vh) > > return __le32_to_cpu((*vh)[0]) & 0xFFFFF; > > } > > > > -static inline u8 vop_hsize(const vop_header *vh) > > +static inline u8 __maybe_unused vop_hsize(const vop_header *vh) > > { > > return (__le32_to_cpu((*vh)[1]) >> 8) & 0xFF; > > } > > > > -static inline u8 vop_vsize(const vop_header *vh) > > +static inline u8 __maybe_unused vop_vsize(const vop_header *vh) > > { > > return __le32_to_cpu((*vh)[1]) & 0xFF; > > } > > @@ -436,12 +436,12 @@ static inline u32 vop_jpeg_size(const vop_header *vh) > > return __le32_to_cpu((*vh)[4]) & 0xFFFFF; > > } > > > > -static inline u32 vop_sec(const vop_header *vh) > > +static inline u32 __maybe_unused vop_sec(const vop_header *vh) > > { > > return __le32_to_cpu((*vh)[5]); > > } > > > > -static inline u32 vop_usec(const vop_header *vh) > > +static inline __maybe_unused u32 vop_usec(const vop_header *vh) > > { > > return __le32_to_cpu((*vh)[6]); > > } > > -- > > 2.33.1 > > > > Thanks, Mauro