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 057A5C4332F for ; Tue, 22 Feb 2022 16:50:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232923AbiBVQvQ (ORCPT ); Tue, 22 Feb 2022 11:51:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48918 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232712AbiBVQvP (ORCPT ); Tue, 22 Feb 2022 11:51:15 -0500 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06D2716AA45; Tue, 22 Feb 2022 08:50:50 -0800 (PST) Received: by verein.lst.de (Postfix, from userid 2407) id A920368B05; Tue, 22 Feb 2022 17:50:45 +0100 (CET) Date: Tue, 22 Feb 2022 17:50:45 +0100 From: Christoph Hellwig To: Joe Perches Cc: Keith Busch , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-crypto@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, axboe@kernel.dk, hch@lst.de, martin.petersen@oracle.com, colyli@suse.de, Bart Van Assche Subject: Re: [PATCHv3 04/10] linux/kernel: introduce lower_48_bits macro Message-ID: <20220222165045.GA14168@lst.de> References: <20220222163144.1782447-1-kbusch@kernel.org> <20220222163144.1782447-5-kbusch@kernel.org> <66a0c8210cf9e7dfcc3fa2d247de1eebd5a8acb7.camel@perches.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <66a0c8210cf9e7dfcc3fa2d247de1eebd5a8acb7.camel@perches.com> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Tue, Feb 22, 2022 at 08:45:53AM -0800, Joe Perches wrote: > On Tue, 2022-02-22 at 08:31 -0800, Keith Busch wrote: > > Recent data integrity field enhancements allow 48-bit reference tags. > > Introduce a helper macro since this will be a repeated operation. > [] > > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > [] > > @@ -63,6 +63,12 @@ > > } \ > > ) > > > > +/** > > + * lower_48_bits - return bits 0-47 of a number > > + * @n: the number we're accessing > > + */ > > +#define lower_48_bits(n) ((u64)((n) & 0xffffffffffffull)) > > why not make this a static inline function? Agreed. > And visually, it's difficult to quickly count a repeated character to 12. > > Perhaps: > > static inline u64 lower_48_bits(u64 val) > { > return val & GENMASK_ULL(47, 0); > } For anyone who has a minimum knowledge of C and hardware your version is an obsfucated clusterfuck, while the version Keith wrote is trivial to read.