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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 37B3CC433EF for ; Tue, 22 Feb 2022 17:12:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=e1GAHP6Odwv8v78Chr08BryhtJI1Mt/yrrIvfGL0fRQ=; b=bWf3HZ5Mtk2Qx7vNq5GzsxxC9B SPyhsHb1U2lakI33TEGmX8HMS9OjbH4xW3ZAyKzysTUJa0Qgb0npXQoackaLdBytIQWHkPJ781Cyd L9L3Dc3birtwh34gwNxUlUh8vDSljuvjvKisOCEcixzpPTqGUUyplCT+pkJWGAgGfZpipzpSh5KC2 EeHkd65gNPCDqtKhVdnwGwCKH2MG1eBj8TSG6j1bDD+DKyuaySbzAbGMUqSxE0L1jWKM0PoouH4+R pb6DBqN5RE3Kp5b5NAk7SnP+YL6L2yumePALZQMBWHhbDzWZ8ZjSwFGDYtzDZ68udWKeICJ09xKZW SAgpl0Sg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nMYhf-00At9i-Tw; Tue, 22 Feb 2022 17:11:55 +0000 Received: from relay4.hostedemail.com ([64.99.140.36]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nMYVA-00AoOW-Uz for linux-nvme@lists.infradead.org; Tue, 22 Feb 2022 16:59:02 +0000 Received: from omf09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay12.hostedemail.com (Postfix) with ESMTP id B256D120966; Tue, 22 Feb 2022 16:58:58 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: joe@perches.com) by omf09.hostedemail.com (Postfix) with ESMTPA id DCE9720028; Tue, 22 Feb 2022 16:58:56 +0000 (UTC) Message-ID: <38d356c2ea0cd9c8cec1e6377793b5c465eca889.camel@perches.com> Subject: Re: [PATCHv3 04/10] linux/kernel: introduce lower_48_bits macro From: Joe Perches To: Christoph Hellwig 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, martin.petersen@oracle.com, colyli@suse.de, Bart Van Assche Date: Tue, 22 Feb 2022 08:58:56 -0800 In-Reply-To: <20220222165045.GA14168@lst.de> References: <20220222163144.1782447-1-kbusch@kernel.org> <20220222163144.1782447-5-kbusch@kernel.org> <66a0c8210cf9e7dfcc3fa2d247de1eebd5a8acb7.camel@perches.com> <20220222165045.GA14168@lst.de> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.40.4-1ubuntu2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspamout05 X-Rspamd-Queue-Id: DCE9720028 X-Stat-Signature: bk4jafjtuowkr7tuxqe1os9d7x7ekmx4 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Session-ID: U2FsdGVkX187kE9xU/fonTPBMMbSmL7JTFcT++IlEDc= X-HE-Tag: 1645549136-753137 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220222_085901_113356_EF112251 X-CRM114-Status: GOOD ( 16.68 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Tue, 2022-02-22 at 17:50 +0100, Christoph Hellwig wrote: > 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. Don't think so. I've dealt with hardware and have more than once seen defects introduced by firmware developers that can't count. be quick, which one is it: 0xfffffffffffULL or 0xffffffffffffULL or 0xfffffffffffffULL or 0xffffffffffffffULL