From owner-svn-src-head@freebsd.org Tue Jun 30 07:30:31 2020 Return-Path: Delivered-To: svn-src-head@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 49F0E360F7C; Tue, 30 Jun 2020 07:30:31 +0000 (UTC) (envelope-from hps@selasky.org) Received: from mail.turbocat.net (turbocat.net [IPv6:2a01:4f8:c17:6c4b::2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 49wwxf6ZfHz42C0; Tue, 30 Jun 2020 07:30:30 +0000 (UTC) (envelope-from hps@selasky.org) Received: from hps2020.home.selasky.org (unknown [178.17.145.105]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mail.turbocat.net (Postfix) with ESMTPSA id DE5F82602DF; Tue, 30 Jun 2020 09:30:27 +0200 (CEST) Subject: Re: svn commit: r362781 - head/sys/compat/linuxkpi/common/include/linux To: Ian Lepore , Warner Losh , Ravi Pokala Cc: src-committers , svn-src-all@freebsd.org, svn-src-head@freebsd.org References: <202006291308.05TD8eTP014019@repo.freebsd.org> <24a300c54e94be8e6915c588a25a641ca0620200.camel@freebsd.org> From: Hans Petter Selasky Message-ID: <5516059a-0168-f1cd-742e-bb7d7a108f67@selasky.org> Date: Tue, 30 Jun 2020 09:30:06 +0200 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <24a300c54e94be8e6915c588a25a641ca0620200.camel@freebsd.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 49wwxf6ZfHz42C0 X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:24940, ipnet:2a01:4f8::/29, country:DE] X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 30 Jun 2020 07:30:31 -0000 On 2020-06-29 22:32, Ian Lepore wrote: > On Mon, 2020-06-29 at 14:26 -0600, Warner Losh wrote: >> On Mon, Jun 29, 2020, 2:15 PM Ravi Pokala >> wrote: >> >>> -----Original Message----- >>> From: on behalf of Hans Petter >>> Selasky >>> >>> Date: 2020-06-29, Monday at 06:08 >>> To: , , < >>> svn-src-head@freebsd.org> >>> Subject: svn commit: r362781 - >>> head/sys/compat/linuxkpi/common/include/linux >>> >>> Author: hselasky >>> Date: Mon Jun 29 13:08:40 2020 >>> New Revision: 362781 >>> URL: https://svnweb.freebsd.org/changeset/base/362781 >>> >>> Log: >>> Implement is_signed(), type_max() and type_min() function >>> macros in >>> the >>> LinuxKPI. >>> >>> MFC after: 1 week >>> Sponsored by: Mellanox Technologies >>> >>> Modified: >>> head/sys/compat/linuxkpi/common/include/linux/kernel.h >>> >>> Modified: >>> head/sys/compat/linuxkpi/common/include/linux/kernel.h >>> >>> =================================================================== >>> =========== >>> --- head/sys/compat/linuxkpi/common/include/linux/kernel.h Mon >>> Jun 29 >>> 12:59:09 2020 (r362780) >>> +++ head/sys/compat/linuxkpi/common/include/linux/kernel.h Mon >>> Jun 29 >>> 13:08:40 2020 (r362781) >>> @@ -564,4 +564,20 @@ linux_ratelimited(linux_ratelimit_t *rl) >>> #define __is_constexpr(x) \ >>> __builtin_constant_p(x) >>> >>> Hi Hans, >>> >>> +#define is_signed(x) (((x)-1 / (x)2) == (x)0) >>> >>> It took me several reads to understand this, until I figured out >>> that 'x' >>> is not a variable, it's the name of a *type*. >>> >>> If 'x' is a variable, then '(x)-1' is subtraction, but '(x)2' and >>> '(x)0' >>> are nonsensical. >>> >>> If 'x' is a *type*, then '(x)-1' is typecasting '-1', and similarly >>> for >>> '(x)2' and '(x)0'. >>> >>> So, perhaps a comment, or a better name for 'x'? >>> >> >> I had similar thoughts. Maybe 't' instead? >> > > Or maybe since there's no one-character restriction on macro variable > names, something actually descriptive like 'datatype'. > > -- Ian > >> Warner >> >> Thanks, >>> >>> Ravi (rpokala@) >>> Thanks for the feedback. I'll have a look at using a more descriptive name there for the macro argument. --HPS