From owner-svn-src-all@freebsd.org Mon Nov 30 17:38:55 2020 Return-Path: Delivered-To: svn-src-all@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 4699E4A382F; Mon, 30 Nov 2020 17:38:55 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [IPv6:2610:1c1:1:606c::24b:4]) (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-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4ClCC31J48z4S57; Mon, 30 Nov 2020 17:38:55 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from John-Baldwins-MacBook-Pro.local (ralph.baldwin.cx [66.234.199.215]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: jhb) by smtp.freebsd.org (Postfix) with ESMTPSA id 5A9A9491; Mon, 30 Nov 2020 17:38:54 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Subject: Re: svn commit: r368187 - head/sys/dev/nvme To: Warner Losh , Michal Meloun Cc: Ian Lepore , src-committers , svn-src-all , svn-src-head References: <202011301451.0AUEpn9w002536@repo.freebsd.org> <5bd6eb969c3a198246ab915257375b02c7b14e0c.camel@freebsd.org> From: John Baldwin Autocrypt: addr=jhb@FreeBSD.org; keydata= mQGiBETQ+XcRBADMFybiq69u+fJRy/0wzqTNS8jFfWaBTs5/OfcV7wWezVmf9sgwn8TW0Dk0 c9MBl0pz+H01dA2ZSGZ5fXlmFIsee1WEzqeJzpiwd/pejPgSzXB9ijbLHZ2/E0jhGBcVy5Yo /Tw5+U/+laeYKu2xb0XPvM0zMNls1ah5OnP9a6Ql6wCgupaoMySb7DXm2LHD1Z9jTsHcAQMD /1jzh2BoHriy/Q2s4KzzjVp/mQO5DSm2z14BvbQRcXU48oAosHA1u3Wrov6LfPY+0U1tG47X 1BGfnQH+rNAaH0livoSBQ0IPI/8WfIW7ub4qV6HYwWKVqkDkqwcpmGNDbz3gfaDht6nsie5Z pcuCcul4M9CW7Md6zzyvktjnbz61BADGDCopfZC4of0Z3Ka0u8Wik6UJOuqShBt1WcFS8ya1 oB4rc4tXfSHyMF63aPUBMxHR5DXeH+EO2edoSwViDMqWk1jTnYza51rbGY+pebLQOVOxAY7k do5Ordl3wklBPMVEPWoZ61SdbcjhHVwaC5zfiskcxj5wwXd2E9qYlBqRg7QeSm9obiBCYWxk d2luIDxqaGJARnJlZUJTRC5vcmc+iGAEExECACAFAkTQ+awCGwMGCwkIBwMCBBUCCAMEFgID AQIeAQIXgAAKCRBy3lIGd+N/BI6RAJ9S97fvbME+3hxzE3JUyUZ6vTewDACdE1stFuSfqMvM jomvZdYxIYyTUpC5Ag0ERND5ghAIAPwsO0B7BL+bz8sLlLoQktGxXwXQfS5cInvL17Dsgnr3 1AKa94j9EnXQyPEj7u0d+LmEe6CGEGDh1OcGFTMVrof2ZzkSy4+FkZwMKJpTiqeaShMh+Goj XlwIMDxyADYvBIg3eN5YdFKaPQpfgSqhT+7El7w+wSZZD8pPQuLAnie5iz9C8iKy4/cMSOrH YUK/tO+Nhw8Jjlw94Ik0T80iEhI2t+XBVjwdfjbq3HrJ0ehqdBwukyeJRYKmbn298KOFQVHO EVbHA4rF/37jzaMadK43FgJ0SAhPPF5l4l89z5oPu0b/+5e2inA3b8J3iGZxywjM+Csq1tqz hltEc7Q+E08AAwUIAL+15XH8bPbjNJdVyg2CMl10JNW2wWg2Q6qdljeaRqeR6zFus7EZTwtX sNzs5bP8y51PSUDJbeiy2RNCNKWFMndM22TZnk3GNG45nQd4OwYK0RZVrikalmJY5Q6m7Z16 4yrZgIXFdKj2t8F+x613/SJW1lIr9/bDp4U9tw0V1g3l2dFtD3p3ZrQ3hpoDtoK70ioIAjjH aIXIAcm3FGZFXy503DOA0KaTWwvOVdYCFLm3zWuSOmrX/GsEc7ovasOWwjPn878qVjbUKWwx Q4QkF4OhUV9zPtf9tDSAZ3x7QSwoKbCoRCZ/xbyTUPyQ1VvNy/mYrBcYlzHodsaqUDjHuW+I SQQYEQIACQUCRND5ggIbDAAKCRBy3lIGd+N/BCO8AJ9j1dWVQWxw/YdTbEyrRKOY8YZNwwCf afMAg8QvmOWnHx3wl8WslCaXaE8= Message-ID: Date: Mon, 30 Nov 2020 09:38:52 -0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 30 Nov 2020 17:38:55 -0000 On 11/30/20 9:04 AM, Warner Losh wrote: > On Mon, Nov 30, 2020 at 9:56 AM Michal Meloun > wrote: > >> >> >> On 30.11.2020 17:02, Ian Lepore wrote: >>> On Mon, 2020-11-30 at 14:51 +0000, Michal Meloun wrote: >>>> Author: mmel >>>> Date: Mon Nov 30 14:51:48 2020 >>>> New Revision: 368187 >>>> URL: https://svnweb.freebsd.org/changeset/base/368187 >>>> >>>> Log: >>>> Unbreak r368167 in userland. Decorate unused arguments. >>>> >>>> Reported by: kp, tuexen, jenkins, and many others >>>> MFC with: r368167 >>>> >>>> Modified: >>>> head/sys/dev/nvme/nvme.h >>>> >>>> Modified: head/sys/dev/nvme/nvme.h >>>> ===================================================================== >>>> ========= >>>> --- head/sys/dev/nvme/nvme.h Mon Nov 30 14:49:13 2020 (r368186) >>>> +++ head/sys/dev/nvme/nvme.h Mon Nov 30 14:51:48 2020 (r368187) >>>> @@ -1728,9 +1728,15 @@ extern int nvme_use_nvd; >>>> >>>> #endif /* _KERNEL */ >>>> >>>> +#if _BYTE_ORDER != _LITTLE_ENDIAN >>>> +#define MODIF >>>> +#else >>>> +#define MODIF __unused >>>> +#endif >>>> + >>>> /* Endianess conversion functions for NVMe structs */ >>>> static inline >>>> -void nvme_completion_swapbytes(struct nvme_completion *s) >>>> +void nvme_completion_swapbytes(struct nvme_completion *s MODIF) >>> >>> IMO, this is pretty ugly, it causes the brain to screech to a halt when >>> you see it. Why not just add an unconditional __unused to the >>> functions? The unused attribute is defined as marking the variable as >>> "potentially unused" -- there is no penalty for having it there and >>> then actually using the variable. >>> >> >> I understand, (and I have significant tendency to agree) but I did not >> find more correct way how to do it. >> Are you sure that __unused is defined as *potentially* unused? I cannot >> find nothing about this and you known how are compiler guys creative >> with generating of new warnings... >> I known that C++17 have 'maybe_unused' attribute, but relationship to >> standard '__unused' looks unclear. >> >> In any case, I have not single problem to change this to the proposed >> style if we found that this is the optimal way. >> > > __unused means 'don't warn me if this is unused' elsewhere in the tree. > Better to use it here. Alternatively, given you already are using #ifdef's in all the function bodies, you could instead do something like this: #if _BYTE_ORDER != _LITTLE_ENDIAN /* Existing functions without #if */ #else #define nvme_completion_swapbytes(s) /* Empty macros for the rest */ #endif This gives only a single #if instead of duplicating them in each function, and it avoids the need for __unused. -- John Baldwin