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[209.85.220.65]) by mx.google.com with SMTPS id 101sor648127plf.70.2019.07.02.16.27.13 for (Google Transport Security); Tue, 02 Jul 2019 16:27:13 -0700 (PDT) Received-SPF: pass (google.com: domain of groeck7@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=tKlI879d; spf=pass (google.com: domain of groeck7@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=groeck7@gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=sIW4c2nsoK1zg9iPJ9PWWFYICxxuZVhWWS0PGONCcT8=; b=tKlI879d6GOCn5/viRbA8CB+2LHjMm+LHx8vu35g2JtHmWRh1MS1K2Oq0gOO4uanyd c15xofeqIVhd7SStkRQtGGQG8ogXRpToC2cmZoqBYxGBLvl9kjjYZ0xuo8mFYG1VEsLy ikmPD7gHqGybsUQltdIn7Jjmkd2wmRlohhi8jmnbU3YIPRnW77+JMRLFQ8emQ6GOC9vD mkgfNh+CChWY9/02UtCZY5Z4d/iptGSMjM4I4uAS4y3vUxK4UYVODhXk0yUlEZGc668+ VgBtNszBl2lr0RVPKRfw91a/mbIqdV4lCzbBpKDNJSCzW2vG9+iNlMhl4b9cvPnPb3/T F3hg== X-Google-Smtp-Source: APXvYqyoBXu4AyqKJhdPuz9LblEnnUpotkfLl9gMkZHnkxwo6EMqYJPvNrNLG2nCtlyB3nXPt7OwmA== X-Received: by 2002:a17:902:467:: with SMTP id 94mr37806898ple.131.1562110033549; Tue, 02 Jul 2019 16:27:13 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id v22sm186381pgk.69.2019.07.02.16.27.11 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 02 Jul 2019 16:27:12 -0700 (PDT) Subject: Re: [PATCH -next] mm: Mark undo_dev_pagemap as __maybe_unused To: Andrew Morton Cc: linux-mm@kvack.org, Stephen Rothwell , Robin Murphy , linux-kernel@vger.kernel.org, "Kirill A. Shutemov" References: <1562072523-22311-1-git-send-email-linux@roeck-us.net> <20190702135418.ce51c988e88ca0d9546a2a11@linux-foundation.org> From: Guenter Roeck Message-ID: Date: Tue, 2 Jul 2019 16:27:10 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.1 MIME-Version: 1.0 In-Reply-To: <20190702135418.ce51c988e88ca0d9546a2a11@linux-foundation.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 7/2/19 1:54 PM, Andrew Morton wrote: > On Tue, 2 Jul 2019 06:02:03 -0700 Guenter Roeck wrote: > >> Several mips builds generate the following build warning. >> >> mm/gup.c:1788:13: warning: 'undo_dev_pagemap' defined but not used >> >> The function is declared unconditionally but only called from behind >> various ifdefs. Mark it __maybe_unused. >> >> ... >> >> --- a/mm/gup.c >> +++ b/mm/gup.c >> @@ -1785,7 +1785,8 @@ static inline pte_t gup_get_pte(pte_t *ptep) >> } >> #endif /* CONFIG_GUP_GET_PTE_LOW_HIGH */ >> >> -static void undo_dev_pagemap(int *nr, int nr_start, struct page **pages) >> +static void __maybe_unused undo_dev_pagemap(int *nr, int nr_start, >> + struct page **pages) >> { >> while ((*nr) - nr_start) { >> struct page *page = pages[--(*nr)]; > > It's not our preferred way of doing it but yes, it would be a bit of a > mess and a bit of a maintenance burden to get the ifdefs correct. > That is why I did it here. I understand that some maintainers don't like it, and I noticed that it wasn't used elsewhere in the file, but it seemed to be to most straightforward solution. > And really, __maybe_unused isn't a bad way at all - it ensures that the > function always gets build-tested and the compiler will remove it so we > don't have to play the chase-the-ifdefs game. > Yes, it does have its advantages. I like it myself, but usually I would not impose my opinion on others. In this case, anything else would have been quite awkward and be prone to never-ending adjustments. Thanks, Guenter