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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id CF5E4C19F2D for ; Tue, 9 Aug 2022 12:37:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 650AC6B0071; Tue, 9 Aug 2022 08:37:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5FF0F6B0072; Tue, 9 Aug 2022 08:37:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 49FC58E0001; Tue, 9 Aug 2022 08:37:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 39EB76B0071 for ; Tue, 9 Aug 2022 08:37:30 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id D1D99AB647 for ; Tue, 9 Aug 2022 12:37:29 +0000 (UTC) X-FDA: 79780005018.30.7E23768 Received: from mail-lj1-f172.google.com (mail-lj1-f172.google.com [209.85.208.172]) by imf08.hostedemail.com (Postfix) with ESMTP id 73802160181 for ; Tue, 9 Aug 2022 12:37:29 +0000 (UTC) Received: by mail-lj1-f172.google.com with SMTP id y23so12802426ljh.12 for ; Tue, 09 Aug 2022 05:37:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rasmusvillemoes.dk; s=google; h=content-transfer-encoding:in-reply-to:from:references:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc; bh=S/vY+pHOAJw8ND8t13oTQazIac4o9LGilFJcZDyaByQ=; b=Mrb2Al4kVt5O3KiUdyGMMX9sVayGDb/FyFERwnGXD0vImjgWnB9fEsdatVsTaDfecG tvBp1u1TXVZ3p9+RiYyop/1CWPisZcwCgR9LRfnwCJTDts+eeXMqzsNrHTfIXOK8bsxg 7oIhTFZA3U3EMwPCbiMwRNLvtfZtB21DPskCo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc; bh=S/vY+pHOAJw8ND8t13oTQazIac4o9LGilFJcZDyaByQ=; b=h8LHsJWjHLj8UrUrMzxlAE6fbVXu73w6cGbXx665jjQB8o8Al7B+voCTzN4K92Ivfe Xa6kD9TG/XTrzMjRG/jfNg38KjD4xBzFCoiHGujiMUlW58NKEb+NahghhwrvnTezAfs4 esjVyC8J1h8KX4Ft1AK6pqHCKCg91fzdwtCmccmiWtfEKnBv/3zMmBLrVFtbkaH4IXMy 1C3gDTp+VJhr9d/8KBiV2f3sa3+zmqqfDUgXBD4pUNFWemA9NABppJbVvRGC/aKi5rLw 146R/mDL4jWr5HO68K23cz7d3IweE0lTCVocR2gM886zLysAlhCrzYiiA1egmMr2Nm7f xcEw== X-Gm-Message-State: ACgBeo2nn8HOEiMQlHndwmB5Dw1lvETclLGnXndJYpT8JU8X0gU5H2yk ykQLIhAiFfWGyVdITzMLf3s7/Q== X-Google-Smtp-Source: AA6agR7VK6CZDk/4NkzM6eVPldsJwBnFAODpPxiIOJfOv7G8gfUodLs+podMq64PJ/ngkiXV2YfR9A== X-Received: by 2002:a05:651c:222:b0:25e:4ae2:c5ae with SMTP id z2-20020a05651c022200b0025e4ae2c5aemr7207953ljn.440.1660048647869; Tue, 09 Aug 2022 05:37:27 -0700 (PDT) Received: from [172.16.11.74] ([81.216.59.226]) by smtp.gmail.com with ESMTPSA id c6-20020a056512324600b0048b2245519asm1753471lfr.192.2022.08.09.05.37.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Aug 2022 05:37:25 -0700 (PDT) Message-ID: <36677eab-6407-afd1-4cbf-a90be9554c8b@rasmusvillemoes.dk> Date: Tue, 9 Aug 2022 14:37:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH 03/16] lib/test_bitmap: don't test bitmap_set if nbits == 0 Content-Language: en-US To: Yury Norov , linux-kernel@vger.kernel.org, Alexander Lobakin , Alexei Starovoitov , Alexey Klimov , Andrew Morton , Andrii Nakryiko , Andy Shevchenko , Ben Segall , Christoph Lameter , Dan Williams , Daniel Borkmann , Daniel Bristot de Oliveira , Dennis Zhou , Dietmar Eggemann , Eric Dumazet , Frederic Weisbecker , Guenter Roeck , Ingo Molnar , Isabella Basso , John Fastabend , Josh Poimboeuf , Juergen Gross , Juri Lelli , KP Singh , Kees Cook , Martin KaFai Lau , Mel Gorman , Miroslav Benes , Nathan Chancellor , "Paul E . McKenney" , Peter Zijlstra , Randy Dunlap , Sebastian Andrzej Siewior , Song Liu , Steven Rostedt , Tejun Heo , Thomas Gleixner , Valentin Schneider , Vincent Guittot , Vlastimil Babka , Yonghong Song , linux-mm@kvack.org, netdev@vger.kernel.org, bpf@vger.kernel.org References: <20220718192844.1805158-1-yury.norov@gmail.com> <20220718192844.1805158-4-yury.norov@gmail.com> From: Rasmus Villemoes In-Reply-To: <20220718192844.1805158-4-yury.norov@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660048649; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=S/vY+pHOAJw8ND8t13oTQazIac4o9LGilFJcZDyaByQ=; b=RqNjG6RCMMV/AsJK/9HcH9AHeip7hJV2iV3bVd3CEWGy31OmT38f6P3IqFadY341bfj5PT /JBd1HHKPXIGL+dRjAfJ8INC9z5+XblSo07K7OZgoBP2O6ohdnNTIQe6aoh6Lupo1T8Osq 4tNObNaeVejjcJ6UOojZM/Gc+8VWX4s= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=rasmusvillemoes.dk header.s=google header.b=Mrb2Al4k; dmarc=none; spf=pass (imf08.hostedemail.com: domain of linux@rasmusvillemoes.dk designates 209.85.208.172 as permitted sender) smtp.mailfrom=linux@rasmusvillemoes.dk ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660048649; a=rsa-sha256; cv=none; b=JrUtABus89EJH5V6J659q/l1IAQysDntPrwrVJlMuy2aCC6+TBvw96ZNLVIjlk/S0eAbpu yg5nbzy6KrKKwrOSCl6oFHMdAXdKM0tz622cjwH0Dc0NLYtzQ+2YJ5WPpBBpqngzFtmDTF 9XHixcb9Wi3Ny+0+YpC/UOLI+s2X+PU= X-Rspamd-Queue-Id: 73802160181 Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=rasmusvillemoes.dk header.s=google header.b=Mrb2Al4k; dmarc=none; spf=pass (imf08.hostedemail.com: domain of linux@rasmusvillemoes.dk designates 209.85.208.172 as permitted sender) smtp.mailfrom=linux@rasmusvillemoes.dk X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: amtzyxyrq6m35fmuzq9si8wrh6ief8zm X-HE-Tag: 1660048649-37699 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 18/07/2022 21.28, Yury Norov wrote: > Don't test bitmap_set(bitmap, start, 0) as it's useless, most probably > a sign of error in real code, No it's not. The nbits can easily be the result of some computation that ended up resulting in 0 being the right number to copy (or set, or whatnot), and it's not unreasonable to _not_ check in the caller for that special case, but rather rely on bitmap_set() to behave sanely - it has perfectly well-defined semantics to "set 0 bits starting at @start". The same way that memset() and memcpy() and memcmp() and countless other functions have perfectly well-defined semantics with a length of 0, and we don't add caller-side checks for those either. NAK on this series. Rasmus