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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E3CDC43382 for ; Tue, 25 Sep 2018 12:58:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2883020880 for ; Tue, 25 Sep 2018 12:58:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2883020880 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=tu-dortmund.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729148AbeIYTF4 (ORCPT ); Tue, 25 Sep 2018 15:05:56 -0400 Received: from mx1.hrz.uni-dortmund.de ([129.217.128.51]:42984 "EHLO unimail.uni-dortmund.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728976AbeIYTF4 (ORCPT ); Tue, 25 Sep 2018 15:05:56 -0400 Received: from [129.217.43.49] (limnos.cs.uni-dortmund.de [129.217.43.49]) (authenticated bits=0) by unimail.uni-dortmund.de (8.16.0.29/8.16.0.29) with ESMTPSA id w8PCwQM7023901 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Tue, 25 Sep 2018 14:58:26 +0200 (CEST) To: Arnd Bergmann Cc: linux-arch , Linux Kernel Mailing List References: <9516e4b3-f9f2-b150-f019-8b1ef465efb3@tu-dortmund.de> <649d3c5c-3d96-0ed3-cd4d-57641f0ee614@tu-dortmund.de> From: Alexander Lochmann Openpgp: preference=signencrypt Autocrypt: addr=alexander.lochmann@tu-dortmund.de; prefer-encrypt=mutual; keydata= xsFNBFQIyUEBEADZ+x+Ssg/46SiU66zm2lPGYAdqYfmXVv+sf/23+/KSj0FQHZKywzWjsmgR vWZZVlGJolwcW3MJ/g6ctZeOpfYiZVpzbZwNgKU0ETGjUmqmlq5/o5KnENKOimZzaKSaNn9p IC+EIeWXvu7pQjW0w1bK/RVVNw0p1Iz82W4Z+vKtD8CS+YJLAcZ6YoZMvQEg84O9odlV2Ryp oVj9EzHH40TWEdtgd4pQkaOks01PEr19sJXUjnP0VxLfs91AZjRnmGJKnI4HcrOKwquoQEeL DtHCxK0VNeoXCWkz33uBxSL5cicQ7D09hxjWthMilUpDZT94x0K452q4nybQ1TSLTYC8mlW+ xKUvJmqfHZbITJ10dTgjNvOe0kLbpXeQ1789lNmnA9bkQAK5Cefo55WbXmr1Mo3PV7y0XCib OaiijPlZo/Isc03EOK3lHPK8NuY8G+ftvphO4RyXCUWXw/o01cDnPaIEcTWkUbXvMhf/6ltP 1QWEfkguzGVjTw7Xssm9YuokC+P+49JKRyZzyCJZ022OxMlsX6c1BNZ4+cWUNmn6xr1xRNse SglpMLL1m3K1KuLf1hdAor6PBzFLiLa33lUhsWtg1ACFhpfZZOQRVas2McXTYUUpmCzOYI5F +km5q6cZStr9m7O3Y3DDGotiaJDpLtATwZ4MIM4ADbg/xl6ZgwARAQABzS9BbGV4YW5kZXIg TG9jaG1hbm4gPGluZm9AYWxleGFuZGVyLWxvY2htYW5uLmRlPsLBfQQTAQgAJwUCV9SHSwIb IwUJCWYBgAULCQgHAgYVCAkKCwIEFgIDAQIeAQIXgAAKCRBZPu0FvD72/eZIEACxnxqYkDaE qI0jn/OJBde6t1uPeOytoWN8aRQVI0eZAkBfnDmF1qQF8p8eeaEu7ouhr8PQpBHDU8VNIlyg WhVcB9I/oXltFQZUHhUEFDd9xtXtjWPqGke4+ukiTiBUoLNSjejo6lGRqkXWklQbFG+jBd7w DEl6ad321QyPeXTOcO1YXeHoSGIYyCdObNBy1UV/r170H6a9H/AJxQWPifAwAairUA3bNVLt HSU7YFhon0OtJQy2CPhDHYkxIZEoNXZht934rTWuGHISGZ2MspMaupNromyoIMhLDK63Cz3n QfT9sjW+3u0ZoSAPz8bFLCALpPPtMRpMonOod3O1INQ9jQBLM690+eQRhkAIJQSX98S1ckNu ZK/bIV52piCkU48lYCLBOrtJ3mO4+SdIga+ZA/ArM3VBVt2NoVmi84+bJhmjYhVMEN73VmAc /xqGbhT8LQgjElE2YgQK9/e/J/Kxq1xvFW1pTg39CHNcGYcGbWOiz/kzcCbWFoen2yIr9cC0 jvvHK39NvF14jI5xmiUPGPCBGXqPxlKMiZeBPzvweyKRkAYbQmeqUiI5o7nwyzPRgQBsYLKG 0R8MbzbgOxSFbf+GVwCY4855r81fjokXNE1DRvKeg1TyNF7T812zfPAEKX8va45emHhwU8cy cchUdfOe9paUy8Ewr1LBDnh7q87BTQRUCMlBARAAnCFuEZ8V7Xh7/x5eP5fdurKMzgi/IsE/ zg/ULy99e9WNTA1/G7fC53jKIeURuEnoLXVWgOIy5Hb/AU5kW2O6ma8yY2CV+D1Mr5rmW6qW vjxdXObqlHLocKV5UALqS9XQoDuadcW3QsRDgfS5vtoVBSctS7L4ncIniXRakZdPWvyMqSra ssCcWurEiafWTzwjzCZycSFcxqgMB1jvOC3yF+SOgUVG6gIcZYyZuNAZO/c/jx3crQ9Emk7l iIbFWERXISi8am16JFISWlrqRNb+MRXtkqrcvb0gqyWTEWUUy754EcWyVRyCSbCuvORzUt0C UqxbapfkhjJDx6V/dvmQpskx+gwEN2NDLYyU3KGCrt3yPCk/QUrC7rl1E6F+2JeEWxQebNK8 GdlzMHiiXZMMqQuX0mZi7RMIIpjEOFXwQVDyQrx4Zrzhyl91pbPfQ+8WFj+y64op5o23bomj vwPmy4wHS6qhiaY0O098/r6sc6dyGnidzm0p55z6aXClQH+qmaruWH3N9avzmJ9fVshiIcCt zLrlZo2rcTJhoJEsc4E0z94xUNNPKspj3IK74DkfjBAgiKV4zjH3pzoYbCp4bhe4cVEv+ibW CrBDBMCV1TedPbDYSYhM0mPavlWJ/SAKx0gTJqYuZel7yNYsDw/R0Tbq7D8SlZX4vJULAu88 bk0AEQEAAcLBZQQYAQIADwUCVAjJQQIbDAUJCWYBgAAKCRBZPu0FvD72/RJJD/9i8hlljqEw BgYc74ComM2q0t1kDWQrhR0nwf114OEkUl9zbMRlWVnS71VYM1qNfrQtUJOsDiFUEksNtMEF 3vG6GfMogfHjOKIX0tJckjvYDpEC2C4o1oNySGME26sitl/C6WwrO3lE1zPTTuqZlbaHNywQ SF0BJV/Iq9AWWdfTgkgqJ05MlR2CuiGxCddT8YyRuWUu2pyOBULdJrs8pGa4ZG5n+SFdw7Sf ylH4UI5yWtgfyqE+xer6UwqMj7WgVB0FxAG9jWmVcBdOll7Kn1+MpXsptyZX8UX2uPgTieBn 9hBXd8GArCG997pWlwS1mvMNwPxXUElvTQTOImJT8UYPuXl5/qGo6ciqjy3rR1kTTDeDUh1U qbviUakZUwztxwp/6XkNDgfyGn9xzdwy2XW47WWONMZdYkfUzIA9n59jJQBct3Uin43ggEGD /XGp9TIHmxO9vTCO0Ibc7lGHR8voiTvxDTZUoBaOQy8EarLBBqlmoNMVj4HJ4lABESE08xyX nr0nmYeU4R8g9e9z8J/rSIUeGyuURcv4J88Kh3JJfB8O6NOpudciOHVFXmrTU5gIja5lt4kJ 73oYy2TmFzl8eKL7Fnb0J9NXVKN4Al3RFkOckCzkERkwnK6tYcwhHf/74svaE7KTa3GSX9aW 6NxCpAsFDwJbauda2prWMzruCg== Subject: Re: [x86] BUG()/BUG_ON() macros cannot be disabled Message-ID: Date: Tue, 25 Sep 2018 14:58:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="i7GBXgWhhOXDNszIRg5BZd7zKotn2cReU" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --i7GBXgWhhOXDNszIRg5BZd7zKotn2cReU Content-Type: multipart/mixed; boundary="cJKPIHbMi1BlL6u3FTCAFsNDb9ONDGZSH"; protected-headers="v1" From: Alexander Lochmann To: Arnd Bergmann Cc: linux-arch , Linux Kernel Mailing List Message-ID: Subject: Re: [x86] BUG()/BUG_ON() macros cannot be disabled References: <9516e4b3-f9f2-b150-f019-8b1ef465efb3@tu-dortmund.de> <649d3c5c-3d96-0ed3-cd4d-57641f0ee614@tu-dortmund.de> In-Reply-To: --cJKPIHbMi1BlL6u3FTCAFsNDb9ONDGZSH Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Am 25.09.2018 um 14:20 schrieb Arnd Bergmann: >=20 > I think it's the most reasonable implementation, otherwise a > function like >=20 > int something(void) > { > if (x) > return 0; > else > BUG(); > } >=20 > will return an uninitialized value. >=20 > The arch specific implementations usually just contain a trapping > instruction. With CONFIG_BUG() you get a nice console output > that indicates where this happened, but without CONFIG_BUG(), > this is just reported as an invalid instruction (if CONFIG_PRINTK > is still enabled), killing the current process. >=20 > Arnd >=20 I see. In that case, you should really update the documentation and help page of CONFIG_BUG. In its current version it is misleading. It can be understood as 'It disables that macro completely.'. Although I know what the purpose of BUG()/BUG_ON() is, I would not consider the above example as valid C code.... Defining BUG as an endless loop to overcome GCC warnings about not returning a value is a dirty hack for me. - Alex --=20 Technische Universit=C3=A4t Dortmund Alexander Lochmann PGP key: 0xBC3EF6FD Otto-Hahn-Str. 16 phone: +49.231.7556141 D-44227 Dortmund fax: +49.231.7556116 http://ess.cs.tu-dortmund.de/Staff/al --cJKPIHbMi1BlL6u3FTCAFsNDb9ONDGZSH-- --i7GBXgWhhOXDNszIRg5BZd7zKotn2cReU Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEElhZsUHzVP0dbkjCRWT7tBbw+9v0FAluqMPIACgkQWT7tBbw+ 9v2ARBAAln1pTyi+L4yWoHlhEAekRa9SaU6BtKiobke2SvtSEgdbrmqpQLTMPiPi vpOPBg8seQz40tEl1PbcOu0lP0zU8sBemLZN61GreTXrjUzahBLw1Enjsz3wSwR6 rpifHSso1wjNzQaIGV0YhbRCI+94EUZ0ybZvHUtbh9502rHqhc5VP5Pf7xg4iPob x11Aqt5ZXXNeY8m7wmrspSn8Iux1F7+tQsOC+25UVziCn7Jh6lM/XRDIeUfYHmo6 PvZkA72I2LXnmX3+DqTja8jrYDIYfbL0b299MQPVLL/hYcbOYLeejjwudiJ3cv6E v5LRei9K8Q1GK68HpRUk6+emKbkoZKhJdnhqzFHNEW4VvFRE6NufRW7hIHky7LXD JP/TE1u89b8eZxg0nfNJiysliyoNN8O73kKdeiRQuDETkHcT4MJSrkcXy1zljFsR emqcOloWJ6Lc1V+tWrby/7hEDiuV/qbDL2XejncgPdNKSHI+2cIiDmn8waU51uA7 fgmLkdwhYUjTGIJx6dJLEcJti7pxADkn/hXHNAY7qFXCH/nv5v7lDC4AGvNZxdcV ezOHxyrZyHH5/lqJy4zZRwc46UEQOpSj+27M0WOy+8EAEg3aOjbePpuWiFJdXLlp ZTLfnCQCSb6oJ8l481HhMAFImSYOgts3Mofh+tWSs178GN7lils= =wr1i -----END PGP SIGNATURE----- --i7GBXgWhhOXDNszIRg5BZd7zKotn2cReU--