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=-13.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 A7E86C38A2A for ; Fri, 8 May 2020 15:04:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 803A821655 for ; Fri, 8 May 2020 15:04:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="YYBbcw9n" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727982AbgEHPEE (ORCPT ); Fri, 8 May 2020 11:04:04 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:44076 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726767AbgEHPEE (ORCPT ); Fri, 8 May 2020 11:04:04 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 048F3oTu122021; Fri, 8 May 2020 15:03:52 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2020-01-29; bh=ak+KS6cmfHXjY6qcAVO3aGp10fSQOuF6YLLnnfnHRtM=; b=YYBbcw9nkzniiFX/z/kJ6hUg0596KLR4N6Sng4tfllHuxeU6JbSlEBO3ojO4dI5/wV+z hIa2AlOzb6Mecytdbepfp4LjqjJgPBAH8ZBPdh6yRgpg62OawOdvyVwBYNmJJ2ZfZ9aO qwr7EJUSKpcax/4VCZTVSKLpCENdIRFdtovSm0mPJaUA2gpn638J85CzTq7/sCqTjKxr js6Fdrqb07IHA9z5HXas2rOANFx8h+XMZvY/QDY4gDnF56MFdU7heEfG+9M4IdkGSbPJ oMLO7TFGj0HoXco3qG8j1Jn7cs/eI+Rt/7MZfIJsuK4svyblQ7XPJcaMDDPoiyAqmKSS Wg== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by userp2120.oracle.com with ESMTP id 30vtexufcr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 08 May 2020 15:03:50 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 048F1tew021973; Fri, 8 May 2020 15:03:46 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userp3030.oracle.com with ESMTP id 30vtecqgae-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 08 May 2020 15:03:44 +0000 Received: from abhmp0018.oracle.com (abhmp0018.oracle.com [141.146.116.24]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 048F3gAv009790; Fri, 8 May 2020 15:03:42 GMT Received: from [192.168.0.190] (/68.201.65.98) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 08 May 2020 08:03:42 -0700 Subject: Re: [Jfs-discussion] [PATCH] JFS: Replace zero-length array with flexible-array To: "Gustavo A. R. Silva" Cc: jfs-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org References: <20200507185550.GA14715@embeddedor> From: Dave Kleikamp Autocrypt: addr=dave.kleikamp@oracle.com; prefer-encrypt=mutual; keydata= mQINBE7VCEMBEAC3kywrdIxxL/I9maTCxaWTBiHZFNhT5K8QZGLUfW3uFrW89PdAtloSEc1W ScC9O+D2Ygqwx46ZVA7qMXHxpNQ6IZp8he88gQ9lilWD8OJ/T3OKyT6ITdkmsgv6G08QdGCP 0+mCpETv79kcj+Z4pzKLN5QyKW40R3LGcJ6a+0AG5As5/ZkmhceSffdSyDS6zKff3c6cgfQH zl+ugygdKItr3UGIfxuzF3b9uYicsVStwIxyuyzY8i1yYYnnXZtWkI9ZwxT+00PqjCvfVioy xswoscukLQntlkfd4gwM8t56RIxqEo4iNmFwmBYHlSd7C+8SrvPAOgvOtr1vjzJhEsJ2uJNW O2pgZc8xMxe8vhyZK1Nih67hbtzSIpFij06zHwAt4AY3sCbWslOExb8JboINWhI89QcgNmMK uwLHag3D/zZQXQIBvC5H27T49NA6scA92j2qFO6Beks3n/HW6TJni/S9sUXRghRiGDdc/pFr 20R3ivRzKyYBoSWl/3Syo0JcWdEpqq6ti/5MTRFZ+HQjwgUGZ5w+Xu2ttq/q9MyjD4odfKuF WoXk3bF+9LozDNkRi+JxCNT9+D4lsm3kdFTUXHf/qU/iHTPjwYZd6UQeCHJPN6fpjiXolF+u qIwOed8g8nXEXKGafIl3zsAzXBeXKZwECi9VPOxT4vrGHnlTHwARAQABtDZEYXZpZCBLbGVp a2FtcCAoQUtBIFNoYWdneSkgPGRhdmUua2xlaWthbXBAb3JhY2xlLmNvbT6JAjgEEwECACIF Ak7VCEMCGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEDaohF61QIxkpSsP/3DtjVT0 4vPPB7WWGWapnIb8INUvMJX84y4jziAk9dSESdPavYguES9KLOTXmAGIVwuZj5UtUNie4Q3V fZp7Mc7Lb3sf9r2fIlVJXVhQwMFjPYkPLbQBAtHlnt8TClkF2te47tVWuDqI4R0pwACKhUht lQRXpJy7/8pHdNfHyBLOqw6ica8R+On9KkcEJCE+e8XiveAC+2+YcZyRwrj0dTfWEQI6CNwW kax4AtXo/+NigwdU0OXopLDpyro7wIVt3gWLPV99Bo387PPyeWUSZOH6kHIXyYky51zzoZF3 1XuX3UvObx7i/f3uH0jd3O/0/h2iHB9QxmykJBG7AJcF5KiunAL+91a0bqr9IHiffDo0oAme 9JFKOrkcODnnWuHABB6U4pT2JQRF199/Vt4qR+kvuo+xy0eO+0CHEhQWfyFyxz8nQJlizq9p jnzaWe8tAbJz2WqB2CNBhLI7Qn8cAEM66v2aRCnJZ4Uty7HRDnIbQ0ixUxLNIAWM8N4C6w2I RxLfIfNqTTqEcz2m2fg8wSiNuFh17HfzFM/ltXs4wJ610IhwXuPPsA2V/j2pT8GDhn/rMAGN IbO8iEbDO+gKpN47r+OVjxq3fWbRc2ouqRN+fHgvLYt1xcZnPD/sGyLJpMdSHlpCpgKr3ijA y16pnepPaVCTY1FTvNCkZ6hmGvuDuQINBE7VCEMBEADEsrKHN4cTmb0Lz4//ah9WMCvZXWD3 2EWhMh+Pqr+yin7Ga77K5FtgirKjYOtymXeMw640cqp6DaIo+N6KPWM2bsos12nIfN9BWisb XhPMmYZtoYALMjn3CYvE01N+Ym/SDFsfjAu3WtbefEC/Hjw2hlCfPMotU1wkfGEgapkFcGsG MxDjdZN7dSkBH1dKkG3Cx7Cni8qn0Q3oJzSfR6H2KZZZWiJGV70WKWE01yQCYLHfbPMQKS1u qTEaCND/iDjZvbungBUR1kg43CpbzpWlY28AuZrNmGpar4h5YwbiJO2fR7WgiDYmXqxQ8DXY uxndrmTOQqj8EizkOifINWQvouMaasKLIK+U38YCG5stImSmKfjBxrICgXITp/YS4/i1yR3r HthdQ5hZVfCDxKjR8knv+6A37588mYE6DTBpFh9To4baNo3N4ikkg4+bAcO/5v3QiFsCdh3H hR9zlBgy2jOUFYSdSxhXx2y0NUxQSUOpw59sqgBFmgTi2FscchgBraujpu7JE8TdOdSMPSNG Dqx8G5a1g3Ot6+HxgQM8LsZ5qq3BGUDB0DLHtMVu3r9x2327QSp/q2CgwPn2XzelQ0yNolAt 6wjbQwZXTGIGQGlpAFk7UOED/je8ANKYCkE0ZdqQigyoQFEZtyjYxzIzJRWLl4lJjhBSar1v TiSreQARAQABiQIfBBgBAgAJBQJO1QhDAhsMAAoJEDaohF61QIxk/DsP/RjCZHGEsiX0uHxu JzPglNp9mjgG5dGmgYn0ERSat4bcTQV5iJN2Qcn1hP5fJxKg55T8+cFYhFJ1dSvyBVvatee7 /A2IcNAIBBTYCPYcBC771KAU/JOokYu2lkrGM2SXq4XxpfDzohOS3LDGif47TYpEKWbP4AHq vcIl9CYvnhnbV+B/SxqhH7iYB6q2bqY6ki7fsk2lK65FFhlkkgsKyeOiuaVNEv3tmPCMAY/v oMAsCTLK63Wsd9pUY2SGt2ACIy7pTq+k1b09cqlTM2vux8/R0HNzQBXNcFiKKz+JNVObP30N /hsLs0+Ko9f/2OcixfkGjdih8I+FnRdS6wAO7k6g+tTBOj/sbSbH+eZbxWwANkiFkykOASGA /4RzIDie72NiM8lKzpyrlaruSFxuj9/wZuCT7jaYIaiOMPy7Y0Lpisy/hRhwDCNlKU6Hcr7k hQ1cIx4CB40fwqjbK61tWrqZR47pDKShl5DBRdeX/1a+WHXzDLVE4sfax5xL2wjiCUfEyH7x 9YJoKXbnOlKuzjsm9lZIwVwqw07Qi1uFmzJopHW0H3P6zUlujM0buDmaio+Q8znJchizOrQ3 58pn7BNKx3mmswoyZlDtukab9QGF7BZBMjwmafn1RuEVGdlSB52F8TShLgKUM+0dkFmI2yf/ rnNNL3zBkwD3nWcTxFnX Message-ID: <141a7573-bd2a-4b89-e62b-8e18464071ae@oracle.com> Date: Fri, 8 May 2020 10:03:41 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200507185550.GA14715@embeddedor> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9614 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 malwarescore=0 mlxlogscore=999 phishscore=0 mlxscore=0 adultscore=0 suspectscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2005080134 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9614 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 lowpriorityscore=0 adultscore=0 spamscore=0 suspectscore=0 bulkscore=0 priorityscore=1501 malwarescore=0 phishscore=0 impostorscore=0 mlxscore=0 mlxlogscore=999 clxscore=1011 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2005080134 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks Gustavo. I have already merged this into jfs-next. It was all I had queued up and I failed to push it in the last merge window to Linus. I'll make sure I get it in the next one. https://github.com/kleikamp/linux-shaggy/commits/jfs-next Shaggy On 5/7/20 1:55 PM, Gustavo A. R. Silva wrote: > The current codebase makes use of the zero-length array language > extension to the C90 standard, but the preferred mechanism to declare > variable-length types such as these ones is a flexible array member[1][2], > introduced in C99: > > struct foo { > int stuff; > struct boo array[]; > }; > > By making use of the mechanism above, we will get a compiler warning > in case the flexible array does not occur last in the structure, which > will help us prevent some kind of undefined behavior bugs from being > inadvertently introduced[3] to the codebase from now on. > > Also, notice that, dynamic memory allocations won't be affected by > this change: > > "Flexible array members have incomplete type, and so the sizeof operator > may not be applied. As a quirk of the original implementation of > zero-length arrays, sizeof evaluates to zero."[1] > > sizeof(flexible-array-member) triggers a warning because flexible array > members have incomplete type[1]. There are some instances of code in > which the sizeof operator is being incorrectly/erroneously applied to > zero-length arrays and the result is zero. Such instances may be hiding > some bugs. So, this work (flexible-array member conversions) will also > help to get completely rid of those sorts of issues. > > This issue was found with the help of Coccinelle. > > [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html > [2] https://github.com/KSPP/linux/issues/21 > [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") > > Signed-off-by: Gustavo A. R. Silva > --- > fs/jfs/jfs_dtree.c | 2 +- > fs/jfs/jfs_xattr.h | 4 ++-- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c > index 3acc954f7c04..837d42f61464 100644 > --- a/fs/jfs/jfs_dtree.c > +++ b/fs/jfs/jfs_dtree.c > @@ -2964,7 +2964,7 @@ struct jfs_dirent { > loff_t position; > int ino; > u16 name_len; > - char name[0]; > + char name[]; > }; > > /* > diff --git a/fs/jfs/jfs_xattr.h b/fs/jfs/jfs_xattr.h > index f0558b3348da..c50167a7bc50 100644 > --- a/fs/jfs/jfs_xattr.h > +++ b/fs/jfs/jfs_xattr.h > @@ -17,12 +17,12 @@ struct jfs_ea { > u8 flag; /* Unused? */ > u8 namelen; /* Length of name */ > __le16 valuelen; /* Length of value */ > - char name[0]; /* Attribute name (includes null-terminator) */ > + char name[]; /* Attribute name (includes null-terminator) */ > }; /* Value immediately follows name */ > > struct jfs_ea_list { > __le32 size; /* overall size */ > - struct jfs_ea ea[0]; /* Variable length list */ > + struct jfs_ea ea[]; /* Variable length list */ > }; > > /* Macros for defining maxiumum number of bytes supported for EAs */ > > > > _______________________________________________ > Jfs-discussion mailing list > Jfs-discussion@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/jfs-discussion >