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Mon, 23 Mar 2020 18:05:19 +0000 From: To: CC: , , , , , , , , Subject: Re: [PATCH][next] mtd: spi-nor: controllers: aspeed-smc: Replace zero-length array with flexible-array member Thread-Topic: [PATCH][next] mtd: spi-nor: controllers: aspeed-smc: Replace zero-length array with flexible-array member Thread-Index: AQHWAT2dYkkVcusgCEGyODgFGQFHog== Date: Mon, 23 Mar 2020 18:05:19 +0000 Message-ID: <3763037.C4K6B0S6ij@192.168.0.120> References: <20200319224326.GA25390@embeddedor.com> In-Reply-To: <20200319224326.GA25390@embeddedor.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Tudor.Ambarus@microchip.com; x-originating-ip: [94.177.32.156] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 9ac718a8-515d-4026-0e01-08d7cf54bfcb x-ms-traffictypediagnostic: BY5PR11MB4273: x-microsoft-antispam-prvs: x-bypassexternaltag: True x-ms-oob-tlc-oobclassifiers: OLM:949; x-forefront-prvs: 0351D213B3 x-forefront-antispam-report: SFV:NSPM;SFS:(10009020)(396003)(39860400002)(136003)(376002)(346002)(366004)(199004)(6486002)(6512007)(316002)(6506007)(53546011)(54906003)(9686003)(6916009)(66946007)(66446008)(66556008)(76116006)(64756008)(66476007)(86362001)(91956017)(71200400001)(8676002)(966005)(8936002)(14286002)(2906002)(81156014)(4326008)(81166006)(5660300002)(7416002)(186003)(26005)(478600001)(39026012);DIR:OUT;SFP:1101;SCL:1;SRVR:BY5PR11MB4273;H:BY5PR11MB4419.namprd11.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1; 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charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 9ac718a8-515d-4026-0e01-08d7cf54bfcb X-MS-Exchange-CrossTenant-originalarrivaltime: 23 Mar 2020 18:05:19.6373 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 3f4057f3-b418-4d4e-ba84-d55b4e897d88 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: In0aEL5bF1Quf+gdTqNNYf1GjBC1gsRqCVTGcgG0lvchSkY+YmfI+8VwPP5ayyrsyuMC1kmbf2aN0D3+p1vqdL6uBQ6KkzlLNovAavHejWs= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR11MB4273 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday, March 20, 2020 12:43:26 AM EET Gustavo A. R. Silva wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you know th= e > content is safe >=20 > 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: >=20 > struct foo { > int stuff; > struct boo array[]; > }; >=20 > 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. >=20 > Also, notice that, dynamic memory allocations won't be affected by > this change: >=20 > "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] >=20 > This issue was found with the help of Coccinelle. >=20 > [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") >=20 > Signed-off-by: Gustavo A. R. Silva > --- > drivers/mtd/spi-nor/controllers/aspeed-smc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Applied, thanks. ta