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R. Silva" , Kalle Valo , "David S. Miller" , Amitkumar Karwar , Xinming Hu , Lennert Buytenhek CC: "linux-wireless@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: RE: [EXT] [PATCH][next] wireless: marvell: Replace zero-length array with flexible-array member Thread-Topic: [EXT] [PATCH][next] wireless: marvell: Replace zero-length array with flexible-array member Thread-Index: AQHV63+AsCX3xTX2i06uJeo56Kx146hBOFgg Date: Tue, 10 Mar 2020 04:28:14 +0000 Message-ID: References: <20200225020413.GA8057@embeddedor> In-Reply-To: <20200225020413.GA8057@embeddedor> 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=ganapathi.bhat@nxp.com; x-originating-ip: [115.112.95.158] x-ms-publictraffictype: Email x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: c8144e9c-555b-4ba0-f2f1-08d7c4ab7367 x-ms-traffictypediagnostic: DB7PR04MB5290: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:9508; x-forefront-prvs: 033857D0BD x-forefront-antispam-report: SFV:NSPM;SFS:(10009020)(4636009)(39860400002)(346002)(396003)(376002)(366004)(136003)(189003)(199004)(478600001)(52536014)(54906003)(5660300002)(110136005)(55016002)(55236004)(6506007)(9686003)(66946007)(66556008)(7696005)(71200400001)(64756008)(2906002)(316002)(76116006)(66476007)(4326008)(44832011)(86362001)(66446008)(4744005)(33656002)(81156014)(186003)(81166006)(8676002)(8936002)(26005);DIR:OUT;SFP:1101;SCL:1;SRVR:DB7PR04MB5290;H:DB7PR04MB5242.eurprd04.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;MX:1;A:1; received-spf: None (protection.outlook.com: nxp.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: DrQz+sO7xkgtVtRDVoQ7Zy2PVHR5ZnioOBfrvOvatO3ZzCnwqUKtwByt/1r+por1pQC6YH1Mqj/enH9dwUf1G5Ac2VUu4VwXw+Rh/HEGkLWTmtNDnJPiZbFGqHdCHk2cJJmS32wuPOhnM/v1JrtWhTkQo8BUJc6wavuUqG0ZEx360WIuFfaXZY6/XS5rXCGC+Y9IjW9KpB5Fsazu91pBBiZmR2wvz9EHEYB7t4GNXYmIEYh9/slaTbt6XChx+sCazwe5hyf1ZJnoGUsN/LOHfSKmoMtwzowL28C8pAlka7a6OSyNQPFOOLSB/lKieqhF3raR7b/06Nxxh0e8en7OSGxqMvhZhlKPplhLHPBn3ELUiGJPjtHXGm36epeb5r81QqG+Mf6k+kPallE1+6Gk42ACbuhbK/W97mSXObir2kaFIzzVRnAM7U8cyEfXmj6f x-ms-exchange-antispam-messagedata: g7MbakOv0WLTXWMT5BtmFA1fW+zIl9/XS70kLzSBIVSYoC6/26kdHZwwwQFQvOP+ZwxtiYIHSHp8ta1ZAquQkE7B5rnpQPi/+RwTKTpqQKH1mkpA1OOTWnKydG9l5yb0qmSTZaMgxUsU499wxw5AgQ== x-ms-exchange-transport-forked: True Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nxp.com X-MS-Exchange-CrossTenant-Network-Message-Id: c8144e9c-555b-4ba0-f2f1-08d7c4ab7367 X-MS-Exchange-CrossTenant-originalarrivaltime: 10 Mar 2020 04:28:14.7460 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: ehJ5UgxYrjJawg8YPGzUTAK4IPZ41jfCnWvYQNHcVwKyKbFmpryI7xDJUlURpdAf/CmaL3Yv72ykK/69NT9QXw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB7PR04MB5290 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Gustavo, > The current codebase makes use of the zero-length array language extensio= n > to the C90 standard, but the preferred mechanism to declare variable-leng= th > 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-len= gth > arrays, sizeof evaluates to zero."[1] Thanks for this path. Acked-by: Ganapathi Bhat =20