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Mon, 18 May 2020 03:12:15 +0000 From: Damien Le Moal To: Bart Van Assche , Jens Axboe CC: "linux-block@vger.kernel.org" , Christoph Hellwig , Ming Lei , Chaitanya Kulkarni , Alexander Potapenko Subject: Re: [PATCH 5/5] null_blk: Zero-initialize read buffers in non-memory-backed mode Thread-Topic: [PATCH 5/5] null_blk: Zero-initialize read buffers in non-memory-backed mode Thread-Index: AQHWKxeutW6PgxRL9Ea9BZV4XxYt6g== Date: Mon, 18 May 2020 03:12:15 +0000 Message-ID: References: <20200516001914.17138-1-bvanassche@acm.org> <20200516001914.17138-6-bvanassche@acm.org> <440743f4-1053-32f3-2edf-3eb0fdd057ef@acm.org> <45f9df39-a62e-4721-5bc8-ac9fa87b02ea@acm.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: acm.org; dkim=none (message not signed) header.d=none;acm.org; dmarc=none action=none header.from=wdc.com; x-originating-ip: [129.253.182.57] x-ms-publictraffictype: Email x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 39956bdb-e4be-4b73-c88b-08d7fad94411 x-ms-traffictypediagnostic: BY5PR04MB6325: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: wdcipoutbound: EOP-TRUE x-ms-oob-tlc-oobclassifiers: OLM:6430; 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x-ms-exchange-antispam-messagedata: 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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-Network-Message-Id: 39956bdb-e4be-4b73-c88b-08d7fad94411 X-MS-Exchange-CrossTenant-originalarrivaltime: 18 May 2020 03:12:15.0688 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: B5keFB0CQRSkI8CVahdhrPvLnwmu5EVWAD6KFOytL6sOslxagF95zmczOcp9oanWAPpr3FkYb3ZSk10hwPzTsw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR04MB6325 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2020/05/18 11:56, Bart Van Assche wrote:=0A= > On 2020-05-17 19:10, Damien Le Moal wrote:=0A= >> On 2020/05/18 10:32, Bart Van Assche wrote:=0A= >>> On 2020-05-17 18:12, Damien Le Moal wrote:=0A= >>>> On 2020/05/16 9:19, Bart Van Assche wrote:=0A= >>>>> +static void nullb_zero_rq_data_buffer(const struct request *rq)=0A= >>>>> +{=0A= >>>>> + struct req_iterator iter;=0A= >>>>> + struct bio_vec bvec;=0A= >>>>> +=0A= >>>>> + rq_for_each_bvec(bvec, rq, iter)=0A= >>>>> + zero_fill_bvec(&bvec);=0A= >>>>> +}=0A= >>>>> +=0A= >>>>> +static void nullb_zero_read_cmd_buffer(struct nullb_cmd *cmd)=0A= >>>>> +{=0A= >>>>> + struct nullb_device *dev =3D cmd->nq->dev;=0A= >>>>> +=0A= >>>>> + if (dev->queue_mode =3D=3D NULL_Q_BIO && bio_op(cmd->bio) =3D=3D RE= Q_OP_READ)=0A= >>>>> + zero_fill_bio(cmd->bio);=0A= >>>>> + else if (req_op(cmd->rq) =3D=3D REQ_OP_READ)=0A= >>>>> + nullb_zero_rq_data_buffer(cmd->rq);=0A= >>>>> +}=0A= >>>>=0A= >>>> Shouldn't the definition of these two functions be under a "#ifdef CON= FIG_KMSAN" ?=0A= >>>=0A= >>> It is on purpose that I used IS_ENABLED(CONFIG_KMSAN) below instead of= =0A= >>> #ifdef CONFIG_KMSAN. CONFIG_KMSAN is not yet upstream and I want to=0A= >>> expose the above code to the build robot.=0A= >>=0A= >> But then you will get a "defined but unused" build warning, no ?=0A= > =0A= > Not when using IS_ENABLED(...).=0A= =0A= I do not understand: the "if (IS_ENABLED(CONFIG_KMSAN))" will be compiled o= ut if=0A= CONFIG_KMSAN is not enabled/defined, but the function definitions will stil= l=0A= remain, won't they ? That will lead to "defined but unused" warning, no ? W= hat=0A= am I missing here ?=0A= =0A= > =0A= > Bart.=0A= > =0A= =0A= =0A= -- =0A= Damien Le Moal=0A= Western Digital Research=0A=