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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 9475FC432BE for ; Thu, 26 Aug 2021 08:51:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6B4146108E for ; Thu, 26 Aug 2021 08:51:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240639AbhHZIwS convert rfc822-to-8bit (ORCPT ); Thu, 26 Aug 2021 04:52:18 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.85.151]:32936 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233195AbhHZIwQ (ORCPT ); Thu, 26 Aug 2021 04:52:16 -0400 Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-140-kV8jce2GMwKPSLUR9I4nHg-1; Thu, 26 Aug 2021 09:51:25 +0100 X-MC-Unique: kV8jce2GMwKPSLUR9I4nHg-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) by AcuMS.aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Thu, 26 Aug 2021 09:51:24 +0100 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.023; Thu, 26 Aug 2021 09:51:23 +0100 From: David Laight To: 'Pavel Skripkin' , "Larry.Finger@lwfinger.net" , "phil@philpotter.co.uk" , "gregkh@linuxfoundation.org" , "straube.linux@gmail.com" , "fmdefrancesco@gmail.com" CC: "linux-staging@lists.linux.dev" , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH v3 5/6] staging: r8188eu: add error handling of rtw_read32 Thread-Topic: [PATCH v3 5/6] staging: r8188eu: add error handling of rtw_read32 Thread-Index: AQHXmLmWEBrRSWSvqkChOMAmAhSABKuFfA1Q Date: Thu, 26 Aug 2021 08:51:23 +0000 Message-ID: <27f5e52d520b453cbcabb3d72f0f5d15@AcuMS.aculab.com> References: <93bf46ce2d0ce12e94672acf28b64dc341fde038.1629789580.git.paskripkin@gmail.com> In-Reply-To: <93bf46ce2d0ce12e94672acf28b64dc341fde038.1629789580.git.paskripkin@gmail.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pavel Skripkin > Sent: 24 August 2021 08:28 > > _rtw_read32 function can fail in case of usb transfer failure. But > previous function prototype wasn't designed to return an error to > caller. It can cause a lot uninit value bugs all across the driver code, > since rtw_read32() returns local stack variable to caller. > > Fix it by changing the prototype of this function. Now it returns an > int: 0 on success, negative error value on failure and callers should pass > the pointer to storage location for register value. Pretty horrid API interface. Functions like readl() - which can fail just return ~0u and let the caller worry about whether that causes serious grief. You could make all the read functions return __u64 and return ~0ull on error. Testing for (value & 1ull << 63) will be reasonable even on 32bit. ... > -static u32 usb_read32(struct intf_hdl *pintfhdl, u32 addr) > +static int usb_read32(struct intf_hdl *pintfhdl, u32 addr, u32 *data) > { > u8 requesttype; > u16 wvalue; > u16 len; > - __le32 data; > + int res; > + __le32 tmp; > + > + if (WARN_ON(unlikely(!data))) > + return -EINVAL; > Kill the NULL check - it is a silly coding error. An OOPS is just as easy to debug. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)