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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 06951C43142 for ; Tue, 26 Jun 2018 02:11:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A41A02642F for ; Tue, 26 Jun 2018 02:11:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A41A02642F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=perches.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965245AbeFZCLE (ORCPT ); Mon, 25 Jun 2018 22:11:04 -0400 Received: from smtprelay0126.hostedemail.com ([216.40.44.126]:59427 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965190AbeFZCLD (ORCPT ); Mon, 25 Jun 2018 22:11:03 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay06.hostedemail.com (Postfix) with ESMTP id 5495F18224D7A; Tue, 26 Jun 2018 02:11:02 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: scent76_8cd89f294c4f X-Filterd-Recvd-Size: 1964 Received: from XPS-9350.home (unknown [47.151.150.235]) (Authenticated sender: joe@perches.com) by omf12.hostedemail.com (Postfix) with ESMTPA; Tue, 26 Jun 2018 02:11:00 +0000 (UTC) Message-ID: Subject: Re: [PATCH v2 net] nfp: cast sizeof() to int when comparing with error code From: Joe Perches To: Chengguang Xu , jakub.kicinski@netronome.com, davem@davemloft.net, LKML , Julia Lawall , cocci Cc: oss-drivers@netronome.com, netdev@vger.kernel.org, Dmitry Torokhov , linux-input , linux-s390 Date: Mon, 25 Jun 2018 19:10:59 -0700 In-Reply-To: <20180626011631.22717-1-cgxu519@gmx.com> References: <20180626011631.22717-1-cgxu519@gmx.com> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.28.1-2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2018-06-26 at 09:16 +0800, Chengguang Xu wrote: > sizeof() will return unsigned value so in the error check > negative error code will be always larger than sizeof(). This looks like a general class of error in the kernel where a signed result that could be returning a -errno is tested against < or <= sizeof() A couple examples: drivers/input/mouse/elan_i2c_smbus.c: len = i2c_smbus_read_block_data(client, ETP_SMBUS_IAP_PASSWORD_READ, val); if (len < sizeof(u16)) { i2c_smbus_read_block_data can return a negative errno net/smc/smc_clc.c: len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1, sizeof(struct smc_clc_msg_decline)); if (len < sizeof(struct smc_clc_msg_decline)) where kernel_sendmsg can return a negative errno There are probably others, I didn't look hard. Perhaps a cocci script to find these could be generated?