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=-7.5 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1017DC07E99 for ; Fri, 9 Jul 2021 14:03:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EC0FE61356 for ; Fri, 9 Jul 2021 14:03:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232244AbhGIOGT (ORCPT ); Fri, 9 Jul 2021 10:06:19 -0400 Received: from smtp-relay-canonical-1.canonical.com ([185.125.188.121]:37730 "EHLO smtp-relay-canonical-1.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229499AbhGIOGR (ORCPT ); Fri, 9 Jul 2021 10:06:17 -0400 Received: from [10.172.193.212] (1.general.cking.uk.vpn [10.172.193.212]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by smtp-relay-canonical-1.canonical.com (Postfix) with ESMTPSA id 9F63C401BE; Fri, 9 Jul 2021 14:03:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1625839412; bh=ArzmOf/twC31usgyIHswXRtlXpE+DnHhLO+/s9grB20=; h=To:From:Subject:Message-ID:Date:MIME-Version:Content-Type; b=HSeoB3pKLFNLm2ZlDuZDlFKnmPTST6OaUdDf0uWdwdaWTIe6didlgnnzagiEzeS6l 3/81HaWIsK5kdygO4gVtpafUpASSSNC05c/vNdww3hP/Oe4GYrdBWw4cVFquUkd3r8 mbuskyedQfceBvQ++NC/jFq9/gmaQSuKOnCKZd25M6bVCcSfvitiwCYLYOGjtxf9iH VwMWHxNlpTsDFsvZQhs4obXz70eH2IyfnmH+CfA1QOoM3FGVHcHGU4EgkWfkeULu9C 2ZFjhf6unyhrW1m8Fyx6RA1j4YGsvYyquDsUA68uk+ims3gAYGUYHvND4uu3Gz4XnZ afw9UkKLI34LQ== To: Byungho An , Siva Reddy Cc: "David S. Miller" , Jakub Kicinski , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" From: Colin Ian King Subject: issue with unreachable code in net sxgbe driver Message-ID: Date: Fri, 9 Jul 2021 15:03:32 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Static analysis with Coverity has detected several occurrences of dead code in the sxgbe driver in function sxgbe_mtl_init. The issue was introduced with the following commit: commit 1edb9ca69e8a7988900fc0283e10550b5592164d Author: Siva Reddy Date: Tue Mar 25 12:10:54 2014 -0700 net: sxgbe: add basic framework for Samsung 10Gb ethernet driver The analysis is as follows: 20static void sxgbe_mtl_init(void __iomem *ioaddr, unsigned int etsalg, 21 unsigned int raa) 22{ 23 u32 reg_val; 24 25 reg_val = readl(ioaddr + SXGBE_MTL_OP_MODE_REG); 26 reg_val &= ETS_RST; 27 28 /* ETS Algorith */ 29 switch (etsalg & SXGBE_MTL_OPMODE_ESTMASK) { Logically dead code (DEADCODE) 30 case ETS_WRR: 31 reg_val &= ETS_WRR; 32 break; Logically dead code (DEADCODE) 33 case ETS_WFQ: 34 reg_val |= ETS_WFQ; 35 break; Logically dead code (DEADCODE) 36 case ETS_DWRR: 37 reg_val |= ETS_DWRR; 38 break; 39 } SXGBE_MTL_OPMODE_ESTMASK is defined as 0x03 ETS_WRR is 0xFFFFFF9F ETS_WFQ is 0x00000020 ETS_DWRR is 0x00000040 so the masking of etsalg & SXGBE_MTL_OPMODE_ESTMASK will never match any of the ETS_* values, hence the dead code. 40 writel(reg_val, ioaddr + SXGBE_MTL_OP_MODE_REG); 41 42 switch (raa & SXGBE_MTL_OPMODE_RAAMASK) { Logically dead code (DEADCODE) 43 case RAA_SP: 44 reg_val &= RAA_SP; 45 break; Logically dead code (DEADCODE) 46 case RAA_WSP: 47 reg_val |= RAA_WSP; 48 break; 49 } 50 writel(reg_val, ioaddr + SXGBE_MTL_OP_MODE_REG); 51} SXGBE_MTL_OPMODE_RAAMASK is defined as 0x1 RAA_SP is 0xFFFFFFFB RAA_WSP is 0x00000004 so masking of raa & SXGBE_MTL_OPMODE_RAAMASK will never match any of the RAA_* values, hence the dead code. I don't think this is intentional. Not sure how to fix this hence I'm reporting this issue. Regards, Colin