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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5C18FC433EF for ; Thu, 9 Jun 2022 20:15:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244052AbiFIUPU (ORCPT ); Thu, 9 Jun 2022 16:15:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50794 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244861AbiFIUPT (ORCPT ); Thu, 9 Jun 2022 16:15:19 -0400 Received: from mx01.omp.ru (mx01.omp.ru [90.154.21.10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1446FF45D7 for ; Thu, 9 Jun 2022 13:15:14 -0700 (PDT) Received: from [192.168.1.103] (31.173.84.193) by msexch01.omp.ru (10.188.4.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.986.14; Thu, 9 Jun 2022 23:15:05 +0300 Subject: Re: [PATCH] ata: libata-core: fix sloppy typing in ata_id_n_sectors() To: Damien Le Moal , References: <2a523107-9838-0940-1402-3b6bdad7e1e1@opensource.wdc.com> From: Sergey Shtylyov Organization: Open Mobile Platform Message-ID: <1651775c-cb00-0bdc-e27f-700d0580ec88@omp.ru> Date: Thu, 9 Jun 2022 23:15:05 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <2a523107-9838-0940-1402-3b6bdad7e1e1@opensource.wdc.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [31.173.84.193] X-ClientProxiedBy: msexch01.omp.ru (10.188.4.12) To msexch01.omp.ru (10.188.4.12) X-KSE-ServerInfo: msexch01.omp.ru, 9 X-KSE-AntiSpam-Interceptor-Info: scan successful X-KSE-AntiSpam-Version: 5.9.20, Database issued on: 06/09/2022 19:56:58 X-KSE-AntiSpam-Status: KAS_STATUS_NOT_DETECTED X-KSE-AntiSpam-Method: none X-KSE-AntiSpam-Rate: 59 X-KSE-AntiSpam-Info: Lua profiles 171038 [Jun 09 2022] X-KSE-AntiSpam-Info: Version: 5.9.20.0 X-KSE-AntiSpam-Info: Envelope from: s.shtylyov@omp.ru X-KSE-AntiSpam-Info: LuaCore: 489 489 b67d2e276d358fa514f5991440453e6a402e3a26 X-KSE-AntiSpam-Info: {rep_avail} X-KSE-AntiSpam-Info: {Tracking_from_domain_doesnt_match_to} X-KSE-AntiSpam-Info: {relay has no DNS name} X-KSE-AntiSpam-Info: {SMTP from is not routable} X-KSE-AntiSpam-Info: {Found in DNSBL: 31.173.84.193 in (user) b.barracudacentral.org} X-KSE-AntiSpam-Info: 127.0.0.199:7.1.2;omp.ru:7.1.1;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1 X-KSE-AntiSpam-Info: ApMailHostAddress: 31.173.84.193 X-KSE-AntiSpam-Info: {DNS response errors} X-KSE-AntiSpam-Info: Rate: 59 X-KSE-AntiSpam-Info: Status: not_detected X-KSE-AntiSpam-Info: Method: none X-KSE-AntiSpam-Info: Auth:dmarc=temperror header.from=omp.ru;spf=temperror smtp.mailfrom=omp.ru;dkim=none X-KSE-Antiphishing-Info: Clean X-KSE-Antiphishing-ScanningType: Heuristic X-KSE-Antiphishing-Method: None X-KSE-Antiphishing-Bases: 06/09/2022 20:00:00 X-KSE-AttachmentFiltering-Interceptor-Info: protection disabled X-KSE-Antivirus-Interceptor-Info: scan successful X-KSE-Antivirus-Info: Clean, bases: 6/9/2022 4:23:00 PM X-KSE-BulkMessagesFiltering-Scan-Result: InTheLimit Precedence: bulk List-ID: X-Mailing-List: linux-ide@vger.kernel.org On 6/8/22 9:47 AM, Damien Le Moal wrote: >> The code multiplying the # of cylinders/heads/sectors in ata_id_n_sectors() >> to get a disk capacity implicitly uses the *int* type for that calculation >> and casting the result to 'u64' before returning ensues a sign extension. >> Explicitly casting the 'u16' typed multipliers to 'u32' results in avoiding >> a sign extension instruction and so in a more compact code... >> >> Found by Linux Verification Center (linuxtesting.org) with the SVACE static >> analysis tool. >> >> Signed-off-by: Sergey Shtylyov >> >> --- >> This patch is against the 'for-next' branch of Damien's 'libata.git' repo. >> >> drivers/ata/libata-core.c | 10 ++++++---- >> 1 file changed, 6 insertions(+), 4 deletions(-) >> >> Index: libata/drivers/ata/libata-core.c >> =================================================================== >> --- libata.orig/drivers/ata/libata-core.c >> +++ libata/drivers/ata/libata-core.c >> @@ -1107,11 +1107,13 @@ static u64 ata_id_n_sectors(const u16 *i >> return ata_id_u32(id, ATA_ID_LBA_CAPACITY); >> } else { >> if (ata_id_current_chs_valid(id)) >> - return id[ATA_ID_CUR_CYLS] * id[ATA_ID_CUR_HEADS] * >> - id[ATA_ID_CUR_SECTORS]; >> + return (u32)id[ATA_ID_CUR_CYLS] * >> + (u32)id[ATA_ID_CUR_HEADS] * >> + (u32)id[ATA_ID_CUR_SECTORS]; >> else >> - return id[ATA_ID_CYLS] * id[ATA_ID_HEADS] * >> - id[ATA_ID_SECTORS]; >> + return (u32)id[ATA_ID_CYLS] * >> + (u32)id[ATA_ID_HEADS] * >> + (u32)id[ATA_ID_SECTORS]; >> } >> } >> > > Applied to for-5.20. Thanks ! Actually I was going to redo it (changing the order of multiplications), but well, it's OK as is... MBR, Sergey