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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 DE3A1C83001 for ; Thu, 30 Apr 2020 08:22:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF62420784 for ; Thu, 30 Apr 2020 08:22:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726808AbgD3IWi (ORCPT ); Thu, 30 Apr 2020 04:22:38 -0400 Received: from mx2.suse.de ([195.135.220.15]:50096 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726412AbgD3IWh (ORCPT ); Thu, 30 Apr 2020 04:22:37 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 73FCFABB2; Thu, 30 Apr 2020 08:22:34 +0000 (UTC) Date: Thu, 30 Apr 2020 10:22:34 +0200 Message-ID: From: Takashi Iwai To: Arnd Bergmann Cc: linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org, Takashi Iwai Subject: Re: [PATCH] ALSA: opti9xx: shut up gcc-10 range warning In-Reply-To: References: <20200429190216.85919-1-arnd@arndb.de> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 30 Apr 2020 08:12:07 +0200, Takashi Iwai wrote: > > On Wed, 29 Apr 2020 21:02:03 +0200, > Arnd Bergmann wrote: > > > > gcc-10 points out a few instances of suspicious integer arithmetic > > leading to value truncation: > > > > sound/isa/opti9xx/opti92x-ad1848.c: In function 'snd_opti9xx_configure': > > sound/isa/opti9xx/opti92x-ad1848.c:322:43: error: overflow in conversion from 'int' to 'unsigned char' changes value from '(int)snd_opti9xx_read(chip, 3) & -256 | 240' to '240' [-Werror=overflow] > > 322 | (snd_opti9xx_read(chip, reg) & ~(mask)) | ((value) & (mask))) > > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~ > > sound/isa/opti9xx/opti92x-ad1848.c:351:3: note: in expansion of macro 'snd_opti9xx_write_mask' > > 351 | snd_opti9xx_write_mask(chip, OPTi9XX_MC_REG(3), 0xf0, 0xff); > > | ^~~~~~~~~~~~~~~~~~~~~~ > > sound/isa/opti9xx/miro.c: In function 'snd_miro_configure': > > sound/isa/opti9xx/miro.c:873:40: error: overflow in conversion from 'int' to 'unsigned char' changes value from '(int)snd_miro_read(chip, 3) & -256 | 240' to '240' [-Werror=overflow] > > 873 | (snd_miro_read(chip, reg) & ~(mask)) | ((value) & (mask))) > > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~ > > sound/isa/opti9xx/miro.c:1010:3: note: in expansion of macro 'snd_miro_write_mask' > > 1010 | snd_miro_write_mask(chip, OPTi9XX_MC_REG(3), 0xf0, 0xff); > > | ^~~~~~~~~~~~~~~~~~~ > > > > These are all harmless here as only the low 8 bit are passed down > > anyway. Change the macros to inline functions to make the code > > more readable and also avoid the warning. > > > > Strictly speaking those functions also need locking to make the > > read/write pair atomic, but it seems unlikely that anyone would > > still run into that issue. > > > > Fixes: 1841f613fd2e ("[ALSA] Add snd-miro driver") > > Signed-off-by: Arnd Bergmann > > Applied now, thanks. BTW, the lack of locking is no problem in this code. Those lines are called only at the initialization in the probe function, so can't race. thanks, Takashi