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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,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 3E715C11F64 for ; Thu, 1 Jul 2021 17:12:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 24ECE61407 for ; Thu, 1 Jul 2021 17:12:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233160AbhGAROe (ORCPT ); Thu, 1 Jul 2021 13:14:34 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:46334 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229971AbhGAROd (ORCPT ); Thu, 1 Jul 2021 13:14:33 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 8A0AF204FE; Thu, 1 Jul 2021 17:12:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1625159522; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=3XpfyVHUOlWrv6SQQLovtw4OceYZ9xPFRnfZZ4hsEpA=; b=Jzy8lKG3gZ98l3QPMWkkB1rWnlh6PReoxVOXXmgEbw5V5hqzX7ZcW03HGZQciYL0g0YQXb M4e1br44lPzSV6qI7UZUx029xIMgIA3pPz+rIiIsz+JsakcBHpr2hRudc2GYljiKwOxPfy HYfJslBcxpy/3MgrG0ZXqKS2z3TRYEk= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1625159522; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=3XpfyVHUOlWrv6SQQLovtw4OceYZ9xPFRnfZZ4hsEpA=; b=ZmCfntObPC5RSENYZUFFfd/Qt6en1yOjAhGPcqvQAUvP45BTnWKYPiXONE0R00XHqh8dfH KtLlYRSGl6UZIzCg== Received: from alsa1.suse.de (alsa1.suse.de [10.160.4.42]) by relay2.suse.de (Postfix) with ESMTP id EBEF9A3B8F; Thu, 1 Jul 2021 17:12:01 +0000 (UTC) Date: Thu, 01 Jul 2021 19:12:01 +0200 Message-ID: From: Takashi Iwai To: Nathan Chancellor Cc: "Geoffrey D. Bennett" , Jaroslav Kysela , Takashi Iwai , clang-built-linux@googlegroups.com, alsa-devel@alsa-project.org, Nick Desaulniers , linux-kernel@vger.kernel.org Subject: Re: [PATCH v5] ALSA: usb-audio: scarlett2: Fix for loop increment in scarlett2_usb_get_config In-Reply-To: <20210627051202.1888250-1-nathan@kernel.org> References: <20210625202604.GB23780@m.b4.vu> <20210627051202.1888250-1-nathan@kernel.org> 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 27 Jun 2021 07:12:03 +0200, Nathan Chancellor wrote: > > Clang warns: > > sound/usb/mixer_scarlett_gen2.c:1189:32: warning: expression result > unused [-Wunused-value] > for (i = 0; i < count; i++, (u16 *)buf++) > ^ ~~~~~ > 1 warning generated. > > It appears the intention was to cast the void pointer to a u16 pointer > so that the data could be iterated through like an array of u16 values. > However, the cast happens after the increment because a cast is an > rvalue, whereas the post-increment operator only works on lvalues, so > the loop does not iterate as expected. This is not a bug in practice > because count is not greater than one at the moment but this could > change in the future so this should be fixed. > > Replace the cast with a temporary variable of the proper type, which is > less error prone and fixes the iteration. Do the same thing for the > 'u8 *' below this if block. > > Fixes: ac34df733d2d ("ALSA: usb-audio: scarlett2: Update get_config to do endian conversion") > Link: https://github.com/ClangBuiltLinux/linux/issues/1408 > Acked-by: Geoffrey D. Bennett > Signed-off-by: Nathan Chancellor > --- > > v1 -> v2: > > * Use temporary variables of proper type rather than casting, as > requested by Takashi. > > * Mention that there is not a bug at the moment per Geoffrey's comment. > > v2 -> v3: > > * Restrict scope of buf_16 more, as requested by Geoffrey. > > * Add Geoffrey's ack. > > v3 -> v4: > > * Fix stray newline added below > > if (config_item->size >= 8) { > > leftover from buf_16's declaration. > > v4 -> v5 (or how many times does it take Nathan to get a patch right): > > * Re-add note about no bug that was dropped in v3 by accident, as > noticed by Geoffrey. My apologies for the multiple revisions. Thanks, applied now. Takashi