From patchwork Sun Jun 27 05:12:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nathan Chancellor X-Patchwork-Id: 467828 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=-22.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 EE2EBC48BC2 for ; Sun, 27 Jun 2021 05:15:05 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 702B761421 for ; Sun, 27 Jun 2021 05:15:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 702B761421 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 0B7D11691; Sun, 27 Jun 2021 07:14:12 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 0B7D11691 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1624770902; bh=8SJ0rdNiF1eGxKYghOID17R/TEXH/bxSrVL61q47o6g=; h=From:To:Subject:Date:In-Reply-To:References:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=Fw1bugtTLQYPU2S1rv2ijdAdm0jthI+601zqHl8AJ9AzV9qPMK3ljWY4+e5fqxD6I jSO2ioGW3k2UK06yHYj9K+/IP8nSMfyKuKNMm/29+Os0EP2b3qWfsvlraDQpri6nfs zcwVg8lgf4Atee7wsoPE/3GTetpFylUe0ISYxWU0= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 66A4FF80240; Sun, 27 Jun 2021 07:14:11 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 205CFF80259; Sun, 27 Jun 2021 07:14:10 +0200 (CEST) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id D1438F80117 for ; Sun, 27 Jun 2021 07:14:02 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz D1438F80117 Authentication-Results: alsa1.perex.cz; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tsvX004s" Received: by mail.kernel.org (Postfix) with ESMTPSA id BFF0561C18; Sun, 27 Jun 2021 05:13:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624770840; bh=8SJ0rdNiF1eGxKYghOID17R/TEXH/bxSrVL61q47o6g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tsvX004sWQ1Vml6hsSQVSayCX2z9ZKSHM9fz3et7JdxKmZ1cJiKkh1mflXfbEnQwK muYfgh+F0tu0MSrKS2CGUF0eEU5C5axXUHbxuxCTxxO/pGnNECZosGR9xRLLFJZ3di vSZ/jtVj1fpSB6bFV+QEQpSgNzPxavCaDIML/q3r/DsAcwuZ8+TJ7Fgx6ZiI3BNo+q crO3gJBWo4DIHWmOIXn9Q7Jn5ls5tRkuPDl0057Yj+e/BGjHwqOol+xKrMR4KMVr6T jlxFAT2ZtHN4qgYOOsmQATGDN7HAm6s/TeBfAPvvfidcf6Nd6PA3VFG0UtMC7a4Ndd wwAA23J8lpUYw== From: Nathan Chancellor To: "Geoffrey D. Bennett" , Jaroslav Kysela , Takashi Iwai Subject: [PATCH v5] ALSA: usb-audio: scarlett2: Fix for loop increment in scarlett2_usb_get_config Date: Sat, 26 Jun 2021 22:12:03 -0700 Message-Id: <20210627051202.1888250-1-nathan@kernel.org> X-Mailer: git-send-email 2.32.0.93.g670b81a890 In-Reply-To: <20210625202604.GB23780@m.b4.vu> References: <20210625202604.GB23780@m.b4.vu> MIME-Version: 1.0 X-Patchwork-Bot: notify Cc: Nathan Chancellor , clang-built-linux@googlegroups.com, alsa-devel@alsa-project.org, Nick Desaulniers , linux-kernel@vger.kernel.org X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" 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. sound/usb/mixer_scarlett_gen2.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) base-commit: 0cbbeaf370221fc469c95945dd3c1198865c5fe4 diff --git a/sound/usb/mixer_scarlett_gen2.c b/sound/usb/mixer_scarlett_gen2.c index fcba682cd422..161d832cafef 100644 --- a/sound/usb/mixer_scarlett_gen2.c +++ b/sound/usb/mixer_scarlett_gen2.c @@ -1177,6 +1177,7 @@ static int scarlett2_usb_get_config( const struct scarlett2_config *config_item = &scarlett2_config_items[info->has_mixer][config_item_num]; int size, err, i; + u8 *buf_8; u8 value; /* For byte-sized parameters, retrieve directly into buf */ @@ -1185,9 +1186,12 @@ static int scarlett2_usb_get_config( err = scarlett2_usb_get(mixer, config_item->offset, buf, size); if (err < 0) return err; - if (size == 2) - for (i = 0; i < count; i++, (u16 *)buf++) - *(u16 *)buf = le16_to_cpu(*(__le16 *)buf); + if (size == 2) { + u16 *buf_16 = buf; + + for (i = 0; i < count; i++, buf_16++) + *buf_16 = le16_to_cpu(*(__le16 *)buf_16); + } return 0; } @@ -1197,8 +1201,9 @@ static int scarlett2_usb_get_config( return err; /* then unpack from value into buf[] */ + buf_8 = buf; for (i = 0; i < 8 && i < count; i++, value >>= 1) - *(u8 *)buf++ = value & 1; + *buf_8++ = value & 1; return 0; }