From patchwork Thu May 7 19:00:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 11534743 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D53D914B4 for ; Thu, 7 May 2020 18:56:40 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 8D11720575 for ; Thu, 7 May 2020 18:56:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="CZtvcf7m"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="j8F77k+h" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8D11720575 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Subject:To:From :Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=3NBZAYuaTBxjkXTOTduhLx7aY9pcNa7I2UcE55H5jrg=; b=CZtvcf7mMEtpg7 DUUb5O4lV8HRUvIzY0Lp9qjQM801ixre8Lz+csbml6cqy9JU/CK9id4PRKIcTwsJ8AZevyG81+N1Q 29WSq+Y8vBE1hr0jBXHlx+0+9wz5QKkIfhNs9+nW+Fdy/MUrKFsWe/JDpvU9hbGJwsLTjlXrXjwF9 Hkw6YNr5vYl2hl9jj1Y1OWPrv5hCp/hnrs+0Pkxxbog0h8/WqCltVSHX1dKfPsPkfevJ0OdJzbwZ3 FgTXnpc+iE9F/Rfx8aTtxZiVGL1t0J3uGWKTtusQpqVm8Ak8k1/SsLFWmSRRjJtUZZq22wcOaGSNE 2KNO820I1iI/unHGfYEA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWlhE-0002om-8E; Thu, 07 May 2020 18:56:36 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWlgy-0002bs-HR for linux-arm-kernel@lists.infradead.org; Thu, 07 May 2020 18:56:23 +0000 Received: from embeddedor (unknown [189.207.59.248]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B3DC9216FD; Thu, 7 May 2020 18:56:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588877780; bh=jm3fKnCO4Xf3QTCG3k8/S+/8DNeXKLAAKD5XoFMMhyY=; h=Date:From:To:Cc:Subject:From; b=j8F77k+hOMYWNsm4ZYGQsIc2ubNpcV2lJi+sF3xlCpyYvURINI7X9RHHgSWg7/c0j k45JS4quwF/uKI6F4RcPAt11oF+N91Qn+NxJt0yJ/nN7nFfTnYIiWChCWiNAjpgmMV lhfWkscvzOYaHFDVlhw9do8omT79Q0bRoM6p4Wh0= Date: Thu, 7 May 2020 14:00:46 -0500 From: "Gustavo A. R. Silva" To: Ludovic Desroches Subject: [PATCH] dmaengine: at_xdmac: Replace zero-length array with flexible-array Message-ID: <20200507190046.GA15298@embeddedor> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200507_115620_608847_35A8F567 X-CRM114-Status: GOOD ( 13.73 ) X-Spam-Score: -5.2 (-----) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-5.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at https://www.dnswl.org/, high trust [198.145.29.99 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva Acked-by: Ludovic Desroches --- drivers/dma/at_xdmac.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c index bb0eaf38b594..fd92f048c491 100644 --- a/drivers/dma/at_xdmac.c +++ b/drivers/dma/at_xdmac.c @@ -212,7 +212,7 @@ struct at_xdmac { struct clk *clk; u32 save_gim; struct dma_pool *at_xdmac_desc_pool; - struct at_xdmac_chan chan[0]; + struct at_xdmac_chan chan[]; };