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=-13.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 AEDE9C38A2A for ; Thu, 7 May 2020 18:46:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 85FA820870 for ; Thu, 7 May 2020 18:46:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588877170; bh=XB1OEP9Z8ItrvrQBAEAdBZa9098nTFA8fhG2K04/eok=; h=Date:From:To:Cc:Subject:List-ID:From; b=r52AiIOpweTojDotooAaRXog7I9Wrk2jiZtFuiED0rDVdZAHO3G3LVef/+PsOaTwO Gb7XbV8mcFTUzP5og4GnR0+HFmEDPH7/03VxvST/pd3wrP8lov21Ws+Gba+StmaAEs mr6BkH/pig8dF0qb1dieHaysGaQx82bA962ZtKQo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728369AbgEGSqJ (ORCPT ); Thu, 7 May 2020 14:46:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:46796 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726320AbgEGSqJ (ORCPT ); Thu, 7 May 2020 14:46:09 -0400 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 528B920870; Thu, 7 May 2020 18:46:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588877168; bh=XB1OEP9Z8ItrvrQBAEAdBZa9098nTFA8fhG2K04/eok=; h=Date:From:To:Cc:Subject:From; b=mFnxf2DfhGCpWJ35fChEKFo7scKXEnSgRzc4fjgs44yqHHDKOMRpP2HiNK22is2hz vw8km9ZDLLFoo1otoT0mpBoIftb+H/YgqTkDwcgdy/I4Q4DoVruboodlywjZESNtlL 6SG/Ji33LPTMomQG3Vcn2uVOoC6l69Zv+U0d1FYY= Date: Thu, 7 May 2020 13:50:35 -0500 From: "Gustavo A. R. Silva" To: linux-kernel@vger.kernel.org Cc: Dan Williams Subject: [PATCH] dmaengine: Replace zero-length array with flexible-array Message-ID: <20200507185035.GA13907@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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 --- drivers/dma/milbeaut-hdmac.c | 2 +- drivers/dma/milbeaut-xdmac.c | 2 +- drivers/dma/moxart-dma.c | 2 +- drivers/dma/ti/edma.c | 2 +- drivers/dma/ti/k3-udma.c | 2 +- drivers/dma/timb_dma.c | 2 +- include/linux/dmaengine.h | 4 ++-- 7 files changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/dma/milbeaut-hdmac.c b/drivers/dma/milbeaut-hdmac.c index 8853d442430b..a8cfb59f6efe 100644 --- a/drivers/dma/milbeaut-hdmac.c +++ b/drivers/dma/milbeaut-hdmac.c @@ -77,7 +77,7 @@ struct milbeaut_hdmac_device { struct dma_device ddev; struct clk *clk; void __iomem *reg_base; - struct milbeaut_hdmac_chan channels[0]; + struct milbeaut_hdmac_chan channels[]; }; static struct milbeaut_hdmac_chan * diff --git a/drivers/dma/milbeaut-xdmac.c b/drivers/dma/milbeaut-xdmac.c index ab3d2f395378..85a597228fb0 100644 --- a/drivers/dma/milbeaut-xdmac.c +++ b/drivers/dma/milbeaut-xdmac.c @@ -74,7 +74,7 @@ struct milbeaut_xdmac_chan { struct milbeaut_xdmac_device { struct dma_device ddev; void __iomem *reg_base; - struct milbeaut_xdmac_chan channels[0]; + struct milbeaut_xdmac_chan channels[]; }; static struct milbeaut_xdmac_chan * diff --git a/drivers/dma/moxart-dma.c b/drivers/dma/moxart-dma.c index e04499c1f27f..2a77fa319d78 100644 --- a/drivers/dma/moxart-dma.c +++ b/drivers/dma/moxart-dma.c @@ -127,7 +127,7 @@ struct moxart_desc { unsigned int dma_cycles; struct virt_dma_desc vd; uint8_t es; - struct moxart_sg sg[0]; + struct moxart_sg sg[]; }; struct moxart_chan { diff --git a/drivers/dma/ti/edma.c b/drivers/dma/ti/edma.c index c4a5c170c1f9..35d81bd857f1 100644 --- a/drivers/dma/ti/edma.c +++ b/drivers/dma/ti/edma.c @@ -211,7 +211,7 @@ struct edma_desc { u32 residue; u32 residue_stat; - struct edma_pset pset[0]; + struct edma_pset pset[]; }; struct edma_cc; diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c index a9c0251adf1a..eb76d546931b 100644 --- a/drivers/dma/ti/k3-udma.c +++ b/drivers/dma/ti/k3-udma.c @@ -170,7 +170,7 @@ struct udma_desc { void *metadata; /* pointer to provided metadata buffer (EPIP, PSdata) */ unsigned int hwdesc_count; - struct udma_hwdesc hwdesc[0]; + struct udma_hwdesc hwdesc[]; }; enum udma_chan_state { diff --git a/drivers/dma/timb_dma.c b/drivers/dma/timb_dma.c index 39382694fdfc..68e48bf54d78 100644 --- a/drivers/dma/timb_dma.c +++ b/drivers/dma/timb_dma.c @@ -88,7 +88,7 @@ struct timb_dma { struct dma_device dma; void __iomem *membase; struct tasklet_struct tasklet; - struct timb_dma_chan channels[0]; + struct timb_dma_chan channels[]; }; static struct device *chan2dev(struct dma_chan *chan) diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index 21065c04c4ac..18b8813fafb2 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -153,7 +153,7 @@ struct dma_interleaved_template { bool dst_sgl; size_t numf; size_t frame_size; - struct data_chunk sgl[0]; + struct data_chunk sgl[]; }; /** @@ -537,7 +537,7 @@ struct dmaengine_unmap_data { struct device *dev; struct kref kref; size_t len; - dma_addr_t addr[0]; + dma_addr_t addr[]; }; struct dma_async_tx_descriptor;