From patchwork Fri Mar 20 23:25:15 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: 11450591 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 9FCB71392 for ; Sat, 21 Mar 2020 00:12:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7FAE820757 for ; Sat, 21 Mar 2020 00:12:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=embeddedor.com header.i=@embeddedor.com header.b="UIXKck/T" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726867AbgCUAM4 (ORCPT ); Fri, 20 Mar 2020 20:12:56 -0400 Received: from gateway23.websitewelcome.com ([192.185.48.71]:32317 "EHLO gateway23.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726738AbgCUAM4 (ORCPT ); Fri, 20 Mar 2020 20:12:56 -0400 X-Greylist: delayed 1500 seconds by postgrey-1.27 at vger.kernel.org; Fri, 20 Mar 2020 20:12:55 EDT Received: from cm11.websitewelcome.com (cm11.websitewelcome.com [100.42.49.5]) by gateway23.websitewelcome.com (Postfix) with ESMTP id 331724849 for ; Fri, 20 Mar 2020 18:25:17 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id FR0vjhM5uSl8qFR0vjFlCf; Fri, 20 Mar 2020 18:25:17 -0500 X-Authority-Reason: nr=8 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=embeddedor.com; s=default; h=Content-Type:MIME-Version:Message-ID:Subject: Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=tp+We5q+QfjK/lqlPn+mWwyn+mIaqLI3anJr08yNMA0=; b=UIXKck/TEIYQC4tKigmWFuF3gj 8UjwPJlbXjYmCBWPR2iFwvbyigdrAAAeK4eqdWsmOBN/+/S51z8AFg7v0vgQHmy/CZUJlCmmVN0yg DeqqlJanPSpIN0RJrZp3s//jMxJk8dgaqD52kQma73EpsCr6fu7iqq6MhA3U1UxmaHi/pwbPB3+6x b/ldkgHliw2QdF4g2stz07QCXoRj6T6CeAvEiUDcaXFKvShi6ZNPbZLRZEP7x6mh8DrNdPcMrC84z oGAM/wdMhveg12QAbI9zOzXwIfifZEAmwBImCfqFP7Ljj84jI9DMW2C8e6sgXnLN/35zIhH0jwy2g 8woQYVlw==; Received: from cablelink-189-218-116-241.hosts.intercable.net ([189.218.116.241]:53616 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1jFR0t-001M8o-Nq; Fri, 20 Mar 2020 18:25:15 -0500 Date: Fri, 20 Mar 2020 18:25:15 -0500 From: "Gustavo A. R. Silva" To: Mark Brown Cc: linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] spi: spi-fsl-lpspi: Replace zero-length array with flexible-array member Message-ID: <20200320232515.GA24800@embeddedor.com> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 189.218.116.241 X-Source-L: No X-Exim-ID: 1jFR0t-001M8o-Nq X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: cablelink-189-218-116-241.hosts.intercable.net (embeddedor) [189.218.116.241]:53616 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 23 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@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] 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/spi/spi-fsl-lpspi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c index 298329b781d2..8b41b70f6f5c 100644 --- a/drivers/spi/spi-fsl-lpspi.c +++ b/drivers/spi/spi-fsl-lpspi.c @@ -123,7 +123,7 @@ struct fsl_lpspi_data { struct completion dma_rx_completion; struct completion dma_tx_completion; - int chipselect[0]; + int chipselect[]; }; static const struct of_device_id fsl_lpspi_dt_ids[] = {