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=-13.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 6C660C35DEA for ; Tue, 25 Feb 2020 00:04:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3C8652072D for ; Tue, 25 Feb 2020 00:04:04 +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="xjMuCcfD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728402AbgBYAED (ORCPT ); Mon, 24 Feb 2020 19:04:03 -0500 Received: from gateway31.websitewelcome.com ([192.185.144.91]:17431 "EHLO gateway31.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728087AbgBYAEC (ORCPT ); Mon, 24 Feb 2020 19:04:02 -0500 Received: from cm14.websitewelcome.com (cm14.websitewelcome.com [100.42.49.7]) by gateway31.websitewelcome.com (Postfix) with ESMTP id E363024C2 for ; Mon, 24 Feb 2020 18:04:00 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 6NhgjOUWdXVkQ6Nhgjk6BM; Mon, 24 Feb 2020 18:04:00 -0600 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=q67V6wkz/vP58iDZWoblidrn9lVnubX/pXsOU2x0CG0=; b=xjMuCcfDK2IR1n0XjWR9lmhBDv 42BFoVIxSRVzKvH836FTURQOhCmJtGhYH/r5hHyXOuzILas2/BCeCkMw+nLzPnCgOH6f47dFqxCnP 4komlYZTAvGklfkzV7OPVXrB15ou3eGQGOtga65+8wR8O/OjiZjYJ5H0YLY2cqnIgNbI2qD4i2H1H Q9hGdi8lpTi8V8JTCfoxOyZLpsBKVExitmnr+x75I4PPz0M1QdbdjPkNYJLFvAOVN9JkSdlfwgkSV JiRSsZ3Sg3G0wLiDkDQswEP+zI3mufPkEE7QGomr13FvlkUHYKUENi2VWwAh/vYk6ZnY8uHE+r1B1 yqMpge3g==; Received: from [201.166.190.71] (port=54310 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j6Nhe-002MWf-3D; Mon, 24 Feb 2020 18:03:59 -0600 Date: Mon, 24 Feb 2020 18:06:47 -0600 From: "Gustavo A. R. Silva" To: Solarflare linux maintainers , Edward Cree , Martin Habets , "David S. Miller" Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] sfc: Replace zero-length array with flexible-array member Message-ID: <20200225000647.GA17795@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii 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: 201.166.190.71 X-Source-L: No X-Exim-ID: 1j6Nhe-002MWf-3D X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.166.190.71]:54310 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 16 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes 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] 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/net/ethernet/sfc/falcon/net_driver.h | 2 +- drivers/net/ethernet/sfc/net_driver.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/sfc/falcon/net_driver.h b/drivers/net/ethernet/sfc/falcon/net_driver.h index a49ea2e719b6..a529ff395ead 100644 --- a/drivers/net/ethernet/sfc/falcon/net_driver.h +++ b/drivers/net/ethernet/sfc/falcon/net_driver.h @@ -288,7 +288,7 @@ struct ef4_rx_buffer { struct ef4_rx_page_state { dma_addr_t dma_addr; - unsigned int __pad[0] ____cacheline_aligned; + unsigned int __pad[] ____cacheline_aligned; }; /** diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h index 9f9886f222c8..392bd5b7017e 100644 --- a/drivers/net/ethernet/sfc/net_driver.h +++ b/drivers/net/ethernet/sfc/net_driver.h @@ -336,7 +336,7 @@ struct efx_rx_buffer { struct efx_rx_page_state { dma_addr_t dma_addr; - unsigned int __pad[0] ____cacheline_aligned; + unsigned int __pad[] ____cacheline_aligned; }; /** -- 2.25.0