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 5D8A0C352A4 for ; Thu, 13 Feb 2020 00:32:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 23C6B206B6 for ; Thu, 13 Feb 2020 00:32:50 +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="ePaXmgnJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729317AbgBMAct (ORCPT ); Wed, 12 Feb 2020 19:32:49 -0500 Received: from gateway34.websitewelcome.com ([192.185.148.196]:43739 "EHLO gateway34.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729152AbgBMAcs (ORCPT ); Wed, 12 Feb 2020 19:32:48 -0500 Received: from cm16.websitewelcome.com (cm16.websitewelcome.com [100.42.49.19]) by gateway34.websitewelcome.com (Postfix) with ESMTP id B497711EE3C for ; Wed, 12 Feb 2020 18:32:47 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 22Qxj0WsT8vkB22QxjySOs; Wed, 12 Feb 2020 18:32:47 -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=7jdsYH/671Xyu2fHGtlm4uwJ6l3oKA/XvfA+LmaM2x4=; b=ePaXmgnJLDY+t61/xA/9Qt1D03 11zu8sn9txEoLZclcQuRim21SH1lvcUr1ri0ZUTF4Hq0Shybls9pEmTb9ysZK/QeV/3aOatcs+vdk 1A6l/Tu9D+hDopqiAmDkjCqswZX5ulSng3nMGQDg2rVV0Ud5wYsHx224lrftG+q9RLEVMWNiG7wWX 6WHlBC0c19cFkAh8I+ozPjhUTeOqqmInvINESRKwxaS4KFKGJ8FUVd1PU/yn57ftVkb95mZlsp0EC d5TOSODQnXKd+vBp38GkaVfBYYd/HKQh4pODGOs+TU67vnRu0uLmcWsrUU5GR3CzOZAMQtferBLiW dQwn6T+g==; Received: from [200.68.141.42] (port=13439 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j22Qv-003dOK-QU; Wed, 12 Feb 2020 18:32:46 -0600 Date: Wed, 12 Feb 2020 18:32:43 -0600 From: "Gustavo A. R. Silva" To: Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] lightnvm: Replace zero-length array with flexible-array member Message-ID: <20200213003243.GA1253@embeddedor.com> 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: 200.68.141.42 X-Source-L: No X-Exim-ID: 1j22Qv-003dOK-QU X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.68.141.42]:13439 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 41 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/nvme/host/lightnvm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c index ec46693f6b64..3002bf972c6b 100644 --- a/drivers/nvme/host/lightnvm.c +++ b/drivers/nvme/host/lightnvm.c @@ -171,7 +171,7 @@ struct nvme_nvm_bb_tbl { __le32 tdresv; __le32 thresv; __le32 rsvd2[8]; - __u8 blk[0]; + __u8 blk[]; }; struct nvme_nvm_id20_addrf { -- 2.23.0