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,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 4430EC4BA21 for ; Wed, 26 Feb 2020 21:13:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0644F2072D for ; Wed, 26 Feb 2020 21:13:16 +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="k3TcKpX0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727578AbgBZVNP (ORCPT ); Wed, 26 Feb 2020 16:13:15 -0500 Received: from gateway32.websitewelcome.com ([192.185.145.107]:45314 "EHLO gateway32.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727446AbgBZVNO (ORCPT ); Wed, 26 Feb 2020 16:13:14 -0500 Received: from cm10.websitewelcome.com (cm10.websitewelcome.com [100.42.49.4]) by gateway32.websitewelcome.com (Postfix) with ESMTP id C69D1275E2D for ; Wed, 26 Feb 2020 15:13:12 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 73zUj5BcdEfyq73zUjAxRi; Wed, 26 Feb 2020 15:13:12 -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=pfFaUhKSUuPWQQ+x7EmGEX71Qn52caOX7mUsVR1i56k=; b=k3TcKpX0wC75g73VOp+k8/+Zua ZmtyCoIJ5MoTfpVsIiL5SQ7A4S4rNmaaWpTAz6IqbxsNckv9U34qFm5Ix0Mi9lYp5hfiiVdMca8HL Cn1xFqYYFTXW72pwea3mMqvG80ROLNZ6g1Z/+UW/7CI/ikI5cjrwHt9t8Mpe3CHAepiRsgqlhsSs+ EW1xe2jdTe+uhX3tAFPXsvjikT9Sx1AQUI+4YKZjbzpIVaDBbWcFyV90Hx5OxpoGmT0WGauaxxE9B tX/A4yChTXLHNMePpE2iTJ8yipIMoupKVQOj2kLyWwvdOUYtrC73eaiC4bH4I05UlwbMXMWo0b76i 5n0RpuvA==; Received: from [200.39.29.129] (port=47544 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j73zS-000iA7-Nm; Wed, 26 Feb 2020 15:13:11 -0600 Date: Wed, 26 Feb 2020 15:16:02 -0600 From: "Gustavo A. R. Silva" To: James Smart , 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] nvme: Replace zero-length array with flexible-array member Message-ID: <20200226211602.GA18590@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: 200.39.29.129 X-Source-L: No X-Exim-ID: 1j73zS-000iA7-Nm X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.39.29.129]:47544 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 7 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/fc.c | 2 +- drivers/nvme/host/lightnvm.c | 2 +- include/linux/nvme.h | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c index 5a70ac395d53..6806a19707fb 100644 --- a/drivers/nvme/host/fc.c +++ b/drivers/nvme/host/fc.c @@ -96,7 +96,7 @@ struct nvme_fc_fcp_op { struct nvme_fcp_op_w_sgl { struct nvme_fc_fcp_op op; struct scatterlist sgl[NVME_INLINE_SG_CNT]; - uint8_t priv[0]; + uint8_t priv[]; }; struct nvme_fc_lport { 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 { diff --git a/include/linux/nvme.h b/include/linux/nvme.h index 3d5189f46cb1..6ee80a44ed4f 100644 --- a/include/linux/nvme.h +++ b/include/linux/nvme.h @@ -1177,7 +1177,7 @@ struct nvmf_disc_rsp_page_hdr { __le64 numrec; __le16 recfmt; __u8 resv14[1006]; - struct nvmf_disc_rsp_page_entry entries[0]; + struct nvmf_disc_rsp_page_entry entries[]; }; enum { -- 2.25.0